EXPRES 2017 - epget.bme.hu

1

Proc

eedi

ngs

9th International Symposium on Exploitation of Renewable Energy Sources and Efficiency

9th International Symposium on Exploitation of Renewable Energy Sources and Efficiency March 30 – April 01, 2017, Subotica, Serbia

EXPRES 2017

2

EXPRES 2017 ____________________________________________________________________

9th International Symposium on Exploitation of Renewable Energy Sources and

Efficiency

March 30- April 01, 2017

Subotica, Serbia

_______________________________________________________________________________

http://expres 2017 ISBN 978-86-919769-1-0

_______________________________________________________________________________

ISBN: 978-86-919769-1-0

2

EXPRES 2017

9th International Symposium on Exploitation of Renewable Energy

Sources and Efficiency

Subotica, Serbia March 30- April 01, 2017

_____________________________________________________________________________

Proceedings

CIP - Каталогизација у публикацији , Библиотека Матице српске, Нови Сад , 620.91(082) INTERNATIONAL Symposium on Exploitation of Renewable Energy Sources and Efficiency (8; 2017; Subotica) Proceedings [Elektronski izvori] / 8th International Symposium on Exploitation of Renewable Energy Sources and Efficiency, Subotica, March 30- April 01, 2017 ; [proceedings editor József Nyers]. - Subotica : Inženjersko-tehničko udruženje vojvođanskih Mađara, 2017. - 1 elektronski optički disk (CD-ROM) ; 12 cm Tekst štampan dvostubačno. - Tiraž 50. - Bibliografija uz svaki rad.

ISBN 978-86-919769-1-0

a) Енергија - Обновљиви извори – Зборници

COBISS.SR-ID 304712967

http://Expres 2017 ISBN 978-86-919769-1-0

3

EXPRES 2017 ____________________________________________________________________

9th International Symposium on Exploitation of Renewable Energy Sources and

Efficiency

March 30- April 01, 2017

Subotica, Serbia

_______________________________________________________________________________

http://expres 2017 ISBN 978-86-919769-1-0

_______________________________________________________________________________

ISBN: 978-86-919769-1-0

2

EXPRES 2017

9th International Symposium on Exploitation of Renewable Energy

Sources and Efficiency

Subotica, Serbia March 30- April 01, 2017

_____________________________________________________________________________

Proceedings

CIP - Каталогизација у публикацији , Библиотека Матице српске, Нови Сад , 620.91(082) INTERNATIONAL Symposium on Exploitation of Renewable Energy Sources and Efficiency (8; 2017; Subotica) Proceedings [Elektronski izvori] / 8th International Symposium on Exploitation of Renewable Energy Sources and Efficiency, Subotica, March 30- April 01, 2017 ; [proceedings editor József Nyers]. - Subotica : Inženjersko-tehničko udruženje vojvođanskih Mađara, 2017. - 1 elektronski optički disk (CD-ROM) ; 12 cm Tekst štampan dvostubačno. - Tiraž 50. - Bibliografija uz svaki rad.

ISBN 978-86-919769-1-0

a) Енергија - Обновљиви извори – Зборници

COBISS.SR-ID 304712967

http://Expres 2017 ISBN 978-86-919769-1-0

4

Numerical investigation on the energy consumption of ventilation systems ............................................................................6 Miklos KassaiBudapest University of Technology and EconomicsDepartment of Building Service Engineering and Process Engineering, Budapest, Hungary

Steady-state mathematical model with lumped parameters of the heat pump evaporator and ...........................................10simulation resultats

Jozsef Nyers, Zoltan Pek Obuda University Budapest, Becsi ut 96, 1034 Budapest, Hungary

Recycling of ashes from biomass-combustion power plant in swage sludgemanagement ..................................................................................................................................................................................15

M. Wójcika, F. Stachowiczb, A. MasłońcDepartment of Materials Forming and Processing,RzeszowUniversity of Technology, 35-959 Rzeszow, Powstańców Warszawy 8, PolandDepartment of Chemistry and Environmental Engineering,RzeszowUniversity of Technology, 35-959 Rzeszow, Powstańców Warszawy 6, Poland

Application of analogy of momentum and heat transfer at shell and tube condenser ..........................................................21 Orsolya Molnar, Zalan Zsigmond BME Budapest, Department of Building Service and Process Engineering, Budapest Hungary

Performance of heat pump’s condenser in heating process .....................................................................................................27J. Nyers, A. NyersObuda UniversityBudapest, HungaryeUniversity BME, Budapest, Hungarye

Increasing efficiency of fixture planning by automating some planning steps .......................................................................32M. Stampfer, A. RétfalviDepartment of Mechanical Engineering, , University of PécsH-7624 Pécs, Boszorkány u. 2, HungaryDepartment of Mechanical Engineering, Subotica Tech24000 Subotica, Marka Oreškovića 16, Serbia

Simulation result of a nuclear power plant cooling system using Matlab ..............................................................................37A, Szente, I. Farkas, P. OdryPaks Nuklear Power Plant, Paks, HungaryUniversity of Dunaújváros/Computer Engineering, Dunaújváros, HungaryUniversity of Dunaújváros/Computer Engineering, Dunaújváros, Hungary

Composite materials for wind power turbine blades ................................................................................................................44R. SZABÓ a, L. SZABÓ bIngtex Bt - Rejtő Sándor Foundation H-1056 Budapest Nyáry Pál u. 5, HungaryInstitute of Environmental Protection Engineering, Rejtő Sándor Faculty of Light Industry and Environmental ProtectionEngineering, Óbuda University, H-1034 Budapest, Doberdó u. 6, Hungary

Application of machine learning techniques in forecasting energy efficiency in buildings ...................................................51O. Grljević, L. Seres, S. BošnjakDepartment of Business Informatics and Quantitative Methods, University of Novi Sad, Faculty of Economics SuboticaSegedinski put 9-11, Serbia

Hydraulics of a thermal network for district heating system ..................................................................................................58J. Takács, Z. Straková, L .RáczSlovak University of Technology in Bratislava, Faculty of Civil Engineering,Department of Building Services, Radlinského 11, 810 05 Bratislava, Slovak Republic

Table of contents

5

Comparisons of experimental measurements of indoor climate parameters in a swimming pool during winter and summer operation period ...........................................................................................................................................................................63

Belo B. Füri, Róbert TurzaDepartment of Building Services, Faculty of Civil Engineering, Slovak University ofTechnology in Bratislava SK-810 05 Bratislava,, Radlinského 11, Slovakia

Optimal operating conditions for manure biogas plants in Serbia .........................................................................................69P. Kovač, S. Kirin, B. Savković, D. Jesic, D. GolubovicDepartment for Production Engineering, Faculty of Technical Sciences, University of Novi Sad21000 Novi Sad, Trg D Obradovica 6, SerbiaInovative Centre of Faculty of Mecchanical Engineering, University of Belgrade11000 Beograd Trg Kraljice Marije, SerbiaInternational Technology and Management Academy – MTMA,TrgD.Obradovića 7, 21000 Novi Sad, SerbiaFaculty of Mechanical Engineering, University of East Sarajevo71123East Sarajevo, Vuka Karadžića 30, Bosnia and Hercegovina

Temperature parameters changing of a space heating element after human action .............................................................75M. KurčováSlovak University of Technology in Bratislava, Faculty of Civil Engineering, Department of Building ServicesSK – 810 05 Bratislava, Radlinského 11, Slovakia

Modern cost accounting techniques for renewable energy and sustainable development ....................................................79Đ. Petkovič, I. MedvedUniversity of Novi Sad, Faculty of Economics, Subotica,Segedinski put 9-11, Serbia

Environmentally sustainable tourist behaviour in the function of sustainable development ...............................................83M. Jelača Strugar, A. Boljević, S. BoljevićDepartment of Management, Faculty of Economics in Subotica,University of Novi Sad, 24000 Subotica, Segedinski put 9-11, Srbija

Seasonal savings of transpired solar collectors .........................................................................................................................89B. Bokor, L. Kajtár, D. Eryener, H. AkhanBudapest University of Technology and Economics, Department of Building Service and Process EngineeringH-1111 Budapest, Műegyetemrkp. 3-9, Hungary

Circular business model – effects on company’s energy efficiency and renewable energy use .............................................95S. Tomić, D. Delić, A. StoiljkovićFaculty of Economics, Universityof Novi Sad24000 Subotica, Segedinski put 9-11, Serbia

The development of plastic rainwater tank by creating a construction which can be economically produced under domestic circumstances .............................................................................................................................................................................101

A. Nagy, B. Dudinszky , A. SzekrényesDepartment of Building Services and Process Engineering, Faculty of Mechanical Engineering,Budapest University of Technology and Economics, Budapest, Hungary

Geothermal heating of public buildings in downtown Zalaegerszeg ....................................................................................107J. Kontra, L. Garbai, J. SzanyiBudapest University of Technology and Economics, Műegyetemrakpart 3., 1111 BudapestUniversity of Szeged, Hungary

Thermal comfort tests using thermal manikin ........................................................................................................................ 111Balázs CakóPhD StudentBreuer Marcell Doctorial School, University of Pécs, Faculty of Engineering and Information TechnologyDepartment of Mechanical Engineering at University of Pécs, Faculty of Engineering and Information Technology2 Boszorkány u.,H-7626 Pécs Hungary

6

EXPRES 2017 ISBN 978-86-919769-1-0

Numerical investigation on the energy consumption of ventilation systems

M. KASSAI a

Department of Building Service Engineering and Process, Budapest University of

Technology and Economics

H-1111 Budapest, Muegyetem rkp. 3-9., Hungary aE-mail:[email protected]

The object of this research study was to investigate the heating energy consumption of ventilation systems with five different

heat-and energy recovery units in three different weather European climates. Using the ambient temperature and enthalpy

duration curves, detailed mathematical expressions are presented to determine the energy consumption of ventilation systems

during the heating period. The three different climate cities are: Palermo (as Mediterranean zone), Krakow (as temperate zone)

and to Helsinki (as cold climate region). The investigated heat recoveries that are suitable only for heat transfer are the fixed-plate

heat exchanger, the run around coil and the heat-pipe technology. Energy exchangers allow both heat-and moisture transfer with

higher moisture transfer effectiveness by a sorption rotor and with lower without sorption coating. The effectiveness values of

heat and energy exchangers were selected based on VDI 2071 standard.

Keywords: ventilation system, energy consumption, heat recovery, numerical investigation

1. Introducn

There is more and more attention for energy

consumption reduction, achieving sustainable

development that by primary energy source (coal,

oil natural gas) saving and utilization of renewable

energy sources [1, 2]. Spread of new techniques in

building construction, low-energy and passive

houses can be seen in recent years [3]. Herewith

the number of ventilation systems used in

buildings has been also increased. The

requirements for air tightness of passive house are

much higher than in case of a traditional house [4].

Due to the increasing indoor air quality

(IAQ) standard, the ventilation loads represent

about 20–50% part of the total heating demand for

new and retrofitted buildings [5,6,7,8,9,10,11],

depending on the building’s insulation,

compactness, air change rate, indoor heat sources,

indoor set points and outdoor climate. Therefore,

there is a need for residential buildings and their

systems to provide a comfortable and acceptable

indoor environment. The usage of mechanical

ventilation system equipped with an air-to-air

recovery heat-and energy exchanger is a solution

to ensure a high global energy performance of the

building and reach the requirements in terms of

IAQ [12]. In these systems, indoor air extracted

from the building is used to pre-heat (in winter) or

pre-cool (in summer) the fresh air flow rate

coming from the outdoor environment. While such

exchangers [13,14] have been on the market for

many years, only a few modeling works are

presented in technical and scientific literature.

Only the parameters having an impact on the

energy performance of heat recovery ventilation

have been investigated deeper in the last years.

Mardiana and Riffat [15] list physical

characteristics ofthe main components: heat

exchanger and fans that influence the efficiency of heat

or energy recovery. Roulet et al. [16] discuss the effect of

leakages and shortcuts on heat recovery unit and show

that the conventional methods to determine the heat

recovery efficiency are not sufficient to outline the global

performance of ventilation systems; and propose a

method based on the specific net energy savings to

characterize the energy performance. Manz et al. [17]

investigate the same effect on a single room ventilation

system and define a heat recovery efficiency based on

heating load reduction. Based on the above mentioned

facts it is easy to see that the calculation of energy

consumption and energy saved of ventilation systems is a

complex design problem requiring many pieces of

information.

The object of this research study was to investigate

the heating energy saved of five different constructed air-

to-air heat-and energy exchangers in three in different

weather European. Using the ambient temperature and

enthalpy duration curves, detailed mathematical

expressions were worked out to determine the heating

energy consumption of the ventilation systems and the

heating energy saved by air-to-air heat-and energy

recovery units during. The three different climate cities

are: Palermo (as Mediterranean zone), Krakow (as

temperate zone) and to Helsinki (as cold climate region).

The investigated heat recoveries that are suitable only for

heat transfer are the fixed-plate heat exchanger, the run

around coil and the heat-pipe technology. Energy

exchangers, that were also considered, allow both heat-

and moisture transfer with higher moisture transfer

effectiveness by a sorption rotor and with lower without

sorption coating. The results by the developed method

show that before the selection of the proper heat-and

energy recovery unit into an air handling unit, their

energy saved has to be investigatedconsidering also the

given climate region.

2. Method

The comparative energetic study was carried out on

the types of heat exchangers most frequently used in

practice. From among heat exchangers only capable

of heat transfer, the energy saving ability of cross-

flow plate heat exchangers, run around coil and heat

pipe heat exchangers was numerically investigated

and from among those capable of heat-, and moisture

transfer, the energy saving ability of rotary heat

exchangers with sorption (sorption wheel) and non-

sorption coating was calculated. The heat and

moisture effectiveness values typical of heat

exchangers were selected from the value range

determined by the VDI 2071 standard [18]. As heat

transfer effectiveness 0.6 for cross flow plate heat

recovery, 0.4 for run around coil heat recovery, 0.3

for heat pipe heat exchanger, 0.8 for rotary energy

recovery unit with sorption coating and also for

rotary energy recovery unit with non-sorption coating

were selected. As moisture transfer effectiveness the

value of 0.65 for rotary energy recovery unit with

sorption coating and 0.15 for rotary energy recovery

unit with non-sorption coating were selected.

During the investigation a steady air volume flow

rate was assumed to 1000 m3/h, and the air density

was assumed to constant 1,2 kg/m3. For heat recovery

systems, that are suitable only for heat transfer,

temperature controlling was considered during

calculations, which means the heat exchanger works

only when outer air temperature is higher than the

exhaust temperature delivered from the conditioned

space. In case of energy recovery systems that are

suitable for both heat-and moisture transfer, enthalpy

controlling was considered, thus energy exchanger

operates until enthalpy of ambient air decreases to the

exhaust air enthalpy value. During the research a

comparative energetic investigation was performed

for the heat-and energy recovery systems most

commonly applied in HVAC practice. Among heat

recovery technologies that transfer only heat energy,

cross flow plate heat recovery, run around coil heat

recovery and heat pipe heat exchangers were

investigated. Among energy recovery systems that

are suitable for both heat and moisture transfer rotary

energy recovery unit with sorption and non-sorption

coating were investigated. The object was to predict

the energy savings in the different cases for heating

season.

In this section of the paper the determining the

energy consumption of ventilation system can be seen

operated by energy recovery unit with sorption

coating in Palermo in heating season. Figure 1 shows

the air handling process of the system on

psychometric chart in sizing winter state conditions

when the ambient air (KM) passes the energy

recovery (HV) then auxiliary re-heater (F) and steam

humidifier (SZ).

Fig. 1.Air handling process with sorption wheel in heating

season

Figure 2 shows the areas proportional with the energy

consumptions on enthalpy duration curve with sorption

wheel operation in heating season in Palermo.

Fig. 2. The areas proportional with the energy consumptions on

the enthalpy duration curve in heating season

To determine the energy consumption of the system

ambient air enthalpy duration curve was used. Figure 2

shows the areas that are proportional with the energy

consumption of the cooling („C”) and the re-heater

(„RH”).

The energy consumption of necessary auxiliary re-

heater:

)(FVQF

KM

h

h

UF ∫⋅⋅= dhhK&ρ

[MJ/year] (1)

where ρ (kg m-3

) represented density of air, V& (m3 h

-1)

was the air volume flow rate, KMh (kJ kg

-1) was the

enthalpy of ambient air, Fh (kJ kg

-1)was the enthalpy

after the re-heater in air handling process and )(F hK [-]

was the ambient enthalpy duration curve.

The energy consumption of the auxiliary steam

humidifier:

τ⋅⋅= GGG hmQ & [ MJ/year] (2)

whereGm& (kg h

-1) represented the steam volume flow

rate, Gh (kJ kg

-1) was the enthalpy of steam and τ (h)

was the operation time of steam humidifier.

3. Results

The following figures (Figures 3-4) show energy

consumptions of ventilation systems operating with

different types of heat- and energy exchangers in

heating season, and the rate of energy saving (Figures

5-6) achievable by the heat and energy exchangers in

MJ measurement units.

7

EXPRES 2017 ISBN 978-86-919769-1-0

Numerical investigation on the energy consumption of ventilation systems

M. KASSAI a

Department of Building Service Engineering and Process, Budapest University of

Technology and Economics

H-1111 Budapest, Muegyetem rkp. 3-9., Hungary aE-mail:[email protected]

The object of this research study was to investigate the heating energy consumption of ventilation systems with five different

heat-and energy recovery units in three different weather European climates. Using the ambient temperature and enthalpy

duration curves, detailed mathematical expressions are presented to determine the energy consumption of ventilation systems

during the heating period. The three different climate cities are: Palermo (as Mediterranean zone), Krakow (as temperate zone)

and to Helsinki (as cold climate region). The investigated heat recoveries that are suitable only for heat transfer are the fixed-plate

heat exchanger, the run around coil and the heat-pipe technology. Energy exchangers allow both heat-and moisture transfer with

higher moisture transfer effectiveness by a sorption rotor and with lower without sorption coating. The effectiveness values of

heat and energy exchangers were selected based on VDI 2071 standard.

Keywords: ventilation system, energy consumption, heat recovery, numerical investigation

1. Introducn

There is more and more attention for energy

consumption reduction, achieving sustainable

development that by primary energy source (coal,

oil natural gas) saving and utilization of renewable

energy sources [1, 2]. Spread of new techniques in

building construction, low-energy and passive

houses can be seen in recent years [3]. Herewith

the number of ventilation systems used in

buildings has been also increased. The

requirements for air tightness of passive house are

much higher than in case of a traditional house [4].

Due to the increasing indoor air quality

(IAQ) standard, the ventilation loads represent

about 20–50% part of the total heating demand for

new and retrofitted buildings [5,6,7,8,9,10,11],

depending on the building’s insulation,

compactness, air change rate, indoor heat sources,

indoor set points and outdoor climate. Therefore,

there is a need for residential buildings and their

systems to provide a comfortable and acceptable

indoor environment. The usage of mechanical

ventilation system equipped with an air-to-air

recovery heat-and energy exchanger is a solution

to ensure a high global energy performance of the

building and reach the requirements in terms of

IAQ [12]. In these systems, indoor air extracted

from the building is used to pre-heat (in winter) or

pre-cool (in summer) the fresh air flow rate

coming from the outdoor environment. While such

exchangers [13,14] have been on the market for

many years, only a few modeling works are

presented in technical and scientific literature.

Only the parameters having an impact on the

energy performance of heat recovery ventilation

have been investigated deeper in the last years.

Mardiana and Riffat [15] list physical

characteristics ofthe main components: heat

exchanger and fans that influence the efficiency of heat

or energy recovery. Roulet et al. [16] discuss the effect of

leakages and shortcuts on heat recovery unit and show

that the conventional methods to determine the heat

recovery efficiency are not sufficient to outline the global

performance of ventilation systems; and propose a

method based on the specific net energy savings to

characterize the energy performance. Manz et al. [17]

investigate the same effect on a single room ventilation

system and define a heat recovery efficiency based on

heating load reduction. Based on the above mentioned

facts it is easy to see that the calculation of energy

consumption and energy saved of ventilation systems is a

complex design problem requiring many pieces of

information.

The object of this research study was to investigate

the heating energy saved of five different constructed air-

to-air heat-and energy exchangers in three in different

weather European. Using the ambient temperature and

enthalpy duration curves, detailed mathematical

expressions were worked out to determine the heating

energy consumption of the ventilation systems and the

heating energy saved by air-to-air heat-and energy

recovery units during. The three different climate cities

are: Palermo (as Mediterranean zone), Krakow (as

temperate zone) and to Helsinki (as cold climate region).

The investigated heat recoveries that are suitable only for

heat transfer are the fixed-plate heat exchanger, the run

around coil and the heat-pipe technology. Energy

exchangers, that were also considered, allow both heat-

and moisture transfer with higher moisture transfer

effectiveness by a sorption rotor and with lower without

sorption coating. The results by the developed method

show that before the selection of the proper heat-and

energy recovery unit into an air handling unit, their

energy saved has to be investigatedconsidering also the

given climate region.

2. Method

The comparative energetic study was carried out on

the types of heat exchangers most frequently used in

practice. From among heat exchangers only capable

of heat transfer, the energy saving ability of cross-

flow plate heat exchangers, run around coil and heat

pipe heat exchangers was numerically investigated

and from among those capable of heat-, and moisture

transfer, the energy saving ability of rotary heat

exchangers with sorption (sorption wheel) and non-

sorption coating was calculated. The heat and

moisture effectiveness values typical of heat

exchangers were selected from the value range

determined by the VDI 2071 standard [18]. As heat

transfer effectiveness 0.6 for cross flow plate heat

recovery, 0.4 for run around coil heat recovery, 0.3

for heat pipe heat exchanger, 0.8 for rotary energy

recovery unit with sorption coating and also for

rotary energy recovery unit with non-sorption coating

were selected. As moisture transfer effectiveness the

value of 0.65 for rotary energy recovery unit with

sorption coating and 0.15 for rotary energy recovery

unit with non-sorption coating were selected.

During the investigation a steady air volume flow

rate was assumed to 1000 m3/h, and the air density

was assumed to constant 1,2 kg/m3. For heat recovery

systems, that are suitable only for heat transfer,

temperature controlling was considered during

calculations, which means the heat exchanger works

only when outer air temperature is higher than the

exhaust temperature delivered from the conditioned

space. In case of energy recovery systems that are

suitable for both heat-and moisture transfer, enthalpy

controlling was considered, thus energy exchanger

operates until enthalpy of ambient air decreases to the

exhaust air enthalpy value. During the research a

comparative energetic investigation was performed

for the heat-and energy recovery systems most

commonly applied in HVAC practice. Among heat

recovery technologies that transfer only heat energy,

cross flow plate heat recovery, run around coil heat

recovery and heat pipe heat exchangers were

investigated. Among energy recovery systems that

are suitable for both heat and moisture transfer rotary

energy recovery unit with sorption and non-sorption

coating were investigated. The object was to predict

the energy savings in the different cases for heating

season.

In this section of the paper the determining the

energy consumption of ventilation system can be seen

operated by energy recovery unit with sorption

coating in Palermo in heating season. Figure 1 shows

the air handling process of the system on

psychometric chart in sizing winter state conditions

when the ambient air (KM) passes the energy

recovery (HV) then auxiliary re-heater (F) and steam

humidifier (SZ).

Fig. 1.Air handling process with sorption wheel in heating

season

Figure 2 shows the areas proportional with the energy

consumptions on enthalpy duration curve with sorption

wheel operation in heating season in Palermo.

Fig. 2. The areas proportional with the energy consumptions on

the enthalpy duration curve in heating season

To determine the energy consumption of the system

ambient air enthalpy duration curve was used. Figure 2

shows the areas that are proportional with the energy

consumption of the cooling („C”) and the re-heater

(„RH”).

The energy consumption of necessary auxiliary re-

heater:

)(FVQF

KM

h

h

UF ∫⋅⋅= dhhK&ρ

[MJ/year] (1)

where ρ (kg m-3

) represented density of air, V& (m3 h

-1)

was the air volume flow rate, KMh (kJ kg

-1) was the

enthalpy of ambient air, Fh (kJ kg

-1)was the enthalpy

after the re-heater in air handling process and )(F hK [-]

was the ambient enthalpy duration curve.

The energy consumption of the auxiliary steam

humidifier:

τ⋅⋅= GGG hmQ & [ MJ/year] (2)

whereGm& (kg h

-1) represented the steam volume flow

rate, Gh (kJ kg

-1) was the enthalpy of steam and τ (h)

was the operation time of steam humidifier.

3. Results

The following figures (Figures 3-4) show energy

consumptions of ventilation systems operating with

different types of heat- and energy exchangers in

heating season, and the rate of energy saving (Figures

5-6) achievable by the heat and energy exchangers in

MJ measurement units.

8

NUMERICAL INVESTIGATION ON THE ENERGY CONSUMPTION OF VENTILATION

SYSTEMS

3

Fig. 3. Heating energy consumption of the ventilation system

with different heat recovery technologies


with different energy recovery technologies

Fig. 5. Heating energy saved by heat recovery technologies

Fig. 6. Heating energy saved by energy recovery technologies

In the course of evaluation of results of the

research, the amount of heating energy saved (Figures

7-8) were also analyzed by the heat/energy exchanger

used in the ventilation system operated in the cities

with the given climate also in contrast with operation

without the heat and energy exchangers, the energy

consumption ratio of which is expressed in percentage

value [%].


correlated without heat recovering case


correlated without energy recovering case

4. Conclusion

Received results show, that during the heating season,

the highest energy saving can be achieved with the

application of energy exchangers with a sorption

coating, capable of moisture transfer, with 156.700

MJ/year in Helsinki, 117.300 MJ/year in Krakow, and

around 44.600 MJ/year in Palermo. Naturally, the rate

of energy consumption also differs between the cities,

therefore besides the received values; it is practical to

take into consideration the amount of savings

expressed in percentage values as well. These values

show, that the highest percentage of energy savings

can be achieved in Helsinki (71.74 % as compared to

ventilation appliances without a heat exchanger), then

in Krakow (71.73 %), and finally in Palermo (66.86

%).

References

[1] Laverge J., &Janssens, A. (2012). Heat recovery ventilation operation traded off against natural and simple exhaust ventilation in Europe by primary energy factor, carbon dioxide emission, household consumer price and exergy. Energy and Buildings, 50, 315–323.

[2] Calay, R. K., & Wang, W. (2011, June). A study of an energy efficient building ventilation system. Paper presented at the 12th International conference on air distribution in rooms, RoomVent 2011, Trondheim.

[3] O’Connor, D., Calautit, J. K. & Hughes, B. R. (2014). A study of passive ventilation integrated with heat recovery”. Journal of Energy and Buildings, 82, 799–811.

[4] M. Fehrm, W. Reiners, M. Ungemach, “Exhaust air heat recovery in buildings”, International Journal of Refrigeration 2002;25:439–449.

[5] M. Orme, “Estimates of the energy impact of ventilation and financial expenditures”. Energy and Buildings 2001;33:199–205.

NUMERICAL INVESTIGATION ON THE ENERGY CONSUMPTION OF VENTILATION SYSTEMS

4

[6] R.M. Lazzarin, A. Gasparella, “Technical and economical analysis of heat recovery in building ventilation systems”. Applied Thermal Engineering 1998;18:47–67.

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[10] R.K. Calay, B.A. Borresen, A.E. Holdø, “Selective ventilation in large enclosures”. Energy and Buildings, vol. 2000;32:281–289.

[11] R.K. Calay, WC. Wang, “A study of an energy efficient building ventilation system”, RoomVent 2011 - 12th International conference on air distribution in rooms, Trondheim, Juny 19-22, pp. 1-8. 2011.

[12] C. Cristiana, N. Ilinca, B. Florin, M. Amina, D. Angel, “Thermal comfort models for indoor spaces and vehicles - Current capabilities and future perspectives”. Renewable and Sustainable Energy Reviews. 2015;44:304–318.

[13] T. Poos, V. Szabo, “Equations of volumetric heat transfer coefficients and mathematical models at rotary drum dryers”, Eurodrying'2015: 5th European Drying Conference. Budapest, October 21-23. 2015:322-328.

[14] T. Poos, E. Varju, “Determination of evaporation rate at free water surface. 8th International Symposium on Exploitation of Renewable Energy Resources”, Subotica, Serbia, 2016.03.31-04.02., 66-71.

[15] A. Mardiana, S.B. Riffat, “Review on physical and performance parameters ofheat recovery systems for building applications”. Renewable Sustainable Energy Rev. 2013;28:174–190.

[16] C.A. Roulet, F.D. Heidt, F. Foradini, M.C. Pibiri, “Real heat recovery with air handling units”, Energy and Buildings 2001;33:495–502.

[17] Manz, H., Huber, H. &Helfenfinger, D. (2001). Impact of air leakages and short circuits in ventilation units with heat recovery on ventilation efficiency and energy requirements for heating. Journal of Energy and Buildings, 33, 133–139.

[18] VereinDeutscherIngenieure. (1997). Heat recovery in heating, ventilation and air conditioning plants, VDI 2071-Richtlinien, Düsseldorf

9

NUMERICAL INVESTIGATION ON THE ENERGY CONSUMPTION OF VENTILATION

SYSTEMS

3


with different heat recovery technologies


with different energy recovery technologies



In the course of evaluation of results of the

research, the amount of heating energy saved (Figures

7-8) were also analyzed by the heat/energy exchanger

used in the ventilation system operated in the cities

with the given climate also in contrast with operation

without the heat and energy exchangers, the energy

consumption ratio of which is expressed in percentage

value [%].


correlated without heat recovering case


correlated without energy recovering case

4. Conclusion

Received results show, that during the heating season,

the highest energy saving can be achieved with the

application of energy exchangers with a sorption

coating, capable of moisture transfer, with 156.700

MJ/year in Helsinki, 117.300 MJ/year in Krakow, and

around 44.600 MJ/year in Palermo. Naturally, the rate

of energy consumption also differs between the cities,

therefore besides the received values; it is practical to

take into consideration the amount of savings

expressed in percentage values as well. These values

show, that the highest percentage of energy savings

can be achieved in Helsinki (71.74 % as compared to

ventilation appliances without a heat exchanger), then

in Krakow (71.73 %), and finally in Palermo (66.86

%).

References

[1] Laverge J., &Janssens, A. (2012). Heat recovery ventilation operation traded off against natural and simple exhaust ventilation in Europe by primary energy factor, carbon dioxide emission, household consumer price and exergy. Energy and Buildings, 50, 315–323.

[2] Calay, R. K., & Wang, W. (2011, June). A study of an energy efficient building ventilation system. Paper presented at the 12th International conference on air distribution in rooms, RoomVent 2011, Trondheim.

[3] O’Connor, D., Calautit, J. K. & Hughes, B. R. (2014). A study of passive ventilation integrated with heat recovery”. Journal of Energy and Buildings, 82, 799–811.

[4] M. Fehrm, W. Reiners, M. Ungemach, “Exhaust air heat recovery in buildings”, International Journal of Refrigeration 2002;25:439–449.

[5] M. Orme, “Estimates of the energy impact of ventilation and financial expenditures”. Energy and Buildings 2001;33:199–205.

NUMERICAL INVESTIGATION ON THE ENERGY CONSUMPTION OF VENTILATION SYSTEMS

4

[6] R.M. Lazzarin, A. Gasparella, “Technical and economical analysis of heat recovery in building ventilation systems”. Applied Thermal Engineering 1998;18:47–67.

[7] A. Dodoo, L. Gustavsson, R. Sathre, “Primary energy implications of ventilation heat recovery in residential buildings”, Energy and Buildings 2011;43:1566–1572.

[8] J. Nyers, L. Kajtar .S. Tomic, A. Nyers, “Investment-savings method for energy-economic optimization of external wall thermal insulation thickness.” Energy and Buildings, 2015;86:268-274.

[9] L. Kajtar, J. Nyers, J. Szabo, “Dynamic thermal dimensioning of underground spaces” Energy 2015;87:361–368.

[10] R.K. Calay, B.A. Borresen, A.E. Holdø, “Selective ventilation in large enclosures”. Energy and Buildings, vol. 2000;32:281–289.

[11] R.K. Calay, WC. Wang, “A study of an energy efficient building ventilation system”, RoomVent 2011 - 12th International conference on air distribution in rooms, Trondheim, Juny 19-22, pp. 1-8. 2011.

[12] C. Cristiana, N. Ilinca, B. Florin, M. Amina, D. Angel, “Thermal comfort models for indoor spaces and vehicles - Current capabilities and future perspectives”. Renewable and Sustainable Energy Reviews. 2015;44:304–318.

[13] T. Poos, V. Szabo, “Equations of volumetric heat transfer coefficients and mathematical models at rotary drum dryers”, Eurodrying'2015: 5th European Drying Conference. Budapest, October 21-23. 2015:322-328.

[14] T. Poos, E. Varju, “Determination of evaporation rate at free water surface. 8th International Symposium on Exploitation of Renewable Energy Resources”, Subotica, Serbia, 2016.03.31-04.02., 66-71.

[15] A. Mardiana, S.B. Riffat, “Review on physical and performance parameters ofheat recovery systems for building applications”. Renewable Sustainable Energy Rev. 2013;28:174–190.

[16] C.A. Roulet, F.D. Heidt, F. Foradini, M.C. Pibiri, “Real heat recovery with air handling units”, Energy and Buildings 2001;33:495–502.

[17] Manz, H., Huber, H. &Helfenfinger, D. (2001). Impact of air leakages and short circuits in ventilation units with heat recovery on ventilation efficiency and energy requirements for heating. Journal of Energy and Buildings, 33, 133–139.

[18] VereinDeutscherIngenieure. (1997). Heat recovery in heating, ventilation and air conditioning plants, VDI 2071-Richtlinien, Düsseldorf

10

EXPRES 2017 ISBN 978-86-919769-1-0

Simulation resultats of the heat pump evaporator by means

the steady-state lumped parameter mathematical model

J. NYERS

A, Z. PEK

b

a,b Doctoral School of Applied Informatics and Applied Mathematics, Obuda University,

1034 Budapest, Bécsi út 96/B, Hungary aDoctoral School of Mechanical Engineering, Szent István University,

2100 Gödöllő, Páter Károly utca 1, Hungary aE-mail:[email protected] bE-mail:[email protected]

The primary objective of the paper is to present the heat pump evaporator's steady-state lumped parameter mathematical model and

apply the model to investigate the thermal behavior of the evaporator. In fact, the ultimate objective is, and the model has been

designed in this sense, the model has to be part of the mathematical model of heat pump heating system. The evaporator's model is

composed of the superheated and evaporation sections. In the model the basic equations are the energy conservation balance

equations, the auxiliary equations are the logarithmic or arithmetic temperature differences, heat transfer coefficients and the overall

heat transfer coefficients. The mentioned equations are algebraic, coupled, nonlinear and with many variables. The solution of the

equation system can be only obtained using iterative numerical procedure. The numerically obtained results are arranged in the

vector or matrix format and presented in 2D graphics. In the case study, we investigated the heat flow behavior in the evaporator as a

function of the well water- and the refrigerant mass flow rate.

Keywords: heat pump evaporator, steady-state mathematical model, lumped parameters

1. Introduction

The lumped parameter mathematical model is only

suitable for the analytical energy optimization of the

heat pump heating system. This statement applies to all

components of the heat pump, including both heat

exchangers, evaporator and condenser as well. The

model is solvable numerically [1].

In this case tested evaporator is chevron plate heat

exchanger. The plates in the exchanger are thin, their

thickness is O.3-O.5 mm and are made of the

Prochrom plates. In the plates the chevrons are of the

60° pressed and in the chevron's perpendicular cross

section the plates have the sinuous shape.The prochrom

plates are brazed with copper [2].

In the plate evaporator on the one side is the

refrigerant while on the other side the well water in the

co-current or countercurrent manner flows. Between

the flowing mediums the heat transfers by convection

and conduction through the plate wall. In deed, the

heat from the warmer well water transfers to the

refrigerant.

In the heat exchanger two processes take place:

evaporation and superheating. From the aspect of the

heat transfer the evaporation is dominant because

almost 95-96% of the heat is transferred in this manner.

The superheating is necessary evil but justifiable

because of the safety operation of the compressor.

The evaporation in opposite of the condensation is

not a self regulated process, but requires

regulation.The process is regulated by thermal

expansion valve. The valve regulates the amount of the

refrigerant mass flow and thereby the evaporating

pressure and temperature as well. The aim of the

regulation is, the evaporation temperature should be at

a low level and the temperature increasing of the

superheated vapour which is flowing out of the

evaporator keeps the referent set value. In practice, the

optimum value of the superheated vapour's

temperature increasing is 4°C [3].

The primary objective of the paper is, to present the

steady-state lumped parameter mathematical model of

the heat pump evaporator and applying the model we

investigated the evaporator's thermal behavior. The

ultimate objective is that the model has to be part of the

mathematical model of heat pump heating system.

Since the ultimate objective is optimization, so the

model is steady-state, namely the model of the heating

system is designed for steady state operation mode.

The analytical optimization requires a lumped

parameter model.

The evaporator's mathematical model consists of

two parts of the superheating and the evaporation

section. The basic equations in the model are the

energy conservation balance equations, the auxiliary

equations are the logarithmic or arithmetic temperature

differences, heat transfer coefficients and the overall

heat transfer coefficients. The listed equations are

algebraic, coupled, non-linear and with many

variables. The solution of the equation system is only

possible using iterative numerical procedure. The

numerically obtained results are arranged in the vector

or matrix format and presented in 2D graphics.

EXPRES 2017 ISBN 978-86-919769-1-0

In the case study, we investigated the heat flow

behavior in the evaporator and the latent heat both as a

function of the well water- and the refrigerant mass

flow rate.

2. The physical model of evaporator

Fig. 1. Shema of heat pump evaporator

3. The basic mathematical model of the

evaporator

Introduction

The steady-state lumped parameter mathematical

model is created on the basis of the energy conservation

and comprises the evaporation and superheat sections.

Both section's thermal behavior describe the three heat

flow balance equations. The equations include

dependent and independent variables.

The independent selected variables of the

evaporator

• Inlet temperature of the refrigerant liquid-vapour

mixture

• Inlet temperature of the well water

• Mass flow rate of the well water

• Mass flow rate of the refrigerant liquid-vapour mixture

• Heat transfer surface area of the evaporator

• Vapour quality

The dependent variables to elimination

The evaporation section

1. The saturated vapour temperature of the evaporating

section

2. The well water temperature at the end of the

evaporation section

3. Heat flow in the evaporation section

4. Heat transfer surface area of the evaporation section

The vapour superheating section

5. Superheated vapour temperature at the end of the

superheating section

6. Well water outlet temperature at the end of the


7. Heat flow in the vapour superheating section

8. Heat transfer surface area of the vapour superheating

section

In addition

• saturated vapour inlet temperature at the superheating

section is equal to the evaporation temperature

• well water inlet temperature at the superheating

section is equal to the well water outlet temperature at

the end of the evaporation section.

The governing equations of the evaporation section

The heat flow from well water to the evaporating

refrigerant

= ∙ ∙ ∆ (1)

The heat flow between the two fluids through the

wall of the heat exchanger

= ∙ ∙ ∆, (2)

The heat flux absorbed by the refrigerant fluid +

vapour phase for evaporation

= ∙ ∆, ∙ (1 − ) (3)

The governing equations of superheating section.

The heat flux from the well water to the refrigerant

vapour

= ∙ ∙ ∆ (4)



= ∙ ∙ ∆, (5)

The heat flux absorbed by the refrigerant vapour

for superheating

= , ∙ ∙ ∆ (6)

The superheatied temperature different

∆ ≅ 4℃ − variable constant (7)

All heat flow tranfered in the evaporator. = + (8)

The heat flow transfered by the well water to the

refrigerant

= ∙ ∙ (, − , )

The all heat flux absorbed by the refrigerant

= ∙ ∆, + , ∙ ∙ ∆= ∙ ∆, + ∆

(9)

All active surface area of the evaporator. Evaporation

and the superheating section surface.

= + (10)

11

EXPRES 2017 ISBN 978-86-919769-1-0

Simulation resultats of the heat pump evaporator by means

the steady-state lumped parameter mathematical model

J. NYERS

A, Z. PEK

b

a,b Doctoral School of Applied Informatics and Applied Mathematics, Obuda University,

1034 Budapest, Bécsi út 96/B, Hungary aDoctoral School of Mechanical Engineering, Szent István University,

2100 Gödöllő, Páter Károly utca 1, Hungary aE-mail:[email protected] bE-mail:[email protected]

The primary objective of the paper is to present the heat pump evaporator's steady-state lumped parameter mathematical model and

apply the model to investigate the thermal behavior of the evaporator. In fact, the ultimate objective is, and the model has been

designed in this sense, the model has to be part of the mathematical model of heat pump heating system. The evaporator's model is

composed of the superheated and evaporation sections. In the model the basic equations are the energy conservation balance

equations, the auxiliary equations are the logarithmic or arithmetic temperature differences, heat transfer coefficients and the overall

heat transfer coefficients. The mentioned equations are algebraic, coupled, nonlinear and with many variables. The solution of the

equation system can be only obtained using iterative numerical procedure. The numerically obtained results are arranged in the

vector or matrix format and presented in 2D graphics. In the case study, we investigated the heat flow behavior in the evaporator as a

function of the well water- and the refrigerant mass flow rate.

Keywords: heat pump evaporator, steady-state mathematical model, lumped parameters

1. Introduction

The lumped parameter mathematical model is only

suitable for the analytical energy optimization of the

heat pump heating system. This statement applies to all

components of the heat pump, including both heat

exchangers, evaporator and condenser as well. The

model is solvable numerically [1].

In this case tested evaporator is chevron plate heat

exchanger. The plates in the exchanger are thin, their

thickness is O.3-O.5 mm and are made of the

Prochrom plates. In the plates the chevrons are of the

60° pressed and in the chevron's perpendicular cross

section the plates have the sinuous shape.The prochrom

plates are brazed with copper [2].

In the plate evaporator on the one side is the

refrigerant while on the other side the well water in the

co-current or countercurrent manner flows. Between

the flowing mediums the heat transfers by convection

and conduction through the plate wall. In deed, the

heat from the warmer well water transfers to the

refrigerant.

In the heat exchanger two processes take place:

evaporation and superheating. From the aspect of the

heat transfer the evaporation is dominant because

almost 95-96% of the heat is transferred in this manner.

The superheating is necessary evil but justifiable

because of the safety operation of the compressor.

The evaporation in opposite of the condensation is

not a self regulated process, but requires

regulation.The process is regulated by thermal

expansion valve. The valve regulates the amount of the

refrigerant mass flow and thereby the evaporating

pressure and temperature as well. The aim of the

regulation is, the evaporation temperature should be at

a low level and the temperature increasing of the

superheated vapour which is flowing out of the

evaporator keeps the referent set value. In practice, the

optimum value of the superheated vapour's

temperature increasing is 4°C [3].

The primary objective of the paper is, to present the

steady-state lumped parameter mathematical model of

the heat pump evaporator and applying the model we

investigated the evaporator's thermal behavior. The

ultimate objective is that the model has to be part of the

mathematical model of heat pump heating system.

Since the ultimate objective is optimization, so the

model is steady-state, namely the model of the heating

system is designed for steady state operation mode.

The analytical optimization requires a lumped

parameter model.

The evaporator's mathematical model consists of

two parts of the superheating and the evaporation

section. The basic equations in the model are the

energy conservation balance equations, the auxiliary

equations are the logarithmic or arithmetic temperature

differences, heat transfer coefficients and the overall

heat transfer coefficients. The listed equations are

algebraic, coupled, non-linear and with many

variables. The solution of the equation system is only

possible using iterative numerical procedure. The

numerically obtained results are arranged in the vector

or matrix format and presented in 2D graphics.

EXPRES 2017 ISBN 978-86-919769-1-0

In the case study, we investigated the heat flow

behavior in the evaporator and the latent heat both as a

function of the well water- and the refrigerant mass

flow rate.

2. The physical model of evaporator

Fig. 1. Shema of heat pump evaporator

3. The basic mathematical model of the

evaporator

Introduction

The steady-state lumped parameter mathematical

model is created on the basis of the energy conservation

and comprises the evaporation and superheat sections.

Both section's thermal behavior describe the three heat

flow balance equations. The equations include

dependent and independent variables.

The independent selected variables of the

evaporator

• Inlet temperature of the refrigerant liquid-vapour

mixture

• Inlet temperature of the well water

• Mass flow rate of the well water

• Mass flow rate of the refrigerant liquid-vapour mixture

• Heat transfer surface area of the evaporator

• Vapour quality

The dependent variables to elimination

The evaporation section

1. The saturated vapour temperature of the evaporating

section

2. The well water temperature at the end of the

evaporation section

3. Heat flow in the evaporation section

4. Heat transfer surface area of the evaporation section

The vapour superheating section

5. Superheated vapour temperature at the end of the


6. Well water outlet temperature at the end of the


7. Heat flow in the vapour superheating section

8. Heat transfer surface area of the vapour superheating

section

In addition

• saturated vapour inlet temperature at the superheating

section is equal to the evaporation temperature

• well water inlet temperature at the superheating

section is equal to the well water outlet temperature at

the end of the evaporation section.

The governing equations of the evaporation section

The heat flow from well water to the evaporating

refrigerant

= ∙ ∙ ∆ (1)



= ∙ ∙ ∆, (2)

The heat flux absorbed by the refrigerant fluid +

vapour phase for evaporation

= ∙ ∆, ∙ (1 − ) (3)

The governing equations of superheating section.

The heat flux from the well water to the refrigerant

vapour

= ∙ ∙ ∆ (4)



= ∙ ∙ ∆, (5)

The heat flux absorbed by the refrigerant vapour

for superheating

= , ∙ ∙ ∆ (6)

The superheatied temperature different

∆ ≅ 4℃ − variable constant (7)

All heat flow tranfered in the evaporator. = + (8)

The heat flow transfered by the well water to the

refrigerant

= ∙ ∙ (, − , )

The all heat flux absorbed by the refrigerant

= ∙ ∆, + , ∙ ∙ ∆= ∙ ∆, + ∆

(9)

All active surface area of the evaporator. Evaporation

and the superheating section surface.

= + (10)

12

EXPRES 2017 ISBN 978-86-919769-1-0

4. Auxiliary equations

The heat flow in the evaporation section

The heat flux in evaporation section equal to the

specific latent heat of evaporation.

The latent heat of evaporation expressed by an

exponential function depending on the evaporation

temperature.

∆, = + ∙ + ∙

(11)

Parameters for the refrigerant R 134a:

= 200.5965715; = −0.709168; =−0.00596796.

The arithmetic and logarithmic temperature

difference

The general form of the logarithmic temperature

difference for the evaporation and superheating

section.

∆,,, = ∆ − ∆(∆ ∕ ∆) (12)

The general form of the arithmetic temperature

difference.

∆,,, ≅ ∆,, + ∆,,2 (13)

Since the evaporation occurs at a near constant

temperature and the superheating section the

temperature decreasing only 4 oC, therefore in the both

section by a negligible difference the logarithmic

temperature difference substitutable with arithmetic.

Temperature differences in evaporation section

The co-current flow

The maximal temperature difference between the

evaporation and the well water temperature.

∆ = − (14)

The the minimul temperature difference between

the evaporation and the well water temperature.

∆ = − (15)

The well water temperature difference between inlet

and outlet at the evaporation section

∆, = − (16)

Temperature differences in vapor superheating

sections

The superheated vapor temperature is same as the

evaporation temperature.

= (17)

The co-current flow.


vapor and the well water input temperature.

∆ = − (18)

The minimal temperature difference between the

vapor and the well water output temperature.

∆ = − (19)


and outlet at the superheating section

∆ = − (20)

The refrigerant temperature difference between inlet


∆ = − (21)

The overall heat transfer coefficients

The plate evaporator can be approximately

considered as a smoot-wall exchager, so the heat

transfer coefficient in both section, in the evaporation

and the superheating section, can be calculated by the

following relationship.

, = 1

+ ∑

+ ,

(22)

Since the wall thickness of the plate evaporator is

only 0.3-0.5 mm, so the heat resistance of the wall

insignificant that is Σδ / λ ≅0. After neglect the

expression of the heat transfer coefficient is:

, ≅ ∙ , + ,

(23)

5. A mathematical procedure

The mathematical model is composed of a non-

linear, multivariable, coupled and large number

algebraic equations. Since the model is so complex the solution can be

obtained by means a numerical iterative procedure.

The Matlab software package has been applied to this

purpose.

6. Case study

The evaporator's heat flux behavior is ivestigated as a

function of the well water and refigerant mass flow

rate using the mathematical model and the iterative

numerical procedure. The known input data.

• Vapour quality, x = 0.25,

• The well water inlet temperature., twi = 14OC -

• The mass flow of the well water., ṁw = 0.3, 0.4, 0.5,

0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2 kg/s,

• The refrigerant mass flow rate., ṁf = 0.03, 0.04,

0.05;0.06;0.07;0.08;0.09;0.1;0.11;0.12 kg/s,

• The size of the evaporator heat transfer surface. F = 2

m2.

EXPRES 2017 ISBN 978-86-919769-1-0

7. The simulation results and discussion

Based on the results of numerical simulations we

can conclude that:

• The heat flux in the evaporation section varies near

linearly depending on the mass flow rates.

• The varation trend of the heat flux and latent heat is

very similer depending on the mass flow rates.

• The heat flow is very slightly decreases with

increasing the mass flow rate of the well water.

• The slightly decreasing first does not look logically but

if we consider, the behavior of the latent heat as a

function of the well water mass flow rate, has the

same behavior as the heat flow.

• On the heat flux the effect of the refrigerant mass flow

rate is much more intensev as the well water's mass

flow rate.

• The increasing of the refrigerant mass flow rate

results a very intensiv increasing of the heat flux.

• The increasing tendency of the heat flux is nearly

linear.

Fig. 2. Heat flux depened on the well water and

refrigerant mass flow rate

Fig. 3. Latent heat depened on the well water and


8. Conclusion

The thermal behavior of the heat pump evaporator

was investigated in a steady-state operation mode,

using the lumped parameter mathematical model and

iterative numerical procedure.

The results show near linear behavior of the heat

flux as a function of the well water and the refrigerant

mass flow rate.

The heat flux follows the behavior of the latent heat,

it is understandable, because the necessary heat flux for

the evaporation is proportional to the latent heat.

One more interesting and important statement, the

heat transfer coefficient does not directly influence the

heat flux, but influences the temperature level of the

well water and refrigerant.

However, the refrigerant temperature affects the

performance of the compressor, thereby the mass flow

rate of the refrigerant.

References

[1] Nyers, J., Pek, Z. (2014), Mathematical model of heat

pumps' coaxial evaporator with distributed parameters,

Acta Polytechnica Hungarica, Volume 11, Issue 10, pp. 41-

57.

[2] Yan Y.-Y., T.-F Lin. (1999), Evaporation Heat Transfer

and Pressure Drop of Refrigerant R-134a in a Plate Heat

Exchanger, Transactions of the ASME, 118 / Vol. 121.

[3] Sayyaadi, H., Amlashi, E. H., Amidpour, M. (2009), Multi-

objective optimization of a vertical ground source heat

pump using evolutionary algorithm, Energy Conversion

and Management, 50 (2009), pp. 2035–2046.

[4] Esen, H., Turgut, E. (2015), Optimization of operating

parameters of a ground coupled heat pump system by

Taguchi method, Energy and Buildings, Volume 107, 15

November 2015, pp. 329–334.

[5] Mu, W., Wang, S., Pan, S., Shi, Y. (2006), Discussion of

an Optimization Scheme for the Ground Source Heat Pump

System of HVAC, Renewable Energy Resources and a

Greener, Future Vol. VIII-13-3 2006, ESL-IC-06-11-315.

[6] Shi, Z., Li, Z. (2011), Thermo-economic Optimization of a

Seawater Source Heat Pump System for Residential

Buildings, Advanced Materials Research Online, 2011-10-

07, ISSN: 1662-8985, Vols. 354-355, pp 794-797.

[7] Ahmadi, M. H., Ahmadi, M. A., Bayat, R., Ashouri, M.,

Feidt, M. (2015), Thermo-economic optimization of

Stirling heat pump by using non-dominated sorting genetic

algorithm, Energy Conversion and Management, 91

(2015), pp. 315–322.

[8] Go, G. H., Lee, S. R., Yoon, S., Kim, M. J. (2016),

Optimum design of horizontal ground-coupled heat pump

systems using spiral-coil-loop heat exchangers, Applied

Energy, Volume 162, 15 January 2016, pp. 330–345

[9] Cui, W., Zhou, S., Liu, X. (2015), Optimization of design

and operation parameters for hybrid ground-source heat

pump assisted with cooling tower, Energy and Buildings,

99 (2015), 253–262

[10] Mokhtari, H., Hadiannasab, H., Mostafavi, M.,

Ahmadibeni, A. (2016), Determination of optimum

geothermal Rankine cycle parameters utilizing coaxial heat

exchanger, Energy, 102 (2016), pp. 260-275

13

EXPRES 2017 ISBN 978-86-919769-1-0

4. Auxiliary equations

The heat flow in the evaporation section

The heat flux in evaporation section equal to the

specific latent heat of evaporation.

The latent heat of evaporation expressed by an

exponential function depending on the evaporation

temperature.

∆, = + ∙ + ∙

(11)

Parameters for the refrigerant R 134a:

= 200.5965715; = −0.709168; =−0.00596796.

The arithmetic and logarithmic temperature

difference

The general form of the logarithmic temperature

difference for the evaporation and superheating

section.

∆,,, = ∆ − ∆(∆ ∕ ∆) (12)

The general form of the arithmetic temperature

difference.

∆,,, ≅ ∆,, + ∆,,2 (13)

Since the evaporation occurs at a near constant

temperature and the superheating section the

temperature decreasing only 4 oC, therefore in the both

section by a negligible difference the logarithmic

temperature difference substitutable with arithmetic.

Temperature differences in evaporation section

The co-current flow


evaporation and the well water temperature.

∆ = − (14)

The the minimul temperature difference between

the evaporation and the well water temperature.

∆ = − (15)


and outlet at the evaporation section

∆, = − (16)

Temperature differences in vapor superheating

sections

The superheated vapor temperature is same as the

evaporation temperature.

= (17)

The co-current flow.


vapor and the well water input temperature.

∆ = − (18)

The minimal temperature difference between the

vapor and the well water output temperature.

∆ = − (19)



∆ = − (20)

The refrigerant temperature difference between inlet


∆ = − (21)

The overall heat transfer coefficients

The plate evaporator can be approximately

considered as a smoot-wall exchager, so the heat

transfer coefficient in both section, in the evaporation

and the superheating section, can be calculated by the

following relationship.

, = 1

+ ∑

+ ,

(22)

Since the wall thickness of the plate evaporator is

only 0.3-0.5 mm, so the heat resistance of the wall

insignificant that is Σδ / λ ≅0. After neglect the

expression of the heat transfer coefficient is:

, ≅ ∙ , + ,

(23)

5. A mathematical procedure

The mathematical model is composed of a non-

linear, multivariable, coupled and large number

algebraic equations. Since the model is so complex the solution can be

obtained by means a numerical iterative procedure.

The Matlab software package has been applied to this

purpose.

6. Case study

The evaporator's heat flux behavior is ivestigated as a

function of the well water and refigerant mass flow

rate using the mathematical model and the iterative

numerical procedure. The known input data.

• Vapour quality, x = 0.25,

• The well water inlet temperature., twi = 14OC -

• The mass flow of the well water., ṁw = 0.3, 0.4, 0.5,

0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2 kg/s,

• The refrigerant mass flow rate., ṁf = 0.03, 0.04,

0.05;0.06;0.07;0.08;0.09;0.1;0.11;0.12 kg/s,

• The size of the evaporator heat transfer surface. F = 2

m2.

EXPRES 2017 ISBN 978-86-919769-1-0

7. The simulation results and discussion

Based on the results of numerical simulations we

can conclude that:

• The heat flux in the evaporation section varies near

linearly depending on the mass flow rates.

• The varation trend of the heat flux and latent heat is

very similer depending on the mass flow rates.

• The heat flow is very slightly decreases with

increasing the mass flow rate of the well water.

• The slightly decreasing first does not look logically but

if we consider, the behavior of the latent heat as a

function of the well water mass flow rate, has the

same behavior as the heat flow.

• On the heat flux the effect of the refrigerant mass flow

rate is much more intensev as the well water's mass

flow rate.

• The increasing of the refrigerant mass flow rate

results a very intensiv increasing of the heat flux.

• The increasing tendency of the heat flux is nearly

linear.

Fig. 2. Heat flux depened on the well water and


Fig. 3. Latent heat depened on the well water and


8. Conclusion

The thermal behavior of the heat pump evaporator

was investigated in a steady-state operation mode,

using the lumped parameter mathematical model and

iterative numerical procedure.

The results show near linear behavior of the heat

flux as a function of the well water and the refrigerant

mass flow rate.

The heat flux follows the behavior of the latent heat,

it is understandable, because the necessary heat flux for

the evaporation is proportional to the latent heat.

One more interesting and important statement, the

heat transfer coefficient does not directly influence the

heat flux, but influences the temperature level of the

well water and refrigerant.

However, the refrigerant temperature affects the

performance of the compressor, thereby the mass flow

rate of the refrigerant.

References

[1] Nyers, J., Pek, Z. (2014), Mathematical model of heat

pumps' coaxial evaporator with distributed parameters,

Acta Polytechnica Hungarica, Volume 11, Issue 10, pp. 41-

57.

[2] Yan Y.-Y., T.-F Lin. (1999), Evaporation Heat Transfer

and Pressure Drop of Refrigerant R-134a in a Plate Heat

Exchanger, Transactions of the ASME, 118 / Vol. 121.

[3] Sayyaadi, H., Amlashi, E. H., Amidpour, M. (2009), Multi-

objective optimization of a vertical ground source heat

pump using evolutionary algorithm, Energy Conversion

and Management, 50 (2009), pp. 2035–2046.

[4] Esen, H., Turgut, E. (2015), Optimization of operating

parameters of a ground coupled heat pump system by

Taguchi method, Energy and Buildings, Volume 107, 15

November 2015, pp. 329–334.

[5] Mu, W., Wang, S., Pan, S., Shi, Y. (2006), Discussion of

an Optimization Scheme for the Ground Source Heat Pump

System of HVAC, Renewable Energy Resources and a

Greener, Future Vol. VIII-13-3 2006, ESL-IC-06-11-315.

[6] Shi, Z., Li, Z. (2011), Thermo-economic Optimization of a

Seawater Source Heat Pump System for Residential

Buildings, Advanced Materials Research Online, 2011-10-

07, ISSN: 1662-8985, Vols. 354-355, pp 794-797.

[7] Ahmadi, M. H., Ahmadi, M. A., Bayat, R., Ashouri, M.,

Feidt, M. (2015), Thermo-economic optimization of

Stirling heat pump by using non-dominated sorting genetic

algorithm, Energy Conversion and Management, 91

(2015), pp. 315–322.

[8] Go, G. H., Lee, S. R., Yoon, S., Kim, M. J. (2016),

Optimum design of horizontal ground-coupled heat pump

systems using spiral-coil-loop heat exchangers, Applied

Energy, Volume 162, 15 January 2016, pp. 330–345

[9] Cui, W., Zhou, S., Liu, X. (2015), Optimization of design

and operation parameters for hybrid ground-source heat

pump assisted with cooling tower, Energy and Buildings,

99 (2015), 253–262

[10] Mokhtari, H., Hadiannasab, H., Mostafavi, M.,

Ahmadibeni, A. (2016), Determination of optimum

geothermal Rankine cycle parameters utilizing coaxial heat

exchanger, Energy, 102 (2016), pp. 260-275

14

EXPRES 2017 ISBN 978-86-919769-1-0

[11] Takács J. (2015), Enhance of the efficiency of exploitation

of geothermal energy, EXPRES 2015 Proceedings, ISBN

978-86-82621-15-7, Subotica, pp. 46-49*

[12] Wu, W., Shi, W., Wang, B., Li, X. (2015), Annual

performance investigation and economic analysis of

heating systems with a compression-assisted air source

absorption heat pump, Energy Conversion and

Management, Volume 98, 1 July 2015, pp. 290–302

[13] Dragičević, S., Bojić, M. (2009), An energy optimization

model for a combined heat and power production energy

supply system with a heat pump, Proc. IMechE Vol. 223

Part A: J. Power and Energy, 2009, pp. 321-328

[14] Kalmár, F. (2016), Interrelation between glazing and

summer operative temperature in buildings, International

Review of Applied Sciences and Engineering, 7 (2016) 1,

pp. 51–60, DOI: 10.1556/1848.2016.7.1.7

[15] Kalmár, F., Csomós, Gy., Lakatos, Á. (2013), Focus on

renewable energy (energy policy) — Editorial,

International Review of Applied Sciences and Engineering,

4 (1), 95-95 (2013)

[16] Kajtár, L., Kassai, M., Bánhidi, L. (2011), Computerized

simulation of the energy consumption of air handling units.

2011, Energy and Buildings, ISSN 0378-7788, (45) pp. 54-

59.

[17] Kassai, M., Ge, G., Simonson, C. J. (2015),

Dehumidification performance investigation of liquid-to-air

membrane energy exchanger system, Thermal Science,

DOI: 10.2298/TSCI140816129K (2015).

[18] Nyers, J., Garbai, L., Nyers, A. (2015), A modified

mathematical model of heat pump's condenser for

analytical optimization, International J. Energy, Vol. 80,

pp. 706-714, 1 February 2015.

DOI:10.1016/j.energy.2014.12.028

[19] Nyers, J., Nyers, A. (2013), Hydraulic Analysis of Heat

Pump's Heating Circuit using Mathematical Model, 9th

ICCC International Conferenc, Proceedings-USB, ISBN

978-1-4799-0061-9, pp. 349-353, Tihany, Hungary, 2013

[20] Nyers, J., Nyers, A.(2011), COP of heating-cooling system

with heat pump, EXPRES 2011, 3rd IEEE International

Symposium on Exploitation of Renewable Energy Sources,

Subotica, Serbia; 2011, Proceedings, pp. 17-21, Article

number 5741809

[21] Kajtár L., Hrustinszky T.: Investigation and influence of

indoor air quality on energy demand of office buildings.

WSEAS Transactions on Heat and Mass Transfer, Issue 4,

Volume 3, October 2008. 219-228 p.

[22] M. Kassai, C. J. Simonson, “Performance investigation of

liquid-to-air membrane energy exchanger under low

solution/air heat capacity rates ratio conditions,” Building

Services Engineering Research & Technology. vol. 36. n.

5. pp. 535-545, 2015.

[23] TK. Dabis, Z. Szánthó: Control of Domestic Hot Water

production is instantaneous heating system with a speed

controlled pump, 6th International symposium “EXPRES

2014 VTS.” Subotica. Serbia, 2014. pp. 101-106. ISBN

978-86-85409-96-7.

[24] Balázs Both, Zoltán Szánthó, Róbert Goda: Numerical

investigation of offset jet attaching to a wall, EXPRES

2015. Subotica. Serbia, 2015. pp. 70-73. ISBN 978-86-

82621-15-7

[25] Mária Kurcová: The effect of thermal insulation of an

apartment house on thermo-hydraulic stability of the space

heating system. EXPRES 2015. Subotica. Serbia, 2015. pp.

88-91. ISBN 978-86-82621-15-7

[26] Miklos Kassai, Mohammad Rafati Nasr, Carey J.

Simonson: A developed procedure to predict annual

heating energy by heat-and energy recovery technologies in

different climate European countries. Energy and

Buildings. Vol. 109, pp. 267-273,

DOI:10.1016/j.enbuild.2015.10.008 (2015).

[27] L. Šereš L., O. Grljević, S. Bošnjak, IT Support of

Buildings Energy Efficiency Improvement, International

Conference on Energy Efficiency and Environmental

Sustainability, EEES 2012, Conference proceedings, ISBN:

978-86-7233-320-6, pp. 55-62.

[28] A. Szente, I. Farkas, and P. Odry: The application of

Thermopile Technology in high Energy Nuclear Power

Plants, EXPRES 2014, pp.23-28, 2014, ISBN 978-86-

85409-96-7

[29] Ferenc Kalmár, Sándor Hámori: Investigation of

unbalancing problems in central heating systems, EXPRES

2015, pp. 7-12. ISBN 978-86-82621-15-7. 2015

[30] Füri, B.: Practical experiences with multi-compressor

refrigeration systems, Proceedings of 6th International

Conference on Compressors and Coolants – Compressors

2006, 27. - 29. 9. 2006, Častá – Papiernička, p. 158– 161.

ISBN 80-968986-5-5

[31] Füri, B. Švingál, J.: Some experimental results with

ammonia base azeotropic refrigerant R 723 in small heat

pump, p. 139 – 142. Proceedings of 7th International


2009, 30. 9.- 2. 10. 2009, Častá -Papiernička, ISBN: 978-

80-89376-02-2

[32] Ján Takács, Marek Bukoviansky: Utilization of Geothermal

Energy for Residential Sector of the City District Galanta

North. EXPRES 2014, pp.82-85, ISBN 978-86-85409-96-

7, 2014.

[33] F. E. Kiss and D. P. Petkovic: Revealing the costs of air

pollution caused by coal-based electricity generation in

Serbia, EXPRES 2015, pp. 96-101. ISBN 978-86-82621-

15-7, 2015.

[34] Slavica Tomic, Aleksandra Stoiljkovic: Energy efficiency

as a precondition of sustainable tourism. EXPRES 2015,

pp. 134-139. ISBN 978-86-82621-15-7, 2015.

[35] A. Nagy: Determination of the Gasket Load Drop at Large

Size Welding Neck Flange Joints in the Case of Nonlinear

Gasket Model. Int. J. Pres. Ves. & Piping. 67 (1996) 243-

248.

[36] A. Nagy: Time Depending Characteristics of Gasket at

Flange Joints. Int. J. Pres. Ves. & Piping. (1997).

[37] Nagy Károly, Divéki Szabolcs, Odry Péter, Sokola Matija,

Vujicic Vladimir:"A Stochastic Approach to Fuzzy

Control", I.J. Acta Polytechnica Hungarica, Vol. 9, No 6,

2012, pp. 29-48. (ISSN: 1785-8860).

EXPRES 2017 ISBN 978-86-919769-1-0

Recycling of ashes from biomass-combustion power plant in swage sludge management M. WÓJCIKa, F. STACHOWICZb

, A. MASŁOŃc a-bDepartment of Materials Forming and Processing,

RzeszowUniversity of Technology

35-959 Rzeszow, Powstańców Warszawy 8, Poland c Department of Chemistry and Environmental Engineering,


35-959 Rzeszow, Powstańców Warszawy 6, Poland aE-mail:[email protected] bE-mail:[email protected] cE-mail:[email protected]

Biomass energy plays an important role in the production of energy from renewable energy sources. Currently, biomass energy

constitutes approximately 8÷15 % of the world energy supplies and it is estimated to increase to 33÷50 % by 2050. During bio-

mass combustion, there are formed combustion products, especially ashes. Available data indicate that only 29.1 % of biomass

ashes were recycled in Poland in 2013. Specific physicochemical properties of biomass combustion products prevent their applica-

tion in many sectors of economy and for this reason, biomass ashes are mainly stored in landfill sites. The growth of biomass share

in energy production requires new biomass ashes utilization methods. Chemical composition and sorptive properties of ashes

enable their application in the sewage sludge treatment. This paper analyses the impact of ashes from biomass combustion power

plant on sewage sludge dewatering and hygienisation. The application of biomass combustion products in sewage sludge manage-

ment can provide methods of their utilization according to law and environmental requirements.

Keywords: biomass ash, sewage sludge, sewage sludge management, recycling, renewable energy

1. Introduction

Energetic industry is one of the main sources ofair pol-

lution today.The combustion of conventional fuels, for

example: coal, causes gas and dust emissions. Coal

combustion also causes emissionof greenhouse gases,

NOx and SOx. Although, the elimination of fossil fuel

combustion is impossible, we can limit their participa-

tion in final energy production. For this reason, acts

that supportthe use of renewable energy sources (cli-

mate and energy package 3 x 20 %) were imple-

mented.

Biomass plays a special importance amongst re-

newable energy sources. It is estimated that biomass

energy constituted approximately 53 % of world re-

newable energy production in 2010 [1]. Hydrogeologi-

cal location of Poland prevents a significant share of

renewable energy from natural sources, for example:

from wind and sun and for this reason, biomass energy

is becoming more and more popular in Poland. For

heating purposes, forest or agricultural biomass are

particularly used [2]. The main sources of biomass in

Poland are energetic crops, for example: straw and Sa-lix viminalis. The largest share of whole energetic

plants has a willow tree. In Poland, there are about 780

willow plant plantations with a surface area of 9480 ha

whichcontains approximately95 % of perennial

plants cultivation [3]. Biomass comprises compo-

nents which are contained in organs, for example:

proteins, fat and lignin and structural material of

biomass: polymerized carbonohydres, lignin and cel-

lulose. The above-mentioned substances consist of

gluconic acid and glucose chains. The definite advan-

tage of biomass combustion is “zero emission” of

carbon dioxide. During the biomass burning, only so

much carbon dioxide is emitted as a plant takes from

the atmosphere by photosynthesis when the plants

grow [4].Therefore, biomass can be treated as a

source of clean energy. Biomass is burnt in fluidized-

bed incinerators in power plants. The biomass con-

sumption is systematically growing. In Poland the

biomass consumption was 9 317 763 GJ in coal-

burning power plants in 2005. For comparison, the

use of biomass grew to 42 917 011 GJ in 2013. In

2013 the biomass consumption was 26 275 970 GJ in

biomass-burning power plants [2]. During the bio-

mass combustion, there are formed combustion prod-

ucts, such as fly and bottom ashes. The increasing

share of biomass in final energy production causes

the problem with the ash utilization. Available data

indicate that only 29.1 % of biomass ashes were re-

cycled in Poland in 2012 [5].

15

EXPRES 2017 ISBN 978-86-919769-1-0

[11] Takács J. (2015), Enhance of the efficiency of exploitation

of geothermal energy, EXPRES 2015 Proceedings, ISBN

978-86-82621-15-7, Subotica, pp. 46-49*

[12] Wu, W., Shi, W., Wang, B., Li, X. (2015), Annual

performance investigation and economic analysis of

heating systems with a compression-assisted air source

absorption heat pump, Energy Conversion and

Management, Volume 98, 1 July 2015, pp. 290–302

[13] Dragičević, S., Bojić, M. (2009), An energy optimization

model for a combined heat and power production energy

supply system with a heat pump, Proc. IMechE Vol. 223

Part A: J. Power and Energy, 2009, pp. 321-328

[14] Kalmár, F. (2016), Interrelation between glazing and

summer operative temperature in buildings, International

Review of Applied Sciences and Engineering, 7 (2016) 1,

pp. 51–60, DOI: 10.1556/1848.2016.7.1.7

[15] Kalmár, F., Csomós, Gy., Lakatos, Á. (2013), Focus on

renewable energy (energy policy) — Editorial,

International Review of Applied Sciences and Engineering,

4 (1), 95-95 (2013)

[16] Kajtár, L., Kassai, M., Bánhidi, L. (2011), Computerized

simulation of the energy consumption of air handling units.

2011, Energy and Buildings, ISSN 0378-7788, (45) pp. 54-

59.

[17] Kassai, M., Ge, G., Simonson, C. J. (2015),

Dehumidification performance investigation of liquid-to-air

membrane energy exchanger system, Thermal Science,

DOI: 10.2298/TSCI140816129K (2015).

[18] Nyers, J., Garbai, L., Nyers, A. (2015), A modified


analytical optimization, International J. Energy, Vol. 80,

pp. 706-714, 1 February 2015.

DOI:10.1016/j.energy.2014.12.028

[19] Nyers, J., Nyers, A. (2013), Hydraulic Analysis of Heat

Pump's Heating Circuit using Mathematical Model, 9th

ICCC International Conferenc, Proceedings-USB, ISBN

978-1-4799-0061-9, pp. 349-353, Tihany, Hungary, 2013

[20] Nyers, J., Nyers, A.(2011), COP of heating-cooling system

with heat pump, EXPRES 2011, 3rd IEEE International

Symposium on Exploitation of Renewable Energy Sources,

Subotica, Serbia; 2011, Proceedings, pp. 17-21, Article

number 5741809

[21] Kajtár L., Hrustinszky T.: Investigation and influence of

indoor air quality on energy demand of office buildings.

WSEAS Transactions on Heat and Mass Transfer, Issue 4,

Volume 3, October 2008. 219-228 p.

[22] M. Kassai, C. J. Simonson, “Performance investigation of

liquid-to-air membrane energy exchanger under low

solution/air heat capacity rates ratio conditions,” Building

Services Engineering Research & Technology. vol. 36. n.

5. pp. 535-545, 2015.

[23] TK. Dabis, Z. Szánthó: Control of Domestic Hot Water

production is instantaneous heating system with a speed

controlled pump, 6th International symposium “EXPRES

2014 VTS.” Subotica. Serbia, 2014. pp. 101-106. ISBN

978-86-85409-96-7.

[24] Balázs Both, Zoltán Szánthó, Róbert Goda: Numerical

investigation of offset jet attaching to a wall, EXPRES

2015. Subotica. Serbia, 2015. pp. 70-73. ISBN 978-86-

82621-15-7

[25] Mária Kurcová: The effect of thermal insulation of an

apartment house on thermo-hydraulic stability of the space

heating system. EXPRES 2015. Subotica. Serbia, 2015. pp.

88-91. ISBN 978-86-82621-15-7

[26] Miklos Kassai, Mohammad Rafati Nasr, Carey J.

Simonson: A developed procedure to predict annual

heating energy by heat-and energy recovery technologies in

different climate European countries. Energy and

Buildings. Vol. 109, pp. 267-273,

DOI:10.1016/j.enbuild.2015.10.008 (2015).

[27] L. Šereš L., O. Grljević, S. Bošnjak, IT Support of

Buildings Energy Efficiency Improvement, International

Conference on Energy Efficiency and Environmental

Sustainability, EEES 2012, Conference proceedings, ISBN:

978-86-7233-320-6, pp. 55-62.

[28] A. Szente, I. Farkas, and P. Odry: The application of

Thermopile Technology in high Energy Nuclear Power

Plants, EXPRES 2014, pp.23-28, 2014, ISBN 978-86-

85409-96-7

[29] Ferenc Kalmár, Sándor Hámori: Investigation of

unbalancing problems in central heating systems, EXPRES

2015, pp. 7-12. ISBN 978-86-82621-15-7. 2015

[30] Füri, B.: Practical experiences with multi-compressor

refrigeration systems, Proceedings of 6th International


2006, 27. - 29. 9. 2006, Častá – Papiernička, p. 158– 161.

ISBN 80-968986-5-5

[31] Füri, B. Švingál, J.: Some experimental results with

ammonia base azeotropic refrigerant R 723 in small heat

pump, p. 139 – 142. Proceedings of 7th International


2009, 30. 9.- 2. 10. 2009, Častá -Papiernička, ISBN: 978-

80-89376-02-2

[32] Ján Takács, Marek Bukoviansky: Utilization of Geothermal

Energy for Residential Sector of the City District Galanta

North. EXPRES 2014, pp.82-85, ISBN 978-86-85409-96-

7, 2014.

[33] F. E. Kiss and D. P. Petkovic: Revealing the costs of air

pollution caused by coal-based electricity generation in

Serbia, EXPRES 2015, pp. 96-101. ISBN 978-86-82621-

15-7, 2015.

[34] Slavica Tomic, Aleksandra Stoiljkovic: Energy efficiency

as a precondition of sustainable tourism. EXPRES 2015,

pp. 134-139. ISBN 978-86-82621-15-7, 2015.

[35] A. Nagy: Determination of the Gasket Load Drop at Large

Size Welding Neck Flange Joints in the Case of Nonlinear

Gasket Model. Int. J. Pres. Ves. & Piping. 67 (1996) 243-

248.

[36] A. Nagy: Time Depending Characteristics of Gasket at

Flange Joints. Int. J. Pres. Ves. & Piping. (1997).

[37] Nagy Károly, Divéki Szabolcs, Odry Péter, Sokola Matija,

Vujicic Vladimir:"A Stochastic Approach to Fuzzy

Control", I.J. Acta Polytechnica Hungarica, Vol. 9, No 6,

2012, pp. 29-48. (ISSN: 1785-8860).

EXPRES 2017 ISBN 978-86-919769-1-0

Recycling of ashes from biomass-combustion power plant in swage sludge management M. WÓJCIKa, F. STACHOWICZb

, A. MASŁOŃc a-bDepartment of Materials Forming and Processing,


35-959 Rzeszow, Powstańców Warszawy 8, Poland c Department of Chemistry and Environmental Engineering,


35-959 Rzeszow, Powstańców Warszawy 6, Poland aE-mail:[email protected] bE-mail:[email protected] cE-mail:[email protected]

Biomass energy plays an important role in the production of energy from renewable energy sources. Currently, biomass energy

constitutes approximately 8÷15 % of the world energy supplies and it is estimated to increase to 33÷50 % by 2050. During bio-

mass combustion, there are formed combustion products, especially ashes. Available data indicate that only 29.1 % of biomass

ashes were recycled in Poland in 2013. Specific physicochemical properties of biomass combustion products prevent their applica-

tion in many sectors of economy and for this reason, biomass ashes are mainly stored in landfill sites. The growth of biomass share

in energy production requires new biomass ashes utilization methods. Chemical composition and sorptive properties of ashes

enable their application in the sewage sludge treatment. This paper analyses the impact of ashes from biomass combustion power

plant on sewage sludge dewatering and hygienisation. The application of biomass combustion products in sewage sludge manage-

ment can provide methods of their utilization according to law and environmental requirements.

Keywords: biomass ash, sewage sludge, sewage sludge management, recycling, renewable energy

1. Introduction

Energetic industry is one of the main sources ofair pol-

lution today.The combustion of conventional fuels, for

example: coal, causes gas and dust emissions. Coal

combustion also causes emissionof greenhouse gases,

NOx and SOx. Although, the elimination of fossil fuel

combustion is impossible, we can limit their participa-

tion in final energy production. For this reason, acts

that supportthe use of renewable energy sources (cli-

mate and energy package 3 x 20 %) were imple-

mented.

Biomass plays a special importance amongst re-

newable energy sources. It is estimated that biomass

energy constituted approximately 53 % of world re-

newable energy production in 2010 [1]. Hydrogeologi-

cal location of Poland prevents a significant share of

renewable energy from natural sources, for example:

from wind and sun and for this reason, biomass energy

is becoming more and more popular in Poland. For

heating purposes, forest or agricultural biomass are

particularly used [2]. The main sources of biomass in

Poland are energetic crops, for example: straw and Sa-lix viminalis. The largest share of whole energetic

plants has a willow tree. In Poland, there are about 780

willow plant plantations with a surface area of 9480 ha

whichcontains approximately95 % of perennial

plants cultivation [3]. Biomass comprises compo-

nents which are contained in organs, for example:

proteins, fat and lignin and structural material of

biomass: polymerized carbonohydres, lignin and cel-

lulose. The above-mentioned substances consist of

gluconic acid and glucose chains. The definite advan-

tage of biomass combustion is “zero emission” of

carbon dioxide. During the biomass burning, only so

much carbon dioxide is emitted as a plant takes from

the atmosphere by photosynthesis when the plants

grow [4].Therefore, biomass can be treated as a

source of clean energy. Biomass is burnt in fluidized-

bed incinerators in power plants. The biomass con-

sumption is systematically growing. In Poland the

biomass consumption was 9 317 763 GJ in coal-

burning power plants in 2005. For comparison, the

use of biomass grew to 42 917 011 GJ in 2013. In

2013 the biomass consumption was 26 275 970 GJ in

biomass-burning power plants [2]. During the bio-

mass combustion, there are formed combustion prod-

ucts, such as fly and bottom ashes. The increasing

share of biomass in final energy production causes

the problem with the ash utilization. Available data

indicate that only 29.1 % of biomass ashes were re-

cycled in Poland in 2012 [5].

16

RECYCLING OF ASHES FROM BIOMASS COMBUSTION POWER PLANT IN SEWAGE SLUDGE MANAGEMENT

Specific properties of biomass combustion prod-

ucts prevent their application in many sectors of econ-

omy. The chemical composition and high losses of ig-

nition lead to the fact that most of biomass ashes fail to

fulfill standard requirements as a component of cement

and concrete production. Biomass ashes are applied as

a valuable fertilizer improving the plant growth. Bio-

mass ashes can be also used as a component improving

geotechnical properties of ground [5].

Sewage sludge is a by-product of sewage

treatment which contains mineral and organic com-

pounds. Due to theconnection of new areas to the se-

wage system, the amount of sewage sludge is syste-

matically growing. According to GUS [6], there were

produced 556 Mg of dry mass of municipal sewage

sludge in Poland in 2014. Before the land application,

sewage sludge have to be processed in order to de-

crease the health risk. Additionally, the effective de-

watering can reduce the transport cost of sewage

sludge. Raw sewage sludge has a stable structure with

a low capacity of dewatering and sedimentation.

Thus, sludge dewateringis enhanced by conditioning

with the application of mineral and organic reagents.

Recently, the application of polyelectrolytes is very

popular in treatment plants. The disadvantages of

aforementioned reagents are their high costs. What is

more, high amountsof polyelectrolytes are required

for effective dewatering. Eye and Basu [7] proved

that the application of coal fly ashes as a conditioner

can reduce operating costs of treatment plant by 88 %

in comparison to other chemical reagents (Table 1).

The alternative solution for popular polyelectro-

lytes could be ashes. Ashes with a diameter below

300 µm are the weights of sewage sludge flocs. In the

wake of incorporation of ash in sludge flocs, the

shape, dimension and structure of flocs are altered.

Ashes are integrated in sewage sludge floc matrix,

what can improve the sewage sludge dewatering

[8,9].

The purpose of the paper was to determine the in-

fluence of biomass ash on sewage sludge dewatering.

The findings show the positive influence of ash on

sewage sludge treatment.Additionally, the mixture of

ash and sewage sludge can be applied as a valuable

fertilizer in plant plantations.

2. Materials and methods

The academic research concerning the influence of

biomass ash on sewage sludge dewatering was per-

formed under laboratory conditions. Sewage sludge

used in tests was obtained from the thickening tank

from Municipal Wastewater Treatment Plant in Świl-

cza in the Podkarpacie region. Sewage sludge was

taken during summer/autumn and was characterized

by grey-brown colour and earthy smell. The physical

and chemical properties of unconditioned sludge were

as follows: pH= 6.40, the moisture content= 97.48 %,

dry mass= 2.52 % , capillary suction time (CST)=

130.89 s.

In laboratory research, ash from biomass combus-

tion power plant was used (Fig.1). Ash was derived

from a power plant “Łężańska” in Krosno, in the

South-Eastern of Poland. In power plant, there is

mainly used biomass from timber industry and green

waste. For biomass combustion, Organic Rankine

Cycle (ORC)technology is used. The simultaneous

transport heat from biomass combustion into electric-

ity and thermal power is the main advantage of ORC

technology.

Malvern Mastersizer 2000 particle size analyser

was used to determine the particle size distribution of

ash. The biomass ash was characterized by particles in

the range of 0.399 ÷ 399 µm (Fig.2). Due to the fact

that ash was not sieved before laboratory research,

there were some coarse particles above 300 µm. To

determine micromorphological characteristics of bio-

mass ash, scanning electron microscope SEM S-

3400N HITACHI was used.SEM images of biomass

ash are shown in Fig. 3. The biomass ash contains the

following micromorphological types of particles: ir-

regular sharp and spongy. The SEM analysis also

shows that the material contains polyhedral and highly

porous particles. The chemical composition of ash was

determined by means of Energy Dispersive Spectros-

copy (EDS). The results of EDS analysis show that the

ash comprises mainly the followingcompounds: Ca, O,

S, and Cl (Fig. 4).

Table1.The economic analyses of sewage sludge conditioning with different reagents [8]

Reagent Dose of reagents [kg per day] Cost of reagents [PLN per year]

FeCl3+CaO 137.7 16700

CaO+ coal fly ash 775 7660

Coal fly ash 3125 9960

RECYCLING OF ASHES FROM BIOMASS COMBUST

Fig.2.

Due to the biomass combustion from surrounding ti

ber industry, ash also contains molybdenum. The phase

composition of biomass ash is as follows:

CaO, Na2O2, SO2, Na2O, P2O5 and KO2.

Laboratory tests of sewage conditioning and d

watering were carried out in tree series. The scope of

the study included the analysis of sewage sludge dew

tering and the determination of the moisture content,

CSK and pH of conditioned sludge. The

of sludge conditioning was compared with the results

for raw sewage sludge. The sewage sludge conditio

ing was carried out as follows: five beakers with

a volume of 1 dm3 were poured into 500 cm cm

a)

Fig. 3.SEM images of biomass ash

0

1

2

3

4

5

0 50 100

Co

nte

nt

of

pa

rtic

les

[%]


Fig.1.The image of biomass ash

Fig.2.The granulometric analysis of biomass ash

Due to the biomass combustion from surrounding tim-

ash also contains molybdenum. The phase

composition of biomass ash is as follows: SiO2, Fe2O3,

age conditioning and de-

tree series. The scope of

study included the analysis of sewage sludge dewa-


CSK and pH of conditioned sludge. The effectiveness

with the results

sludge. The sewage sludge condition-

ried out as follows: five beakers with

500 cm cm3 of

raw sewage sludge. The appropriate

biomass ash: 5 g·dm-3

, 7.5 g·dm-3

,

g·dm-3

were applied to four beakers with sludge.

dosages of biomass ash were expressed as the weight

ratio ofash to sewage sludge dry mass, based on

literature review. Firstly, mixtures were rapidly stirred

with a speed of 200 rpm for 1 minute and after that,

they were stirred with a speed o

minutes by means of flocculator.

after conditioning, pH and capillary suction time

(CST) were determined. Then, for prepared samples

of sewage sludge, the dewatering capacity

was investigated.

b)

SEM images of biomass ash at two magnifications: 1000x (a) and 3500x (b)

150 200 250 300 350 400

Diameter of particles [µm]

MANAGEMENT

appropriate dosages of

, 15 g·dm-3

and 30

were applied to four beakers with sludge.The


ash to sewage sludge dry mass, based on

Firstly, mixtures were rapidly stirred

speed of 200 rpm for 1 minute and after that,

speed of 50 rpm for 15

In sewage sludge


determined. Then, for prepared samples

capacity of sludge

400 450

17


Specific properties of biomass combustion prod-

ucts prevent their application in many sectors of econ-

omy. The chemical composition and high losses of ig-

nition lead to the fact that most of biomass ashes fail to

fulfill standard requirements as a component of cement

and concrete production. Biomass ashes are applied as

a valuable fertilizer improving the plant growth. Bio-

mass ashes can be also used as a component improving

geotechnical properties of ground [5].

Sewage sludge is a by-product of sewage

treatment which contains mineral and organic com-

pounds. Due to theconnection of new areas to the se-

wage system, the amount of sewage sludge is syste-

matically growing. According to GUS [6], there were

produced 556 Mg of dry mass of municipal sewage

sludge in Poland in 2014. Before the land application,

sewage sludge have to be processed in order to de-

crease the health risk. Additionally, the effective de-

watering can reduce the transport cost of sewage

sludge. Raw sewage sludge has a stable structure with

a low capacity of dewatering and sedimentation.

Thus, sludge dewateringis enhanced by conditioning

with the application of mineral and organic reagents.

Recently, the application of polyelectrolytes is very

popular in treatment plants. The disadvantages of

aforementioned reagents are their high costs. What is

more, high amountsof polyelectrolytes are required

for effective dewatering. Eye and Basu [7] proved

that the application of coal fly ashes as a conditioner

can reduce operating costs of treatment plant by 88 %

in comparison to other chemical reagents (Table 1).

The alternative solution for popular polyelectro-

lytes could be ashes. Ashes with a diameter below

300 µm are the weights of sewage sludge flocs. In the

wake of incorporation of ash in sludge flocs, the

shape, dimension and structure of flocs are altered.

Ashes are integrated in sewage sludge floc matrix,

what can improve the sewage sludge dewatering

[8,9].

The purpose of the paper was to determine the in-

fluence of biomass ash on sewage sludge dewatering.

The findings show the positive influence of ash on

sewage sludge treatment.Additionally, the mixture of

ash and sewage sludge can be applied as a valuable

fertilizer in plant plantations.

2. Materials and methods

The academic research concerning the influence of

biomass ash on sewage sludge dewatering was per-

formed under laboratory conditions. Sewage sludge

used in tests was obtained from the thickening tank

from Municipal Wastewater Treatment Plant in Świl-

cza in the Podkarpacie region. Sewage sludge was

taken during summer/autumn and was characterized

by grey-brown colour and earthy smell. The physical

and chemical properties of unconditioned sludge were

as follows: pH= 6.40, the moisture content= 97.48 %,

dry mass= 2.52 % , capillary suction time (CST)=

130.89 s.

In laboratory research, ash from biomass combus-

tion power plant was used (Fig.1). Ash was derived

from a power plant “Łężańska” in Krosno, in the

South-Eastern of Poland. In power plant, there is

mainly used biomass from timber industry and green

waste. For biomass combustion, Organic Rankine

Cycle (ORC)technology is used. The simultaneous

transport heat from biomass combustion into electric-

ity and thermal power is the main advantage of ORC

technology.

Malvern Mastersizer 2000 particle size analyser

was used to determine the particle size distribution of

ash. The biomass ash was characterized by particles in

the range of 0.399 ÷ 399 µm (Fig.2). Due to the fact

that ash was not sieved before laboratory research,

there were some coarse particles above 300 µm. To

determine micromorphological characteristics of bio-

mass ash, scanning electron microscope SEM S-

3400N HITACHI was used.SEM images of biomass

ash are shown in Fig. 3. The biomass ash contains the

following micromorphological types of particles: ir-

regular sharp and spongy. The SEM analysis also

shows that the material contains polyhedral and highly

porous particles. The chemical composition of ash was

determined by means of Energy Dispersive Spectros-

copy (EDS). The results of EDS analysis show that the

ash comprises mainly the followingcompounds: Ca, O,

S, and Cl (Fig. 4).

Table1.The economic analyses of sewage sludge conditioning with different reagents [8]

Reagent Dose of reagents [kg per day] Cost of reagents [PLN per year]

FeCl3+CaO 137.7 16700

CaO+ coal fly ash 775 7660

Coal fly ash 3125 9960

RECYCLING OF ASHES FROM BIOMASS COMBUST

Fig.2.

Due to the biomass combustion from surrounding ti

ber industry, ash also contains molybdenum. The phase

composition of biomass ash is as follows:

CaO, Na2O2, SO2, Na2O, P2O5 and KO2.

Laboratory tests of sewage conditioning and d

watering were carried out in tree series. The scope of

the study included the analysis of sewage sludge dew


CSK and pH of conditioned sludge. The

of sludge conditioning was compared with the results

for raw sewage sludge. The sewage sludge conditio

ing was carried out as follows: five beakers with

a volume of 1 dm3 were poured into 500 cm cm

a)

Fig. 3.SEM images of biomass ash

0

1

2

3

4

5

0 50 100

Co

nte

nt

of

pa

rtic

les

[%]


Fig.1.The image of biomass ash

Fig.2.The granulometric analysis of biomass ash

Due to the biomass combustion from surrounding tim-

ash also contains molybdenum. The phase

composition of biomass ash is as follows: SiO2, Fe2O3,

age conditioning and de-

tree series. The scope of

study included the analysis of sewage sludge dewa-


CSK and pH of conditioned sludge. The effectiveness

with the results

sludge. The sewage sludge condition-

ried out as follows: five beakers with

500 cm cm3 of

raw sewage sludge. The appropriate

biomass ash: 5 g·dm-3

, 7.5 g·dm-3

,

g·dm-3

were applied to four beakers with sludge.


ratio ofash to sewage sludge dry mass, based on

literature review. Firstly, mixtures were rapidly stirred

with a speed of 200 rpm for 1 minute and after that,

they were stirred with a speed o

minutes by means of flocculator.


(CST) were determined. Then, for prepared samples

of sewage sludge, the dewatering capacity

was investigated.

b)

SEM images of biomass ash at two magnifications: 1000x (a) and 3500x (b)

150 200 250 300 350 400

Diameter of particles [µm]

MANAGEMENT

appropriate dosages of

, 15 g·dm-3

and 30

were applied to four beakers with sludge.The


ash to sewage sludge dry mass, based on

Firstly, mixtures were rapidly stirred

speed of 200 rpm for 1 minute and after that,

speed of 50 rpm for 15

In sewage sludge


determined. Then, for prepared samples

capacity of sludge

400 450

18


Fig. 4. The EDS analysis of biomass ash

Mechanical dewatering process was done

in a Büchner funnel and in a centrifuge. The sewage

sludge after conditioning was poured into: a Büchner

funnel, a pressure filter and centrifuge tubes. The vac-

uum filtration was done under 0.01 and 0.02 MPa vac-

uum pressure for about 15 minutes. Centrifugation

of sewage sludge was done for two rotation speeds:

2000 and 2500 rpm for 5 minutes in the laboratory cen-

trifuge after mechanical dewatering, the moisture con-

tent and CST were determined according to PN-EN

15934: 2013-02.CST was measured by means of CST

meter in accordance with PN-EN 147011:2007. In se-

wage sludge, the pH was analyzed with pH-meter

HACH HQ40d in line with PN-EN 15933: 2013-02.

3. Results and discussion

This study has shown different efficiencies in the im-

provement of sewage sludge dewatering, depending on

the amount of biomass ash. At the beginning, ash from biomass combustion in

the power plant was investigated as a conditioner. The

effectiveness of sludge conditioning was done by

means of CST measurement (ProLabTech). The ob-

tained results have shown that the biomass ash influ-

enced the improvement of sewage sludgedewatering

in a various ways. CST of raw sewage sludge was

130.89 s, showing the poor dewaterability. CST after

conditioning with the biomass ash in the highest dose

(30 g dm-3

) was 20.08s (Fig. 5a). The application of

biomass ash has resulted in the decline of CST in the

whole range of agent used. The best result was

achieved for a dose of 30 g·dm-3

and for this reason,

this amount of ash was considered as an optimal dos-

age. For the dosage of 30 g· dm-3

, CST was of about

84.66 % lower than for non-conditioned sewage

sludge. In comparison with commonly used polyelec-

trolytes, ash from biomass combustion in power plant

has a similar effectiveness as polyelectrolytes. The

research has shown that the application of cationic

polyelectrolyte 26508 VP in dose of 2 mg·(g d.m.)-1

reduced the CST value of about 83.19 % (from

149.21 s to 25.07 s).

Biomass ashes can be an effective reagent in sew-

age sludge hygienisation. pH for raw sewage sludge

was 6.40 and for sewage sludge after conditioning

with biomass ash in dosage of 30 g·dm-3

was 12.24

(Fig. 5b). The positive impact of biomass ash from

power plant on the growth of pH is connected with

the content of alkaline metals, such as: Ca, Mg and

Na. Thus, ash can be an effective reagent in sewage

sludge hygienisation.

Fig.5.The influence of sewage sludge conditioning with the biomass ash on CST (a) and on the pH of sewage sludge (b)

0

25

50

75

100

125

150

0 5 10 15 20 25 30

CS

T [

s]

Dosage of ash [g·dm-3]

6

7

8

9

10

11

12

13

0 5 10 15 20 25 30

pH

Dosage of ash [g·dm-3]a)

)

b)

)


In order to determine the effectiveness of sewage

sludge conditioning with biomass ash,, sewage sludge

as investigated by means of centrifugation. The re-

search was carried out for two rotation speed: 2000

rpm and 2500 rpm. As with the pressure filtration, the

moisture content decreased with an increase of dosage

of ash. The changes of moisture content are shown in

Fig. 6. The best results were obtained for the highest

amount of ash. With 30 g·dm-3

dosage of ash, the

moisture content decreased from 92.71 % (rawsewage

sludge) to84.52 % (conditioned sewage sludge) for the

rotation speed of 2000 rpm. Better results were ob-

tained for higher rotation speed. The application of 30

g·dm-3

dosage of biomass ash reduced the moisture

content from 92.52 % (raw sludge) to 76.21 % (condi-

tioned sludge). In comparison to raw sewage sludge,

the highest dosage of biomass ash reduced the moisture

content of about 10.23 % for a rotation speed of 2000

rpm and of about 19.06 % for a rotation speed of 2500

rpm. In any case, low dosages of ash did not influence

the reduction of moisture content in a significant way.

Additionally, the centrifugation of conditioned

sewage sludge was more efficient in comparison to raw

sewage sludge, as witnesses by the liquidvolume

after mechanical dewatering. The water volume was

approximately 27 cm3 for raw sewage sludge and in the

range of 31÷34 cm3

(2000 rpm) and 33÷34 cm3 (2500

rpm) for sewage sludge after conditioning with bio-

mass ash from power plant. Although the water volume

didnot change significantly, the dividing line between

sludge and liquid was clearer than for raw sewage

sludge.

Finally, sewage sludge was dewatered by means

of vacuum filtration. This method provided the best

results of sewage sludge dewatering. The filter cake

moisture for raw sewage sludge was respectively 88.21

% for 0.01 MPa vacuum pressure and 87.94% for 0.02

MPa vacuum pressure. The hydration of sewage sludge

decreasedas the dosage of ash and the vacuum pressure

increased. The dose of 30 g· dm-3

of biomass ash de-

creased themoisture content to 75.64 % (0.01 MPa) and

to 70.91% (0.02 MPa) (Fig.7). For the vacuum filtra-

tion process, the application of biomass ash is effective

in a whole range of doses. The lowest dosage of bio-

mass ash reduced the moisture content of about 11.72

% (0.01 MPa) and of about 14.15 % (0.02 MPa). But

the optimal dosage of biomass ash was the most effec-

tive in sewage sludge dewatering with a Büchner fun-

nel. The application of biomass ash in a dose of 30

g·dm-3

reduced the moisture content of about 19.66 %

for a vacuum pressure 0.01 MPa and 24.68 % for a

vacuum pressure 0.02 MPa. Considering the other

methods of sewage sludge dewatering, the filtered wa-

ter volume did not change significantly.

But the sludge filtration was more rapid in

comparison to raw sewage sludge. With a biomass ash

dosage of 30 g·dm-3

, the filter duration reduced from

200 s to about 60 s. The effectiveness of sewage sludge

conditioning with ash results from the special structural

properties of ash. Sewage sludge has a negative charge

and createsa stable system with low-sediment and low-

dewatering capacity. After conditioning with biomass

ash, the sludge particles congregated around the ash

microspheres and flocs were formed. When the raw

sewage sludge was compressed, a highly compressible

sludge might deform under pressure. The biomass ash

acts as skeleton builders and formed a permeable and

rigid lattice structure. Opposite to raw sewage sludge,

conditioned sludge remained porous under high pres-

sure [9].

Fig.6.The influence of sewage sludge conditioning with biomass ash on the moisture content after centrifugation

75

80

85

90

95

0 5 10 15 20 25 30

the

mois

ture

con

ten

t [%

]


2000 rpm

2500 rpm

19


Fig. 4. The EDS analysis of biomass ash

Mechanical dewatering process was done

in a Büchner funnel and in a centrifuge. The sewage

sludge after conditioning was poured into: a Büchner

funnel, a pressure filter and centrifuge tubes. The vac-

uum filtration was done under 0.01 and 0.02 MPa vac-

uum pressure for about 15 minutes. Centrifugation

of sewage sludge was done for two rotation speeds:

2000 and 2500 rpm for 5 minutes in the laboratory cen-

trifuge after mechanical dewatering, the moisture con-

tent and CST were determined according to PN-EN

15934: 2013-02.CST was measured by means of CST

meter in accordance with PN-EN 147011:2007. In se-

wage sludge, the pH was analyzed with pH-meter

HACH HQ40d in line with PN-EN 15933: 2013-02.

3. Results and discussion

This study has shown different efficiencies in the im-

provement of sewage sludge dewatering, depending on

the amount of biomass ash. At the beginning, ash from biomass combustion in

the power plant was investigated as a conditioner. The

effectiveness of sludge conditioning was done by

means of CST measurement (ProLabTech). The ob-

tained results have shown that the biomass ash influ-

enced the improvement of sewage sludgedewatering

in a various ways. CST of raw sewage sludge was

130.89 s, showing the poor dewaterability. CST after

conditioning with the biomass ash in the highest dose

(30 g dm-3

) was 20.08s (Fig. 5a). The application of

biomass ash has resulted in the decline of CST in the

whole range of agent used. The best result was

achieved for a dose of 30 g·dm-3

and for this reason,

this amount of ash was considered as an optimal dos-

age. For the dosage of 30 g· dm-3

, CST was of about

84.66 % lower than for non-conditioned sewage

sludge. In comparison with commonly used polyelec-

trolytes, ash from biomass combustion in power plant

has a similar effectiveness as polyelectrolytes. The

research has shown that the application of cationic

polyelectrolyte 26508 VP in dose of 2 mg·(g d.m.)-1

reduced the CST value of about 83.19 % (from

149.21 s to 25.07 s).

Biomass ashes can be an effective reagent in sew-

age sludge hygienisation. pH for raw sewage sludge

was 6.40 and for sewage sludge after conditioning

with biomass ash in dosage of 30 g·dm-3

was 12.24

(Fig. 5b). The positive impact of biomass ash from

power plant on the growth of pH is connected with

the content of alkaline metals, such as: Ca, Mg and

Na. Thus, ash can be an effective reagent in sewage

sludge hygienisation.

Fig.5.The influence of sewage sludge conditioning with the biomass ash on CST (a) and on the pH of sewage sludge (b)

0

25

50

75

100

125

150

0 5 10 15 20 25 30

CS

T [

s]


6

7

8

9

10

11

12

13

0 5 10 15 20 25 30

pH

Dosage of ash [g·dm-3]a)

)

b)

)


In order to determine the effectiveness of sewage

sludge conditioning with biomass ash,, sewage sludge

as investigated by means of centrifugation. The re-

search was carried out for two rotation speed: 2000

rpm and 2500 rpm. As with the pressure filtration, the

moisture content decreased with an increase of dosage

of ash. The changes of moisture content are shown in

Fig. 6. The best results were obtained for the highest

amount of ash. With 30 g·dm-3

dosage of ash, the

moisture content decreased from 92.71 % (rawsewage

sludge) to84.52 % (conditioned sewage sludge) for the

rotation speed of 2000 rpm. Better results were ob-

tained for higher rotation speed. The application of 30

g·dm-3

dosage of biomass ash reduced the moisture

content from 92.52 % (raw sludge) to 76.21 % (condi-

tioned sludge). In comparison to raw sewage sludge,

the highest dosage of biomass ash reduced the moisture

content of about 10.23 % for a rotation speed of 2000

rpm and of about 19.06 % for a rotation speed of 2500

rpm. In any case, low dosages of ash did not influence

the reduction of moisture content in a significant way.

Additionally, the centrifugation of conditioned

sewage sludge was more efficient in comparison to raw

sewage sludge, as witnesses by the liquidvolume

after mechanical dewatering. The water volume was

approximately 27 cm3 for raw sewage sludge and in the

range of 31÷34 cm3

(2000 rpm) and 33÷34 cm3 (2500

rpm) for sewage sludge after conditioning with bio-

mass ash from power plant. Although the water volume

didnot change significantly, the dividing line between

sludge and liquid was clearer than for raw sewage

sludge.

Finally, sewage sludge was dewatered by means

of vacuum filtration. This method provided the best

results of sewage sludge dewatering. The filter cake

moisture for raw sewage sludge was respectively 88.21

% for 0.01 MPa vacuum pressure and 87.94% for 0.02

MPa vacuum pressure. The hydration of sewage sludge

decreasedas the dosage of ash and the vacuum pressure

increased. The dose of 30 g· dm-3

of biomass ash de-

creased themoisture content to 75.64 % (0.01 MPa) and

to 70.91% (0.02 MPa) (Fig.7). For the vacuum filtra-

tion process, the application of biomass ash is effective

in a whole range of doses. The lowest dosage of bio-

mass ash reduced the moisture content of about 11.72

% (0.01 MPa) and of about 14.15 % (0.02 MPa). But

the optimal dosage of biomass ash was the most effec-

tive in sewage sludge dewatering with a Büchner fun-

nel. The application of biomass ash in a dose of 30

g·dm-3

reduced the moisture content of about 19.66 %

for a vacuum pressure 0.01 MPa and 24.68 % for a

vacuum pressure 0.02 MPa. Considering the other

methods of sewage sludge dewatering, the filtered wa-

ter volume did not change significantly.

But the sludge filtration was more rapid in

comparison to raw sewage sludge. With a biomass ash

dosage of 30 g·dm-3

, the filter duration reduced from

200 s to about 60 s. The effectiveness of sewage sludge

conditioning with ash results from the special structural

properties of ash. Sewage sludge has a negative charge

and createsa stable system with low-sediment and low-

dewatering capacity. After conditioning with biomass

ash, the sludge particles congregated around the ash

microspheres and flocs were formed. When the raw

sewage sludge was compressed, a highly compressible

sludge might deform under pressure. The biomass ash

acts as skeleton builders and formed a permeable and

rigid lattice structure. Opposite to raw sewage sludge,

conditioned sludge remained porous under high pres-

sure [9].

Fig.6.The influence of sewage sludge conditioning with biomass ash on the moisture content after centrifugation

75

80

85

90

95

0 5 10 15 20 25 30

the

mois

ture

con

ten

t [%

]


2000 rpm

2500 rpm

20


Fig.7.The influence of sewage sludge conditioning with biomass ash on the moisture content after vacuum filtration

4. Summary

The biomass ash is problematic waste which hasto

be managed in line with environmental and law re-

quirements. Stringent requirements prevent biomass

ashes from being used as a component in concrete and

cement production. For this reason, the new biomass

ash utilization methods are developed.

The article shows the proposal of recycling of

biomass combustion products. According to the specif-

ic physic-chemical properties, biomass ashes could be

used as a sewage sludge conditioner. Sewage sludge

after conditioning with ash showed a much stronger

dewatering capacity than raw sewage sludge. With a 30

g·dm-3

dosage of biomass ash, the moisture cake con-

tent decreased of approximately 10.23÷24.68 %, de-

pending on the method of dewatering. The main sludge

conditioning mechanisms with application of biomass

ash canimprove the floc formation and provide the wa-

ter transmitting passages by skeleton builder [8, 9].

The mixture of sewage sludge and biomass ash

may be successfully used in the cultivation of energy

plants plantations. For the application of sewage sludge

into the ground, the device for injection dosage of or-

ganic and mineral fertilizers can be used [11]. The ap-

plication of sludge after conditioning with biomass ash

enables to retain the turnover of nutrients. Moreover,

chemical compounds contained in sewage sludge are

excluded from human food chain [10].

References

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(WWA) zawartymi w popiołach lotnych pochodzących

z kotłów energetycznych. ScientificWorks of Institute

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[3] Rajczyk K., Giergiczny E., Szota M. (2013), Ocena

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[6] GUS Report on Environmental Protection, 2015.

[7] Eye J. D., Basu T.K. (1970), The use of flyash in

wastewater treatment and sludge conditioning. Jour-

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R125-R135.

[8] Zhang P., Haifeng L. (2010), Sewage sludge

conditioning with coal fly ash modified by sulfuric

acid, The Chemical Engineering Journal, 158(3),

616-622.

[9] Wang S., Viraraghavan T. (1997), Wastewater sludge

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443- 450.

[10] Stachowicz F., Trzepieciński T., Wójcik M., Masłoń

A.,Niemiec W., Piech A. (2016), Agricultural

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E3S Web of Conferences, 10, 1-6.

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L., Dziurka M.: Development of harvestingmachines

for willow small-sizes plantation in East-Central

Europe, Croatian Journal of Forest Engineering, 37

(2016) 185-198.

[12] Szabo J., Kajtar L., Nyers J., Bokor B.: A new

approach and results of Wall and Air Temperature

Dynamic Analysis in Underground Spaces.

International J. Energy. Vol. 106, pp.520 -527, 1.

July 2016. doi:10.1016/j.energy.2016.03.008.

70

75

80

85

90

0 5 10 15 20 25 30

the

mois

ture

co

nte

nt

[%]


0.01 MPa

0.02 MPa

EXPRES 2017 ISBN 978-86-919769-1-0

Application of analogy of momentum and heat transfer at shell and tube condenser

O. MOLNARa, Z. ZSIGMOND

b

Department of Building Services and Process Engineering, Faculty of Mechanical Engineering,

Budapest University of Technology and Economics,

H-1111 Budapest, Műegyetem rkp. 3, Hungary aE-mail: [email protected] bE-mail: [email protected]

In environmental and chemical industry majority of processes are based on the simultaneous transfer of extensive properties.

These can be the heat, mass and momentum transfer. Because of the close relation of these transport phenomena, correlations

can be created between transport coefficients. These are the so-called transport analogies. In this paper relation of heat and

momentum transfer is studied. In order to perform the analysis, experimental investigations were made on a shell and tube

heat exchanger device. Goals of our work are to calculate tube side heat transfer coefficient and Nu number with formulas of

transport analogies; to validate them by measured data; to find reason of decreasing Nu number with increasing Re number in

the condenser at higher Re levels. Finally operation of the condenser is modelled by the analogy of heat and momentum

transfer.

Keywords: shell and tube heat exchanger, transport analogy, friction factor, heat transfer coefficient

1. Introduction

In environmental and chemical engineering

majority of processes are based on the

simultaneous transfer of extensive properties.

These can be the heat- mass- and momentum

transfer. Because of the close relation of these

transport phenomena, correlations can be created

among transport properties.

At the end of 19th

century Osborne

Reynolds was the first who recognized the

analogy between heat and momentum transfer

during his experimental investigation on rough

tubes. His observations resulted in the so-called

Reynolds analogy which describes the

connection between heat transfer coefficient and

friction factor [1, 2]:

= ∙ = ℎ = 2 (1)

Eq (1) is applicable for turbulent flow in a pipe

or over a flat plate when Pr is equal or close to

unity. This is a reasonable approximation for

many gases, but for liquids the Pr numbers are

much larger than 1. Therefore this analogy is not

appropriate for liquids.

Since applicability of the Reynolds analogy

is very limited, derivation of a more general

expression was necessary. In independent works

Ludwig Prandtl and Geoffry Ingram Taylor

modified the Reynolds analogy in the first half of

the 20th

century. A new formula was created

between heat transfer coefficient and friction

factor by combining the resistances of a viscous

sublayer where molecular effects dominate with

a turbulent outer layer where turbulent effects

control [1, 2]:

= ℎ =1 + 5 ( − 1) (2)

Prandtl-Taylor analogy can be applied in a wider

range, it allows Pr to differ from 1. Hence it is

applicable mainly in case of Pr smaller than 2

[1].

Theodore von Kármán (1881-1963)

extended Reynolds analogy even further by

including an intermittent boundary layer between

the viscous sublayer and the turbulent bulk.

Turbulent viscosity and turbulent heat

conductivity were determined from the universal

velocity profile. Thus the Kármán analogy is [1,

3]:

21


Fig.7.The influence of sewage sludge conditioning with biomass ash on the moisture content after vacuum filtration

4. Summary

The biomass ash is problematic waste which hasto

be managed in line with environmental and law re-

quirements. Stringent requirements prevent biomass

ashes from being used as a component in concrete and

cement production. For this reason, the new biomass

ash utilization methods are developed.

The article shows the proposal of recycling of

biomass combustion products. According to the specif-

ic physic-chemical properties, biomass ashes could be

used as a sewage sludge conditioner. Sewage sludge

after conditioning with ash showed a much stronger

dewatering capacity than raw sewage sludge. With a 30

g·dm-3

dosage of biomass ash, the moisture cake con-

tent decreased of approximately 10.23÷24.68 %, de-

pending on the method of dewatering. The main sludge

conditioning mechanisms with application of biomass

ash canimprove the floc formation and provide the wa-

ter transmitting passages by skeleton builder [8, 9].

The mixture of sewage sludge and biomass ash

may be successfully used in the cultivation of energy

plants plantations. For the application of sewage sludge

into the ground, the device for injection dosage of or-

ganic and mineral fertilizers can be used [11]. The ap-

plication of sludge after conditioning with biomass ash

enables to retain the turnover of nutrients. Moreover,

chemical compounds contained in sewage sludge are

excluded from human food chain [10].

References

[1] Poluszyńska J. (2013), Ocena możliwości

zanieczyszczenia środowiska glebowo-gruntowego

wielopierścieniowymi węglowodorami aromatycznymi

(WWA) zawartymi w popiołach lotnych pochodzących

z kotłów energetycznych. ScientificWorks of Institute

of Ceramics and Building Materials, 12, 60.

[2] Uliasz-Bocheńczuk A., Pawluk A., Skierka J. (2015),

Wymywalność zanieczyszczeń z popiołów lotnych ze

spalania biomasy. MineralResources Management,

31, 145-156.

[3] Rajczyk K., Giergiczny E., Szota M. (2013), Ocena

możliwości wykorzystania w drogownictwie

popiołów nowej generacji powstających ze spalania

biomasy. Scientific Works of Institute of Ceramics

and Building Materials, 12, 73.

[4] Czech T., Sobczyk T.A., Jaworek A., Krupa A.

Porównanie własności fizycznych popiołów lotnych

ze spalania węgla kamiennego, brunatnego i

biomasy. The Conference POL-EMIS, Sienna 2012,

73-82.

[5] Jarema-Suchorowska S. (2015), Popioły z

biomasy.http.://www.kierunekenergetyka.pl/magazyn

,popiołyzbiomasy.html, lastaccessed: January 10,

2017.

[6] GUS Report on Environmental Protection, 2015.

[7] Eye J. D., Basu T.K. (1970), The use of flyash in

wastewater treatment and sludge conditioning. Jour-

nal of The Water Pollution Control Federation, 42(5),

R125-R135.

[8] Zhang P., Haifeng L. (2010), Sewage sludge

conditioning with coal fly ash modified by sulfuric

acid, The Chemical Engineering Journal, 158(3),

616-622.

[9] Wang S., Viraraghavan T. (1997), Wastewater sludge

conditioning by fly ash. Waste Management, 17 (7),

443- 450.

[10] Stachowicz F., Trzepieciński T., Wójcik M., Masłoń

A.,Niemiec W., Piech A. (2016), Agricultural

utilisation of municipal sludge in willow plantation.

E3S Web of Conferences, 10, 1-6.

[11] Niemiec W., Stachowicz F., Trzepieciński T., Kępa

L., Dziurka M.: Development of harvestingmachines

for willow small-sizes plantation in East-Central

Europe, Croatian Journal of Forest Engineering, 37

(2016) 185-198.




International J. Energy. Vol. 106, pp.520 -527, 1.

July 2016. doi:10.1016/j.energy.2016.03.008.

70

75

80

85

90

0 5 10 15 20 25 30

the

mois

ture

co

nte

nt

[%]


0.01 MPa

0.02 MPa

EXPRES 2017 ISBN 978-86-919769-1-0

Application of analogy of momentum and heat transfer at shell and tube condenser

O. MOLNARa, Z. ZSIGMOND

b



H-1111 Budapest, Műegyetem rkp. 3, Hungary aE-mail: [email protected] bE-mail: [email protected]

In environmental and chemical industry majority of processes are based on the simultaneous transfer of extensive properties.

These can be the heat, mass and momentum transfer. Because of the close relation of these transport phenomena, correlations

can be created between transport coefficients. These are the so-called transport analogies. In this paper relation of heat and

momentum transfer is studied. In order to perform the analysis, experimental investigations were made on a shell and tube

heat exchanger device. Goals of our work are to calculate tube side heat transfer coefficient and Nu number with formulas of

transport analogies; to validate them by measured data; to find reason of decreasing Nu number with increasing Re number in

the condenser at higher Re levels. Finally operation of the condenser is modelled by the analogy of heat and momentum

transfer.

Keywords: shell and tube heat exchanger, transport analogy, friction factor, heat transfer coefficient

1. Introduction

In environmental and chemical engineering

majority of processes are based on the

simultaneous transfer of extensive properties.

These can be the heat- mass- and momentum

transfer. Because of the close relation of these

transport phenomena, correlations can be created

among transport properties.

At the end of 19th

century Osborne

Reynolds was the first who recognized the

analogy between heat and momentum transfer

during his experimental investigation on rough

tubes. His observations resulted in the so-called

Reynolds analogy which describes the

connection between heat transfer coefficient and

friction factor [1, 2]:

= ∙ = ℎ = 2 (1)

Eq (1) is applicable for turbulent flow in a pipe

or over a flat plate when Pr is equal or close to

unity. This is a reasonable approximation for

many gases, but for liquids the Pr numbers are

much larger than 1. Therefore this analogy is not

appropriate for liquids.

Since applicability of the Reynolds analogy

is very limited, derivation of a more general

expression was necessary. In independent works

Ludwig Prandtl and Geoffry Ingram Taylor

modified the Reynolds analogy in the first half of

the 20th

century. A new formula was created

between heat transfer coefficient and friction

factor by combining the resistances of a viscous

sublayer where molecular effects dominate with

a turbulent outer layer where turbulent effects

control [1, 2]:

= ℎ =1 + 5 ( − 1) (2)

Prandtl-Taylor analogy can be applied in a wider

range, it allows Pr to differ from 1. Hence it is

applicable mainly in case of Pr smaller than 2

[1].

Theodore von Kármán (1881-1963)

extended Reynolds analogy even further by

including an intermittent boundary layer between

the viscous sublayer and the turbulent bulk.

Turbulent viscosity and turbulent heat

conductivity were determined from the universal

velocity profile. Thus the Kármán analogy is [1,

3]:

22

APPLICATION OF ANALOGY OF MOMENTUM AND HEAT TRANSFER AT SHELL AND TUBE CONDENSER

2

= 1 + 5 ( − 1 + ) (3)

Thomas H. Chilton and Allan P. Colburn

expanded the Prandtl-Taylor analogy for fluids

with varying Prandtl number. Intensive

properties (velocity and temperature) were

assumed to be varying linearly in the intermittent

boundary layer similarly to the viscous sublayer

[1]. Chilton-Colburn analogy (1933) – also called

j factor analogy – is also a modification of the

Reynolds analogy based on purely experimental

results [4]. Regarding to heat and momentum

transfer [1]:

∙ = = 2 (4)

Where z is an experimentally determined

constant, e.g. at fluid flows inside tubes z = 2/3.

Above mentioned j factor in Eq(4) can be

determined with friction factor only, if drag

coefficient comes from friction and shape

resistance can be neglected (e.g. flows inside or

outside tube parallel to its longitudinal axis,

flows above a flat plate) [1]. Chilton-Colburn

analogy is still popular and widely used because

of its accuracy and simplicity. For instance it can

be applied reasonably for industrial sugarcane

juices in shell and tube heat exchangers [5], and

at shape optimization of chevron-type plate heat

exchangers [6].

At fluids characterized by small Pr numbers

(e.g. liquid phase metals) the Martinelly analogy

can be applied. At this analogy Nu-Re-Pr

correlation is represented by monograms.

In the middle of 20th

century Robert

Deissler proved that at increasing Pr numbers (Pr

>> 10) result of the Kármán analogy differ more

and more from the experimentally obtained data.

It was recognized that near to the wall where

high temperature gradients exist description of

the eddy diffusivity had to be modified. Result of

Diessler analogy is [3]:

= 0,111 ∙ 2 ∙ (5)

W.L.Friend and A.D Metzner made

measurements in a wide range of Sc and Pr

numbers to obtain a correlation between heat-,

mass- and momentum transfer [4]:

= ∙ ,1,2 + 11,8 ∙ ( − 1) ∙ (6)

Although Eq (6) is recommended for wide range

of Pr numbers, at small ones (Pr < 0.5) it can not

be applied.

2. Material and methods

Test device

Experimental measurements were

conducted on a shell and tube heat exchanger

system (Table 1, Fig. 1). The first unit of the

system is a condenser with moderate pressure

steam in the shell side and water as the product in

tube side. The second unit is a cooler where the

heated product coming from the first body is

cooled down before letting it to the drainage

system. This work is focused on the process

taking place in the condenser. The targeted

device is two pass on tube side and one pass on

shell side where the saturated steam coming from

an electric steam generator is admitted. The

temperature of steam is measured and kept

constant (≈103°C) during the measurement

process. Mass flow rate of steam is measured by

measuring weighing the mass of condensate after

the steam trap by using a stop watch and a

bucket. Flow rate of product is measured by a

rotameter. Inlet and outlet temperatures are

measured by temperature transmitters (Fe-CuNi

thermocouples), temperature data are collected

by an ALMEMO data collector and recorded by

Win Control. During the experimental work

product flow rate isvaried between 600 and

1300l/h. At different product flow rates - after

reaching the steady state operating mode -

temperature and flow rate data are recorded.At

each individual operating state heat balance and

heat transfer coefficients are evaluated.

Table1.Data of the shell and tube heat exchanger device

Heat transfer area Number of tubes Size of tubes Size of shell Heat conductivity of

the wall

A = 1.5 m2 N = 48 L = 1 m; dout/din = 10/8 mm

L = 1 m; dout/din = 200/196 mm kw = 14 W/mK


3

Evaluation of heat transfer coefficient

There is sensible heat transfer in tube side,

while condensation on shell side in the first unit

of the device. The tube side heat transfer

coefficient can be determined from the next

equation:

ℎ = 1 − − (7)

The condensation heat transfer coefficient along

vertical tubs can be calculated by the next

correlation [7]:

ℎ = 1.47 ∙ ∙ ∙ ∙ (8)

In Eq (8) the Reynolds number of the

condensation film:

= 4 ∙ ∙ ∙ ∙ (9)

The overall heat transfer coefficient can be

calculated from the transferred heat flow rate and

the logarithmic temperature difference:

= ∆ ∙ (10)

The transferred heat is the average of deflated

and admitted heat:

= ∙ 2 (11)

Deflated heat flow rate by the steam on shell

side: = ∙ ∆ℎ (12)

Admitted heat flow rate by the product on tube

side [9, 10]: = ∙ ∙ ( − ) (13)

During the conducted series of experimental

measurements it was found that - contrary to

expectations - the tube side heat transfer

coefficient (and Nu number)at a distinct level of

Re numberdoes not continue increasing but

slightly decreases instead (at Tst ≈ 103°C, this

level is Re ≈ 4000) (Fig. 2). Just before thislevel

of Re number temperature of the condensate

measured at the outlet pipe of the shell side starts

strongly falling (Fig. 3). It can be suspected that

condensate does not leave the device due to

inappropriate installation and shell side becomes

flooded (Fig. 4). This phenomenon is realized

directly through the cut down of the condensate

temperature. To verify this hypothesis we turned

to transport analogies to simulate the operation of

the condenser.

Fig. 1. Flow chart of the test equipment

23


2

= 1 + 5 ( − 1 + ) (3)

Thomas H. Chilton and Allan P. Colburn

expanded the Prandtl-Taylor analogy for fluids

with varying Prandtl number. Intensive

properties (velocity and temperature) were

assumed to be varying linearly in the intermittent

boundary layer similarly to the viscous sublayer

[1]. Chilton-Colburn analogy (1933) – also called

j factor analogy – is also a modification of the

Reynolds analogy based on purely experimental

results [4]. Regarding to heat and momentum

transfer [1]:

∙ = = 2 (4)

Where z is an experimentally determined

constant, e.g. at fluid flows inside tubes z = 2/3.

Above mentioned j factor in Eq(4) can be

determined with friction factor only, if drag

coefficient comes from friction and shape

resistance can be neglected (e.g. flows inside or

outside tube parallel to its longitudinal axis,

flows above a flat plate) [1]. Chilton-Colburn

analogy is still popular and widely used because

of its accuracy and simplicity. For instance it can

be applied reasonably for industrial sugarcane

juices in shell and tube heat exchangers [5], and

at shape optimization of chevron-type plate heat

exchangers [6].

At fluids characterized by small Pr numbers

(e.g. liquid phase metals) the Martinelly analogy

can be applied. At this analogy Nu-Re-Pr

correlation is represented by monograms.

In the middle of 20th

century Robert

Deissler proved that at increasing Pr numbers (Pr

>> 10) result of the Kármán analogy differ more

and more from the experimentally obtained data.

It was recognized that near to the wall where

high temperature gradients exist description of

the eddy diffusivity had to be modified. Result of

Diessler analogy is [3]:

= 0,111 ∙ 2 ∙ (5)

W.L.Friend and A.D Metzner made

measurements in a wide range of Sc and Pr

numbers to obtain a correlation between heat-,

mass- and momentum transfer [4]:

= ∙ ,1,2 + 11,8 ∙ ( − 1) ∙ (6)

Although Eq (6) is recommended for wide range

of Pr numbers, at small ones (Pr < 0.5) it can not

be applied.

2. Material and methods

Test device

Experimental measurements were

conducted on a shell and tube heat exchanger

system (Table 1, Fig. 1). The first unit of the

system is a condenser with moderate pressure

steam in the shell side and water as the product in

tube side. The second unit is a cooler where the

heated product coming from the first body is

cooled down before letting it to the drainage

system. This work is focused on the process

taking place in the condenser. The targeted

device is two pass on tube side and one pass on

shell side where the saturated steam coming from

an electric steam generator is admitted. The

temperature of steam is measured and kept

constant (≈103°C) during the measurement

process. Mass flow rate of steam is measured by

measuring weighing the mass of condensate after

the steam trap by using a stop watch and a

bucket. Flow rate of product is measured by a

rotameter. Inlet and outlet temperatures are

measured by temperature transmitters (Fe-CuNi

thermocouples), temperature data are collected

by an ALMEMO data collector and recorded by

Win Control. During the experimental work

product flow rate isvaried between 600 and

1300l/h. At different product flow rates - after

reaching the steady state operating mode -

temperature and flow rate data are recorded.At

each individual operating state heat balance and

heat transfer coefficients are evaluated.

Table1.Data of the shell and tube heat exchanger device

Heat transfer area Number of tubes Size of tubes Size of shell Heat conductivity of

the wall

A = 1.5 m2 N = 48 L = 1 m; dout/din = 10/8 mm

L = 1 m; dout/din = 200/196 mm kw = 14 W/mK


3

Evaluation of heat transfer coefficient

There is sensible heat transfer in tube side,

while condensation on shell side in the first unit

of the device. The tube side heat transfer

coefficient can be determined from the next

equation:

ℎ = 1 − − (7)

The condensation heat transfer coefficient along

vertical tubs can be calculated by the next

correlation [7]:

ℎ = 1.47 ∙ ∙ ∙ ∙ (8)

In Eq (8) the Reynolds number of the

condensation film:

= 4 ∙ ∙ ∙ ∙ (9)

The overall heat transfer coefficient can be

calculated from the transferred heat flow rate and

the logarithmic temperature difference:

= ∆ ∙ (10)

The transferred heat is the average of deflated

and admitted heat:

= ∙ 2 (11)

Deflated heat flow rate by the steam on shell

side: = ∙ ∆ℎ (12)

Admitted heat flow rate by the product on tube

side [9, 10]: = ∙ ∙ ( − ) (13)

During the conducted series of experimental

measurements it was found that - contrary to

expectations - the tube side heat transfer

coefficient (and Nu number)at a distinct level of

Re numberdoes not continue increasing but

slightly decreases instead (at Tst ≈ 103°C, this

level is Re ≈ 4000) (Fig. 2). Just before thislevel

of Re number temperature of the condensate

measured at the outlet pipe of the shell side starts

strongly falling (Fig. 3). It can be suspected that

condensate does not leave the device due to

inappropriate installation and shell side becomes

flooded (Fig. 4). This phenomenon is realized

directly through the cut down of the condensate

temperature. To verify this hypothesis we turned

to transport analogies to simulate the operation of

the condenser.

Fig. 1. Flow chart of the test equipment

24

EXPRES 2017 ISBN 978-86-919769-1-0

3. Results

Since all analogies are very sensible to

friction factor, exact determination of that has

high relevance. Several friction models were

investigated (Hagen-Poiseuille, Blasius, Kármán,

Colebrook-White, Panhandle-A) but two of them

can be considered due to roughness of the inside

pipe wall and Re restrictions: Blasius formula

can be applied in the turbulent range

(2300…3000 < Re < 105) for hydraulic smooth

tubes:

= 0.03164/ (14)

and Panhandle-A formula [8] is useful at the

lower part of turbulent range for smooth tubes:

= 447.22 ∙ ∙ . (15)

E is the efficiency coefficient which can vary

from 0.85 to 1. In Eq (14) and Eq (15) express

Darcy’s friction which is in direct connection

with Fanning friction applied in analogies’

equations Eq(1)…Eq(6):

= 4 (16)

Application of analogies was investigated

by looking for the minimum of sum of squared

residuals:

= − () (17)

All analogies were combined with different

friction correlations (Blasius, Panhandle-A with

E = 0.85, 0.9, 0.95, 1.0). SSR values can be

found in (Table 2). It can be seen that measured

Nu numbers do not fit on Reynolds analogy and

Diessler analogy at all. Prandtl-Taylor, Kármán,

Chilton-Colburn and Friend Metzner analogy can

be applied quite well with friction given by

Panhandle-A formula, but friction given by

Blasius formula can be applied only with Friend-

Metzner analogy. The minimum value of SSR is

obtained by Chilton-Colburn analogy with

friction by Panhandle-A with E = 0.9. Result of

this analogy with measured values can be seen in

Fig. 5.

Fig. 4.Flooded shell and tube condenser

Fig. 3Temperature of the condensate versus Re

Fig. 2.Measured Nu versus Re


5

Table 2. SSR values of the analogies with different

friction formulas

REYNOLDS ANALOGY with

Blasius Pan-A(E=0,85)

Pan-A (E=0,9)

Pan-A (E=0,95)

Pan-A (E=1)

741,7 437,6 277,0 170,3 100,4

PRANDTL-TAYLOR ANALOGY with

Blasius Pan-A (E=0,85)

Pan-A (E=0,9)

Pan-A (E=0,95)

Pan-A (E=1)

102,9 49,3 24,4 11,6 7,0

KARMAN ANALOGY with


Pan-A (E=0,9)

Pan-A (E=0,95)

Pan-A (E=1)

31,7 12,7 7,1 7,7 12,7

CHILTON-COLBURN ANALOGY with


Pan-A (E=0,9)

Pan-A (E=0,95)

Pan-A (E=1)

30,0 8,9 6,7 12,8 23,9

DEISSLER ANALOGY with


Pan-A (E=0,9)

Pan-A (E=0,95)

Pan-A (E=1)

237,5 169,2 127,0 94,6 69,8

FRIEND-METZNER ANALOGY with


Pan-A (E=0,9)

Pan-A (E=0,95)

Pan-A (E=1)

8,8 7,2 11,7 19,9 30,3

At Re > 4000 the measured heat transfer

coefficients and Nu numbers start falling because

of suspected reduction of condensation heat

transfer area of the device which is probably

caused by condensate retention. Due to

inadequate condensate drainage in the bottom of

the heat exchanger there is sensible heat transfer

instead of condensation (Fig. 4). At Re > 4000

modified heat transfer area can be calculated

from the predicted heat transfer coefficient from

the Chilton-Colburn analogy by Eq (18) and Eq

(19). The predicted condensate level is

represented in Fig. 6.

′ = 1 + + (18)

′ = ∆ ∙ ′ (19)

4. Conclusion

Several analogies of heat and momentum

transfer can be applied quite well at shell and

tube heat exchanger. Since all analogies are very

sensible on friction coefficient, determination of

its exact value needs further investigations.

Inappropriate operation of the condenser could

be modeled successfully. Installation of a

condensate pump in the system is recommended

to prevent flooding of the shell (Fig.6).

Fig. 6.Installation of a condensate pump in the system

Fig. 6.Condensate level in the shell at large Re range

Fig. 5.Measured and predicted (by Chilton-Colburn

analogy) Nu versus Re

25

EXPRES 2017 ISBN 978-86-919769-1-0

3. Results

Since all analogies are very sensible to

friction factor, exact determination of that has

high relevance. Several friction models were

investigated (Hagen-Poiseuille, Blasius, Kármán,

Colebrook-White, Panhandle-A) but two of them

can be considered due to roughness of the inside

pipe wall and Re restrictions: Blasius formula

can be applied in the turbulent range

(2300…3000 < Re < 105) for hydraulic smooth

tubes:

= 0.03164/ (14)

and Panhandle-A formula [8] is useful at the

lower part of turbulent range for smooth tubes:

= 447.22 ∙ ∙ . (15)

E is the efficiency coefficient which can vary

from 0.85 to 1. In Eq (14) and Eq (15) express

Darcy’s friction which is in direct connection

with Fanning friction applied in analogies’

equations Eq(1)…Eq(6):

= 4 (16)

Application of analogies was investigated

by looking for the minimum of sum of squared

residuals:

= − () (17)

All analogies were combined with different

friction correlations (Blasius, Panhandle-A with

E = 0.85, 0.9, 0.95, 1.0). SSR values can be

found in (Table 2). It can be seen that measured

Nu numbers do not fit on Reynolds analogy and

Diessler analogy at all. Prandtl-Taylor, Kármán,

Chilton-Colburn and Friend Metzner analogy can

be applied quite well with friction given by

Panhandle-A formula, but friction given by

Blasius formula can be applied only with Friend-

Metzner analogy. The minimum value of SSR is

obtained by Chilton-Colburn analogy with

friction by Panhandle-A with E = 0.9. Result of

this analogy with measured values can be seen in

Fig. 5.

Fig. 4.Flooded shell and tube condenser

Fig. 3Temperature of the condensate versus Re

Fig. 2.Measured Nu versus Re


5

Table 2. SSR values of the analogies with different

friction formulas

REYNOLDS ANALOGY with


Pan-A (E=0,9)

Pan-A (E=0,95)

Pan-A (E=1)

741,7 437,6 277,0 170,3 100,4

PRANDTL-TAYLOR ANALOGY with


Pan-A (E=0,9)

Pan-A (E=0,95)

Pan-A (E=1)

102,9 49,3 24,4 11,6 7,0

KARMAN ANALOGY with


Pan-A (E=0,9)

Pan-A (E=0,95)

Pan-A (E=1)

31,7 12,7 7,1 7,7 12,7

CHILTON-COLBURN ANALOGY with


Pan-A (E=0,9)

Pan-A (E=0,95)

Pan-A (E=1)

30,0 8,9 6,7 12,8 23,9

DEISSLER ANALOGY with


Pan-A (E=0,9)

Pan-A (E=0,95)

Pan-A (E=1)

237,5 169,2 127,0 94,6 69,8

FRIEND-METZNER ANALOGY with


Pan-A (E=0,9)

Pan-A (E=0,95)

Pan-A (E=1)

8,8 7,2 11,7 19,9 30,3

At Re > 4000 the measured heat transfer

coefficients and Nu numbers start falling because

of suspected reduction of condensation heat

transfer area of the device which is probably

caused by condensate retention. Due to

inadequate condensate drainage in the bottom of

the heat exchanger there is sensible heat transfer

instead of condensation (Fig. 4). At Re > 4000

modified heat transfer area can be calculated

from the predicted heat transfer coefficient from

the Chilton-Colburn analogy by Eq (18) and Eq

(19). The predicted condensate level is

represented in Fig. 6.

′ = 1 + + (18)

′ = ∆ ∙ ′ (19)

4. Conclusion

Several analogies of heat and momentum

transfer can be applied quite well at shell and

tube heat exchanger. Since all analogies are very

sensible on friction coefficient, determination of

its exact value needs further investigations.

Inappropriate operation of the condenser could

be modeled successfully. Installation of a

condensate pump in the system is recommended

to prevent flooding of the shell (Fig.6).

Fig. 6.Installation of a condensate pump in the system

Fig. 6.Condensate level in the shell at large Re range

Fig. 5.Measured and predicted (by Chilton-Colburn

analogy) Nu versus Re

26


6

Nomenclature

A [m2] surface

c [J/kgK] specific heat

d [m] diameter

E [1] hydraulic efficiency coefficient

f [1] friction factor

g [m/s2] gravitational acceleration

h [W/m2K] heat transfer coefficient

∆h [J/kg] heat of condensation

H [m] height

j [1] colburn factor

k [W/mK] heat conductivity

L [m] length [kg/s] mass flow rate

N [1] number of tubes

Nu [1] Nusselt number

Pr [1] Prandtl number [J/s] heat flow rate

Re [1] Reynolds number

s [m] wall thickness

SSR [1] sum of squared residuals

St [1] Stanton number

T [°C] temperature

∆T [°C] temperature difference

U [W/m2K] overall heat transfer coefficient

z [1] constant

µ [kg/ms] dynamic viscosity

ν [m2/s] kinematic viscosity

ρ [kg/m3] density

subscripts:

adm admitted

Ch-C Chilton-Colburn

cond condensation

D Darcy’s

defl deflated

F Fanning

f condensate film

H heat transfer

in inside/inlet

ln logarithmic

meas measured

out outside/outlet

p at constant pressure

pr product

pred predicted

s steam

sens sensible

tr transferred

w wall

References

[1] S. Szentgyörgyi, K. Molnár, M. Parti: Transzport

folyamatok, Tankönyvkiadó, Budapest (1986)

[2] E.U. Schündler: Analogy between heat and

momentum transfer, Chemical Engineering and

Processing, Vol.37 (1998), pp.103-107

[3] R.G. Deissler: Analysis of turbulent heat transfer,

mass transfer and friction in smooth tubes at high

Prandtl and Schmidt numbers – Lewis Flight

Propulsion Laboratory (1954)

[4] R.S. Brodkey, H.C. Hershey: Transport Phenomena:

A unified approach, McGraw-Hill Chemical

Engineering Series (1988)

[5] Z. Astolfi-Filho, E.B. de Oliveira: Friction factors,

convective heat transfer coefficients and the

Colburn analogy for industrial sugarcane juices,

Biochemical Engineering Journal, Vol.60 (2012),

pp.111-118

[6] L. Jonghyeok, L. Kwan-Soo: Friction and Colburn

factor correlations and shape optimization of

chevron-type plate heat exchangers, Applied

Thermal Engineering, Vol.89 (2015), pp.62-69

[7] T. Környei: Hőátvitel, Műegyetemi Kiadó, (1999)

[8] L. Tihanyi: A gázhálózati modellek kulcsparaméter,

Kőolaj és Földgáz Vol.35 No.7-8, (2002)

[9] J. Nyers, L. Garbai, A. Nyers: Analysis of Heat

Pump's Condenser Performance by means of

Mathematical Model, International J. Acta

Polytechnica Hungarica Vol. 11, No. 3, pp.139-

152, 2014. DOI: 10.12700/APH.11.03.2014.03.9.

[10] J. Nyers, L. Garbai, A. Nyers: A modified


analytical optimization, International J. Energy,

Vol. 80, pp. 706-714, 1 February 2015.

DOI:10.1016/j.energy.2014.12.028.

EXPRES 2017

ISBN 978-86-919769-1-0

Performance of heat pump's condenser in heating process

J. NYERS a, A. NYERS b

aObuda UniversityBudapest, Hungarye-mail:[email protected]

University BME, Budapest, Hugary e-mail:[email protected] The general aim of article is to analyze in wide range the behavior of performance of heat pump's plate condenser depending on

theexternal impacts. The external impacts are the inlet temperature of hot water, the hydraulic resistance of hot water circuit, the

powerof circulation pump, the surface dimension of condenser.The additional practical goal is to find the quasi-optimal power of

circulation pump to obtain the near maximum performance of condenser as a function of resistance to flow in the hot water

circuitand dimension of condenser.

The performance of condenser is the quantity of heat exchanged inside the condenser between the refrigerant and the hot water. The

analysis of performance and quasi-optimization is done using the non-linear lumped parameter mathematical model.

Themathematical model includes equations of heat transfer between the hot water and the refrigerant inside the condenser, the

power of circulation pump, the hydraulic resistance in hot water circuit.Mathematical model of condenser is divided into a section

ofsuperheated steam cooling and a section of saturation steam condensation of refrigerant.

In order to solve the mathematical model, who is consist of nonlinear algebraic equation system, the Newton-Taylor linearization

and Gauss elimination method has been applied.

By simulation obtained numerical results in two or three-dimensional graphics are presented.

Keywords:condenser, heat pump, quasi optimization,circulation pump, mathematicalmodel.

1. Introduction

In the scientific journals many articles deal with the

research of heat pumps in stationary regime using

various lumped parameter mathematical models.

Most of the mathematical models contain the main

four components including the condenser, as well.

Research of all reviewed articles focused on the

behavior of complete system rather than individual

components, such as the condenser.

In the enclosed article, research has focused on

investigating the performance of condenser as a

function of external impacts. The performance of

condenser represents the efficiency and the quantity

of heat transferred between the hot water and the

refrigerant inside the condenser. In the analyzed

system the external impacts are the power of

circulation pump, the inlet temperature of hot water,

the hydraulic resistance in hot water circuit, the

surface dimension of condenser. The hydraulic

resistance of hot water circuit is expressed in

measurable parameter of the system, in the pressure

drop.

The general aim of the investigation is to analyze in

wide range the behavior of performance of heat

pump's plate condenser.

The proposed procedure provides the analyze of

influence of above-mentioned four external impacts

on the performance of condenser.

The most influential external impact on the

performance of condenser is the inlet temperature of

hot water. If the inlet temperature is changed in the

range 21-50 °C then causes the increment of

performance of condenser for 17 kW.

The least impact on the performance of condenser

produces the hydraulic characteristics of hot water

circuit. Increases the power of circulation pump from

21-310 W hardly enhances the performance of

condenser only for 1 kW. From the above data it follows that the best

improvement of performance of condenser is achieved

with increasing the surface of heating bodies in the hot

water circuit. Advisable to apply panel heating bodies

instead radiators. Panels consist of pipe packages in the

floor, wall and ceiling and have a significantly higher

heating surfaces from the radiators, with that the inlet

temperature of hot water for heating decreases and

increases the performance of condenser. Increasing the

power of circulation pump very poorly enhances the

performance of condenser.

The additional practical goal is to find the quasi-optimal

power of circulation pump.The quasi-optimal

powerprovides the near maximum performance of

condenser at the defined hydraulic resistance of hot

water circuit and the defined dimension of condenser.

The theoretical optimum power of circulation pump is in

infinity.

Upper statement can to confirm the results of attached

simulations. With increasing the power of circulation

pump the performance of condenser at the beginning

exponentially but later slow monotonically increases and

in the infinity reaches maximum.

In practice, to the end of exponential increasing of

performance it makes sense to increase the power of

circulation pump. In this point are the quasi-optimal

power of circulation pump and the near maximum


27


6

Nomenclature

A [m2] surface

c [J/kgK] specific heat

d [m] diameter

E [1] hydraulic efficiency coefficient

f [1] friction factor

g [m/s2] gravitational acceleration

h [W/m2K] heat transfer coefficient

∆h [J/kg] heat of condensation

H [m] height

j [1] colburn factor

k [W/mK] heat conductivity

L [m] length [kg/s] mass flow rate

N [1] number of tubes

Nu [1] Nusselt number

Pr [1] Prandtl number [J/s] heat flow rate

Re [1] Reynolds number

s [m] wall thickness

SSR [1] sum of squared residuals

St [1] Stanton number

T [°C] temperature

∆T [°C] temperature difference

U [W/m2K] overall heat transfer coefficient

z [1] constant

µ [kg/ms] dynamic viscosity

ν [m2/s] kinematic viscosity

ρ [kg/m3] density

subscripts:

adm admitted

Ch-C Chilton-Colburn

cond condensation

D Darcy’s

defl deflated

F Fanning

f condensate film

H heat transfer

in inside/inlet

ln logarithmic

meas measured

out outside/outlet

p at constant pressure

pr product

pred predicted

s steam

sens sensible

tr transferred

w wall

References

[1] S. Szentgyörgyi, K. Molnár, M. Parti: Transzport

folyamatok, Tankönyvkiadó, Budapest (1986)

[2] E.U. Schündler: Analogy between heat and

momentum transfer, Chemical Engineering and

Processing, Vol.37 (1998), pp.103-107

[3] R.G. Deissler: Analysis of turbulent heat transfer,

mass transfer and friction in smooth tubes at high

Prandtl and Schmidt numbers – Lewis Flight

Propulsion Laboratory (1954)

[4] R.S. Brodkey, H.C. Hershey: Transport Phenomena:

A unified approach, McGraw-Hill Chemical

Engineering Series (1988)

[5] Z. Astolfi-Filho, E.B. de Oliveira: Friction factors,

convective heat transfer coefficients and the

Colburn analogy for industrial sugarcane juices,

Biochemical Engineering Journal, Vol.60 (2012),

pp.111-118

[6] L. Jonghyeok, L. Kwan-Soo: Friction and Colburn

factor correlations and shape optimization of

chevron-type plate heat exchangers, Applied

Thermal Engineering, Vol.89 (2015), pp.62-69

[7] T. Környei: Hőátvitel, Műegyetemi Kiadó, (1999)

[8] L. Tihanyi: A gázhálózati modellek kulcsparaméter,

Kőolaj és Földgáz Vol.35 No.7-8, (2002)

[9] J. Nyers, L. Garbai, A. Nyers: Analysis of Heat

Pump's Condenser Performance by means of

Mathematical Model, International J. Acta

Polytechnica Hungarica Vol. 11, No. 3, pp.139-

152, 2014. DOI: 10.12700/APH.11.03.2014.03.9.

[10] J. Nyers, L. Garbai, A. Nyers: A modified


analytical optimization, International J. Energy,

Vol. 80, pp. 706-714, 1 February 2015.

DOI:10.1016/j.energy.2014.12.028.

EXPRES 2017

ISBN 978-86-919769-1-0

Performance of heat pump's condenser in heating process

J. NYERS a, A. NYERS b

aObuda UniversityBudapest, Hungarye-mail:[email protected]

University BME, Budapest, Hugary e-mail:[email protected] The general aim of article is to analyze in wide range the behavior of performance of heat pump's plate condenser depending on

theexternal impacts. The external impacts are the inlet temperature of hot water, the hydraulic resistance of hot water circuit, the

powerof circulation pump, the surface dimension of condenser.The additional practical goal is to find the quasi-optimal power of

circulation pump to obtain the near maximum performance of condenser as a function of resistance to flow in the hot water

circuitand dimension of condenser.

The performance of condenser is the quantity of heat exchanged inside the condenser between the refrigerant and the hot water. The

analysis of performance and quasi-optimization is done using the non-linear lumped parameter mathematical model.

Themathematical model includes equations of heat transfer between the hot water and the refrigerant inside the condenser, the

power of circulation pump, the hydraulic resistance in hot water circuit.Mathematical model of condenser is divided into a section

ofsuperheated steam cooling and a section of saturation steam condensation of refrigerant.

In order to solve the mathematical model, who is consist of nonlinear algebraic equation system, the Newton-Taylor linearization

and Gauss elimination method has been applied.

By simulation obtained numerical results in two or three-dimensional graphics are presented.

Keywords:condenser, heat pump, quasi optimization,circulation pump, mathematicalmodel.

1. Introduction

In the scientific journals many articles deal with the

research of heat pumps in stationary regime using

various lumped parameter mathematical models.

Most of the mathematical models contain the main

four components including the condenser, as well.

Research of all reviewed articles focused on the

behavior of complete system rather than individual

components, such as the condenser.

In the enclosed article, research has focused on

investigating the performance of condenser as a

function of external impacts. The performance of

condenser represents the efficiency and the quantity

of heat transferred between the hot water and the

refrigerant inside the condenser. In the analyzed

system the external impacts are the power of

circulation pump, the inlet temperature of hot water,

the hydraulic resistance in hot water circuit, the

surface dimension of condenser. The hydraulic

resistance of hot water circuit is expressed in

measurable parameter of the system, in the pressure

drop.

The general aim of the investigation is to analyze in

wide range the behavior of performance of heat

pump's plate condenser.

The proposed procedure provides the analyze of

influence of above-mentioned four external impacts

on the performance of condenser.

The most influential external impact on the

performance of condenser is the inlet temperature of

hot water. If the inlet temperature is changed in the

range 21-50 °C then causes the increment of

performance of condenser for 17 kW.

The least impact on the performance of condenser

produces the hydraulic characteristics of hot water

circuit. Increases the power of circulation pump from

21-310 W hardly enhances the performance of

condenser only for 1 kW. From the above data it follows that the best

improvement of performance of condenser is achieved

with increasing the surface of heating bodies in the hot

water circuit. Advisable to apply panel heating bodies

instead radiators. Panels consist of pipe packages in the

floor, wall and ceiling and have a significantly higher

heating surfaces from the radiators, with that the inlet

temperature of hot water for heating decreases and

increases the performance of condenser. Increasing the

power of circulation pump very poorly enhances the


The additional practical goal is to find the quasi-optimal

power of circulation pump.The quasi-optimal

powerprovides the near maximum performance of

condenser at the defined hydraulic resistance of hot

water circuit and the defined dimension of condenser.

The theoretical optimum power of circulation pump is in

infinity.

Upper statement can to confirm the results of attached

simulations. With increasing the power of circulation

pump the performance of condenser at the beginning

exponentially but later slow monotonically increases and

in the infinity reaches maximum.

In practice, to the end of exponential increasing of

performance it makes sense to increase the power of

circulation pump. In this point are the quasi-optimal

power of circulation pump and the near maximum


28

EXPRES 2017

ISBN 978-86-919769-1-0

After this interval the power of circulation pumps

linearly but performance of the condenser only

minimally increases, nearly constant.

In the attached simulation, based on the obtained

graphics by the given data quasi-optimum of the

power of the circulation pump is about 110 W.

The proposed procedure consists of the accurate

mathematical model, an appropriate numerical

procedure and two and three dimensional graphics.

Created mathematical model describes the stationary

behavior of condenser, circulation pump and hot

water circuits in terms of hydraulics. The condenser

is plate and divided into section for cooling and

condensing of refrigerant vapor. The circulating

pump is described by power.

The hydraulic characteristic of a hot water circuit is

expressed using the pressure drop.

In the model all equations are algebraic, nonlinear

and coupled.

For solving the system of nonlinear, algebraic and of

coupled equations the Newton-Taylor's linearization

and Gauss's elimination method has been applied.

Results in numerical form were obtained and in two

or three dimensional graphics are presented.

The next objective of development is to expand the

model with compressor, and to determine the

optimal power of the circulation pump so that the

COP of condenser's performance reaches maximum.

2. Physical model

The physical model includes the condenser and its

environment. The environment is the hot water

circuit with pipline and the circulation pump.

The effect of the circulation pump on condenser's

performance is realized through the hot water mass

flow rate and hot water temperature difference.

Pipelinebythe pressure dropin thehotwatercircuit is

manifested

The effect of compressorthroughtheparameters as

the mass flow rate and the inlet temperature of

refrigerate is manifested.

Fig.1. Physical model

3. Mathematica lmodel

The general description of the condenser

The mathematical model of the condenser and its

environment is stationary and with lumped parameters.

In the condenser's mathematical model the governing

equations are based on the energy balance, separately

for the vapor cooling section and separately for the

condensing section. Three balance equations can be

created within the sections. These are the balance

equation of the refrigerant, the water and the heat

transfer between the water and the refrigerant.

The condenser's environment are the mathematical

model of the circulation pump's power and pressure

drop in hot water circuit.

The condenser's governing equations

Cooling section of superheated vapor

Heat flux of the refrigerant's vapor transferred to water

= ∙ ∙ ∆ (1)

Heat transfer between the superheated vapor and hot

water

= ∙ ∙ ∆ (2)

Heat flux absorbed by water

= ∙ ∙ ∆ (3)

Condensing section of saturated vapor

Heat transferred to water delivered by the condensation

of the refrigerant.

= ∙ ∆ (4)

Heat transfer between the vapor and water in the

condensation section.

= ∙ ∙ ∆ (5)

Heat flux absorbed by the water

= ∙ ∙ ∆ (6)

Auxiliary equations of the condenser

Logarithmic temperature difference between the

refrigerant and water

∆ = ∆ − ∆ ∆

∆

(7)

Overall heat transfer coefficient

Since the condenser wall of metal and thin therefore

thermal resistance tends to zero.

The obtained relation.

= 1

+ ∑

+

≅ ∙ +

(8)

The water convective heat transfer coefficient [4]

= 0.2121 ∙

∙ .( ) ∙ (9)

EXPRES 2017

ISBN 978-86-919769-1-0

The refrigerant vapor convective heat transfer

coefficient

= 0,004 ∙

∙ . ∙

(10)

The refrigerant condensate convective heat transfer

coefficient when x = 0 - 1 [4]

α = 4.118 ∙ λd

∙ Re.(m ) ∙ Pr

(11)

The latent heat of condensing vapor as the function

of the condensation temperature

di = a + a ∙ t + a ∙ t

(12)

Wheretheconstants of therefrigerant R 134a are:

a = 200.5965715

a = −0.709168

a = −0.00596796

The condenser’s total surface

= + (13)

The total amount of heat transferred between the


= + (14)

The condensing temperature and the inner boundary

temperature of the refrigerant is equal

= (15)

Circulation pump

The circulation pump supplies the hot water with the

energy to stream. The energy to stream serves to

overcome the resistance to flow in the condenser,

the pipeline and in the heating bodies. The hot water

mass flow rate and pressure drop determine the

demand of the circulation pump's power.

Pressure drop in the hot water circuit according to

Darcy-Weissbach relations

∆ = k1( ) ∙ (16)

Power demand of the circulation pump

2 = k1( ) ∙

= 2( ) ∙ (17)

4. The simulation results

By applying the proposed mathematical model, the

numerical procedure and 2D and 3D graphics, the

behavior of performance of condenser depending on

the power of circulation pump, pressure drop in the

hot water circuit, dimensions of the condenser and

inlet temperature of hot water in the condenser have

been investigated.Power of compressor during the

simulation was constant.Simulations were

performed with the following data. Compressor's

power is constant Pcomp = 4000 W. Other data are

changed in intervals that were taken from practice.

Power of circulation pump Pcirc = 20-310 W, input

water temperature Twi = 21-50 C, the pressure drop

in the hot water circuit Ap = 0.15-0.81 bar,

Condenser's surface f = 0.6-4.2 m2.

Discussion of three typical cases on the basis of

simulation results are follow.

Performance of condenser depending on the power of

circulation pump and pressure drop in the hot water

circuit if tvi=35 ℃ and f=2m2. Figures 2, 3.

Fig. 2. Performanceofcondenseras a functionofpower of

circulation pumpand of pressure drop in the hot water

circuit.


circulation pump.

1-Theoretical optimum power of circulation pump is

infinite because the performance of condenser

asymptotically toward one the values and it reaches to

infinity. (Figure 2).

2-Practically, only to the quasi optimum makes sense to

increase the power of circulation pump. For the further

increase the power the performance of condenser only

minimal increases, monotonically approaches to the

asymptote.

3-Quasi-optimum power of circulation pump is

determined by visually estimation from diagram (Fig.

3).

4-Criteria for the evaluating the quasi optimum is, the

end of exponential increases the performance of

condenser.

5- Quasi optimum power of circulation pump around

Pcirc = 120 W if ∆p = 0.81 bar, and around Pcirc = 80 W if

∆p = 0.15 bar at the conditions tvi= 35 C and f = 2 m2.

(Figure 3).

6- Increasing the power of circulation pump from Pcirc

= 20W to 321W, ie 16 times, the increment of

performance of condenser only ∆q = 1 kW if ∆p = 0.15

29

EXPRES 2017

ISBN 978-86-919769-1-0

After this interval the power of circulation pumps

linearly but performance of the condenser only

minimally increases, nearly constant.

In the attached simulation, based on the obtained

graphics by the given data quasi-optimum of the

power of the circulation pump is about 110 W.

The proposed procedure consists of the accurate

mathematical model, an appropriate numerical

procedure and two and three dimensional graphics.

Created mathematical model describes the stationary

behavior of condenser, circulation pump and hot

water circuits in terms of hydraulics. The condenser

is plate and divided into section for cooling and

condensing of refrigerant vapor. The circulating

pump is described by power.

The hydraulic characteristic of a hot water circuit is

expressed using the pressure drop.

In the model all equations are algebraic, nonlinear

and coupled.

For solving the system of nonlinear, algebraic and of

coupled equations the Newton-Taylor's linearization

and Gauss's elimination method has been applied.

Results in numerical form were obtained and in two

or three dimensional graphics are presented.

The next objective of development is to expand the

model with compressor, and to determine the

optimal power of the circulation pump so that the

COP of condenser's performance reaches maximum.

2. Physical model

The physical model includes the condenser and its

environment. The environment is the hot water

circuit with pipline and the circulation pump.

The effect of the circulation pump on condenser's

performance is realized through the hot water mass

flow rate and hot water temperature difference.

Pipelinebythe pressure dropin thehotwatercircuit is

manifested

The effect of compressorthroughtheparameters as

the mass flow rate and the inlet temperature of

refrigerate is manifested.

Fig.1. Physical model

3. Mathematica lmodel

The general description of the condenser

The mathematical model of the condenser and its

environment is stationary and with lumped parameters.

In the condenser's mathematical model the governing

equations are based on the energy balance, separately

for the vapor cooling section and separately for the

condensing section. Three balance equations can be

created within the sections. These are the balance

equation of the refrigerant, the water and the heat

transfer between the water and the refrigerant.

The condenser's environment are the mathematical

model of the circulation pump's power and pressure

drop in hot water circuit.

The condenser's governing equations

Cooling section of superheated vapor

Heat flux of the refrigerant's vapor transferred to water

= ∙ ∙ ∆ (1)

Heat transfer between the superheated vapor and hot

water

= ∙ ∙ ∆ (2)

Heat flux absorbed by water

= ∙ ∙ ∆ (3)

Condensing section of saturated vapor

Heat transferred to water delivered by the condensation

of the refrigerant.

= ∙ ∆ (4)

Heat transfer between the vapor and water in the

condensation section.

= ∙ ∙ ∆ (5)

Heat flux absorbed by the water

= ∙ ∙ ∆ (6)

Auxiliary equations of the condenser

Logarithmic temperature difference between the


∆ = ∆ − ∆ ∆

∆

(7)

Overall heat transfer coefficient

Since the condenser wall of metal and thin therefore

thermal resistance tends to zero.

The obtained relation.

= 1

+ ∑

+

≅ ∙ +

(8)

The water convective heat transfer coefficient [4]

= 0.2121 ∙

∙ .( ) ∙ (9)

EXPRES 2017

ISBN 978-86-919769-1-0

The refrigerant vapor convective heat transfer

coefficient

= 0,004 ∙

∙ . ∙

(10)

The refrigerant condensate convective heat transfer

coefficient when x = 0 - 1 [4]

α = 4.118 ∙ λd

∙ Re.(m ) ∙ Pr

(11)

The latent heat of condensing vapor as the function

of the condensation temperature

di = a + a ∙ t + a ∙ t

(12)

Wheretheconstants of therefrigerant R 134a are:

a = 200.5965715

a = −0.709168

a = −0.00596796

The condenser’s total surface

= + (13)

The total amount of heat transferred between the


= + (14)

The condensing temperature and the inner boundary

temperature of the refrigerant is equal

= (15)

Circulation pump

The circulation pump supplies the hot water with the

energy to stream. The energy to stream serves to

overcome the resistance to flow in the condenser,

the pipeline and in the heating bodies. The hot water

mass flow rate and pressure drop determine the

demand of the circulation pump's power.

Pressure drop in the hot water circuit according to

Darcy-Weissbach relations

∆ = k1( ) ∙ (16)

Power demand of the circulation pump

2 = k1( ) ∙

= 2( ) ∙ (17)

4. The simulation results

By applying the proposed mathematical model, the

numerical procedure and 2D and 3D graphics, the

behavior of performance of condenser depending on

the power of circulation pump, pressure drop in the

hot water circuit, dimensions of the condenser and

inlet temperature of hot water in the condenser have

been investigated.Power of compressor during the

simulation was constant.Simulations were

performed with the following data. Compressor's

power is constant Pcomp = 4000 W. Other data are

changed in intervals that were taken from practice.

Power of circulation pump Pcirc = 20-310 W, input

water temperature Twi = 21-50 C, the pressure drop

in the hot water circuit Ap = 0.15-0.81 bar,

Condenser's surface f = 0.6-4.2 m2.

Discussion of three typical cases on the basis of

simulation results are follow.

Performance of condenser depending on the power of

circulation pump and pressure drop in the hot water

circuit if tvi=35 ℃ and f=2m2. Figures 2, 3.


circulation pumpand of pressure drop in the hot water

circuit.


circulation pump.

1-Theoretical optimum power of circulation pump is

infinite because the performance of condenser

asymptotically toward one the values and it reaches to

infinity. (Figure 2).

2-Practically, only to the quasi optimum makes sense to

increase the power of circulation pump. For the further

increase the power the performance of condenser only

minimal increases, monotonically approaches to the

asymptote.

3-Quasi-optimum power of circulation pump is

determined by visually estimation from diagram (Fig.

3).

4-Criteria for the evaluating the quasi optimum is, the

end of exponential increases the performance of

condenser.

5- Quasi optimum power of circulation pump around

Pcirc = 120 W if ∆p = 0.81 bar, and around Pcirc = 80 W if

∆p = 0.15 bar at the conditions tvi= 35 C and f = 2 m2.

(Figure 3).

6- Increasing the power of circulation pump from Pcirc

= 20W to 321W, ie 16 times, the increment of

performance of condenser only ∆q = 1 kW if ∆p = 0.15

30

EXPRES 2017

ISBN 978-86-919769-1-0

bar and initial performance q = 21 kW, increases in

percent only 4.7% . In case if ∆p = 0.81 bar and q =

17.5 kW increment is ∆q = 4.2 kW, increment in the

percent only 24%.

7-The value of the quasi-optimal power of

circulation pump is reduced if decreases resistance

to flow. If ∆p = 0.81 bar then the quasi optimum

power is around Pcirc = 120 W, if ∆p = 0.15 bar then

power around Pcirc = 80 W.

8-The most important conclusion is, by increasing

the power of circulation pump the performance of

condenser only in a very narrow interval enhances.

Performance of condenser depending on the power

of circulation pump and surface of condensers if Tvi

= 35 ℃ and ∆p = 0.5 bar. Figures 4.

Fig. 4. Performance of condenser as a function of

power of circulation pump and furface

1-Performance at the upper of condenser conditions

at low power of circulation pump Pcirc = 20W and

small surface of condenser f = 0.6m² has the lowest

value of q = 14.2 kW.

2-Performance of condenser has a maximum value

when the power and surface have maximum. q =

22.1 kW if Pcirc = 310W, f = 4.2m².

3-Observed from the minimum point, the value of

condenser's performance grows exponentially to the

value of quasi-optimum, if the power and surface

increase linearly.

4-After the quasi-optimum the performance of

condenser monotonically increases and approaches

to the asymptote if power and surface increase

linearly. (Figure 5).

5-Quasi optimal surface estimate from the diagram 6

and has a value of about f = 2m2 if tvi = 35 ℃, ∆p =

0.5 bar and power of circulation pump are in the

range Pcirc = 80-120W. (Figure 6).

6-Quasi optimal surface is very small depends on the

power of circulation pump. After the quasi-optimal

points, lines of constant surface almost parallel to

the axis of power of circulation pump.

7-Increasing the surface of condenser causes more

intense increase the performance of condenser, as

the power of circulation pump.


of circulation pump and inlet temperature of hot

water in the condenser if f = 2m² and∆p = 0.5 bar.

Figures 5.


power of circulation pump and temperature of inlet

water

1-Inlet temperature of hot water in the condenser to

mostly affect on the performace of condenser.

2-In the temperature range of 50-20 ℃tvi = performance

of condenser moves between q = 15-28.5 kW if Pcirc =

120W, f = 2m2 and ∆p = 0.5 bar. Figure 8

3-Performance of condenser increases by 1.9 times if the

temperature of inlet hot water decreases from 50 ℃. on

20 ℃.

4-With increasing the surface of heating body the input

temperature of hot water in the condenser exponentially

decreases.

5-Greatest heating surfaces are floor, wall and ceiling

panels for them is sufficient inlet temperature of hot

water in the condenser tvi= 20-30 ℃. For this

temperature interval the performance of condenser is the

largest q = 28.5 to 26 kW.

6-Smaller heating surface are fan-coils for them interval

of inlet temperature of hot water in the condenser tvi=

35-40 ℃. Therefore the performance of condenser

reduces on q = 21.9-19 kW.

7-At least the heating surface have radiators for them

necessary inlet temperature of hot water in the

condenser is tvi= 45-50 ℃. So the performance of

condenser significantly reduces q = 17-15 kW.

References

[1] HatefMadani, Joachim Claesson, Per Lundqvist:

„Capacitycontrolingroundsourceheatpumpsystems Part

I: modeling and simulation" I J Refrigeration, Vol

34 (2011), pp 1338-1347.

[2] EliasKinab, DominiqueMarchio, Philippe Riviere,

AssaadZoughaib:

„Reversibleheatpumpmodelforseasonal performance

optimization” I J Energy and Buildings, Vol 42 (2010),

pp 2269-2280.

[3] HongtaoQiao, VikrantAute, Hoseong Lee,

KhaledSaleh, ReinhardRadermacher: ”A

newmodelforplateheatexchangerswithgeneralized flow

configurations and phasechange” I J RefrigerationVol

36 (2013), pp 622-632.

[4] Julio Cesar Pacio, Carlos Alberto Dorao: A review on

heat exchanger thermal hydraulic models for cryogenic

applications. I J Cryogenics Vol. 51 (2011), pp 366–

379.

[5] Róbert Sánta: „The Analysis of Two-

PhaseCondensationHeatTransferModelsBasedontheCo

mparison of theBoundaryCondition” ActaPolytechnica

EXPRES 2017

ISBN 978-86-919769-1-0

Hungarica Vol. 9, No. 6, 2012, pp 167-180.

[6] Yi-YieYan, Hsiang-ChaoLio, Tsing-FaLin:

”Condensationheattransfer and pressuredrop of

refrigerant R-134ain a plateheatexchanger”

International Journal of Heat and MassTransferVol

42 (1999), pp 993-1006.

[7] Imrich Bartal, Hc László Bánhidi, László Garbai:

”Analysis of thestaticthermalcomfortequation”

Energy and BuildingsVol. 49 (2012), pp 188-191.

[8] Garbai L., JasperA. : A matematikai

rendszerelmélet feldolgozása és alkalmazása

épületgépészeti optimalizációs feladatok

megoldására; Magyar Épületgépészet LX.

évfolyam, 2011/3. szám, pp. 3-6.

[9] ]Garbai L., Méhes Sz.: Energy Analysis of

Geothermal Heat Pump with U-tube Installations. IEEE

International Symposium CFP 1188N-PRT “EXPRES

2011.” Proceedings, pp 107-112. Subotica, Serbia. 11-

12 03. 2011.

[10] M. M. Awad, H. M. Mostafa, G. I. Sultan, A. Elbooz,

A. M. K. El-ghonemy: Performance Enhancement of

Air-cooled Condensers, ActaPolytechnicaHungarica,

Volume 4, No. 2, pp. 125-142, 2007

[11] Nyers J. Stoyan G.:" A Dynamical Model Adequate for

Controlling the Evaporator of Heat Pump",

Internationale Journal of Refrigeration,Vol.17, Issue 2,

p.101-108, 1994.

31

EXPRES 2017

ISBN 978-86-919769-1-0

bar and initial performance q = 21 kW, increases in

percent only 4.7% . In case if ∆p = 0.81 bar and q =

17.5 kW increment is ∆q = 4.2 kW, increment in the

percent only 24%.

7-The value of the quasi-optimal power of

circulation pump is reduced if decreases resistance

to flow. If ∆p = 0.81 bar then the quasi optimum

power is around Pcirc = 120 W, if ∆p = 0.15 bar then

power around Pcirc = 80 W.

8-The most important conclusion is, by increasing

the power of circulation pump the performance of

condenser only in a very narrow interval enhances.


of circulation pump and surface of condensers if Tvi

= 35 ℃ and ∆p = 0.5 bar. Figures 4.


power of circulation pump and furface

1-Performance at the upper of condenser conditions

at low power of circulation pump Pcirc = 20W and

small surface of condenser f = 0.6m² has the lowest

value of q = 14.2 kW.

2-Performance of condenser has a maximum value

when the power and surface have maximum. q =

22.1 kW if Pcirc = 310W, f = 4.2m².

3-Observed from the minimum point, the value of

condenser's performance grows exponentially to the

value of quasi-optimum, if the power and surface

increase linearly.

4-After the quasi-optimum the performance of

condenser monotonically increases and approaches

to the asymptote if power and surface increase

linearly. (Figure 5).

5-Quasi optimal surface estimate from the diagram 6

and has a value of about f = 2m2 if tvi = 35 ℃, ∆p =

0.5 bar and power of circulation pump are in the

range Pcirc = 80-120W. (Figure 6).

6-Quasi optimal surface is very small depends on the

power of circulation pump. After the quasi-optimal

points, lines of constant surface almost parallel to

the axis of power of circulation pump.

7-Increasing the surface of condenser causes more

intense increase the performance of condenser, as

the power of circulation pump.


of circulation pump and inlet temperature of hot

water in the condenser if f = 2m² and∆p = 0.5 bar.

Figures 5.


power of circulation pump and temperature of inlet

water

1-Inlet temperature of hot water in the condenser to

mostly affect on the performace of condenser.

2-In the temperature range of 50-20 ℃tvi = performance

of condenser moves between q = 15-28.5 kW if Pcirc =

120W, f = 2m2 and ∆p = 0.5 bar. Figure 8

3-Performance of condenser increases by 1.9 times if the

temperature of inlet hot water decreases from 50 ℃. on

20 ℃.

4-With increasing the surface of heating body the input

temperature of hot water in the condenser exponentially

decreases.

5-Greatest heating surfaces are floor, wall and ceiling

panels for them is sufficient inlet temperature of hot

water in the condenser tvi= 20-30 ℃. For this

temperature interval the performance of condenser is the

largest q = 28.5 to 26 kW.

6-Smaller heating surface are fan-coils for them interval

of inlet temperature of hot water in the condenser tvi=

35-40 ℃. Therefore the performance of condenser

reduces on q = 21.9-19 kW.

7-At least the heating surface have radiators for them

necessary inlet temperature of hot water in the

condenser is tvi= 45-50 ℃. So the performance of

condenser significantly reduces q = 17-15 kW.

References

[1] HatefMadani, Joachim Claesson, Per Lundqvist:

„Capacitycontrolingroundsourceheatpumpsystems Part

I: modeling and simulation" I J Refrigeration, Vol

34 (2011), pp 1338-1347.

[2] EliasKinab, DominiqueMarchio, Philippe Riviere,

AssaadZoughaib:

„Reversibleheatpumpmodelforseasonal performance

optimization” I J Energy and Buildings, Vol 42 (2010),

pp 2269-2280.

[3] HongtaoQiao, VikrantAute, Hoseong Lee,

KhaledSaleh, ReinhardRadermacher: ”A

newmodelforplateheatexchangerswithgeneralized flow

configurations and phasechange” I J RefrigerationVol

36 (2013), pp 622-632.

[4] Julio Cesar Pacio, Carlos Alberto Dorao: A review on

heat exchanger thermal hydraulic models for cryogenic

applications. I J Cryogenics Vol. 51 (2011), pp 366–

379.

[5] Róbert Sánta: „The Analysis of Two-

PhaseCondensationHeatTransferModelsBasedontheCo

mparison of theBoundaryCondition” ActaPolytechnica

EXPRES 2017

ISBN 978-86-919769-1-0

Hungarica Vol. 9, No. 6, 2012, pp 167-180.

[6] Yi-YieYan, Hsiang-ChaoLio, Tsing-FaLin:

”Condensationheattransfer and pressuredrop of

refrigerant R-134ain a plateheatexchanger”

International Journal of Heat and MassTransferVol

42 (1999), pp 993-1006.

[7] Imrich Bartal, Hc László Bánhidi, László Garbai:

”Analysis of thestaticthermalcomfortequation”

Energy and BuildingsVol. 49 (2012), pp 188-191.

[8] Garbai L., JasperA. : A matematikai

rendszerelmélet feldolgozása és alkalmazása

épületgépészeti optimalizációs feladatok

megoldására; Magyar Épületgépészet LX.

évfolyam, 2011/3. szám, pp. 3-6.

[9] ]Garbai L., Méhes Sz.: Energy Analysis of

Geothermal Heat Pump with U-tube Installations. IEEE

International Symposium CFP 1188N-PRT “EXPRES

2011.” Proceedings, pp 107-112. Subotica, Serbia. 11-

12 03. 2011.

[10] M. M. Awad, H. M. Mostafa, G. I. Sultan, A. Elbooz,

A. M. K. El-ghonemy: Performance Enhancement of

Air-cooled Condensers, ActaPolytechnicaHungarica,

Volume 4, No. 2, pp. 125-142, 2007

[11] Nyers J. Stoyan G.:" A Dynamical Model Adequate for

Controlling the Evaporator of Heat Pump",

Internationale Journal of Refrigeration,Vol.17, Issue 2,

p.101-108, 1994.

32

EXPRES 2017 ISBN 978-86-919769-1-0

Increasing efficiency of fixture planning by

automating some planning steps M. STAMPFERa,b, A. RÉTFALVIb

a) Department of Mechanical Engineering, , University of Pécs

H-7624 Pécs, Boszorkány u. 2, Hungary

b) Department of Mechanical Engineering, Subotica Tech

24000 Subotica, Marka Oreškovića 16, Serbia a E-mail: [email protected] b E-mail: [email protected]

In this paper a short description of an expert system for setup and fixture planning and fixture design is presented. The expert system

reduces the time spent on fixture design compared to manual fixture design.

Keywords: Computer Aided Fixture Design (CAFD), Process Planning

1. Introduction

The technological planning can be broken down

into several steps (Figure1): (1) setup planning and

conceptual design of fixtures; (2) operation planning:

(3) fixture configuration and design. The setup planning and conceptual design of fixtures

is one of the most complex intellectual tasks in the

process of industrial design and can be automated

only with great difficulty. The reason is perhaps that

the existing knowledge for the fixture solution is not

available in explicit form as formulas, logical

diagrams, or well-defined processes. Some of the

major achievements in this field are listed below.

[1] presented the FIXES system for setup and fixture

planning for prismatic parts. It is a subsystem of the

PART CAPP system which is the first complete

expert process planning system to be commercialised

and covers most of the process planning functions.

The approach of [2] provided a short description of a

Setup planner, and a more detailed description of a

Fixture planning program. [3] presented an

automated fixture design system in which the

fixturing surfaces are automatically determined based

on geometric and operational information. [4] offered

a method for setup planning and setup sequence

optimising by applying genetic algorithms. [5]

applied case-based reasoning for process planning for

prismatic parts where the clamping device is a vice.

[6] developed a method which deals with

simultaneous grouping of machining operations in

the setup and selects adapted fixturing solutions. [7]

presented an integrated setup and fixture planning

system that sets out from the STEP (Standard for

Exhcahnge of Product model data) format model of

the workpiece. Several researchers have employed

modular fixturing principles to generate fixture

designs.

Although numerous CAFD (Computer Aided Fixture

Design) techniques have been proposed and

implemented, fixture design still continues to be a

major bottleneck in the integration of CAD (Computer

Aided Design) and CAM (Computer Aided

Manufacturing) activities. With the review of the new

method for fixture planning, developed for box-shaped

parts machined on four-axis horizontal machines, we

wish to contribute to overcoming the difficulty.

Figure 1 Integrated Process Planning and Fixture Planning

System

INCREASING EFFICIENCY OF FIXTURE PLANNING BY AUTOMATING SOME PLANNING STEPS

2. The IGES postprocessing / SUPFIX

preprocessing module (IPPO) [8] Nowadays product design is mainly done with the

help of some kind of 3D modeling software. Since

different software packages stores the models made

with them in a little bit different format, several so-

called neutral (platform independent) file format

standard have been developed. The most commonly

used are STEP and IGES (Initial Graphics Exchange

Specifications). Our system contains a module which

can open CAD models saved in IGES format, and

from that data set regenerates the curves and surfaces

of the model, and visualize them. This module

examines curves and surfaces, picks common curves

and surfaces they belong, and examines if they form

a machining feature. This module can recognize the

features shown in Figure 2, these features are most

frequently present on box-shaped parts, especially on

gearbox casings.

Figure 2 Most common features on gearbox casings

The program at first looks for common circular or

elliptical arcs and investigates if they are part of any

feature marked with tf 1.., tf 2.. or tf 3.. . Then it

examines plane surfaces and looks if there are such

coplanar surfaces that could serve as supporting,

locating or clamping surfaces. Finally from those

surfaces that do not belong either of above mentioned

two groups, and are not hindered (less than 40% of

their surface area is covered, so they could be used for

locating or clamping) the program makes stand alone

features (one surface features). Of course besides

recognizing features, the program extracts their

characteristic parameters like diameter or length, etc.

The most important parameters of each feature are also

shown in Figure 2

After feature recogniton we can define which features

should be machined. Technologycal requirements like

IT class and surface roughness can be determined, as

well as whether or not a surface should be threaded. If

a feature is selected and the “tolerances” button

clicked on, then another feature may be selected, and

position or distance tolerance between them

prescribed. When all technological requirements are

defined we store all data in such a form that the next

module (SUPFIX) can process. In other words the data

stored in the form shown in Figure 3 are converted and

stored in form as shown in Figure 4

Figure 3 Data structure of IGES files

Figure 4 Data structure of IPPO files

3. The Setup and Fixture Planning

module (SUPFIX) [9][10]

This module uses data stored by IGES postprocessing

module. It analyzes machining requirements and

relationship tolerances, and selects eligible supporting

side and supporting type. First it tries to find such

supporting surface that ensures the machining of all

tolerance connected surfaces in the same setup (the

ideal technological position). If this succeeds, it checks

if there are eligible locating and clamping surfaces. If

it finds eligible surfaces, it gives us a proposal. The

process engineer can accept or refuse that proposal. In

case of rejection the program tries to find another

solution. If the ideal technological position strategy

does not bring fruits, the program tries to find such a

solution at which at least the strictly connected

surfaces are machined in the same setup. If this

attempt fails, the program decomposes a strictly

connected side and all strictly connected surfaces are

machined in the same setup, while the loosely

connected surfaces in the other setup. This solution

needs special fixture solution, which ensures that the

33

EXPRES 2017 ISBN 978-86-919769-1-0

Increasing efficiency of fixture planning by

automating some planning steps M. STAMPFERa,b, A. RÉTFALVIb

a) Department of Mechanical Engineering, , University of Pécs

H-7624 Pécs, Boszorkány u. 2, Hungary

b) Department of Mechanical Engineering, Subotica Tech

24000 Subotica, Marka Oreškovića 16, Serbia a E-mail: [email protected] b E-mail: [email protected]

In this paper a short description of an expert system for setup and fixture planning and fixture design is presented. The expert system

reduces the time spent on fixture design compared to manual fixture design.

Keywords: Computer Aided Fixture Design (CAFD), Process Planning

1. Introduction

The technological planning can be broken down

into several steps (Figure1): (1) setup planning and

conceptual design of fixtures; (2) operation planning:

(3) fixture configuration and design. The setup planning and conceptual design of fixtures

is one of the most complex intellectual tasks in the

process of industrial design and can be automated

only with great difficulty. The reason is perhaps that

the existing knowledge for the fixture solution is not

available in explicit form as formulas, logical

diagrams, or well-defined processes. Some of the

major achievements in this field are listed below.

[1] presented the FIXES system for setup and fixture

planning for prismatic parts. It is a subsystem of the

PART CAPP system which is the first complete

expert process planning system to be commercialised

and covers most of the process planning functions.

The approach of [2] provided a short description of a

Setup planner, and a more detailed description of a

Fixture planning program. [3] presented an

automated fixture design system in which the

fixturing surfaces are automatically determined based

on geometric and operational information. [4] offered

a method for setup planning and setup sequence

optimising by applying genetic algorithms. [5]

applied case-based reasoning for process planning for

prismatic parts where the clamping device is a vice.

[6] developed a method which deals with

simultaneous grouping of machining operations in

the setup and selects adapted fixturing solutions. [7]

presented an integrated setup and fixture planning

system that sets out from the STEP (Standard for

Exhcahnge of Product model data) format model of

the workpiece. Several researchers have employed

modular fixturing principles to generate fixture

designs.

Although numerous CAFD (Computer Aided Fixture

Design) techniques have been proposed and

implemented, fixture design still continues to be a

major bottleneck in the integration of CAD (Computer

Aided Design) and CAM (Computer Aided

Manufacturing) activities. With the review of the new

method for fixture planning, developed for box-shaped

parts machined on four-axis horizontal machines, we

wish to contribute to overcoming the difficulty.

Figure 1 Integrated Process Planning and Fixture Planning

System


2. The IGES postprocessing / SUPFIX

preprocessing module (IPPO) [8] Nowadays product design is mainly done with the

help of some kind of 3D modeling software. Since

different software packages stores the models made

with them in a little bit different format, several so-

called neutral (platform independent) file format

standard have been developed. The most commonly

used are STEP and IGES (Initial Graphics Exchange

Specifications). Our system contains a module which

can open CAD models saved in IGES format, and

from that data set regenerates the curves and surfaces

of the model, and visualize them. This module

examines curves and surfaces, picks common curves

and surfaces they belong, and examines if they form

a machining feature. This module can recognize the

features shown in Figure 2, these features are most

frequently present on box-shaped parts, especially on

gearbox casings.

Figure 2 Most common features on gearbox casings

The program at first looks for common circular or

elliptical arcs and investigates if they are part of any

feature marked with tf 1.., tf 2.. or tf 3.. . Then it

examines plane surfaces and looks if there are such

coplanar surfaces that could serve as supporting,

locating or clamping surfaces. Finally from those

surfaces that do not belong either of above mentioned

two groups, and are not hindered (less than 40% of

their surface area is covered, so they could be used for

locating or clamping) the program makes stand alone

features (one surface features). Of course besides

recognizing features, the program extracts their

characteristic parameters like diameter or length, etc.

The most important parameters of each feature are also

shown in Figure 2

After feature recogniton we can define which features

should be machined. Technologycal requirements like

IT class and surface roughness can be determined, as

well as whether or not a surface should be threaded. If

a feature is selected and the “tolerances” button

clicked on, then another feature may be selected, and

position or distance tolerance between them

prescribed. When all technological requirements are

defined we store all data in such a form that the next

module (SUPFIX) can process. In other words the data

stored in the form shown in Figure 3 are converted and

stored in form as shown in Figure 4

Figure 3 Data structure of IGES files

Figure 4 Data structure of IPPO files

3. The Setup and Fixture Planning

module (SUPFIX) [9][10]

This module uses data stored by IGES postprocessing

module. It analyzes machining requirements and

relationship tolerances, and selects eligible supporting

side and supporting type. First it tries to find such

supporting surface that ensures the machining of all

tolerance connected surfaces in the same setup (the

ideal technological position). If this succeeds, it checks

if there are eligible locating and clamping surfaces. If

it finds eligible surfaces, it gives us a proposal. The

process engineer can accept or refuse that proposal. In

case of rejection the program tries to find another

solution. If the ideal technological position strategy

does not bring fruits, the program tries to find such a

solution at which at least the strictly connected

surfaces are machined in the same setup. If this

attempt fails, the program decomposes a strictly

connected side and all strictly connected surfaces are

machined in the same setup, while the loosely

connected surfaces in the other setup. This solution

needs special fixture solution, which ensures that the

34


part can be partly machined on the supporting side

too. If the program is unable to find such solution,

then some strictly connected surfaces must be

machined in different setups. In that case complicated

and expensive fixtures are needed.

During the analysis of a feature from the aspect of

supporting eligibility the program performs shape,

size, machining requirements and tolerance

relationships analysis. The locating surface

candidates are investigated from the aspects of shape,

size and location. The clamping surface candidates

are investigated from the aspects of shape, size,

location and force closure.

4. The Fixture Configuration module

(FIXCO)

In the possession of (by the SUPFIX module)

proposed supporting, locating and clamping surfaces,

this module tries to build a modular fixture that is

eligible for precise and stable clamping of the

workpiece. In first step the program selects the

proper ground plate and (if needed) supporting

elements, then puts the workpiece on the centre of the

ground plate, then selects locating elements

depending on the kind, height and orientation of

locating surfaces. In the following step the program

moves the workpiece as the locating elements

require. After that the program tries to place

clamping elements over such ground plate holes

which are close enough to the clamping surface

contour to ensure stiff clamping. If this attempt does

not succeed, then adopting elements should be used.

Adopting elements are used to increase the height of

functional elements, or when we have to move the

functional elements along a given direction, in order

to be at the ideal position. But by applying adopter

elements the fixture becomes complicated, increases

the fixture weight and decreases the stability and

accuracy. So if possible, it is better to design fixture

with possible least number of elements. When the

fixture – built only from standard modular elements –

would be too complicated, or the precision of the

fixture would not be satisfying, then the system can

generate extra locator elements. Thenks to these extra

locator elements the resulting fixture is much

simpler. The system also can modify these extra

locator elements – if it is required, for example in the

sake of avoiding some interference between the

fixtrure elements, or between the extra locator

element and the workpiece. To make the process

planning easier, the program visualizes not only the

3D image of the fixture, but in a separate window it

shows the 2D views of the fixture from top and side

directions. This way it is easier to notice if any

element is not in the right position. In such cases the

process engineer can grasp the element with the

mouse and move it to the right place.

5. Implementation and test example

The Integrated Process Planning and Fixture Planning

System is made up of several modules presented in

Figure 1. All modules are implemented in Visual

Prolog programming language. The feature-based

workpiece model, which is created by the CAD model

post processing module, is the input of the Fixture

Planning System. Based on this input the system

generates an acceptable solution for setup(s) and

fixture(s) definition. Search for a fixture solution is

carried out automatically, but the solution offered by

the system must be approved by the user. This may

primarily be necessary regarding the selection of the

clamping points, as it may happen that the clamping

element obstructs the machining and, at its current

level of development, the system is unable to detect

this kind of inference.

The approach described above has been tested on

industrial parts. Presented in Figure 5 is an example of

a typical workpiece. The surfaces (features) of the

workpiece are marked with numbers on the drawing.

With geometrical – and tolerance analysis of the

workpiece, the following facts are known: Strictly

connected features of the workpiece are the features

marked with the numbers 2, 3, 12 and 13. Loosely

connected features are marked with 1 and 11.

Respectively the front – and the back faces are strictly

connected faces, and the top, bottom, left and right

faces are free faces. In the first step, the system tries to

solve the main clamping, applying the first strategy,

namely the main clamping fixture solution for the

technologically ideal position of the workpiece. The

workpiece can be placed in the workspace of the

machine tool in the technologically ideal workpiece

position if, for example, the plane locating face is at

the bottom because the bottom face and top faces are

not tolerance-related faces, but the bottom face is not

suitable for plane locating. Hence this attempt will fail.

The same problem occurs by supposing the plane

locating face is the top, left, or right face. That is why

this strategy must be skipped and the second strategy

be applied. By using the second strategy, namely the

Fixture solution based on disregarding the loosely

tolerance-related faces, the same problems are likely to

occur as with the first strategy. After the failure of

both the first and second strategies the system will

apply the third strategy, which is the fixture solution

based on the reduction of a strictly tolerance-related

side into loosely tolerance-related surfaces and strictly

tolerance-related surfaces. According to this strategy

the plane locating type is vertical with ability of partial

machining of the locating face. The system checks the

suitability of possible workpiece positions for locating

and clamping. At this strategy the system looks for

supporting faces only among the strictly connected

faces.


Figure 5 Test example

If it is assumed that the plane locating face is the

front face, the system will yield the fixture solution

for the main clamping (Figure 6). The plane locating

surface is the feature marked by number 1. The side

locating is possible by using two threaded joints

denoted with number 4 and 5 on the front face. The

clamping is done by screws and threaded joints on

the front face denoted with number 4, 5, 6, 7. The

features on the front face denoted with number 1, 4,

5, 6 and 7 will be machined in additional clamping

while the strictly connected features 2 and 3 will be

machined in the main clamping together with the

other strictly connected features of the workpiece.

This is possible only through the opening in the

fixture body (Figure 7).

Figure 6 The proposed conceptual solution for the main setup

Figure 7 The realised fixture for the main clamping with the

workpiece

6. Conclusions

By automating the feature recognition, the search for

the conceptual solution of the fixture, and the building

of the model of the modular fixture substantial time

can be spared during the fixture planning. The model

or the fixture is built from standard modular elements,

and when it is required, is complemented withe some

extra locator element. The generation and modification

of the extra elements is also automated. In Table 1 the

time costs (AMD Athlon 64 processor, 3200+, 2,01

GHz and 2GB RAM) of the stages of fixture planning

and design can be seen for the gearbox housings

shown in Figure 8. Earlier these stages took several

hours, now – thanks to automation of some fixture

35


part can be partly machined on the supporting side

too. If the program is unable to find such solution,

then some strictly connected surfaces must be

machined in different setups. In that case complicated

and expensive fixtures are needed.

During the analysis of a feature from the aspect of

supporting eligibility the program performs shape,

size, machining requirements and tolerance

relationships analysis. The locating surface

candidates are investigated from the aspects of shape,

size and location. The clamping surface candidates

are investigated from the aspects of shape, size,

location and force closure.

4. The Fixture Configuration module

(FIXCO)

In the possession of (by the SUPFIX module)

proposed supporting, locating and clamping surfaces,

this module tries to build a modular fixture that is

eligible for precise and stable clamping of the

workpiece. In first step the program selects the

proper ground plate and (if needed) supporting

elements, then puts the workpiece on the centre of the

ground plate, then selects locating elements

depending on the kind, height and orientation of

locating surfaces. In the following step the program

moves the workpiece as the locating elements

require. After that the program tries to place

clamping elements over such ground plate holes

which are close enough to the clamping surface

contour to ensure stiff clamping. If this attempt does

not succeed, then adopting elements should be used.

Adopting elements are used to increase the height of

functional elements, or when we have to move the

functional elements along a given direction, in order

to be at the ideal position. But by applying adopter

elements the fixture becomes complicated, increases

the fixture weight and decreases the stability and

accuracy. So if possible, it is better to design fixture

with possible least number of elements. When the

fixture – built only from standard modular elements –

would be too complicated, or the precision of the

fixture would not be satisfying, then the system can

generate extra locator elements. Thenks to these extra

locator elements the resulting fixture is much

simpler. The system also can modify these extra

locator elements – if it is required, for example in the

sake of avoiding some interference between the

fixtrure elements, or between the extra locator

element and the workpiece. To make the process

planning easier, the program visualizes not only the

3D image of the fixture, but in a separate window it

shows the 2D views of the fixture from top and side

directions. This way it is easier to notice if any

element is not in the right position. In such cases the

process engineer can grasp the element with the

mouse and move it to the right place.

5. Implementation and test example

The Integrated Process Planning and Fixture Planning

System is made up of several modules presented in

Figure 1. All modules are implemented in Visual

Prolog programming language. The feature-based

workpiece model, which is created by the CAD model

post processing module, is the input of the Fixture

Planning System. Based on this input the system

generates an acceptable solution for setup(s) and

fixture(s) definition. Search for a fixture solution is

carried out automatically, but the solution offered by

the system must be approved by the user. This may

primarily be necessary regarding the selection of the

clamping points, as it may happen that the clamping

element obstructs the machining and, at its current

level of development, the system is unable to detect

this kind of inference.

The approach described above has been tested on

industrial parts. Presented in Figure 5 is an example of

a typical workpiece. The surfaces (features) of the

workpiece are marked with numbers on the drawing.

With geometrical – and tolerance analysis of the

workpiece, the following facts are known: Strictly

connected features of the workpiece are the features

marked with the numbers 2, 3, 12 and 13. Loosely

connected features are marked with 1 and 11.

Respectively the front – and the back faces are strictly

connected faces, and the top, bottom, left and right

faces are free faces. In the first step, the system tries to

solve the main clamping, applying the first strategy,

namely the main clamping fixture solution for the

technologically ideal position of the workpiece. The

workpiece can be placed in the workspace of the

machine tool in the technologically ideal workpiece

position if, for example, the plane locating face is at

the bottom because the bottom face and top faces are

not tolerance-related faces, but the bottom face is not

suitable for plane locating. Hence this attempt will fail.

The same problem occurs by supposing the plane

locating face is the top, left, or right face. That is why

this strategy must be skipped and the second strategy

be applied. By using the second strategy, namely the

Fixture solution based on disregarding the loosely

tolerance-related faces, the same problems are likely to

occur as with the first strategy. After the failure of

both the first and second strategies the system will

apply the third strategy, which is the fixture solution

based on the reduction of a strictly tolerance-related

side into loosely tolerance-related surfaces and strictly

tolerance-related surfaces. According to this strategy

the plane locating type is vertical with ability of partial

machining of the locating face. The system checks the

suitability of possible workpiece positions for locating

and clamping. At this strategy the system looks for

supporting faces only among the strictly connected

faces.


Figure 5 Test example

If it is assumed that the plane locating face is the

front face, the system will yield the fixture solution

for the main clamping (Figure 6). The plane locating

surface is the feature marked by number 1. The side

locating is possible by using two threaded joints

denoted with number 4 and 5 on the front face. The

clamping is done by screws and threaded joints on

the front face denoted with number 4, 5, 6, 7. The

features on the front face denoted with number 1, 4,

5, 6 and 7 will be machined in additional clamping

while the strictly connected features 2 and 3 will be

machined in the main clamping together with the

other strictly connected features of the workpiece.

This is possible only through the opening in the

fixture body (Figure 7).

Figure 6 The proposed conceptual solution for the main setup

Figure 7 The realised fixture for the main clamping with the

workpiece

6. Conclusions

By automating the feature recognition, the search for

the conceptual solution of the fixture, and the building

of the model of the modular fixture substantial time

can be spared during the fixture planning. The model

or the fixture is built from standard modular elements,

and when it is required, is complemented withe some

extra locator element. The generation and modification

of the extra elements is also automated. In Table 1 the

time costs (AMD Athlon 64 processor, 3200+, 2,01

GHz and 2GB RAM) of the stages of fixture planning

and design can be seen for the gearbox housings

shown in Figure 8. Earlier these stages took several

hours, now – thanks to automation of some fixture

36


planning steps – they take remarkably less time.

Figure 8 Gearbox housings [11]

Table 1 The time needed for different stages of the fixture planning and design [11]

Stages of the fixture planning and design

Gearbox housings

Part A Part B Part C Part D

Regeneration of the model and feature recognition 1 min 8 s 9 s 10 s 7 s

Defining machining requirements 12 min 9 min 13 min 7 min

Finding the conceptual solution of the fixture 1 min 42 s 1 min 8 s 2 min 10 s 1 min 56 s

Fixture configuration Auxiliary setup 56 s

Main setup 32

s

Auxiliary setup 46 s

Main setup 22 s


Main setup 28 s


Main setup 24 s

References

[1] J. R.. Boerma, H. J. J. Kals: „FIXES, a System for

Automatic Selection of Setups and Design of Fixtures”,

Annals of CIRP Vol. 37/1, 1988. pp. 443-446.

[2] A. Joneja, T-C Chang „Setup and fixture planning in

autmated process planning systems”, IIE Transaction

31, 1999. pp. 653-665.

[3] W. Ma, J. Li and Y. Rong, „Development of Automated

Fixture Planning Systems”, Int. J. of Adv. Manuf.

Techn. 15, pp. 171-181, 1999.

[4] M. Horváth, A. Márkus, J. Váncza „Process planning

with genetic algorithms on results of knowledge-based

reasoning”, Int. J. Comp. Integ. Manuf. 9,No.2, 1996,

pp. 145-166.

[5] M. Marefat, J. Britanik „Case-based process planning

using an object-oriented model representation”, Robo.

and Comp.-Integ. Manuf. 13, No. 3, 1997. pp. 229-251..

[6] H. Paris, D. Brissaud „Process planning strategy based

on fixturing indicator evaluation”, Int. J. of Adv.

Manuf. Techn. 25, pp. 913-922, 2005.

[7] S. Bansal, S. Nagarajan, N. Venkata Reddy „An

integrated fixture planning system for minimum

tolerances”, Int. J. of Adv. Manuf. Techn. 38, pp. 501-

513, 2008.

[8] A. Rétfalvi “IGES-based CAD model postprocessing

module of a Setup and Fixture Planning System for box-

shaped parts”, IEEE 9th Symp. on Intel. Syst. and Inform.,

September 8-10, 2011, Subotica, Serbia

[9] M. Stampfer „Integrated Setup and Fixture Planning

System for Gearbox Casings”, Int. J. of Adv. Manuf.

Techn., 26, pp.310-318, 2005.

[10] M. Stampfer „Automated setup and fixture planning

system for box-shaped parts”, Int. J. of Adv. Manuf.

Techn. 45, pp. 540-552, 2009.

[11] A. Rétfalvi „Fixture Design System with Automatic

Generation and Modification of Compementary Elements

for Modular Fixtures”, Acta Polytechnica Hungarica,

vol.12, No.7, pp. 163-182, 2015

EXPRES 2017

ISBN 978-86-919769-1-0

Simulation result of a nuclear power plant cooling system using Matlab

A, SZENTE a , I. FARKAS

b, P. ODRY

c

a Paks Nuklear Power Plant, Paks, Hungary, E-mail: [email protected] b University of Dunaújváros/Computer Engineering, Dunaújváros, Hungary, E-mail: [email protected] c University of Dunaújváros/Computer Engineering, Dunaújváros, Hungary, E-mail: [email protected]

It has been shown in recent years that there is a great need for additional security measures to be taken in high security systems in

case of occurrence of unanticipated events. A Nuclear Power Plant is exactly such kind of a sophisticated system. Thou, before

we begin to work on improving the overall security of a system, we must familiarize ourselves with the type of event that causes

the issue during an unanticipated event. For this we need a well-constructed simulation. The fortification of the removal of decay

heat following the subcritical stage of a reactor shutdown forms a significant portion of the workings of a nuclear power plant.

The lack of such a measure could lead to a catastrophic meltdown (Fukushima 2011). The necessary electrical energy for this

process under normal conditions is supplied by the primary (national and home power grids) and secondary (diesel generators)

electrical supply systems. One of the key factors of the insurance of higher plant safety could be the application of a third diverse

decay heat removal ensuring system. The solutions that we came up with were based on the observations of the Paks Nuclear

Power Plant in Hungary VVER440 type reactor cores, thou it could be reflected to any similar working nuclear power plant type.

Keywords: Nuclear Power Plant, subcritical stage of a reactor, primary electrical supply systems, security,

simulation

1. The basics of nuclear power plant

cooling

Once the adequate boric concentration is reached

during shutdown the reactor needs to be cooled down,

and kept at a desirable temperature. During cooldown

on the one hand the heat stored in the structure as well

as the decay heat generated by the active zone needs to

be removed.

During the first stage of the process, it’s necessary to

set the prescribed temperature difference of 60oC in the

primary circuit-pressurizer, using the cooling of the

pressurizer. Naturally, this implies that the pressure in

the primary circuit needs to be lowered. Later, besides

the cooling of the primary circuit it’s important to

constantly keep this difference.

Due to the constant pressure lowering in the primary

circuit, the hydro-accumulators need to be disengaged

from the primary circuit once a pI<75bar pressure is

reached, also as the primary circuit is being cooled, it’s

pressure needs to be let out by releasing the nitrogen

(to avoid any risk of brittle fracture). Once we reach a

pressure of pI≤20[bar] during the depressurization of

the primary circuit, the steam cushion in the

pressurizers needs to be changed to nitrogen. To

minimize the necessary quantity of nitrogen, it’s

imperative that the pressurizers are to be filled to their

maximal capacity (LYP10 = 7.5±0.5 m) before the

administration of nitrogen. In the following the precise

level in the pressurizers should be kept particularly in

mind, because the changes in that significantly affect the

primary circuit pressure. (Due to the continuous primary

circuit cooling, the constant level in the pressurizer can

only be ensured if the drop-in volume is substituted

continuously with water, unlike the power stage, where

per the average temperature we let the level change,

namely we keep a constant volume of water.) The

∆T=60oC between the primary circuit and the

pressurizer needs to be kept at until TI≤ 150oC,

following which it’s needs to be lowered to ∆T = 30oC.

Attention needs to be paid during the set of the

cooling speed, so as the maximum allowed is not

exceeded, therefore it must be approached from below.

In the case of huge supply tanks and big primary circuit

temperature differences the exceedance can easily

occur. The cooling must be carried out by the

Fig. 1. The remanans heat generation performance

Fig. 2. Diagram of the cooling for a normal cooling process

37


planning steps – they take remarkably less time.

Figure 8 Gearbox housings [11]

Table 1 The time needed for different stages of the fixture planning and design [11]

Stages of the fixture planning and design

Gearbox housings

Part A Part B Part C Part D

Regeneration of the model and feature recognition 1 min 8 s 9 s 10 s 7 s

Defining machining requirements 12 min 9 min 13 min 7 min

Finding the conceptual solution of the fixture 1 min 42 s 1 min 8 s 2 min 10 s 1 min 56 s

Fixture configuration Auxiliary setup 56 s

Main setup 32

s


Main setup 22 s


Main setup 28 s


Main setup 24 s

References

[1] J. R.. Boerma, H. J. J. Kals: „FIXES, a System for

Automatic Selection of Setups and Design of Fixtures”,

Annals of CIRP Vol. 37/1, 1988. pp. 443-446.

[2] A. Joneja, T-C Chang „Setup and fixture planning in

autmated process planning systems”, IIE Transaction

31, 1999. pp. 653-665.

[3] W. Ma, J. Li and Y. Rong, „Development of Automated

Fixture Planning Systems”, Int. J. of Adv. Manuf.

Techn. 15, pp. 171-181, 1999.

[4] M. Horváth, A. Márkus, J. Váncza „Process planning

with genetic algorithms on results of knowledge-based

reasoning”, Int. J. Comp. Integ. Manuf. 9,No.2, 1996,

pp. 145-166.

[5] M. Marefat, J. Britanik „Case-based process planning

using an object-oriented model representation”, Robo.

and Comp.-Integ. Manuf. 13, No. 3, 1997. pp. 229-251..

[6] H. Paris, D. Brissaud „Process planning strategy based

on fixturing indicator evaluation”, Int. J. of Adv.

Manuf. Techn. 25, pp. 913-922, 2005.

[7] S. Bansal, S. Nagarajan, N. Venkata Reddy „An

integrated fixture planning system for minimum

tolerances”, Int. J. of Adv. Manuf. Techn. 38, pp. 501-

513, 2008.

[8] A. Rétfalvi “IGES-based CAD model postprocessing

module of a Setup and Fixture Planning System for box-

shaped parts”, IEEE 9th Symp. on Intel. Syst. and Inform.,

September 8-10, 2011, Subotica, Serbia

[9] M. Stampfer „Integrated Setup and Fixture Planning

System for Gearbox Casings”, Int. J. of Adv. Manuf.

Techn., 26, pp.310-318, 2005.

[10] M. Stampfer „Automated setup and fixture planning

system for box-shaped parts”, Int. J. of Adv. Manuf.

Techn. 45, pp. 540-552, 2009.

[11] A. Rétfalvi „Fixture Design System with Automatic

Generation and Modification of Compementary Elements

for Modular Fixtures”, Acta Polytechnica Hungarica,

vol.12, No.7, pp. 163-182, 2015

EXPRES 2017

ISBN 978-86-919769-1-0

Simulation result of a nuclear power plant cooling system using Matlab

A, SZENTE a , I. FARKAS

b, P. ODRY

c

a Paks Nuklear Power Plant, Paks, Hungary, E-mail: [email protected] b University of Dunaújváros/Computer Engineering, Dunaújváros, Hungary, E-mail: [email protected] c University of Dunaújváros/Computer Engineering, Dunaújváros, Hungary, E-mail: [email protected]

It has been shown in recent years that there is a great need for additional security measures to be taken in high security systems in

case of occurrence of unanticipated events. A Nuclear Power Plant is exactly such kind of a sophisticated system. Thou, before

we begin to work on improving the overall security of a system, we must familiarize ourselves with the type of event that causes

the issue during an unanticipated event. For this we need a well-constructed simulation. The fortification of the removal of decay

heat following the subcritical stage of a reactor shutdown forms a significant portion of the workings of a nuclear power plant.

The lack of such a measure could lead to a catastrophic meltdown (Fukushima 2011). The necessary electrical energy for this

process under normal conditions is supplied by the primary (national and home power grids) and secondary (diesel generators)

electrical supply systems. One of the key factors of the insurance of higher plant safety could be the application of a third diverse

decay heat removal ensuring system. The solutions that we came up with were based on the observations of the Paks Nuclear

Power Plant in Hungary VVER440 type reactor cores, thou it could be reflected to any similar working nuclear power plant type.

Keywords: Nuclear Power Plant, subcritical stage of a reactor, primary electrical supply systems, security,

simulation

1. The basics of nuclear power plant

cooling

Once the adequate boric concentration is reached

during shutdown the reactor needs to be cooled down,

and kept at a desirable temperature. During cooldown

on the one hand the heat stored in the structure as well

as the decay heat generated by the active zone needs to

be removed.

During the first stage of the process, it’s necessary to

set the prescribed temperature difference of 60oC in the

primary circuit-pressurizer, using the cooling of the

pressurizer. Naturally, this implies that the pressure in

the primary circuit needs to be lowered. Later, besides

the cooling of the primary circuit it’s important to

constantly keep this difference.

Due to the constant pressure lowering in the primary

circuit, the hydro-accumulators need to be disengaged

from the primary circuit once a pI<75bar pressure is

reached, also as the primary circuit is being cooled, it’s

pressure needs to be let out by releasing the nitrogen

(to avoid any risk of brittle fracture). Once we reach a

pressure of pI≤20[bar] during the depressurization of

the primary circuit, the steam cushion in the

pressurizers needs to be changed to nitrogen. To

minimize the necessary quantity of nitrogen, it’s

imperative that the pressurizers are to be filled to their

maximal capacity (LYP10 = 7.5±0.5 m) before the

administration of nitrogen. In the following the precise

level in the pressurizers should be kept particularly in

mind, because the changes in that significantly affect the

primary circuit pressure. (Due to the continuous primary

circuit cooling, the constant level in the pressurizer can

only be ensured if the drop-in volume is substituted

continuously with water, unlike the power stage, where

per the average temperature we let the level change,

namely we keep a constant volume of water.) The

∆T=60oC between the primary circuit and the

pressurizer needs to be kept at until TI≤ 150oC,

following which it’s needs to be lowered to ∆T = 30oC.

Attention needs to be paid during the set of the

cooling speed, so as the maximum allowed is not

exceeded, therefore it must be approached from below.

In the case of huge supply tanks and big primary circuit

temperature differences the exceedance can easily

occur. The cooling must be carried out by the

Fig. 1. The remanans heat generation performance

Fig. 2. Diagram of the cooling for a normal cooling process

38

2

subtraction of steam from the fresh steam collector

until TI = 140oC is reached. The condensate condensed

in the technology condenser is returned to the

secondary supply tank. In the last third of the water-

steam cooling the heating of the supply containers

should be gradually reduced to ensure the temperature

step between the primary - secondary circuit.

While above TI>190oC it’s advisable to avoid a too

high active zone pressure difference, an FKSZ needs to

be shut down. Because of the even cooling of primary

circuit pipes, the shutdown FKSZ needs to be restarted

(TI =175 and at 160oC) once we stopped an operator.

Once TI< 150oC is reached the speed of cooling drops

significantly, because the ∆T between the supply water

and the primary circuit is low. Once a stable value of

below 150oC is reached, the system should be switched

from steam – water to water – water cooling. To do

this the GF, fresh steam lines, fresh steam collectors,

and the cooling system should be filled with feed

water. Before the start of the filling, prevention of

inadvertent defense operations must take place, the

security of the GF’s need to be paralyzed on the BER

panel, because LGF>Lnominal+600mm excludes the

upload path. The speed of the filling needs to be set in

such a way that it’s minimum 3.5h’s. At this stage of

the cool-down the migration from the Stepped Start

Programs to the SSP II should be checked. The switch

to this program also means that some elements of the

ZÜHR systems are no longer needed now, in fact their

trigger could lead to adverse consequences, and

therefore, they should be staggered.

(Eg., Under pressure, still closed, but cooled reactor, if

the TH pumps are started even if for a false signal, we

can go beyond the allowed pressure of the brittle

temperature in seconds, or the sprinkler system starts

for a wrong signal, since on this primary temperature

it’s unlikely that even in the event of a broken pipe the

pressure of the containment reaches the limit.)Since

the amount of heat removal is steadily declining over

the filling, care should be taken that the primary circuit

does not warm up to above 150°C.

After filling the secondary side, the cooling must

continue a water - water mode of operation using five

FKSZ while TI <100°C is reached. The secondary side

circulation is ensured by chilling pumps. If the primary

circuit average temperature is below 100°C, the FKSZ’s

need to be stopped by detaching the earlier used two

loops. Secondary side steam generators that have been

taken out of the plant loops should not be excluded,

ensuring their intense chilling. Their detachment should

be carried out at TGF fal≤ 4°C but no later than before the

reactor is depressurized. If the difference in temperature

between the pressurizer and the added water is ∆T < 80oC

the cooling of the pressurizer can be continued by using

supplement pumps

2. The simulation of the cooling

To be able to analyze the task, in the first step let’s see

how large this energy is [1,5]. The codes that use

numerical methods to estimate the remnant heat (decay

heat) (Melcor, Relap 1-2-3, Trac, Origen) are capable to

model the state with a precision of 3-5%.

A. The simulation of remanent heat

Using MATLAB R2013a with numerical methods we

simulated (Figure 5.), a T=335days constantly

operational P0 = 1485MWt („Megawatt thermal”) heat

energy producing reactor, it’s remnant heat 10 days

following it’s shutdown (864000s) is shown on figure6.

This value even after ten days is more than 3MWt.

Fig. 3. Tipical cooling diagram for a rector block

Fig. 4. Change of the remanent thermal power in six-month

period at the Fukushima power plant

3

The algorithm used [M. Ragheb, 3/22/2011] [2]:

P(t) = 6.48x10-3

P0 [t -0.2

– (t+T0) -0.2

] [MWt] (1)

B. The emergency stop in the system after shutdown

Hereinafter, we excited the SCRAM (emergency

stop) signal shutdown reactor and associated metalwork

combined transfer function with the current heat output

signal (Figure 7.).

The transfer function was determined by a single

proportional storage member (PT1) function,

determined because of water and metal mass,

considering the reactor, fuel, main water circuit lines,

primary coolant masses and specific heat values.

Without forced circulation or additional heat removal,

using an account with very high heat storage capacity,

the output function scaled in average temperatures

even after ten days shows a monotonic character

(Figure 4.). Assuming continuously available (fixed)

emergency stop heat extracting system and power, the

about 4MWt heat removal reverses its trend on the

seventh day, at a temperature of 300°C (Figure 8, the

third chart).

Fig. 5. Simulation modelling of remanent heat

Fig. 6. The simulated remanent thermal power

Fig. 7. Extended simulation model

39

2

subtraction of steam from the fresh steam collector

until TI = 140oC is reached. The condensate condensed

in the technology condenser is returned to the

secondary supply tank. In the last third of the water-

steam cooling the heating of the supply containers

should be gradually reduced to ensure the temperature

step between the primary - secondary circuit.

While above TI>190oC it’s advisable to avoid a too

high active zone pressure difference, an FKSZ needs to

be shut down. Because of the even cooling of primary

circuit pipes, the shutdown FKSZ needs to be restarted

(TI =175 and at 160oC) once we stopped an operator.

Once TI< 150oC is reached the speed of cooling drops

significantly, because the ∆T between the supply water

and the primary circuit is low. Once a stable value of

below 150oC is reached, the system should be switched

from steam – water to water – water cooling. To do

this the GF, fresh steam lines, fresh steam collectors,

and the cooling system should be filled with feed

water. Before the start of the filling, prevention of

inadvertent defense operations must take place, the

security of the GF’s need to be paralyzed on the BER

panel, because LGF>Lnominal+600mm excludes the

upload path. The speed of the filling needs to be set in

such a way that it’s minimum 3.5h’s. At this stage of

the cool-down the migration from the Stepped Start

Programs to the SSP II should be checked. The switch

to this program also means that some elements of the

ZÜHR systems are no longer needed now, in fact their

trigger could lead to adverse consequences, and

therefore, they should be staggered.

(Eg., Under pressure, still closed, but cooled reactor, if

the TH pumps are started even if for a false signal, we

can go beyond the allowed pressure of the brittle

temperature in seconds, or the sprinkler system starts

for a wrong signal, since on this primary temperature

it’s unlikely that even in the event of a broken pipe the

pressure of the containment reaches the limit.)Since

the amount of heat removal is steadily declining over

the filling, care should be taken that the primary circuit

does not warm up to above 150°C.

After filling the secondary side, the cooling must

continue a water - water mode of operation using five

FKSZ while TI <100°C is reached. The secondary side

circulation is ensured by chilling pumps. If the primary

circuit average temperature is below 100°C, the FKSZ’s

need to be stopped by detaching the earlier used two

loops. Secondary side steam generators that have been

taken out of the plant loops should not be excluded,

ensuring their intense chilling. Their detachment should

be carried out at TGF fal≤ 4°C but no later than before the

reactor is depressurized. If the difference in temperature

between the pressurizer and the added water is ∆T < 80oC

the cooling of the pressurizer can be continued by using

supplement pumps

2. The simulation of the cooling

To be able to analyze the task, in the first step let’s see

how large this energy is [1,5]. The codes that use

numerical methods to estimate the remnant heat (decay

heat) (Melcor, Relap 1-2-3, Trac, Origen) are capable to

model the state with a precision of 3-5%.

A. The simulation of remanent heat

Using MATLAB R2013a with numerical methods we

simulated (Figure 5.), a T=335days constantly

operational P0 = 1485MWt („Megawatt thermal”) heat

energy producing reactor, it’s remnant heat 10 days

following it’s shutdown (864000s) is shown on figure6.

This value even after ten days is more than 3MWt.

Fig. 3. Tipical cooling diagram for a rector block

Fig. 4. Change of the remanent thermal power in six-month

period at the Fukushima power plant

3

The algorithm used [M. Ragheb, 3/22/2011] [2]:

P(t) = 6.48x10-3

P0 [t -0.2

– (t+T0) -0.2

] [MWt] (1)

B. The emergency stop in the system after shutdown

Hereinafter, we excited the SCRAM (emergency

stop) signal shutdown reactor and associated metalwork

combined transfer function with the current heat output

signal (Figure 7.).

The transfer function was determined by a single

proportional storage member (PT1) function,

determined because of water and metal mass,

considering the reactor, fuel, main water circuit lines,

primary coolant masses and specific heat values.

Without forced circulation or additional heat removal,

using an account with very high heat storage capacity,

the output function scaled in average temperatures

even after ten days shows a monotonic character

(Figure 4.). Assuming continuously available (fixed)

emergency stop heat extracting system and power, the

about 4MWt heat removal reverses its trend on the

seventh day, at a temperature of 300°C (Figure 8, the

third chart).

Fig. 5. Simulation modelling of remanent heat

Fig. 6. The simulated remanent thermal power

Fig. 7. Extended simulation model

40

4

It should be noted, a lesser value is also capable of

reversing the trend, that is to cause cooling, since the

thermal decomposition function decreases

monotonically, the question is when and how long will

it allow the average temperature to climb up. In the

case of our operating systems protection signals are

formed at - 305°C and 310°C values, it is not

appropriate to allow a higher value for a standing

block either. An obvious question is whether the huge,

metal and water - weight stored heat energy should be

directly converted in to electrical energy by an

electrical (TEG) converter and used for powering the

residual heat removal as a "third kind" diverse

authoritarian type supply.

Main equipment otherwise covered with insulation if

you cover them with TEG –considering characteristics

of temperature and ventilation of the area (the box) will

continue, - it is required due to cold-side heat removal

by the TEG–to generate approximately 2.5 - 3.0MW of

electricity, if we assume current TEG efficiencies [4].

C. The installation of TEG as a residual heat-

absorber

A system thus formed, from a thermal perspective is a

negative feedback system, which guarantees safety (9)

for protection against overtemperature. The

thermoelectric generator in the feedback path can also

be modeled as a PT1 member, however, it’s time

constant is much smaller than the pre-coupling loop, the

time constant of the technology.

The thus constructed MATLAB model can be seen on

figure 10., while the cooling curves are shown on figure

11. The “minima” function that does not allow the

temperature to climb above 300°C, should have at least

a transfer function. Increasing the time

constant does not affect the shape of the curve, it

determines the availability of electric power that can be

extracted from the TEG, while the proportional transfer

component has effect on the slope of the cooling.

Fig. 8. Without forced circulation or additional heat

removal SCRAM

PT1

PT1

-

TEG

Technológia

Fig. 10. The model of effect for incorporated TEG heat removal

5

D. TEG as a residual heat-absorber

The increase of storage capacity can be resolved by the

storage of electricity generated by the TEG’s in

batteries (Figure 12).

During the campaign, the heat produced is

continuously "there" in a time after SCRAM as well in

the form of stored heat, so during the residual heat

removal’s critical stage of 2-3 days the multiple

amount of charger (conditioning)power could be

removed from the batteries to maintain the circulation.

Each plant has a battery-supported DC rail (220V or

24V), so building that will not be an additional cost.

3. Analysis of a nuclear power plant from

the usage perspective of a TEG

The thermopile technology is turning out to be an

interesting application in the field of nuclear power

plants. It has been successfully used for some time

now in outer space electric power generation [3]. It

holds additional capabilities in high-energy nuclear

systems. Continued, we explore these application

possibilities in this article.

Nuclear power plants are essentially thermal power

plants fueled by nuclear fission reactions. Instead of the

conventional burning of fuels like in the furnaces of

thermal power plants, nuclear reactions in the reactor

are generating the energy. However, using the hot water

coming out the reactor, only relatively low pressure (40-

60bar) saturated steam can be produced, so the cycle’s

parameters are rather moderate. This is the cause of the

relatively low efficiency of nuclear power plants (η = 30

- 40%). The following table shows the thermal

characteristics of the main types of thermal reactors:

Huge volumetric heat capacity and low efficiency

entail considerable heat loss. This parameter gives a

good chance for the study of the application of

thermopile effect. The study of the usage of thermopile

cells in nuclear power plants could cover case studies

of:

- detailed exploration of the heat loss in certain

reactors (holding tanks, heat exchange pipes, rotary

machines)

- for the calculation of recoverable electrical energy,

and the maximum increase in efficiency

- for the thus obtained usability of the electrical

energy for feed-in the safety system, increasing the

availability of the safety system.

4. Performance conditions, normal VVER 440

reactor shutdown needs

Given that only measuring circuits and signal

processing systems (providing feedback information)

are used and for emergency powering of about 4 -

20mA, this implies a few 100W of power demand. (In

this case, the wireless sensor technology, as a stand-by

measuring system can play a significant role, but power

consumption is not a major surplus.)

Power consumption of a residual heat removal

(cooling), after normal or emergency shutdown, during

the cooling period from 72 to 120 hours, considering the

main consumers:

- 2 pc of main circulation pumps 1600kW/pump

(6kV);

- 1 pc Feed pump 2500kW (6kV)

- 1 pc Emergency pump 200kW (0.4kV)

0.0015

700S + 0.1YTEG =

0.015

700S + 0.1

0.15

700S + 0.1

YTEG =

YTEG =

Fig. 11. The simulation results for the installated TEG

heat removal

SCRAM

PT1

PT1

-

TEG

Technológia

akkutelep

Fig. 12. Model of installated battery pack system

Table 1. Thermal charachterictic of reactor types

Reactor PWR BWR GGR AGR HTGR Volumetric heat capacity (W/cm3)

70-110 40-50 3-5 5-10 10-20

Efficiency (%)

30-40 30-40 30-40 40-45 40-45

PWR (Pressurized Water Reactor)

BWR (Boiling Water Reactor)

GGR (Gas cooled, Graphite moderated Reactor)

AGR (Advanced Gas cooled Reactor)

HTGR (High Temperature, Gas cooled Reactor)

41

4

It should be noted, a lesser value is also capable of

reversing the trend, that is to cause cooling, since the

thermal decomposition function decreases

monotonically, the question is when and how long will

it allow the average temperature to climb up. In the

case of our operating systems protection signals are

formed at - 305°C and 310°C values, it is not

appropriate to allow a higher value for a standing

block either. An obvious question is whether the huge,

metal and water - weight stored heat energy should be

directly converted in to electrical energy by an

electrical (TEG) converter and used for powering the

residual heat removal as a "third kind" diverse

authoritarian type supply.

Main equipment otherwise covered with insulation if

you cover them with TEG –considering characteristics

of temperature and ventilation of the area (the box) will

continue, - it is required due to cold-side heat removal

by the TEG–to generate approximately 2.5 - 3.0MW of

electricity, if we assume current TEG efficiencies [4].

C. The installation of TEG as a residual heat-

absorber

A system thus formed, from a thermal perspective is a

negative feedback system, which guarantees safety (9)

for protection against overtemperature. The

thermoelectric generator in the feedback path can also

be modeled as a PT1 member, however, it’s time

constant is much smaller than the pre-coupling loop, the

time constant of the technology.

The thus constructed MATLAB model can be seen on

figure 10., while the cooling curves are shown on figure

11. The “minima” function that does not allow the

temperature to climb above 300°C, should have at least

a transfer function. Increasing the time

constant does not affect the shape of the curve, it

determines the availability of electric power that can be

extracted from the TEG, while the proportional transfer

component has effect on the slope of the cooling.

Fig. 8. Without forced circulation or additional heat

removal SCRAM

PT1

PT1

-

TEG

Technológia

Fig. 10. The model of effect for incorporated TEG heat removal

5

D. TEG as a residual heat-absorber

The increase of storage capacity can be resolved by the

storage of electricity generated by the TEG’s in

batteries (Figure 12).

During the campaign, the heat produced is

continuously "there" in a time after SCRAM as well in

the form of stored heat, so during the residual heat

removal’s critical stage of 2-3 days the multiple

amount of charger (conditioning)power could be

removed from the batteries to maintain the circulation.

Each plant has a battery-supported DC rail (220V or

24V), so building that will not be an additional cost.

3. Analysis of a nuclear power plant from

the usage perspective of a TEG

The thermopile technology is turning out to be an

interesting application in the field of nuclear power

plants. It has been successfully used for some time

now in outer space electric power generation [3]. It

holds additional capabilities in high-energy nuclear

systems. Continued, we explore these application

possibilities in this article.

Nuclear power plants are essentially thermal power

plants fueled by nuclear fission reactions. Instead of the

conventional burning of fuels like in the furnaces of

thermal power plants, nuclear reactions in the reactor

are generating the energy. However, using the hot water

coming out the reactor, only relatively low pressure (40-

60bar) saturated steam can be produced, so the cycle’s

parameters are rather moderate. This is the cause of the

relatively low efficiency of nuclear power plants (η = 30

- 40%). The following table shows the thermal

characteristics of the main types of thermal reactors:

Huge volumetric heat capacity and low efficiency

entail considerable heat loss. This parameter gives a

good chance for the study of the application of

thermopile effect. The study of the usage of thermopile

cells in nuclear power plants could cover case studies

of:

- detailed exploration of the heat loss in certain

reactors (holding tanks, heat exchange pipes, rotary

machines)

- for the calculation of recoverable electrical energy,

and the maximum increase in efficiency

- for the thus obtained usability of the electrical

energy for feed-in the safety system, increasing the

availability of the safety system.

4. Performance conditions, normal VVER 440

reactor shutdown needs

Given that only measuring circuits and signal

processing systems (providing feedback information)

are used and for emergency powering of about 4 -

20mA, this implies a few 100W of power demand. (In

this case, the wireless sensor technology, as a stand-by

measuring system can play a significant role, but power

consumption is not a major surplus.)

Power consumption of a residual heat removal

(cooling), after normal or emergency shutdown, during

the cooling period from 72 to 120 hours, considering the

main consumers:

- 2 pc of main circulation pumps 1600kW/pump

(6kV);

- 1 pc Feed pump 2500kW (6kV)

- 1 pc Emergency pump 200kW (0.4kV)

0.0015

700S + 0.1YTEG =

0.015

700S + 0.1

0.15

700S + 0.1

YTEG =

YTEG =

Fig. 11. The simulation results for the installated TEG

heat removal

SCRAM

PT1

PT1

-

TEG

Technológia

akkutelep

Fig. 12. Model of installated battery pack system

Table 1. Thermal charachterictic of reactor types

Reactor PWR BWR GGR AGR HTGR Volumetric heat capacity (W/cm3)

70-110 40-50 3-5 5-10 10-20

Efficiency (%)

30-40 30-40 30-40 40-45 40-45

PWR (Pressurized Water Reactor)

BWR (Boiling Water Reactor)

GGR (Gas cooled, Graphite moderated Reactor)

AGR (Advanced Gas cooled Reactor)

HTGR (High Temperature, Gas cooled Reactor)

42

6

In the last stages of cooling only two cooling

pumps are operating (160kW/machine, 0.4kV voltage).

Additional one needs to add the above (typically relay

activated) control, measurement and control loops

consumption as well. During the stage of shut down

the greatest power requirement approximately is

6000kW (6MW), which after 72-120 drops to 300 -

400kW. It’s not negligible that the “big” pumps have

6kV 50Hz voltage needs.

Emergency core cooling systems power

consumption, for an automatic protection signal in case

of declared types of breakdown is:

- 3 pc High pressure emergency core pump

520kW/pump, 6kV

- 3 pc Low pressure emergency core pump

125kW/pump, 0.4kV

- 3 pc Spinkler system pump160kW/pump,

0.4kV.

Given for worst case emergency scenario, an

approximately 2500kW power demand occurs in the

emergency cooling period.

The surface temperature of the reactor (more

precisely the reactors metal walls temperature) is being

constantly monitored and registered, illustrated on a

self-made P&I schema which means the usage of 3

Pt46 resistance-thermometers (YA00T101B1, B3, B5

alphanumeric measurements, disposed 120° relative to

each other). During normal operation, at any point in

time these measurements show values of 240°C-

250°C. I am not aware of the surface temperature

distribution modeling, but this is the true value for

about the entire wall surface. The blue colored

measurements are computer measurement, they are

available in an archived (trend) form. The trend shows

the temperature measurements of six concrete consoles

(YA00T001B1-B6).

5. Approximation of the extractable power

with the TEG

An assessment of the potential primary circuit

surfaces: in the situation with six main water conduits,

their coverable length with TEG in total is 120m,

accounted for a hot and cold branch of 10-10m.

Obviously, the treatment, operation equipment, nozzles,

valves, thermometer bag places cannot be affected with

the TEG covering. With a 560mm diameter, main water

conduit, on most the pipe surfaces we can have access to

a usable surface of 210m2, with 270°C average

temperature. This means that on the cold end 250°C, on

the hot end 280°C temperatures can heat the placed

TEG’s. Calculating with six, 10m long, 4m diameter

steam generators we get a surface of 754m2, at 220°C

which is coverable. A major piece of equipment surface

is the pressurizer where the coverable area is 52m2, but

the temperature of the surface is 280°C. The similar

exploration of the secondary circuit: a 135m long,

465mm diameter main steam pipe means a surface of

197m2, at 220°C. Calculating with a water supply

system average temperature of 180°C, with a 426mm

diameter on 120m length, we get a similar surface of

160m2. The major secondary containers, low - and high-

pressure preheater lines, supply containers usable

surfaces relative to the block are: 395m2, 100°C average

temperature preheater, 480m2, 200°C average

temperature high pressure preheater, two 105m2, 150°C

temperature supply tanks. The above are the major

places for energy retrieval, leaving out the auxiliary

systems and small unusable surfaces. The room

temperatures, „cold side temperatures” are between

30°C - 50°C.

Fig. 13. Self-made P&I schema

Fig. 14. TEG material pair efficieny

7

Thanks to Thomson, Seebeck and Peltier’s research,

we use thermocouples for measurement purposes for a

long time now. However, the phenomenon of using it

as an energy source application is made possible

through experimenting with new materials. One of the

best types of such thermoelectric modules (TEG’s)

with the best thermoelectric properties is the bismuth-

telluride (Bi2TE3) based pseudo-binary group of alloys.

Figure 7. shows some of the more important TEG

material pairs efficiency as a function of temperature.

6. Summary

In this paper, we have tried to show how is it possible

to simulate processes taking place in an abandoned

nuclear power plant. As you can see this can be

resolved perfectly using MATLAB. We have outlined

the theoretical possibility of usage of residual heat

removal using a third, diverse way method. In further

studies, we try to put more emphasis on the fine tuning

of the simulated system and to clarify the physical

realization of the possibilities.

During the study, it can be concluded that, yes, there is

justification in using the TEG in nuclear power plants.

We may have to wait a few years so that TEG’s with

such parameters hit the market that enable greater power

generation (and thus enabling the operation of stronger

motors with them), but the results outlined here are said

to be promising. If we only consider that the resulting

2.68MW, the daily consumption of a small town, can be

covered by it, or it can supply the mentioned measuring

and signaling devices current needs, we should look at it

as it is worth it. In any case, its usage is worth further

consideration when critical outages, or emergencies

occur.

Acknowledgements This work/publication is supported by the EFOP-3.6.1-

16-2016-00003 project. The project is co-financed by

the European Union.

References [1] Laszlo Kajtar, Jozsef Nyers, Janos Szabo: Dynamic

thermal dimensioning of underground spaces;

Volume 87, 1 July 2015, Pages 361–368

[2] M. Ragheb: Decay heat generation in fission

reactors, 3/22/2011

[3] A. Szente, I. Farkas and P. Odry: The application of

ThermopileTechnology in high Energy Nuclear

Power Plants,Expres 2014

[4] http://www.tecteg.com/

[5] Nyers József, Kajtar Laszlo, Slavica Tomic, Nyers

ArpadInvestment-savings Method for Energy-

economic Optimization of External Wall Thermal

Insulation ThicknessENERGY AND BUILDINGS

86: pp. 268-274. (2014)

Hot side

Heat source temperature: 500°C Hot side temperature 480°C Cool side temperature: 45°C Open circuit voltage: 19.45V Output voltage: 9.75V Load current: 1.13 A Output power: 11.0 W Surface: 0.004 m2

Cool side Fig. 15. CMO-32-62S CASCADE TEG module

43

6

In the last stages of cooling only two cooling

pumps are operating (160kW/machine, 0.4kV voltage).

Additional one needs to add the above (typically relay

activated) control, measurement and control loops

consumption as well. During the stage of shut down

the greatest power requirement approximately is

6000kW (6MW), which after 72-120 drops to 300 -

400kW. It’s not negligible that the “big” pumps have

6kV 50Hz voltage needs.

Emergency core cooling systems power

consumption, for an automatic protection signal in case

of declared types of breakdown is:

- 3 pc High pressure emergency core pump

520kW/pump, 6kV

- 3 pc Low pressure emergency core pump

125kW/pump, 0.4kV

- 3 pc Spinkler system pump160kW/pump,

0.4kV.

Given for worst case emergency scenario, an

approximately 2500kW power demand occurs in the

emergency cooling period.

The surface temperature of the reactor (more

precisely the reactors metal walls temperature) is being

constantly monitored and registered, illustrated on a

self-made P&I schema which means the usage of 3

Pt46 resistance-thermometers (YA00T101B1, B3, B5

alphanumeric measurements, disposed 120° relative to

each other). During normal operation, at any point in

time these measurements show values of 240°C-

250°C. I am not aware of the surface temperature

distribution modeling, but this is the true value for

about the entire wall surface. The blue colored

measurements are computer measurement, they are

available in an archived (trend) form. The trend shows

the temperature measurements of six concrete consoles

(YA00T001B1-B6).

5. Approximation of the extractable power

with the TEG

An assessment of the potential primary circuit

surfaces: in the situation with six main water conduits,

their coverable length with TEG in total is 120m,

accounted for a hot and cold branch of 10-10m.

Obviously, the treatment, operation equipment, nozzles,

valves, thermometer bag places cannot be affected with

the TEG covering. With a 560mm diameter, main water

conduit, on most the pipe surfaces we can have access to

a usable surface of 210m2, with 270°C average

temperature. This means that on the cold end 250°C, on

the hot end 280°C temperatures can heat the placed

TEG’s. Calculating with six, 10m long, 4m diameter

steam generators we get a surface of 754m2, at 220°C

which is coverable. A major piece of equipment surface

is the pressurizer where the coverable area is 52m2, but

the temperature of the surface is 280°C. The similar

exploration of the secondary circuit: a 135m long,

465mm diameter main steam pipe means a surface of

197m2, at 220°C. Calculating with a water supply

system average temperature of 180°C, with a 426mm

diameter on 120m length, we get a similar surface of

160m2. The major secondary containers, low - and high-

pressure preheater lines, supply containers usable

surfaces relative to the block are: 395m2, 100°C average

temperature preheater, 480m2, 200°C average

temperature high pressure preheater, two 105m2, 150°C

temperature supply tanks. The above are the major

places for energy retrieval, leaving out the auxiliary

systems and small unusable surfaces. The room

temperatures, „cold side temperatures” are between

30°C - 50°C.

Fig. 13. Self-made P&I schema

Fig. 14. TEG material pair efficieny

7

Thanks to Thomson, Seebeck and Peltier’s research,

we use thermocouples for measurement purposes for a

long time now. However, the phenomenon of using it

as an energy source application is made possible

through experimenting with new materials. One of the

best types of such thermoelectric modules (TEG’s)

with the best thermoelectric properties is the bismuth-

telluride (Bi2TE3) based pseudo-binary group of alloys.

Figure 7. shows some of the more important TEG

material pairs efficiency as a function of temperature.

6. Summary

In this paper, we have tried to show how is it possible

to simulate processes taking place in an abandoned

nuclear power plant. As you can see this can be

resolved perfectly using MATLAB. We have outlined

the theoretical possibility of usage of residual heat

removal using a third, diverse way method. In further

studies, we try to put more emphasis on the fine tuning

of the simulated system and to clarify the physical

realization of the possibilities.

During the study, it can be concluded that, yes, there is

justification in using the TEG in nuclear power plants.

We may have to wait a few years so that TEG’s with

such parameters hit the market that enable greater power

generation (and thus enabling the operation of stronger

motors with them), but the results outlined here are said

to be promising. If we only consider that the resulting

2.68MW, the daily consumption of a small town, can be

covered by it, or it can supply the mentioned measuring

and signaling devices current needs, we should look at it

as it is worth it. In any case, its usage is worth further

consideration when critical outages, or emergencies

occur.

Acknowledgements This work/publication is supported by the EFOP-3.6.1-

16-2016-00003 project. The project is co-financed by

the European Union.

References [1] Laszlo Kajtar, Jozsef Nyers, Janos Szabo: Dynamic

thermal dimensioning of underground spaces;

Volume 87, 1 July 2015, Pages 361–368

[2] M. Ragheb: Decay heat generation in fission

reactors, 3/22/2011

[3] A. Szente, I. Farkas and P. Odry: The application of

ThermopileTechnology in high Energy Nuclear

Power Plants,Expres 2014

[4] http://www.tecteg.com/

[5] Nyers József, Kajtar Laszlo, Slavica Tomic, Nyers

ArpadInvestment-savings Method for Energy-

economic Optimization of External Wall Thermal

Insulation ThicknessENERGY AND BUILDINGS

86: pp. 268-274. (2014)

Hot side

Heat source temperature: 500°C Hot side temperature 480°C Cool side temperature: 45°C Open circuit voltage: 19.45V Output voltage: 9.75V Load current: 1.13 A Output power: 11.0 W Surface: 0.004 m2

Cool side Fig. 15. CMO-32-62S CASCADE TEG module

44

EXPRES 2017 ISBN 978-86-919769-1-0

Composite materials for wind power turbine blades R. SZABÓ a, L. SZABÓ b

a Ingtex Bt - Rejtő Sándor Foundation H-1056 Budapest Nyáry Pál u. 5, Hungary

E-mail: [email protected] b

Institute of Environmental Protection Engineering, Rejtő Sándor Faculty of Light Industry and Environmental Protection

Engineering, Óbuda University, H-1034 Budapest, Doberdó u. 6, Hungary

E-mail: [email protected]

Energy is an essential ingredient of socio-economic development and economic growth. Renewable energy sources like wind

energy is domestic and can help in reducing the dependency on fossil fuels. Renewable energy resources, of which wind

energy is prominent, are part of the solution to the global energy problem and reduce the CO₂ emission. Wind turbine and the

rotorblade concepts are reviewed, and loadings by wind and gravity as important factors for the fatigue performance of the

materials are considered.Composites are discussed as candidates for rotor blades. The fibers and matrices for composites are

described, and their high stiffness, low density, and good fatigue performance are emphasized. This presentation will explore

properties of carbon fiber, the advantages/ disadvantage between CFRP and competitive materials as GFRP.

Keywords: airfoil, wind turbine blade, carbon fiber, composites, CFRP, power

1. Introduction

Windmills have been assisting mankind to

convert the energy contained in wind to many

other useful forms for the last three thousand

years. In the early 70s, the serial production of

GRP (glass-fibre reinforced plastics) rotor blades

a length of 17 metres was developed on small

systems, starting in Denmark. In the initial

phases, the achieved performance was

approximately 10 kilowatts bu now we are able

to attain magnitudes of 8 to 10 Megawatts.

Today’s wind turbines are capable of converting

a great amount of energy in the wind into

electricity. This is due to blades which are

developed using state-of-the-art aerodynamic

analysis and other performance-enhancing

equipment. The wind turbine performance

improvement is the key to increase the length of

the blade. The wind blades to make are needed

extremely high loads, high stiffness and high-

strength structural materials. The environmental

load of electricity produced from wind power

generation is the most favourable, so you can

expect a bright future.

2. The wind blade functions

Main components of wind turbines:

Rotor – generates aerodynamic torque from the

wind

Nacelle – converters the torque into electrical

power

Tower – holds nacelle and rotor blades up in the

wind and provides access to the nacelle

Foundation – ensures that the turbine stays upright

The presentation mainly focused on the turbine

blade.

If the blowing wind can turn the blade, we will

receive electricity from the generator that is

attached to it. A lift force is produced when air

moves over an airfoil (Bernoulli-equation) (Fig. 1).

Fig. 1.

The pressure difference on the airfoil makes the

wind turbine blade turn. This way the wind turbine

achieves the basic rotation. Wind turbine blades

turn at a very low rate of rpm. So before the low

speed shaft connecting to the generator the speed

is increased in a gearbox (planetary gear set,

speed ratio ~ 1:90) to achieve the high speed

ratio. The moving wind turbine blade also

experiences the relative wind velocity is as

shown in Fig. 2. [12].

EXPRES 2017 ISBN 978-86-919769-1-0

Fig. 2.

As the blade velocity increases to the tip the

relative wind speed become more inclined

towards the trip. The blade has a lot of air foil

cross-section consisting of different sizes and

shapes from the root to tip. This means by the

manufacturing that a continuous twist is given to

the blade from the root to tip. Therefore the wind

turbine is positioned in a pitched manner in order

to align with the relative wind speed.

Wind turbine always be aligned with the wind

direction. Wind velocity sensor on top of the

nacelle measures the wind speed and direction.

The deviation in the wind’s direction yawing

mechanism to correct the error (picture).

According to the wind speed the relative velocity

angle of the wind also changes. A blade pitching

mechanism turns the blades and guarantees a

proper alignment of the blade with the relative

velocity. Thus the blades are always at the

optimum angle of attack with the relative wind

flow. Pitch control mechanism keep the rotation

speed of a turbine constant for changing wind

speed. This is necessary to keep the rpm of the

generator constant.

The swept area increases by approximately the

square of blade length. Spinning blades cause

wind behind turbine to rotate. Faster moving

blades tip cause less rotation and have less wake

rotation losses. The longer the turbine blades to

achieve the goal.

3. Wind turbine power

The wind power depends on the wind speed.

During excessively windy (cut off speed ~ 80

km/h) the brake is arrest wind blade rotation (Fig.

3).

Fig. 3.

The power of the wind turbine

P = 1/2 η ρ A v v² = 1/2 η ρ π r² v³

where:

P – Performance of wind turbine,

η – Efficiency of wind turbine,

ρ – Air density (1.2 kg/m³),

A – Swept area of wind turbine (A = L²π),

L – Length of blade,

v – wind velocity.

To gain a good insight into wind turbine

efficiency assume that you are measuring wind

speed at upstream and downstream over wind

turbine. The wind speed at the downstream is

much smaller than the upstream because the

blades absorb some kinetic energy from the

wind.

The efficiency of wind turbine (η): Energy out/

Energy in.

The concept would also allow the blades to

spread out when the wind is blowing lightly to

capture as much power as possible.

A portion of the kinetic energy of wind the

turbine blades converts the torque work (M= F x

r). The wind turbines theoretically of the wind

kinetic energy is 59.26% (Betz's law) exploits

(Fig. 4).

Fig. 4

Increasing wind turbine blade lengths lead to

higher energy production (Fig. 5).

45

EXPRES 2017 ISBN 978-86-919769-1-0

Composite materials for wind power turbine blades R. SZABÓ a, L. SZABÓ b

a Ingtex Bt - Rejtő Sándor Foundation H-1056 Budapest Nyáry Pál u. 5, Hungary

E-mail: [email protected] b

Institute of Environmental Protection Engineering, Rejtő Sándor Faculty of Light Industry and Environmental Protection

Engineering, Óbuda University, H-1034 Budapest, Doberdó u. 6, Hungary


Energy is an essential ingredient of socio-economic development and economic growth. Renewable energy sources like wind

energy is domestic and can help in reducing the dependency on fossil fuels. Renewable energy resources, of which wind

energy is prominent, are part of the solution to the global energy problem and reduce the CO₂ emission. Wind turbine and the

rotorblade concepts are reviewed, and loadings by wind and gravity as important factors for the fatigue performance of the

materials are considered.Composites are discussed as candidates for rotor blades. The fibers and matrices for composites are

described, and their high stiffness, low density, and good fatigue performance are emphasized. This presentation will explore

properties of carbon fiber, the advantages/ disadvantage between CFRP and competitive materials as GFRP.

Keywords: airfoil, wind turbine blade, carbon fiber, composites, CFRP, power

1. Introduction

Windmills have been assisting mankind to

convert the energy contained in wind to many

other useful forms for the last three thousand

years. In the early 70s, the serial production of

GRP (glass-fibre reinforced plastics) rotor blades

a length of 17 metres was developed on small

systems, starting in Denmark. In the initial

phases, the achieved performance was

approximately 10 kilowatts bu now we are able

to attain magnitudes of 8 to 10 Megawatts.

Today’s wind turbines are capable of converting

a great amount of energy in the wind into

electricity. This is due to blades which are

developed using state-of-the-art aerodynamic

analysis and other performance-enhancing

equipment. The wind turbine performance

improvement is the key to increase the length of

the blade. The wind blades to make are needed

extremely high loads, high stiffness and high-

strength structural materials. The environmental

load of electricity produced from wind power

generation is the most favourable, so you can

expect a bright future.

2. The wind blade functions

Main components of wind turbines:

Rotor – generates aerodynamic torque from the

wind

Nacelle – converters the torque into electrical

power

Tower – holds nacelle and rotor blades up in the

wind and provides access to the nacelle

Foundation – ensures that the turbine stays upright

The presentation mainly focused on the turbine

blade.

If the blowing wind can turn the blade, we will

receive electricity from the generator that is

attached to it. A lift force is produced when air

moves over an airfoil (Bernoulli-equation) (Fig. 1).

Fig. 1.

The pressure difference on the airfoil makes the

wind turbine blade turn. This way the wind turbine

achieves the basic rotation. Wind turbine blades

turn at a very low rate of rpm. So before the low

speed shaft connecting to the generator the speed

is increased in a gearbox (planetary gear set,

speed ratio ~ 1:90) to achieve the high speed

ratio. The moving wind turbine blade also

experiences the relative wind velocity is as

shown in Fig. 2. [12].

EXPRES 2017 ISBN 978-86-919769-1-0

Fig. 2.

As the blade velocity increases to the tip the

relative wind speed become more inclined

towards the trip. The blade has a lot of air foil

cross-section consisting of different sizes and

shapes from the root to tip. This means by the

manufacturing that a continuous twist is given to

the blade from the root to tip. Therefore the wind

turbine is positioned in a pitched manner in order

to align with the relative wind speed.

Wind turbine always be aligned with the wind

direction. Wind velocity sensor on top of the

nacelle measures the wind speed and direction.

The deviation in the wind’s direction yawing

mechanism to correct the error (picture).

According to the wind speed the relative velocity

angle of the wind also changes. A blade pitching

mechanism turns the blades and guarantees a

proper alignment of the blade with the relative

velocity. Thus the blades are always at the

optimum angle of attack with the relative wind

flow. Pitch control mechanism keep the rotation

speed of a turbine constant for changing wind

speed. This is necessary to keep the rpm of the

generator constant.

The swept area increases by approximately the

square of blade length. Spinning blades cause

wind behind turbine to rotate. Faster moving

blades tip cause less rotation and have less wake

rotation losses. The longer the turbine blades to

achieve the goal.

3. Wind turbine power

The wind power depends on the wind speed.

During excessively windy (cut off speed ~ 80

km/h) the brake is arrest wind blade rotation (Fig.

3).

Fig. 3.

The power of the wind turbine

P = 1/2 η ρ A v v² = 1/2 η ρ π r² v³

where:

P – Performance of wind turbine,

η – Efficiency of wind turbine,

ρ – Air density (1.2 kg/m³),

A – Swept area of wind turbine (A = L²π),

L – Length of blade,

v – wind velocity.

To gain a good insight into wind turbine

efficiency assume that you are measuring wind

speed at upstream and downstream over wind

turbine. The wind speed at the downstream is

much smaller than the upstream because the

blades absorb some kinetic energy from the

wind.

The efficiency of wind turbine (η): Energy out/

Energy in.

The concept would also allow the blades to

spread out when the wind is blowing lightly to

capture as much power as possible.

A portion of the kinetic energy of wind the

turbine blades converts the torque work (M= F x

r). The wind turbines theoretically of the wind

kinetic energy is 59.26% (Betz's law) exploits

(Fig. 4).

Fig. 4

Increasing wind turbine blade lengths lead to

higher energy production (Fig. 5).

46

EXPRES 2017 ISBN 978-86-919769-1-0

Fig. 5.

The ability to „add a few meters” to a wind

turbine blade set is far from simple.

Theoretically, blade weights increase as a cubic

function of blade length when similar designs

and processes are used. The use of alternate

materials, most notably carbon fiber, can help

reduce the weight penalty associated with

increasing blade length.

4. The wind blades loads

The main load of blades is the aerodynamic load

in flap wise direction. This trust force produces

the torque, so a power. The turbine blade sheet is

parallel to the rotation sheet to blades. The high

loads due to the blades tip moves toward the

tower. The blades collision to the tower can be

eliminated with a large sheet directional rigidity

of blades (Fig. 6) [8].

Fig. 6

The plane of the turbine blades are parallel to the

rotating basis. The high load causes the blade tip

is moved towards the turret. The collision of a

large tower paddle board directional stiffness

eliminated. The other loads on the blades made

the gravity in edgewise direction (Fig. 7).

Fig. 7

Wind plate air foil cross section illustrated in 8.

Figure.

Fig. 8.

The critical situation caused by the flap wise load

direction. Aerodynamic wing thickness point of

view of reduction is preferred, and the long blade

large load requires high bending stiffness.

Estimate a number of load cycles:

5. CF and CFRP features

Lightness the key to the future. There is virtually

no alternative to lightweight constructions:

carbon fibres, the black wonder fibres that are

superior to steel and aluminium in almost all

respects when it comes to cutting weight. And, in

terms of stability and lightness, carbon-

reinforced plastic is simply unbeatable. The

aerospace, automobile and wind-power industries

have been aware of this and have been using

EXPRES 2017 ISBN 978-86-919769-1-0

carbon fiber reinforced polymer for many years.

Without it, much of what we nowadays regard as

given – from Formula 1 racing cars, via the

Airbus A350 to the innumerable large wind

turbines – would not be possible.

The quantity of CF (Carbon Fiber) to other

structural material is a little, but many specific

area key important (Fig. 9).

Fig. 9.

6. Carbon fiber

The excellent mechanical properties of

composites with a thin fibrous materials in the

array relative to a significantly higher strength

and, secondly, in accordance with the load

direction are arranged in a large number of

matrix imbedded fiber structure (anisotropic)

results (Fig. 10) [1].

Fig. 10

The reinforcing fibers (carbon fiber, glass fiber,

p-aramid fibers), and comparison of the steel and

the aluminium main mechanical properties are

shown in Table 1.

Table 1. Strength properties of structural materials

7. Carbon fiber production and

characteristics

Most of the carbon fiber is used reinforced

composite. The growth of demand and

production capacity of carbon fibers is shown in

Figure 11.

Fig. 11.

The structure of carbon fiber from the atomic

structure to the composites are shown in 12.

figure [6].

Fig. 12

The engineering practice previously used for

steel, the strength and stiffness values given in

pascals (N/m²). The density of composites more

lighter then steel, so advisable the specific

strength (free breaking length) and specific

stiffness to use (Fig. 12) [2].

47

EXPRES 2017 ISBN 978-86-919769-1-0

Fig. 5.

The ability to „add a few meters” to a wind

turbine blade set is far from simple.

Theoretically, blade weights increase as a cubic

function of blade length when similar designs

and processes are used. The use of alternate

materials, most notably carbon fiber, can help

reduce the weight penalty associated with

increasing blade length.

4. The wind blades loads

The main load of blades is the aerodynamic load

in flap wise direction. This trust force produces

the torque, so a power. The turbine blade sheet is

parallel to the rotation sheet to blades. The high

loads due to the blades tip moves toward the

tower. The blades collision to the tower can be

eliminated with a large sheet directional rigidity

of blades (Fig. 6) [8].

Fig. 6

The plane of the turbine blades are parallel to the

rotating basis. The high load causes the blade tip

is moved towards the turret. The collision of a

large tower paddle board directional stiffness

eliminated. The other loads on the blades made

the gravity in edgewise direction (Fig. 7).

Fig. 7

Wind plate air foil cross section illustrated in 8.

Figure.

Fig. 8.

The critical situation caused by the flap wise load

direction. Aerodynamic wing thickness point of

view of reduction is preferred, and the long blade

large load requires high bending stiffness.

Estimate a number of load cycles:

5. CF and CFRP features

Lightness the key to the future. There is virtually

no alternative to lightweight constructions:

carbon fibres, the black wonder fibres that are

superior to steel and aluminium in almost all

respects when it comes to cutting weight. And, in

terms of stability and lightness, carbon-

reinforced plastic is simply unbeatable. The

aerospace, automobile and wind-power industries

have been aware of this and have been using

EXPRES 2017 ISBN 978-86-919769-1-0

carbon fiber reinforced polymer for many years.

Without it, much of what we nowadays regard as

given – from Formula 1 racing cars, via the

Airbus A350 to the innumerable large wind

turbines – would not be possible.

The quantity of CF (Carbon Fiber) to other

structural material is a little, but many specific

area key important (Fig. 9).

Fig. 9.

6. Carbon fiber

The excellent mechanical properties of

composites with a thin fibrous materials in the

array relative to a significantly higher strength

and, secondly, in accordance with the load

direction are arranged in a large number of

matrix imbedded fiber structure (anisotropic)

results (Fig. 10) [1].

Fig. 10

The reinforcing fibers (carbon fiber, glass fiber,

p-aramid fibers), and comparison of the steel and

the aluminium main mechanical properties are

shown in Table 1.

Table 1. Strength properties of structural materials

7. Carbon fiber production and

characteristics

Most of the carbon fiber is used reinforced

composite. The growth of demand and

production capacity of carbon fibers is shown in

Figure 11.

Fig. 11.

The structure of carbon fiber from the atomic

structure to the composites are shown in 12.

figure [6].

Fig. 12

The engineering practice previously used for

steel, the strength and stiffness values given in

pascals (N/m²). The density of composites more

lighter then steel, so advisable the specific

strength (free breaking length) and specific

stiffness to use (Fig. 12) [2].

48

EXPRES 2017 ISBN 978-86-919769-1-0

Fig 12

The properties and the price can be very different

in the different types of carbon fiber (Fig. 13).

Fig. 13.

8. Composites properties

Composites differ from traditional materials in

that composite parts comprise two distinctly

different components — fibers and a matrix

material (most often, a polymer resin) — that,

when combined, remain discrete but function

interactively to make a new material, the

properties of which cannot be predicted by

simply summing the properties of its

components. In fact, one of the major advantages

of the fiber/resin combination is its

complementary nature.

Thin high-tech fibers, for example, exhibit

relatively high tensile strength, but are

susceptible to damage. By contrast, most

polymer resins are weak in tensile strength but

are extremely tough and malleable. When

combined, however, the fiber and resin each

counteract the other’s weakness, producing a

material far more useful than either of its

individual components (Fig. 14).

Fig. 14

Overall, the properties of the composite are

determined by:

- The properties of the fiber

- The properties of the resin

- The ratio of fiber to resin in the

composite (Fiber Volume Fraction)

- The geometry and orientation of the

fibers in the composite.

9. Wind blade architecture, the spar

caps structure

In many areas, the rapidly growing use of CFRP

production of wind blades to dominate the field

(Fig. 15).

Fig. 15

The development of wind plate is one of the most

mechanical critical requirement for ensuring the

high flap wise stiffness of the blade. The spar

caps stucture of the length wind blades

particularly rigid CFRP (Carbon Fiber

EXPRES 2017 ISBN 978-86-919769-1-0

Reinforced Polimer) with UD (Uni Directionally)

fiber orientacio. Wind blade is some of the

world's biggest constructions (fig. 16).

Fig. 16

Global wind installations were 54.6 GW in 2016,

some 14% lower than the record 63.6 GW

installed in 2015. In 2016 to implement the ten

largest wind turbine capacity increase investment

in the country's pie chat illustrated.

10. Market characteristics of wind

turbines



installed in 2015. In China, the most active wind

power market, annual wind installations fell from

30 GW in 2015 to 23 GW in 2016 (Fig. 16).

Fig. 16

The world wind power capacity and the increase

of the annual variation in the 17. Figure

illustrates [10].

Fig. 17

The wind turbines can be placed on land (onshore)

at sea (offshore fix and float). The greatest wind

blade (d=180 m) constructed offshore, the water

depth 10-50 m. By countries wind power capacity

in 2015 and has an installed capacity shown in Fig.

18.

Fig. 18

Europe wind investments rise 5% on offshore

surge. Europe's total installed wind capacity was

153.7 GW at the end of 2016. Wind power

provided 10% of Europe's power last year

(Fig.19).

Fig. 19

49

EXPRES 2017 ISBN 978-86-919769-1-0

Fig 12

The properties and the price can be very different

in the different types of carbon fiber (Fig. 13).

Fig. 13.

8. Composites properties

Composites differ from traditional materials in

that composite parts comprise two distinctly

different components — fibers and a matrix

material (most often, a polymer resin) — that,

when combined, remain discrete but function

interactively to make a new material, the

properties of which cannot be predicted by

simply summing the properties of its

components. In fact, one of the major advantages

of the fiber/resin combination is its

complementary nature.

Thin high-tech fibers, for example, exhibit

relatively high tensile strength, but are

susceptible to damage. By contrast, most

polymer resins are weak in tensile strength but

are extremely tough and malleable. When

combined, however, the fiber and resin each

counteract the other’s weakness, producing a

material far more useful than either of its

individual components (Fig. 14).

Fig. 14

Overall, the properties of the composite are

determined by:

- The properties of the fiber

- The properties of the resin

- The ratio of fiber to resin in the

composite (Fiber Volume Fraction)

- The geometry and orientation of the

fibers in the composite.

9. Wind blade architecture, the spar

caps structure

In many areas, the rapidly growing use of CFRP

production of wind blades to dominate the field

(Fig. 15).

Fig. 15

The development of wind plate is one of the most

mechanical critical requirement for ensuring the

high flap wise stiffness of the blade. The spar

caps stucture of the length wind blades

particularly rigid CFRP (Carbon Fiber

EXPRES 2017 ISBN 978-86-919769-1-0

Reinforced Polimer) with UD (Uni Directionally)

fiber orientacio. Wind blade is some of the

world's biggest constructions (fig. 16).

Fig. 16



installed in 2015. In 2016 to implement the ten

largest wind turbine capacity increase investment

in the country's pie chat illustrated.

10. Market characteristics of wind

turbines



installed in 2015. In China, the most active wind

power market, annual wind installations fell from

30 GW in 2015 to 23 GW in 2016 (Fig. 16).

Fig. 16

The world wind power capacity and the increase

of the annual variation in the 17. Figure

illustrates [10].

Fig. 17

The wind turbines can be placed on land (onshore)

at sea (offshore fix and float). The greatest wind

blade (d=180 m) constructed offshore, the water

depth 10-50 m. By countries wind power capacity

in 2015 and has an installed capacity shown in Fig.

18.

Fig. 18

Europe wind investments rise 5% on offshore

surge. Europe's total installed wind capacity was

153.7 GW at the end of 2016. Wind power

provided 10% of Europe's power last year

(Fig.19).

Fig. 19

50

EXPRES 2017 ISBN 978-86-919769-1-0

11. Conclusion

To lower the cost of energy from wind turbines,

designers have focused on the power-generating

capacity of each turbine. Carbon fibre-reinforced

plastics make it possible to create even larger and

better optimised rotor blades for wind power

systems. They have lengthened blades to capture

more wind. The size of these gigantic blade

length has increased 10 per cent annually and

doubled approximately every seven years.

Automated manufacturing processes will be

further developed to reduce costs and improve

quality. Further, performance, aerodynamics and

aero acoustics will also be improved. And we

will have large, divided blades which will enable

the challenges of transportation and installation

to be solved more easily.

References

[1] Steinmann: Carbon fibers: an overview on manufacturing, research and market ITA/RWTH Aachen University Mitteilungen 2015.

[2] Szabó L. – Szabó R.: Kompozitok Magyar Textiltechnika 2014/4. p. 2-7.

[3] T. Gries, – B.: Veihelmann: Kombinierte Faserverbundstrukturen zum Aufprallschutz Institut für Textiltechnik der RWTH Aachen (ITA)

[4] Czvikovszky T. – Nagy P. – Gaál J.: A polimertechnika alapjai Műegyetemi

[5] K. Durst: Faserverbunde im Automobilbau: Warum „leicht“ schwer ist Material 13. 10. 2009, München

[6] Szabó R.: A könnyű a jövő XVII. ENELKO 2016. Kolozsvár, 2016. október 6-9. p. 146-151.

[7] www.google.hu The wind resource - Sustainable Energy - TU Delft

[8] www.google.hu Aerodynamic theory - Sustainable Energy - TU Delft

[9] www.google.hu Future trends in wind energy - Sustainable Energy - TU Delft

[10] www.google.hu Global wind report annual market update 2015

[11] www.google.hu Global wind installs dip as China growth slows; Vestas

[12] www.google.hu How do Wind Turbines work ?

EXPRES 2017 ISBN 978-86-919769-1-0

Application of machine learning techniques in forecasting energy efficiency in buildings

O. GRLJEVIĆ a, L. SERES b, S. BOŠNJAK c

Department of Business Informatics and Quantitative Methods, University of Novi Sad, Faculty of Economics Subotica,

Segedinski put 9-11, Serbia a E-mail: [email protected] b E-mail: [email protected] c E-mail: [email protected]

Improvement of energy efficiency in buildings is crucial to achieving the goals of efficient energy consumption, to tackle climate

change and secure energy supply. This paper illustrates potential use of machine learning approaches, in particular classification,

for prediction of the heating load and the cooling load. These two aspects are crucial for energy efficient building design. We

study the effect of eight different variables on the heating and cooling loads and examine results of different classifiers. The

results prove suitability of machine learning approach in the field of energy efficiency in buildings, as well as the fact that rule-

based classifiers perform better on the given set of inputs.

Keywords: Building energy evaluation, Heating load, Cooling load, Machine learning, Classification

1. Introduction Efficient consumption of energy, as a general social

imperative, implies ensuring a stable financial system,

appropriate institutional and legislative framework

and activities to promote public awareness and change

in the habits regarding energy consumption.

The European Union (EU) has adopted Directive

[3] for efficient usage of energy among end-users and

energy services which include achieving significant

energy savings (20% of the greenhouse gases

emissions by 2020 and a 20% energy savings by

2020), as well as obligations to introduce measures

and incentives to promote energy efficiency at the

national level for all Member States [1]. Under the

Energy efficiency Directive EU countries must draw

up National Energy Efficiency Action Plans every

three years. These Action Plans include improvement

measures for energy performance of products,

buildings and services, the improvement of energy

production and distribution, reduction of the impact of

transport on energy consumption, facilitation of

financing and investments in the sector, and

encouragement of rational energy consumption.

The population can have little influence on

energy supply, due to the given natural resources.

However, they can influence the energy demand by

reducing energy consumption. In order to mitigate

climate change the general public has to change its

lifestyle to a less energy-intensive. According to the

report presented in [2] average global temperatures are

likely to rise by 2–3 °C within the next 50 years if a

current emission trends continue. Efficient

consumption of the end-users is also gaining an

increased importance within the European national

policy and the EU objectives related to climate and

energy. According to the European Commission,

residential buildings are responsible for 40% of

energy consumption and 36% of carbon dioxide

emissions in the EU. Potential energy savings in

residential areas and commercial buildings are

estimated at about 27% and 30%, respectively [1].

Similarly to the EU, residential buildings are the

largest consumers of energy in Serbia. The share of

renewable energy in total energy consumption of the

EU for the year 2014 was only 12.5% [3], and Serbia

is only at the beginning of use of renewable energy

sources.

Heating, ventilation, and air conditioning

(HVAC) play crucial role in regulation of indoor

temperatures and have the highest impact on energy

consumption in buildings. One of the ways to mitigate

increased demand for energy is to design and build

energy efficient buildings. EU Directive on energy

performance of buildings [1] obligates Member States

to apply minimum requirements to the energy

performance of new and existing buildings, to ensure

the certification of their energy performance and

require the regular inspection of boilers and air

conditioning systems in buildings. Similar to the EU

Directive, Serbia complies to the Regulations on

energy efficiency of buildings [4] which regulates

assessment of the energy efficiency of the building

based on the heating load, while it is planned to

include the cooling load in the future. Evaluation of

the overall energy efficiency of a building, according

51

EXPRES 2017 ISBN 978-86-919769-1-0

11. Conclusion

To lower the cost of energy from wind turbines,

designers have focused on the power-generating

capacity of each turbine. Carbon fibre-reinforced

plastics make it possible to create even larger and

better optimised rotor blades for wind power

systems. They have lengthened blades to capture

more wind. The size of these gigantic blade

length has increased 10 per cent annually and

doubled approximately every seven years.

Automated manufacturing processes will be

further developed to reduce costs and improve

quality. Further, performance, aerodynamics and

aero acoustics will also be improved. And we

will have large, divided blades which will enable

the challenges of transportation and installation

to be solved more easily.

References

[1] Steinmann: Carbon fibers: an overview on manufacturing, research and market ITA/RWTH Aachen University Mitteilungen 2015.

[2] Szabó L. – Szabó R.: Kompozitok Magyar Textiltechnika 2014/4. p. 2-7.

[3] T. Gries, – B.: Veihelmann: Kombinierte Faserverbundstrukturen zum Aufprallschutz Institut für Textiltechnik der RWTH Aachen (ITA)

[4] Czvikovszky T. – Nagy P. – Gaál J.: A polimertechnika alapjai Műegyetemi

[5] K. Durst: Faserverbunde im Automobilbau: Warum „leicht“ schwer ist Material 13. 10. 2009, München

[6] Szabó R.: A könnyű a jövő XVII. ENELKO 2016. Kolozsvár, 2016. október 6-9. p. 146-151.

[7] www.google.hu The wind resource - Sustainable Energy - TU Delft

[8] www.google.hu Aerodynamic theory - Sustainable Energy - TU Delft

[9] www.google.hu Future trends in wind energy - Sustainable Energy - TU Delft

[10] www.google.hu Global wind report annual market update 2015

[11] www.google.hu Global wind installs dip as China growth slows; Vestas

[12] www.google.hu How do Wind Turbines work ?

EXPRES 2017 ISBN 978-86-919769-1-0

Application of machine learning techniques in forecasting energy efficiency in buildings

O. GRLJEVIĆ a, L. SERES b, S. BOŠNJAK c

Department of Business Informatics and Quantitative Methods, University of Novi Sad, Faculty of Economics Subotica,

Segedinski put 9-11, Serbia a E-mail: [email protected] b E-mail: [email protected] c E-mail: [email protected]

Improvement of energy efficiency in buildings is crucial to achieving the goals of efficient energy consumption, to tackle climate

change and secure energy supply. This paper illustrates potential use of machine learning approaches, in particular classification,

for prediction of the heating load and the cooling load. These two aspects are crucial for energy efficient building design. We

study the effect of eight different variables on the heating and cooling loads and examine results of different classifiers. The

results prove suitability of machine learning approach in the field of energy efficiency in buildings, as well as the fact that rule-

based classifiers perform better on the given set of inputs.

Keywords: Building energy evaluation, Heating load, Cooling load, Machine learning, Classification

1. Introduction Efficient consumption of energy, as a general social

imperative, implies ensuring a stable financial system,

appropriate institutional and legislative framework

and activities to promote public awareness and change

in the habits regarding energy consumption.

The European Union (EU) has adopted Directive

[3] for efficient usage of energy among end-users and

energy services which include achieving significant

energy savings (20% of the greenhouse gases

emissions by 2020 and a 20% energy savings by

2020), as well as obligations to introduce measures

and incentives to promote energy efficiency at the

national level for all Member States [1]. Under the

Energy efficiency Directive EU countries must draw

up National Energy Efficiency Action Plans every

three years. These Action Plans include improvement

measures for energy performance of products,

buildings and services, the improvement of energy

production and distribution, reduction of the impact of

transport on energy consumption, facilitation of

financing and investments in the sector, and

encouragement of rational energy consumption.

The population can have little influence on

energy supply, due to the given natural resources.

However, they can influence the energy demand by

reducing energy consumption. In order to mitigate

climate change the general public has to change its

lifestyle to a less energy-intensive. According to the

report presented in [2] average global temperatures are

likely to rise by 2–3 °C within the next 50 years if a

current emission trends continue. Efficient

consumption of the end-users is also gaining an

increased importance within the European national

policy and the EU objectives related to climate and

energy. According to the European Commission,

residential buildings are responsible for 40% of

energy consumption and 36% of carbon dioxide

emissions in the EU. Potential energy savings in

residential areas and commercial buildings are

estimated at about 27% and 30%, respectively [1].

Similarly to the EU, residential buildings are the

largest consumers of energy in Serbia. The share of

renewable energy in total energy consumption of the

EU for the year 2014 was only 12.5% [3], and Serbia

is only at the beginning of use of renewable energy

sources.

Heating, ventilation, and air conditioning

(HVAC) play crucial role in regulation of indoor

temperatures and have the highest impact on energy

consumption in buildings. One of the ways to mitigate

increased demand for energy is to design and build

energy efficient buildings. EU Directive on energy

performance of buildings [1] obligates Member States

to apply minimum requirements to the energy

performance of new and existing buildings, to ensure

the certification of their energy performance and

require the regular inspection of boilers and air

conditioning systems in buildings. Similar to the EU

Directive, Serbia complies to the Regulations on

energy efficiency of buildings [4] which regulates

assessment of the energy efficiency of the building

based on the heating load, while it is planned to

include the cooling load in the future. Evaluation of

the overall energy efficiency of a building, according

52

to these minimal requirements, requires tracking the

consumption of (cold) water, electricity, gas, remotely

delivered hot water and other energy resources.

Architects and engineers need a range of information

regarding characteristics of the building to estimate

energy efficiency of a building. This information is

compactness, surface, wall and roof area, overall

height of a building, orientation, glazing area and

distribution.

This paper illustrates how machine learning

techniques can be used to analyze and forecast energy

consumption in buildings using aforementioned

characteristics of the building. The paper is organized

as follows. The next chapter summarizes the basic

elements used in evaluation of energy efficiency of a

building. The third chapter gives literature review,

presents the dataset we used to illustrate applicability

of different classifiers in the field of energy efficiency

in buildings, and the results of conducted analysis.

The last chapter summarizes conclusions.

2. Evaluation of energy efficiency in

residential buildings

Regulations on energy efficiency, aforementioned,

state that the amount of energy consumed for heating

and cooling with minimal environmental pollution are

the basic determinants of the energy efficiency in

buildings. This is expressed through the heating load

and cooling load.

The heating load is the heat lost while achieving

the required temperatures during the winter season.

Calculation of the heating load assumes steady state

conditions, meaning no solar radiation and steady

outdoor conditions, neglecting internal heat sources.

For more accurate calculation thermal capacity of the

walls and internal heat sources must be taken into

account1. In calculation of the cooling load the

unsteady state is considered, and all internal sources

add to the cooling loads. Heating and cooling loads

are derived from several critical inputs which are also

regulated through aforementioned Directive and refer

to the efficiency of the building shell or envelope,

such as the structure of the parts which are being

heated or cooled, as well as different parts of HVAC.

These elements are explained in the following.

The form of the object, meaning it is not too

sprawled and it is more compact, is very important for

its energy efficiency. In this way, there is less energy

waste, especially from the viewpoint of the heat.

For the calculation of energy efficiency heating

surface, the volume of the building, and its thermal

layer, which consist the wall area, roof area, glazing

area and glazing area distribution, are important.

These elements also comprise building envelope.

Directive on energy performance in buildings has

defined coefficients of thermal conductivity of all the

elements of a building envelope, depending whether it

is a new or old building, whether the wall is facing the

adjacent building or (non)heated inner wall, and

similarly. Glazing area and its distribution also has

strong impact on heating and cooling loads in

combination with the orientation of the building.

Orientation of the residential building must be

taken into account in calculation of the cooling load.

The orientation changes solar heat gains during

various times of day and the impact of the gain.

Figure 1 illustrates how the cooling load varies

between the worst case and the best case of

orientation of a house [5].

Fig. 1. Building orientation cooling load, [5].

3. Application of machine learning

techniques Machine learning and data mining techniques are

widely used in domain of energy performance in

buildings. As stated in paper [10] complexity and

uncertainty of factors which influence building energy

demand (weather conditions, HVAC equipment,

building envelopes or occupant behavior) are

overcome by utilizing data mining techniques.

Application of these techniques facilitates fast and

easy derivation of the answers through variations of

some building design parameters once a model has

been adequately trained [6]. Mostly different

classification techniques have been used to predict

demand for energy [7], energy consumption [8] or

hourly cooling load [9], as well as artificial neural

networks [11]

Authors in paper [7] used decision trees to model

energy demands. Developed model estimates

residential building energy performance indexes by

modeling building energy use intensity levels.

Decision tree has classified and predicted building

energy demand levels with 92% of accuracy, as well

as automatically identified and ranked significant

factors of building energy use intensity.

Support vector machines (SVM) algorithm is

wider spread comparing to decision trees. Authors in

paper [8] used SVM to predict building energy

consumption in tropical region using four randomly

chosen commercial buildings in Singapore. They used

weather data, including monthly mean outdoor dry-

bulb temperature, relative humidity and global solar

radiation as an input features. Mean monthly utility

bills are collected for developing and testing models.

The results showed the superiority of the SVM

for hourly changes in cooling load. They used the

outdoor dry-bulb temperature, relative humidity and

solar radiation as the input parameters. The results

also proved superiority of SVM method in terms of

accuracy and generalization comparing to traditional

artificial neural network model.

Artificial neural networks are more reliable than

traditional simulation models and regression

techniques in predicting energy consumption. As

demonstrated in [12, 13] neural networks successfully

predict heating and cooling loads of a building. In

paper [12] authors used 250 known cases of heating

load in combination with type of room and its

characteristics to train neural network, such as areas

of windows, walls, partitions and floors, the type of

windows and walls, roof or ceiling. The accuracy of

the prediction was improved by grouping the input

data into two categories, one with spaces of floor

areas up to 7 m2 and another with floor areas from 7

to 100 m2. Authors in [13] used neural networks to

predict both heating and cooling loads in nine

different buildings in Cyprus. In addition to daily

loads authors used single and double walls, as well as

different roof insulations. High accuracy was achieved

for both types of loads (R2-values are 0.9885 for

heating load and 0.9905 for cooling load) and the

results indicate that the proposed method can be used

for the required predictions for buildings of different

constructions.

In the following we present the case study based

on the publicly available data regarding energy

efficiency in buildings. We extend research presented

in the paper [6] experimenting with different

classifiers compared to the classifiers used in

previously described papers.

Energy efficiency dataset

Simulations of building energy aspects are widely

used approach. Although, it is impossible to

guarantee that the simulation findings will perfectly

reflect actual data in the real world simulated results

give good indication of the likely percentage change

and underlying trend of the actual data and enable

energy comparisons of buildings [6]. Authors of the

paper [6] associated heating load (Y1) and cooling

load (Y2) with eight variables: relative compactness

(X1), surface area (X2), wall area (X3), roof area

(X4), overall height (X5), orientation (X6), glazing

area (X7), and glazing area distribution (X8). These

parameters are used in an environmental analysis

tool Ecotect, which allows designers to simulate

building performance from the earliest stages of

conceptual design, to simulate 768 different

buildings with the same volume of 771.75 m2, but

different surface areas and dimensions. Detailed

description of used parameters, building

characteristics, location, occupancy, and internal

design conditions, as well as the simulation process

is described in the paper [6]. Resulting dataset is

publicly available2 and it is used in this paper to

further the research presented in the paper [6]. The

authors of the paper [6] used standard robust linear

regression technique, and a powerful nonlinear non-

parametric classifier, while this paper presents

comparison of different classifiers. In addition to

regression we used meta-, lazy-, rule- and tree-based

classifiers. Our approach illustrates that rule-based

classifiers outperform all other classifiers.

Dataset contains all numeric variables. There

are no missing values. Table 1 presents basic

statistics of dataset and correlation of input and

output attributes (Y1 and Y2).

Table 1. Basic statistics of the dataset

Simple statistics illustrate the need for data

normalization, since values of attributes vary on

quite different spans. Normalization refers to data

transformation which will result in scaling of all

attributes on the range from 0 to 1. Such preparation

facilitates comparison of attributes. Statistics

presented in Table 1 point to conclusion that the

strongest association is between X4 and X5 input

attributes with both output attributes. X4 attribute, i.e. roof area, is inversely proportional to Y1

(heating load) and Y2 (cooling load) attributes,

while X5 attribute, i.e. overall height, is in positive

and proportional relationship with output attributes.

Prediction models of heating and cooling loads

Classification represents well known supervised data

mining approach. It is a process of finding the

common properties of data objects that belong to the

same class [16]. Data labeled by the class to which

each object belongs is used to train classifier [14].

The main task of classification is to build a model

that will enable correct classification of the newly

encountered instances. Authors of the [15] have

formally defined classification as follows. A dataset

of observations is described with a fix number of

attributes Ai, and designated class attribute C. The

learning task is to find a mapping f that is able to

compute the class value C = f (A1, ... , An) from the

attribute values of new, previously unseen

observations.

Based on the input attributes we developed

Min Max Mean StdCorrel

Y1

Correl

Y2

X1 0.62 0.98 0.76 0.11 0.62 0.63

X2 514.50 808.50 671.71 88.09 -0.66 -0.67

X3 245.00 416.50 318.50 43.63 0.46 0.43

X4 110.25 220.50 176.60 45.17 -0.86 -0.86

X5 3.50 7.00 5.25 1.75 0.89 0.90

X6 2.00 5.00 3.50 1.12 0.00 0.01

X7 0.00 0.40 0.23 0.13 0.27 0.21

X8 0.00 5.00 2.81 1.55 0.09 0.05

Y1 6.01 43.10 22.31 10.09 - 0.98

Y2 10.90 48.03 24.59 9.51 0.98 -

53

to these minimal requirements, requires tracking the

consumption of (cold) water, electricity, gas, remotely

delivered hot water and other energy resources.

Architects and engineers need a range of information

regarding characteristics of the building to estimate

energy efficiency of a building. This information is

compactness, surface, wall and roof area, overall

height of a building, orientation, glazing area and

distribution.

This paper illustrates how machine learning

techniques can be used to analyze and forecast energy

consumption in buildings using aforementioned

characteristics of the building. The paper is organized

as follows. The next chapter summarizes the basic

elements used in evaluation of energy efficiency of a

building. The third chapter gives literature review,

presents the dataset we used to illustrate applicability

of different classifiers in the field of energy efficiency

in buildings, and the results of conducted analysis.

The last chapter summarizes conclusions.

2. Evaluation of energy efficiency in

residential buildings

Regulations on energy efficiency, aforementioned,

state that the amount of energy consumed for heating

and cooling with minimal environmental pollution are

the basic determinants of the energy efficiency in

buildings. This is expressed through the heating load

and cooling load.

The heating load is the heat lost while achieving

the required temperatures during the winter season.

Calculation of the heating load assumes steady state

conditions, meaning no solar radiation and steady

outdoor conditions, neglecting internal heat sources.

For more accurate calculation thermal capacity of the

walls and internal heat sources must be taken into

account1. In calculation of the cooling load the

unsteady state is considered, and all internal sources

add to the cooling loads. Heating and cooling loads

are derived from several critical inputs which are also

regulated through aforementioned Directive and refer

to the efficiency of the building shell or envelope,

such as the structure of the parts which are being

heated or cooled, as well as different parts of HVAC.

These elements are explained in the following.

The form of the object, meaning it is not too

sprawled and it is more compact, is very important for

its energy efficiency. In this way, there is less energy

waste, especially from the viewpoint of the heat.

For the calculation of energy efficiency heating

surface, the volume of the building, and its thermal

layer, which consist the wall area, roof area, glazing

area and glazing area distribution, are important.

These elements also comprise building envelope.

Directive on energy performance in buildings has

defined coefficients of thermal conductivity of all the

elements of a building envelope, depending whether it

is a new or old building, whether the wall is facing the

adjacent building or (non)heated inner wall, and

similarly. Glazing area and its distribution also has

strong impact on heating and cooling loads in

combination with the orientation of the building.

Orientation of the residential building must be

taken into account in calculation of the cooling load.

The orientation changes solar heat gains during

various times of day and the impact of the gain.

Figure 1 illustrates how the cooling load varies

between the worst case and the best case of

orientation of a house [5].

Fig. 1. Building orientation cooling load, [5].

3. Application of machine learning

techniques Machine learning and data mining techniques are

widely used in domain of energy performance in

buildings. As stated in paper [10] complexity and

uncertainty of factors which influence building energy

demand (weather conditions, HVAC equipment,

building envelopes or occupant behavior) are

overcome by utilizing data mining techniques.

Application of these techniques facilitates fast and

easy derivation of the answers through variations of

some building design parameters once a model has

been adequately trained [6]. Mostly different

classification techniques have been used to predict

demand for energy [7], energy consumption [8] or

hourly cooling load [9], as well as artificial neural

networks [11]

Authors in paper [7] used decision trees to model

energy demands. Developed model estimates

residential building energy performance indexes by

modeling building energy use intensity levels.

Decision tree has classified and predicted building

energy demand levels with 92% of accuracy, as well

as automatically identified and ranked significant

factors of building energy use intensity.

Support vector machines (SVM) algorithm is

wider spread comparing to decision trees. Authors in

paper [8] used SVM to predict building energy

consumption in tropical region using four randomly

chosen commercial buildings in Singapore. They used

weather data, including monthly mean outdoor dry-

bulb temperature, relative humidity and global solar

radiation as an input features. Mean monthly utility

bills are collected for developing and testing models.

The results showed the superiority of the SVM

for hourly changes in cooling load. They used the

outdoor dry-bulb temperature, relative humidity and

solar radiation as the input parameters. The results

also proved superiority of SVM method in terms of

accuracy and generalization comparing to traditional

artificial neural network model.

Artificial neural networks are more reliable than

traditional simulation models and regression

techniques in predicting energy consumption. As

demonstrated in [12, 13] neural networks successfully

predict heating and cooling loads of a building. In

paper [12] authors used 250 known cases of heating

load in combination with type of room and its

characteristics to train neural network, such as areas

of windows, walls, partitions and floors, the type of

windows and walls, roof or ceiling. The accuracy of

the prediction was improved by grouping the input

data into two categories, one with spaces of floor

areas up to 7 m2 and another with floor areas from 7

to 100 m2. Authors in [13] used neural networks to

predict both heating and cooling loads in nine

different buildings in Cyprus. In addition to daily

loads authors used single and double walls, as well as

different roof insulations. High accuracy was achieved

for both types of loads (R2-values are 0.9885 for

heating load and 0.9905 for cooling load) and the

results indicate that the proposed method can be used

for the required predictions for buildings of different

constructions.

In the following we present the case study based

on the publicly available data regarding energy

efficiency in buildings. We extend research presented

in the paper [6] experimenting with different

classifiers compared to the classifiers used in

previously described papers.

Energy efficiency dataset

Simulations of building energy aspects are widely

used approach. Although, it is impossible to

guarantee that the simulation findings will perfectly

reflect actual data in the real world simulated results

give good indication of the likely percentage change

and underlying trend of the actual data and enable

energy comparisons of buildings [6]. Authors of the

paper [6] associated heating load (Y1) and cooling

load (Y2) with eight variables: relative compactness

(X1), surface area (X2), wall area (X3), roof area

(X4), overall height (X5), orientation (X6), glazing

area (X7), and glazing area distribution (X8). These

parameters are used in an environmental analysis

tool Ecotect, which allows designers to simulate

building performance from the earliest stages of

conceptual design, to simulate 768 different

buildings with the same volume of 771.75 m2, but

different surface areas and dimensions. Detailed

description of used parameters, building

characteristics, location, occupancy, and internal

design conditions, as well as the simulation process

is described in the paper [6]. Resulting dataset is

publicly available2 and it is used in this paper to

further the research presented in the paper [6]. The

authors of the paper [6] used standard robust linear

regression technique, and a powerful nonlinear non-

parametric classifier, while this paper presents

comparison of different classifiers. In addition to

regression we used meta-, lazy-, rule- and tree-based

classifiers. Our approach illustrates that rule-based

classifiers outperform all other classifiers.

Dataset contains all numeric variables. There

are no missing values. Table 1 presents basic

statistics of dataset and correlation of input and

output attributes (Y1 and Y2).

Table 1. Basic statistics of the dataset

Simple statistics illustrate the need for data

normalization, since values of attributes vary on

quite different spans. Normalization refers to data

transformation which will result in scaling of all

attributes on the range from 0 to 1. Such preparation

facilitates comparison of attributes. Statistics

presented in Table 1 point to conclusion that the

strongest association is between X4 and X5 input

attributes with both output attributes. X4 attribute, i.e. roof area, is inversely proportional to Y1

(heating load) and Y2 (cooling load) attributes,

while X5 attribute, i.e. overall height, is in positive

and proportional relationship with output attributes.

Prediction models of heating and cooling loads

Classification represents well known supervised data

mining approach. It is a process of finding the

common properties of data objects that belong to the

same class [16]. Data labeled by the class to which

each object belongs is used to train classifier [14].

The main task of classification is to build a model

that will enable correct classification of the newly

encountered instances. Authors of the [15] have

formally defined classification as follows. A dataset

of observations is described with a fix number of

attributes Ai, and designated class attribute C. The

learning task is to find a mapping f that is able to

compute the class value C = f (A1, ... , An) from the

attribute values of new, previously unseen

observations.

Based on the input attributes we developed

Min Max Mean StdCorrel

Y1

Correl

Y2

X1 0.62 0.98 0.76 0.11 0.62 0.63

X2 514.50 808.50 671.71 88.09 -0.66 -0.67

X3 245.00 416.50 318.50 43.63 0.46 0.43

X4 110.25 220.50 176.60 45.17 -0.86 -0.86

X5 3.50 7.00 5.25 1.75 0.89 0.90

X6 2.00 5.00 3.50 1.12 0.00 0.01

X7 0.00 0.40 0.23 0.13 0.27 0.21

X8 0.00 5.00 2.81 1.55 0.09 0.05

Y1 6.01 43.10 22.31 10.09 - 0.98

Y2 10.90 48.03 24.59 9.51 0.98 -

54

several classification models in Weka

3 tool. We

experimented with different types of algorithms:

functions (Gaussian Processes, Isotonic Regression,

Least Med Sq, Linear Regression, Pace Regression,

Simple Linear Regression, SMO reg and Multilayer

Perceptron), lazy classifiers (IBk and KStar),

Bagging meta classifier, classifiers based on rules

(Decision table and M5Rules) and classification

trees (M5P and REPTree). Since both heating and

cooling load are relevant for energy efficiency of the

building, two scenarios are taken into account for

their classification: 1. the second output attribute is

known, and 2. the second output attribute is

unknown. Figure 2 and Figure 3 illustrate

comparison of these scenarios when classification

error is observed.

General conclusions, derived from Figure 2 and

Figure 3, are described in the following.

• Almost every classifier classifies heating

load, i.e. attribute Y1, with lower

classification error compared to the cooling

load classification, i.e. Y2 attribute.

• Based on the input parameters it is far more

difficult to predict values of the cooling load

in comparison to the prediction of the heating

load. Results are explained in more details in

the following.

• Ruled based classifiers and classification

trees are performing better in classification of

both output attributes than functions, lazy or

meta classifiers.

• Classifiers predict values with larger

deviations when it comes to higher values of

the heating and the cooling loads, i.e. it is

easier to predict smaller values.

• Decision table algorithm gives the best

classification results for both heating and

cooling load.

A decision table consists of a hierarchical table

in which each entry in a higher level table gets

broken down by the values of a pair of additional

attributes to form another table [17]. It is formally

defined in [16] as follows. Decision table for dataset

D with n attributes A1, A2, ..., An is a table with

schema R (A1, A2, ... , An, Class, Sup, Conf). A row

Ri = ( a1i, a2i, ... , ani, ci,supi, confi) in table R

represents a classification rule, where aij (1 ≤ j ≤ n)

can be either from DOM(Ai) or a special value ANY,

ci ∈ { c1, c2, ..., cm}, minsup ≤ supi ≤ 1, and minconf ≤

confi ≤ 1 and minsup and minconf are predetermined

thresholds. The interpretation of the rule is if (A1 =

a1) and (A2 = a2) and … and (An= an) then class= ci

with probability confi and having support supi, where

aj ≠ ANY, 1 ≤ j ≤ n.

In classification of the heating load higher

precision is achieved if cooling loads are familiar,

except in the case of Bagging meta classifier,

Decision table and REPTree, Figure 2. Classification

based on a decision table is resulting with the

smallest classification error: 4% if the cooling load

3 Weka tool http://www.cs.waikato.ac.nz/ml/weka/.

is familiar and used in classification and 3.54% if the

value of the cooling load is unfamiliar, Figure 2, i.e.

in 3.54% cases building will be assigned false value.

Even though an overall error is smaller when cooling

load is unfamiliar and it is not used in the

classification process, smaller deviations between

the actual and predicted value are achieved in the

classification which is using the cooling load as an

input parameter. Table 2 illustrates the first 10 rules

– results of a classification based on decision table.

Resulting rules point to the variables that are the

most important for the precise classification of the

heating load: surface area, wall area, glazing area,

and glazing area distribution.

Classification of the cooling load is more

precise if value of the heating load is familiar and

taken into account, Figure 3. Approximate

classification error, in both scenarios, is achieved

with Bagging meta classifier, Decision table and

REPTree. Classification with decision table is

resulting with the smallest classification error:

9.81% if the heating load is familiar and taken into

account and 11.19% if it is not considered in the

classification, Figure 3. Table 3 illustrates the first

10 rules – results of a classification based on

decision table. Resulting rules point to the most

important variables for the precise classification of

Fig. 2. Comparison of classification errors for heating load (Y1)

Table 2. Classification rules for the heating load

the cooling load: surface area, wall area, and glazing

area.

4. Conclusion Improvement of energy efficiency in buildings is

crucial to achieving the goals of efficient energy

consumption, to tackle climate change and secure

energy supply. If we want to achieve significant and

sustainable energy savings, primarily we need to

develop energy-efficient technology, pr

services, and change consumer habits in terms of

energy use, in order to maintain the same quality of

life with less energy consumption. As one of the

steps towards efficient energy consumption,

Surface area Wall area Glazing area

Glazing area

distribution

'(632.1-661.5]' '(399.35-inf)' '(0.36-inf)' '(4.5-inf)'

'(779.1-inf)' '(365.05-382.2]' '(0.36-inf)' '(4.5-inf)'

'(779.1-inf)' '(330.75-347.9]' '(0.36-inf)' '(4.5-inf)'

'(632.1-661.5]' '(330.75-347.9]' '(0.36-inf)' '(4.5-inf)'

'(749.7-779.1]' '(313.6-330.75]' '(0.36-inf)' '(4.5-inf)'

'(602.7-632.1]' '(313.6-330.75]' '(0.36-inf)' '(4.5-inf)'

'(543.9-573.3]' '(313.6-330.75]' '(0.36-inf)' '(4.5-inf)'

'(632.1-661.5]' '(399.35-inf)' '(0.36-inf)' '(3.5-4]'

'(632.1-661.5]' '(399.35-inf)' '(0.24-0.28]' '(4.5-inf)'

'(720.3-749.7]' '(279.3-296.45]' '(0.36-inf)' '(4.5-inf)'


Table 2. Classification rules for the heating load Table 3. Classification rules for the cooling load


energy efficiency in buildings is





ient technology, products and

consumer habits in terms of




buildings in European countries are legally bound to

conform to appropriate minimum requirements

regarding energy efficiency following the European

Directive 2002/91/EC. In efficient building design

computation of the heating and the cooling loads are

required. They determine the specif

heating and cooling equipment needed to maintain

comfortable indoor air conditions. This paper

illustrates possibilities of machine learning

applications for prediction of the heating and the

cooling loads in buildings. We used publicly

available dataset which comprise 8 input variables

(relative compactness, surface area, wall area, roof

area, overall height, orientation, glazing area and

Glazing area

distribution Heating load

'(4.5-inf)' 39.43

'(4.5-inf)' 16.53

'(4.5-inf)' 17.98

'(4.5-inf)' 41.49

'(4.5-inf)' 14.99

'(4.5-inf)' 29.62

'(4.5-inf)' 35.16

'(3.5-4]' 40.45

'(4.5-inf)' 36.27

'(4.5-inf)' 14.25


'(632.1-661.5]' '(399.35-inf)' '(0.36-inf)'

'(779.1-inf)' '(365.05-382.2]' '(0.36-inf)'

'(779.1-inf)' '(330.75-347.9]' '(0.36-inf)'

'(632.1-661.5]' '(330.75-347.9]' '(0.36-inf)'

'(749.7-779.1]' '(313.6-330.75]' '(0.36-inf)'

'(602.7-632.1]' '(313.6-330.75]' '(0.36-inf)'

'(543.9-573.3]' '(313.6-330.75]' '(0.36-inf)'

'(632.1-661.5]' '(399.35-inf)' '(0.24-0.28]'

'(720.3-749.7]' '(279.3-296.45]' '(0.36-inf)'

'(573.3-602.7]' '(279.3-296.45]' '(0.36-inf)'

Classification rules for the cooling load

are legally bound to





required. They determine the specifications of the




of the heating and the


ilable dataset which comprise 8 input variables



Glazing area Cooling load

'(0.36-inf)' 39.638

'(0.36-inf)' 16.892

'(0.36-inf)' 21.709

'(0.36-inf)' 42.4515

'(0.36-inf)' 17.941

'(0.36-inf)' 30.5995

'(0.36-inf)' 36.685

'(0.24-0.28]' 36.9115

'(0.36-inf)' 16.7715

'(0.36-inf)' 33.483

55

several classification models in Weka

3 tool. We

experimented with different types of algorithms:

functions (Gaussian Processes, Isotonic Regression,

Least Med Sq, Linear Regression, Pace Regression,

Simple Linear Regression, SMO reg and Multilayer

Perceptron), lazy classifiers (IBk and KStar),

Bagging meta classifier, classifiers based on rules

(Decision table and M5Rules) and classification

trees (M5P and REPTree). Since both heating and

cooling load are relevant for energy efficiency of the

building, two scenarios are taken into account for

their classification: 1. the second output attribute is

known, and 2. the second output attribute is

unknown. Figure 2 and Figure 3 illustrate

comparison of these scenarios when classification

error is observed.

General conclusions, derived from Figure 2 and

Figure 3, are described in the following.

• Almost every classifier classifies heating

load, i.e. attribute Y1, with lower

classification error compared to the cooling

load classification, i.e. Y2 attribute.

• Based on the input parameters it is far more

difficult to predict values of the cooling load

in comparison to the prediction of the heating

load. Results are explained in more details in

the following.

• Ruled based classifiers and classification

trees are performing better in classification of

both output attributes than functions, lazy or

meta classifiers.

• Classifiers predict values with larger

deviations when it comes to higher values of

the heating and the cooling loads, i.e. it is

easier to predict smaller values.

• Decision table algorithm gives the best

classification results for both heating and

cooling load.

A decision table consists of a hierarchical table

in which each entry in a higher level table gets

broken down by the values of a pair of additional

attributes to form another table [17]. It is formally

defined in [16] as follows. Decision table for dataset

D with n attributes A1, A2, ..., An is a table with

schema R (A1, A2, ... , An, Class, Sup, Conf). A row

Ri = ( a1i, a2i, ... , ani, ci,supi, confi) in table R

represents a classification rule, where aij (1 ≤ j ≤ n)

can be either from DOM(Ai) or a special value ANY,

ci ∈ { c1, c2, ..., cm}, minsup ≤ supi ≤ 1, and minconf ≤

confi ≤ 1 and minsup and minconf are predetermined

thresholds. The interpretation of the rule is if (A1 =

a1) and (A2 = a2) and … and (An= an) then class= ci

with probability confi and having support supi, where

aj ≠ ANY, 1 ≤ j ≤ n.

In classification of the heating load higher

precision is achieved if cooling loads are familiar,

except in the case of Bagging meta classifier,

Decision table and REPTree, Figure 2. Classification

based on a decision table is resulting with the

smallest classification error: 4% if the cooling load

3 Weka tool http://www.cs.waikato.ac.nz/ml/weka/.

is familiar and used in classification and 3.54% if the

value of the cooling load is unfamiliar, Figure 2, i.e.

in 3.54% cases building will be assigned false value.

Even though an overall error is smaller when cooling

load is unfamiliar and it is not used in the

classification process, smaller deviations between

the actual and predicted value are achieved in the

classification which is using the cooling load as an

input parameter. Table 2 illustrates the first 10 rules

– results of a classification based on decision table.

Resulting rules point to the variables that are the

most important for the precise classification of the

heating load: surface area, wall area, glazing area,

and glazing area distribution.

Classification of the cooling load is more

precise if value of the heating load is familiar and

taken into account, Figure 3. Approximate

classification error, in both scenarios, is achieved

with Bagging meta classifier, Decision table and

REPTree. Classification with decision table is

resulting with the smallest classification error:

9.81% if the heating load is familiar and taken into

account and 11.19% if it is not considered in the

classification, Figure 3. Table 3 illustrates the first

10 rules – results of a classification based on

decision table. Resulting rules point to the most

important variables for the precise classification of


Table 2. Classification rules for the heating load


area.

4. Conclusion Improvement of energy efficiency in buildings is





develop energy-efficient technology, pr

services, and change consumer habits in terms of





Glazing area

distribution

'(632.1-661.5]' '(399.35-inf)' '(0.36-inf)' '(4.5-inf)'

'(779.1-inf)' '(365.05-382.2]' '(0.36-inf)' '(4.5-inf)'

'(779.1-inf)' '(330.75-347.9]' '(0.36-inf)' '(4.5-inf)'

'(632.1-661.5]' '(330.75-347.9]' '(0.36-inf)' '(4.5-inf)'

'(749.7-779.1]' '(313.6-330.75]' '(0.36-inf)' '(4.5-inf)'

'(602.7-632.1]' '(313.6-330.75]' '(0.36-inf)' '(4.5-inf)'

'(543.9-573.3]' '(313.6-330.75]' '(0.36-inf)' '(4.5-inf)'

'(632.1-661.5]' '(399.35-inf)' '(0.36-inf)' '(3.5-4]'

'(632.1-661.5]' '(399.35-inf)' '(0.24-0.28]' '(4.5-inf)'

'(720.3-749.7]' '(279.3-296.45]' '(0.36-inf)' '(4.5-inf)'


Table 2. Classification rules for the heating load Table 3. Classification rules for the cooling load


energy efficiency in buildings is





ient technology, products and

consumer habits in terms of




buildings in European countries are legally bound to





required. They determine the specif




applications for prediction of the heating and the


available dataset which comprise 8 input variables



Glazing area

distribution Heating load

'(4.5-inf)' 39.43

'(4.5-inf)' 16.53

'(4.5-inf)' 17.98

'(4.5-inf)' 41.49

'(4.5-inf)' 14.99

'(4.5-inf)' 29.62

'(4.5-inf)' 35.16

'(3.5-4]' 40.45

'(4.5-inf)' 36.27

'(4.5-inf)' 14.25


'(632.1-661.5]' '(399.35-inf)' '(0.36-inf)'

'(779.1-inf)' '(365.05-382.2]' '(0.36-inf)'

'(779.1-inf)' '(330.75-347.9]' '(0.36-inf)'

'(632.1-661.5]' '(330.75-347.9]' '(0.36-inf)'

'(749.7-779.1]' '(313.6-330.75]' '(0.36-inf)'

'(602.7-632.1]' '(313.6-330.75]' '(0.36-inf)'

'(543.9-573.3]' '(313.6-330.75]' '(0.36-inf)'

'(632.1-661.5]' '(399.35-inf)' '(0.24-0.28]'

'(720.3-749.7]' '(279.3-296.45]' '(0.36-inf)'

'(573.3-602.7]' '(279.3-296.45]' '(0.36-inf)'

Classification rules for the cooling load

are legally bound to





required. They determine the specifications of the




of the heating and the


ilable dataset which comprise 8 input variables



Glazing area Cooling load

'(0.36-inf)' 39.638

'(0.36-inf)' 16.892

'(0.36-inf)' 21.709

'(0.36-inf)' 42.4515

'(0.36-inf)' 17.941

'(0.36-inf)' 30.5995

'(0.36-inf)' 36.685

'(0.24-0.28]' 36.9115

'(0.36-inf)' 16.7715

'(0.36-inf)' 33.483

56

Fig. 3. Comparison of classification errors for cooling loads (Y2)

glazing area distribution) and 2 output variables

(heating and cooling loads). We applied different

classifiers on the input variables in order to predict

the heating load and the cooling load. Based on the

results we can conclude that machine learning

approach is well suited for this problem and the rule

and tree-based classifiers outperform all other

classification techniques. Surface area, wall area,

glazing area and glazing area distribution are the key

parameters in predicting heating and cooling load

Classifiers are more efficient in predicting heating

loads than cooling loads leading to the conclusion

that some additional variables may

when predicting cooling loads.

References

[1] Directive 2010/31/EU of the European Parliament and of

the Council of 19 May 2010 on the energy performance

of buildings, available at http://eur-lex.europa.eu/legal

content/EN/ALL/;ELX_SESSIONID=FZMjThLLzfxmm

MCQGp2Y1s2d3TjwtD8QS3pqdkhXZbwqGwlgY9KN!

2064651424?uri=CELEX:32010L0031.

[2] HMT, 2006. Stern Review: The Economics of Climate

Change. Her Majesty’s Treasury.

/http://www.hmtreasury.gov.uk/independent_reviews/ster

n_review_economics_climate_change/stern_review_

report.cfmS.


the Council of 25 October 2012 on energy efficiency,

amending Directives 2009/125/EC and 2010/30/EU and

repealing Directives 2004/8/EC and 2006/32/EC Text

with EEA relevance, available on: http://eur

lex.europa.eu/legal-

content/EN/TXT/?uri=celex%3A32012L0027

[4] Regulations on energy efficiency in building in Serbia,

available at:

http://www.ingkomora.org.rs/strucniispiti/download/ee/P







roach is well suited for this problem and the rule-

based classifiers outperform all other

. Surface area, wall area,


parameters in predicting heating and cooling loads.



be considered

Directive 2010/31/EU of the European Parliament and of

May 2010 on the energy performance




424?uri=CELEX:32010L0031.

HMT, 2006. Stern Review: The Economics of Climate




ean Parliament and of

October 2012 on energy efficiency,



with EEA relevance, available on: http://eur-

/?uri=celex%3A32012L0027.

Regulations on energy efficiency in building in Serbia,

available at:


Energy, IBACOS, Inc. Pittsburg, USA. Available at:

http://www.nrel.gov/docs/fy11osti/51603.pdf. Accesed

on 20th February 2017.

[6] Tsanas A., Xifara A. (2012), Accurate quantitative

estimation of energy performance of residential

using statistical machine learning tools

Buildings, Vol. 49, 560–567.

[7] Yu Z., Haghigrat F., Fung B.C.M., Yoshimo H. (2010),

A decision tree method for building energy demand

modeling. Energy and Buildings, Vol. 42, 1637

[8] Dong B., Cao C., Lee S.E. (2005), Applying support

vector machines to predict building energy consumption

in tropical region. Energy and Buildings, Vol. 37, 545

553.

[9] Li Q., Meng Q., Cai J., Yoshino H., Mochida A. (2009),

Applying support vector machine to predict

cooling load in the building. Applied Energy, Vol. 86,

2249–2256.

[10] Yu Z., Haghighat F., Fung B.C.M. (2016)

challenges in building engineering and data mining

applications for energy-efficient communities

Sustainable Cities and Society, Vol.

[11] Kumar R., Aggarwal R.K., Sharmaa J.D. (2013)

analysis of a building using artificial neural network: A

review. Energy and Buildings, Vol.

[12] Kaligirou S.A., Neocleous C., Schizas C.

Artificial neural networks used for estimation of building

heating load. Proceedings of the CLIMA 2000

International Conference, Brussels, Belgium, Paper

Number P 159, 1997.

[13] Kaligirou S.A., Florides G., Neocleous

(2001), Estimation of daily heating and cooling loads

using artificial neural networks.

CLIMA 2000 International Conference on CD

Naples, Italy.

[14] Kotsiantis S. B., Zaharakis I. D.,

Machine learning: a review of classif

combining techniques. Artificial Intelligence Review,

Vol. 26 (3), 159-190.

[15] Fürnkranz J., Gamberger D., Lavra

Foundations of Rule Learning. Berlin, Germany.



Accurate quantitative

estimation of energy performance of residential buildings

using statistical machine learning tools. Energy and

Yu Z., Haghigrat F., Fung B.C.M., Yoshimo H. (2010),


modeling. Energy and Buildings, Vol. 42, 1637–1646.

Cao C., Lee S.E. (2005), Applying support


in tropical region. Energy and Buildings, Vol. 37, 545–

Li Q., Meng Q., Cai J., Yoshino H., Mochida A. (2009),

Applying support vector machine to predict hourly


C.M. (2016), Advances and


efficient communities.

. 25, 33–38.

, Aggarwal R.K., Sharmaa J.D. (2013), Energy


Vol. 65, 352–358.

Kaligirou S.A., Neocleous C., Schizas C. (2000),


Proceedings of the CLIMA 2000


, Neocleous C., Schizas C.

Estimation of daily heating and cooling loads

Proceedings of the

CLIMA 2000 International Conference on CD-ROM,

, Pintelas P. E. (2006)

Machine learning: a review of classification and

Artificial Intelligence Review,

, Lavrač N. (2012),


Proceedings of the 26th International Conference on

Very Large Databases, Cairo, Egypt, 373-384.

[17] Becker B.G. (1998), Visualizing decision table

classifiers. Proceedings IEEE Symposium on Information

Visualization, 102-105.

57







approach is well suited for this problem and the rule

and tree-based classifiers outperform all other

classification techniques. Surface area, wall area,


parameters in predicting heating and cooling load



that some additional variables may

when predicting cooling loads.

References


the Council of 19 May 2010 on the energy performance

of buildings, available at http://eur-lex.europa.eu/legal



2064651424?uri=CELEX:32010L0031.

[2] HMT, 2006. Stern Review: The Economics of Climate




report.cfmS.


the Council of 25 October 2012 on energy efficiency,



with EEA relevance, available on: http://eur


content/EN/TXT/?uri=celex%3A32012L0027

[4] Regulations on energy efficiency in building in Serbia,

available at:








roach is well suited for this problem and the rule-

based classifiers outperform all other

. Surface area, wall area,


parameters in predicting heating and cooling loads.



be considered

Directive 2010/31/EU of the European Parliament and of

May 2010 on the energy performance




424?uri=CELEX:32010L0031.

HMT, 2006. Stern Review: The Economics of Climate




ean Parliament and of

October 2012 on energy efficiency,



with EEA relevance, available on: http://eur-

/?uri=celex%3A32012L0027.

Regulations on energy efficiency in building in Serbia,

available at:




on 20th February 2017.

[6] Tsanas A., Xifara A. (2012), Accurate quantitative

estimation of energy performance of residential

using statistical machine learning tools

Buildings, Vol. 49, 560–567.

[7] Yu Z., Haghigrat F., Fung B.C.M., Yoshimo H. (2010),


modeling. Energy and Buildings, Vol. 42, 1637

[8] Dong B., Cao C., Lee S.E. (2005), Applying support


in tropical region. Energy and Buildings, Vol. 37, 545

553.

[9] Li Q., Meng Q., Cai J., Yoshino H., Mochida A. (2009),

Applying support vector machine to predict


2249–2256.

[10] Yu Z., Haghighat F., Fung B.C.M. (2016)


applications for energy-efficient communities

Sustainable Cities and Society, Vol.

[11] Kumar R., Aggarwal R.K., Sharmaa J.D. (2013)


review. Energy and Buildings, Vol.

[12] Kaligirou S.A., Neocleous C., Schizas C.


heating load. Proceedings of the CLIMA 2000


Number P 159, 1997.

[13] Kaligirou S.A., Florides G., Neocleous

(2001), Estimation of daily heating and cooling loads

using artificial neural networks.

CLIMA 2000 International Conference on CD

Naples, Italy.

[14] Kotsiantis S. B., Zaharakis I. D.,

Machine learning: a review of classif

combining techniques. Artificial Intelligence Review,

Vol. 26 (3), 159-190.

[15] Fürnkranz J., Gamberger D., Lavra




Accurate quantitative

estimation of energy performance of residential buildings

using statistical machine learning tools. Energy and

Yu Z., Haghigrat F., Fung B.C.M., Yoshimo H. (2010),


modeling. Energy and Buildings, Vol. 42, 1637–1646.

Cao C., Lee S.E. (2005), Applying support


in tropical region. Energy and Buildings, Vol. 37, 545–

Li Q., Meng Q., Cai J., Yoshino H., Mochida A. (2009),

Applying support vector machine to predict hourly


C.M. (2016), Advances and


efficient communities.

. 25, 33–38.

, Aggarwal R.K., Sharmaa J.D. (2013), Energy


Vol. 65, 352–358.

Kaligirou S.A., Neocleous C., Schizas C. (2000),


Proceedings of the CLIMA 2000


, Neocleous C., Schizas C.

Estimation of daily heating and cooling loads

Proceedings of the

CLIMA 2000 International Conference on CD-ROM,

, Pintelas P. E. (2006)

Machine learning: a review of classification and

Artificial Intelligence Review,

, Lavrač N. (2012),


Proceedings of the 26th International Conference on

Very Large Databases, Cairo, Egypt, 373-384.

[17] Becker B.G. (1998), Visualizing decision table

classifiers. Proceedings IEEE Symposium on Information

Visualization, 102-105.

58

EXPRES 2017

ISBN 978-86-919769-1-0

Hydraulics of a thermal network for district heating system J. TAKÁCS a, Z. STRAKOVÁ b, L .RÁCZ c

Slovak University of Technology in Bratislava, Faculty of Civil Engineering,

Department of Building Services, Radlinského 11, 810 05 Bratislava, Slovak Republic a E-mail: [email protected]

bE-mail: [email protected]

cE-mail: [email protected]

The hydraulics of a thermal network of a district heating system is a very important issue, to which not enough attention is often

paid. In this paper the authors want to point out some of the important aspects of the design and operation of thermal networks in

district heating systems. The design boundary conditions of a heat distribution network and the requirements on active pressure –

circulation pump – influencing the operation costs of the centralized district heating system as a whole, are analyzed in detail. The

heat generators and the heat exchange stations are designed according to the design heat loads after thermal insulation, and modern

boiler units are installed in the heating plant.

Keywords: District heating, circulation pump, heating network, pressure diagram

1. Introduction The heat for the district heating (DH) supply system is generated by a hot water heating plant (Figure 1.) with the design temperature gradient of 120/70 °C. Two circulation pumps are installed to assure circulation of the heat carrier within the network, connected in parallel, when the second pump presents a 100 % backup in case of failure [1], [2].

Outlet pipes of hot water boilers are connected with a hot water manifold. From the manifold pipes are connected to the heat distribution net, led under the ground. Through the insulated distribution pipes the heat carrier flows to pressure independent heat exchanger stations (HES 1 to HES 5). A scheme of the network is shown in Figure 2.

2. Principle of Operation

The heat is transferred to the objects through a

compact heat exchange station equipped with plate

heat exchangers. The heat from the heat carrier (hot

water with a temperature of 130/70 °C) is transferred

through the heat exchange surface in the plate heat

exchanger to the heating network, as well as to the

domestic hot water network in buildings. The

secondary hot water heating networks have the

temperature gradient of 80/60 °C or alternatively

75/55 °C, depending on the physical condition of each

respective apartment building

Figure 1. Example of hot water heating plant

Figure 2. Scheme of the district heating network

HYDRAULICS OF A THERMAL NETWORK FOR DISTRICT HEATING SYSTEM

The heating networks are designed based on

hydraulic equations for hot water networks and the pressure losses consist of the friction pressure losses in pipes and the losses due to local resistances (twists, reductions, branches and closing valves). The share of pressure losses due to the local resistances is estimated to 10 to 20 % of the total pressure losses, depending on the complexity of the heating network. The recommended flow speed of the heat carrier is in the range of w = 0.5 to 2.5 m/s and the specific pressure drop in the pipes is in the range of R = 100 to 200 Pa/m. Lower values are recommended, which put lower demands on the pump, however, they increase the initial investment to the heating network [3].

Example of the heat source – heating plant with boilers burning natural gas – is shown in Figure 3. The heating medium is circulated by circulation pumps. The heat is exchanged to the heating systems through compact heat exchange stations (Figure 4.).

Figure 3. Heat source – hot water heating plant station

Figure 4. Compact heat exchange station

3. Boundary Conditions

The monitored DH will be analyzed for two

alternatives [4]:

Alternative I. – representing the perspective of an

investor, who wants to save money on investments to

the heating network, where the designer will be

expected to design pipes of a smaller diameter,

resulting in higher demands on the circulation pump.

Alternative II. – representing the perspective of an

operator, who wants to save money on the operation of

the DH, which will require the designer to design a

network with larger pipe diameters, resulting in lower

power consumption of the pumps.

The circulation pump must overcome the friction

pressure losses and the local resistances and also

pressure losses of the heat exchange station. The value

of the coefficient 1.1 in eq. 1 reflects the increase in

pressure losses by the pressure loss of the heat source

itself (boiler, pipes in heat plants, hot water manifold

and so on) [9].

4. Calculation and Design of Circulation

Pumps

The required operation pressure of the circulation

pump ∆pp integrated in the heat source is calculated by following equation [5]:

( )[ ]∑ ∑ ++= HESp pZlR11p ∆∆ .., (1)

where: ∆pp is required operation pressure (kPa),

Σ(R.l) is the friction pressure loss in the piping of the heating network (kPa),

ΣZ is the pressure loss by local resistances (kPa), about 10 to 20 % of the friction pressure loss (R.l), depending on the complexity of the proposed DH network,

∆pHES is hydraulic gradient of the district heating on the primary side (kPa).

Calculation of Alternative I.

The pressure losses of the DH network calculated for Alternative I. are summarized in Table I.

TABLE I.

PRESSURE LOSSES OF THE DH NETWORK – ALTERNATIVE I.

59

EXPRES 2017

ISBN 978-86-919769-1-0

Hydraulics of a thermal network for district heating system J. TAKÁCS a, Z. STRAKOVÁ b, L .RÁCZ c

Slovak University of Technology in Bratislava, Faculty of Civil Engineering,

Department of Building Services, Radlinského 11, 810 05 Bratislava, Slovak Republic a E-mail: [email protected]

bE-mail: [email protected]

cE-mail: [email protected]

The hydraulics of a thermal network of a district heating system is a very important issue, to which not enough attention is often

paid. In this paper the authors want to point out some of the important aspects of the design and operation of thermal networks in

district heating systems. The design boundary conditions of a heat distribution network and the requirements on active pressure –

circulation pump – influencing the operation costs of the centralized district heating system as a whole, are analyzed in detail. The

heat generators and the heat exchange stations are designed according to the design heat loads after thermal insulation, and modern

boiler units are installed in the heating plant.

Keywords: District heating, circulation pump, heating network, pressure diagram

1. Introduction The heat for the district heating (DH) supply system is generated by a hot water heating plant (Figure 1.) with the design temperature gradient of 120/70 °C. Two circulation pumps are installed to assure circulation of the heat carrier within the network, connected in parallel, when the second pump presents a 100 % backup in case of failure [1], [2].

Outlet pipes of hot water boilers are connected with a hot water manifold. From the manifold pipes are connected to the heat distribution net, led under the ground. Through the insulated distribution pipes the heat carrier flows to pressure independent heat exchanger stations (HES 1 to HES 5). A scheme of the network is shown in Figure 2.

2. Principle of Operation

The heat is transferred to the objects through a

compact heat exchange station equipped with plate

heat exchangers. The heat from the heat carrier (hot

water with a temperature of 130/70 °C) is transferred

through the heat exchange surface in the plate heat

exchanger to the heating network, as well as to the

domestic hot water network in buildings. The

secondary hot water heating networks have the

temperature gradient of 80/60 °C or alternatively

75/55 °C, depending on the physical condition of each

respective apartment building

Figure 1. Example of hot water heating plant

Figure 2. Scheme of the district heating network


The heating networks are designed based on

hydraulic equations for hot water networks and the pressure losses consist of the friction pressure losses in pipes and the losses due to local resistances (twists, reductions, branches and closing valves). The share of pressure losses due to the local resistances is estimated to 10 to 20 % of the total pressure losses, depending on the complexity of the heating network. The recommended flow speed of the heat carrier is in the range of w = 0.5 to 2.5 m/s and the specific pressure drop in the pipes is in the range of R = 100 to 200 Pa/m. Lower values are recommended, which put lower demands on the pump, however, they increase the initial investment to the heating network [3].

Example of the heat source – heating plant with boilers burning natural gas – is shown in Figure 3. The heating medium is circulated by circulation pumps. The heat is exchanged to the heating systems through compact heat exchange stations (Figure 4.).

Figure 3. Heat source – hot water heating plant station

Figure 4. Compact heat exchange station

3. Boundary Conditions

The monitored DH will be analyzed for two

alternatives [4]:

Alternative I. – representing the perspective of an

investor, who wants to save money on investments to

the heating network, where the designer will be

expected to design pipes of a smaller diameter,

resulting in higher demands on the circulation pump.

Alternative II. – representing the perspective of an

operator, who wants to save money on the operation of

the DH, which will require the designer to design a

network with larger pipe diameters, resulting in lower

power consumption of the pumps.

The circulation pump must overcome the friction

pressure losses and the local resistances and also

pressure losses of the heat exchange station. The value

of the coefficient 1.1 in eq. 1 reflects the increase in

pressure losses by the pressure loss of the heat source

itself (boiler, pipes in heat plants, hot water manifold

and so on) [9].

4. Calculation and Design of Circulation

Pumps

The required operation pressure of the circulation

pump ∆pp integrated in the heat source is calculated by following equation [5]:

( )[ ]∑ ∑ ++= HESp pZlR11p ∆∆ .., (1)

where: ∆pp is required operation pressure (kPa),

Σ(R.l) is the friction pressure loss in the piping of the heating network (kPa),

ΣZ is the pressure loss by local resistances (kPa), about 10 to 20 % of the friction pressure loss (R.l), depending on the complexity of the proposed DH network,

∆pHES is hydraulic gradient of the district heating on the primary side (kPa).

Calculation of Alternative I.

The pressure losses of the DH network calculated for Alternative I. are summarized in Table I.

TABLE I.

PRESSURE LOSSES OF THE DH NETWORK – ALTERNATIVE I.

60


The graphical representation of the calculation output is a pressure diagram, showing the increase of pressure losses for the reference thermal network. The pressure diagram for Alternative I. (the perspective of investor) is shown in Figure 5. For each heat exchange station it is necessary to ensure an overpressure of ∆pHES = 100 kPa.

The selected smaller pipe dimensions result in

significant pressure losses, with the outcome that the

required working pressure of the pump at the

mass flow rate of M1 = M2 = 99.69 m3/h corresponds

to the value of ∆p1 = 474 kPa and to the value of

H1 = 47.4 mvs, respectively.

Figure 5. Pressure diagram – Alternative I.

The electric input of the circulating pump is

P1 = 20.6 kW. The energy consumption for heating

period of d = 202 days, assuming continual operation,

is E1 = 24 843 kWh.

Calculation of Alternative II.

The pressure losses of the DH network calculated for Alternative II. are summarized in Table II. For each

heat exchange station it is necessary to ensure an overpressure of 100 kPa. In this alternative larger dimensions are used, resulting in significantly lower pressure loss and the required operation pressure of the pump ∆p2 = 230 kPa at a mass flow rate of M1 = M2 = 99.69 m

3/h. The pressure diagram for

Alternative II. is shown in Figure 6.

TABLE II. PRESSURE LOSSES OF THE DH NETWORK – ALTERNATIVE II.

Figure 6. Pressure diagram – Alternative II.


The input power of the circulation pump is

P2 = 11.4 kW. The energy consumption for the heating period d = 202 days in continual operation is E2 = 12 924 kWh. This value is 48 % less than in Alternative I.

Economic Evaluation

It can be concluded that at the cost of 4.72 thousand € the circulation pumps in Alternative I. are more expensive than in Alternative II. by 2.27 thousands €, which is caused by higher requirements on operation of the circulation pumps. The total initial investments in the heating networks in Alternative I. are 8.69 thousand €.

Although the investments in the circulation pumps

(2.45 thousand €) are lower for Alternative II. by 2.27 thousand €/per year, the investments in the heating networks (11.77 thousand €) are higher by 3.08 thousand € for this Alternative.

Thus, the total investments to purchase the

equipment are higher by 4.2 thousand € for Alternative II., which represents 12.7 %, but the operation expenses in Alternative II. are lower by 2.27 thousand €.

The most substantial savings will be achieved in the

operation costs in the period of 25 years, when Alternative II. is cheaper by 56.6 thousand €. In Figure 7 the resulting evaluation confirms the viability of the Alternative II. (Figure 8) with the savings of 52.4 thousand €, representing 34.7 %.

The economic calculations for the circulation pumps, heating network and operation costs for the period of 25 years, along with the inflation rate and the increase in energy prices, considered in the calculation, are shown in Table III.

Payback of the investments is shown in Figure 9.

Figure 7. Operation curve of the proposed the circulation pump

Figure 8. Operation curve of the circulation pump

TABLE III. EVALUATION OF THE PERFORMANCE OF ALTERNATIVE I. AND ALTERNATIVE II. IN TERMS OF INVESTMENT AND OPERATION COSTS

Figure 9. Payback of the investment

Figure 9 clearly indicates the payback of the systems

from the side of view of the investor and operator. The

higher investment will return after 2 years of service.

61


The graphical representation of the calculation output is a pressure diagram, showing the increase of pressure losses for the reference thermal network. The pressure diagram for Alternative I. (the perspective of investor) is shown in Figure 5. For each heat exchange station it is necessary to ensure an overpressure of ∆pHES = 100 kPa.

The selected smaller pipe dimensions result in

significant pressure losses, with the outcome that the

required working pressure of the pump at the

mass flow rate of M1 = M2 = 99.69 m3/h corresponds

to the value of ∆p1 = 474 kPa and to the value of

H1 = 47.4 mvs, respectively.

Figure 5. Pressure diagram – Alternative I.

The electric input of the circulating pump is

P1 = 20.6 kW. The energy consumption for heating

period of d = 202 days, assuming continual operation,

is E1 = 24 843 kWh.

Calculation of Alternative II.

The pressure losses of the DH network calculated for Alternative II. are summarized in Table II. For each

heat exchange station it is necessary to ensure an overpressure of 100 kPa. In this alternative larger dimensions are used, resulting in significantly lower pressure loss and the required operation pressure of the pump ∆p2 = 230 kPa at a mass flow rate of M1 = M2 = 99.69 m

3/h. The pressure diagram for

Alternative II. is shown in Figure 6.

TABLE II. PRESSURE LOSSES OF THE DH NETWORK – ALTERNATIVE II.

Figure 6. Pressure diagram – Alternative II.


The input power of the circulation pump is

P2 = 11.4 kW. The energy consumption for the heating period d = 202 days in continual operation is E2 = 12 924 kWh. This value is 48 % less than in Alternative I.

Economic Evaluation

It can be concluded that at the cost of 4.72 thousand € the circulation pumps in Alternative I. are more expensive than in Alternative II. by 2.27 thousands €, which is caused by higher requirements on operation of the circulation pumps. The total initial investments in the heating networks in Alternative I. are 8.69 thousand €.

Although the investments in the circulation pumps

(2.45 thousand €) are lower for Alternative II. by 2.27 thousand €/per year, the investments in the heating networks (11.77 thousand €) are higher by 3.08 thousand € for this Alternative.

Thus, the total investments to purchase the

equipment are higher by 4.2 thousand € for Alternative II., which represents 12.7 %, but the operation expenses in Alternative II. are lower by 2.27 thousand €.

The most substantial savings will be achieved in the

operation costs in the period of 25 years, when Alternative II. is cheaper by 56.6 thousand €. In Figure 7 the resulting evaluation confirms the viability of the Alternative II. (Figure 8) with the savings of 52.4 thousand €, representing 34.7 %.

The economic calculations for the circulation pumps, heating network and operation costs for the period of 25 years, along with the inflation rate and the increase in energy prices, considered in the calculation, are shown in Table III.

Payback of the investments is shown in Figure 9.

Figure 7. Operation curve of the proposed the circulation pump

Figure 8. Operation curve of the circulation pump

TABLE III. EVALUATION OF THE PERFORMANCE OF ALTERNATIVE I. AND ALTERNATIVE II. IN TERMS OF INVESTMENT AND OPERATION COSTS

Figure 9. Payback of the investment

Figure 9 clearly indicates the payback of the systems

from the side of view of the investor and operator. The

higher investment will return after 2 years of service.

62


Figure 10. Operating costs of the alternatives

The results of Table No. III are graphically shown in

FIG. 9. From the figure it is clear:

1. The investment costs for piping networks:

Alternative I. represent 18 491 EUR against 24 982

EUR compared to the second Alternative.

Therefore Alternative. II. It is financially

demanding by 35 %.

2. The investment costs for circulator pumps: I.

Alternative represent 15 500 EUR compared to the

II. Alternative 12188 EUR. It means that the

investment is 16 % cheaper.

3. The operating costs for the lifetime of the system

(25 years). I. Alternative represents 118 581 EUR

compared to the II. Alternative 61 452 EUR. Clear

savings of the second alternative is 48 %.

4. Total cost: I. Alternative represent 151 572 EUR

compared to Alternative II. is 98 622 EUR, saving

45 %.

In conclusion we can say that the second alternative it

is more efficient and determined to carry out the work.

Conclusion

In conclusion we can say that in the planning, design and implementation process of the heat supply system it is important to take into consideration all circumstances limiting optimum supply of the heat in buildings.

It is not sufficient only to design a state-of-the-art heating systems, circulation pump, heating network and heat exchangers, but the operation of the system as

a whole is important to ensure optimum operation parameters [6], [7].

As proved by this example, in order to maximize the savings it is important to propose more variants in order to allow comparison and to make the best decision. In the present study Alternative II was more profitable by almost 2 years due to efficient operation, although the initial investment costs were higher for this alternative [8].

References [1] D. Petráš: Vykurovanie rodinných a bytových domov:

(Heating of family and residental buildings). Bratislava: JAGA, 2005. 246 p. ISBN 80-8076-012-8

[2] I. Csoknyai, T. Doholuczki: Tobb, mint hidraulika (More than

hydraulic). Budapest: Herz Armatura Hungaria Kft., 2013.

ISBN 978-963-08-7808-1

[3] K. Laboutka, T. Suchánek: Výpočtové tabulky pro vytápění: Vztahy a pomůcky 9. (Calculation tables for heating: Formulas

and utilities 9.). Praha : STP, 2001. 208 p. ISBN 80-02-

01466-9

[4] J. Pekarovič, D. Petráš, O. Lulkovičová and J. Takács: Vykurovanie I. a II. diel (Heating I. and II. Part). Bratislava:

ES STU, 1991. 493 p. ISBN 80-227-0334-6

[5] Z. Straková : Zásobovanie priemyselných celkov s napojením na sústavy CZT: (Supply of industrial units connected to the

CZT heat system). In: iDB Journal. ISSN 1338-3337, 2015,

vol. 5, no. 1, 44-46 p.

[6] M. Kotrbatý, O. Hojer, Z. Kovářová: Hospodaření teplem v průmyslu, Nejlevnější energie je energie ušetřena. (The heat

management in industry. The cheapest energy is energy

spared). Praha : ČSTZ, 2009. 266 p. ISBN 978-80-86028-41-

5

[7] Gy. Homonnay: Épületgépészet 2000 - Fűtéstechnika II. Budapest: Épületgépészet kiadó Kft., 2001

[8] F. Vranay, F.: Application of renewable energy sources in central heat supply systems. In: Czasopis motechniczne:

Budownictwo, 2010. vol. 107, no. 4, 221-228 p. ISSN 0011-

4561 [9] Épületgépészet 2000, Fűtestechnika, Épuletgépészet kiadó

kft., Budatest 2001

[10] Homonnay Gy.:: Épületgépészet 2000 - Fűtéstechnika II.

Budapest, Épületgépészet kiadó Kft. 2001.

[11] Bánhidi L., Kajtár L.: Komfortelmélet 2000 Budapest, Műegyetemi Kiadó, ISBN 963 420 633 6.

[12] Nyers J., Slavica T., Nyers A.: Economic optimum of thermal insulating layer for external wall of brick Acta Politechnica Hungarica 11(7) pp. 209-222. Bp. 2014

[13] Hurych M., Doubrava J.: Vyvažování potrubních sítí. Praha,

IMI International s.r.o., 2000.

[14] Skovraard A.: Grundgos System Guide: Comercial Building

Services 2004

[15] Nyers J., Nyers A.: Hydraulic Analysis of Heat Pump's

Heating Circuit using Mathematical Model, 9rd ICCC

International Conference, Proceedings-USB, ISBN 978-1-

4799-0061-9 pp 349-353, Tihany, Hungary. 04-08. 07. 2013.

EXPRES 2017 ISBN 978-86-919769-1-0

Comparisons of experimental measurements of indoor climate parameters in a swimming pool during winter and summer operation period Belo B. FÜRI a, Róbert TURZA b

Department of Building Services, Faculty of Civil Engineering, Slovak University of

Technology in Bratislava SK-810 05 Bratislava,, Radlinského 11, Slovakia a E-mail: [email protected] b E-mail: [email protected]

Number of indoor swimming pools and wellness centers currently is growing, it is necessary to concern on parameters of their indoor environment. These parameters are necessary for the design of HVAC systems that operate in these premises. In indoor swimming pool facilities, the energy demand is large due to ventilation losses with the exhaust air. Since water is evaporated from the pool surface, the exhaust air has a high water content and specific enthalpy. In this publication measurements of indoor climate parameters and the comparison of indoor climate parameter during winter and summer operation period are described.

Keywords: swimming pool, measurements, water evaporation, air temperature, relative humidity, air velocity

1. Introduction

This paper deals with the topic of hygro-thermal

climate in indoor swimming pool. Ventilation in

these places ensures mainly the hygienic function. A

ventilation device provide internal environment for

people to feel comfortable in the swimming pool,

protecting their health by eliminating pollutants and

finally keep the technology in run and protects the

building structure. Indoor swimming pools belong

to premises with high moisture production,

respectively water vapor, where the relative

humidity in this area is usually between 60 to 80 %

and in rare cases even more.

Indoor swimming pools are water bodies

designed for recreational or competitive swimming,

diving and other water sports that require swimming

or aquatic exercise. Indoor swimming pools make

use artificial environment with technological

elements (filtration, ventilation equipments, pumps,

dosing of chemicals, etc.). Water temperature

depends on pool type. In table 1 are described

design water temperatures for different pool types.

The water temperature affects the heat and mass

transfer between water and human body. Because of

evaporation of the film of water on the unclothed

body additional heat is lost. Therefore to minimize

feel of cold, air temperature should be 2 K to 4 K

(min. 1 °C according to [6]) above the water

temperature, but not above 34 °C [4, 5]. Relative

humidity in swimming pool hall should be within

the range 40 ÷ 65 %. Air flow velocity in the zone

of stay should be below 0,2 m/s.

The water evaporation is a natural process and it

is a critical energy parameter in design and control

system. The forecast of water evaporation from

swimming pools by its reliable calculation is

required for accurate projection of HVAC systems.

In order to eliminate condensation on cold surfaces

in a swimming pool, water vapor has to be removed

by HVAC system and on the other hand water in the

pool has to heated to compensate the heat lost by

evaporation. According to statistics, 70 % of energy

loss in swimming pools goes to water evaporation.

Water evaporation rate to its complex and

stochastic nature is nearly impossible to predict. In

the literature is available wide variation in

correlations for predicting water evaporation and

energy consumption.

63


Figure 10. Operating costs of the alternatives

The results of Table No. III are graphically shown in

FIG. 9. From the figure it is clear:

1. The investment costs for piping networks:

Alternative I. represent 18 491 EUR against 24 982

EUR compared to the second Alternative.

Therefore Alternative. II. It is financially

demanding by 35 %.

2. The investment costs for circulator pumps: I.

Alternative represent 15 500 EUR compared to the

II. Alternative 12188 EUR. It means that the

investment is 16 % cheaper.

3. The operating costs for the lifetime of the system

(25 years). I. Alternative represents 118 581 EUR

compared to the II. Alternative 61 452 EUR. Clear

savings of the second alternative is 48 %.

4. Total cost: I. Alternative represent 151 572 EUR

compared to Alternative II. is 98 622 EUR, saving

45 %.

In conclusion we can say that the second alternative it

is more efficient and determined to carry out the work.

Conclusion

In conclusion we can say that in the planning, design and implementation process of the heat supply system it is important to take into consideration all circumstances limiting optimum supply of the heat in buildings.

It is not sufficient only to design a state-of-the-art heating systems, circulation pump, heating network and heat exchangers, but the operation of the system as

a whole is important to ensure optimum operation parameters [6], [7].

As proved by this example, in order to maximize the savings it is important to propose more variants in order to allow comparison and to make the best decision. In the present study Alternative II was more profitable by almost 2 years due to efficient operation, although the initial investment costs were higher for this alternative [8].

References [1] D. Petráš: Vykurovanie rodinných a bytových domov:

(Heating of family and residental buildings). Bratislava: JAGA, 2005. 246 p. ISBN 80-8076-012-8

[2] I. Csoknyai, T. Doholuczki: Tobb, mint hidraulika (More than

hydraulic). Budapest: Herz Armatura Hungaria Kft., 2013.

ISBN 978-963-08-7808-1

[3] K. Laboutka, T. Suchánek: Výpočtové tabulky pro vytápění: Vztahy a pomůcky 9. (Calculation tables for heating: Formulas

and utilities 9.). Praha : STP, 2001. 208 p. ISBN 80-02-

01466-9

[4] J. Pekarovič, D. Petráš, O. Lulkovičová and J. Takács: Vykurovanie I. a II. diel (Heating I. and II. Part). Bratislava:

ES STU, 1991. 493 p. ISBN 80-227-0334-6

[5] Z. Straková : Zásobovanie priemyselných celkov s napojením na sústavy CZT: (Supply of industrial units connected to the

CZT heat system). In: iDB Journal. ISSN 1338-3337, 2015,

vol. 5, no. 1, 44-46 p.

[6] M. Kotrbatý, O. Hojer, Z. Kovářová: Hospodaření teplem v průmyslu, Nejlevnější energie je energie ušetřena. (The heat

management in industry. The cheapest energy is energy

spared). Praha : ČSTZ, 2009. 266 p. ISBN 978-80-86028-41-

5

[7] Gy. Homonnay: Épületgépészet 2000 - Fűtéstechnika II. Budapest: Épületgépészet kiadó Kft., 2001

[8] F. Vranay, F.: Application of renewable energy sources in central heat supply systems. In: Czasopis motechniczne:

Budownictwo, 2010. vol. 107, no. 4, 221-228 p. ISSN 0011-

4561 [9] Épületgépészet 2000, Fűtestechnika, Épuletgépészet kiadó

kft., Budatest 2001

[10] Homonnay Gy.:: Épületgépészet 2000 - Fűtéstechnika II.

Budapest, Épületgépészet kiadó Kft. 2001.

[11] Bánhidi L., Kajtár L.: Komfortelmélet 2000 Budapest, Műegyetemi Kiadó, ISBN 963 420 633 6.

[12] Nyers J., Slavica T., Nyers A.: Economic optimum of thermal insulating layer for external wall of brick Acta Politechnica Hungarica 11(7) pp. 209-222. Bp. 2014

[13] Hurych M., Doubrava J.: Vyvažování potrubních sítí. Praha,

IMI International s.r.o., 2000.

[14] Skovraard A.: Grundgos System Guide: Comercial Building

Services 2004

[15] Nyers J., Nyers A.: Hydraulic Analysis of Heat Pump's

Heating Circuit using Mathematical Model, 9rd ICCC

International Conference, Proceedings-USB, ISBN 978-1-

4799-0061-9 pp 349-353, Tihany, Hungary. 04-08. 07. 2013.

EXPRES 2017 ISBN 978-86-919769-1-0

Comparisons of experimental measurements of indoor climate parameters in a swimming pool during winter and summer operation period Belo B. FÜRI a, Róbert TURZA b

Department of Building Services, Faculty of Civil Engineering, Slovak University of

Technology in Bratislava SK-810 05 Bratislava,, Radlinského 11, Slovakia a E-mail: [email protected] b E-mail: [email protected]

Number of indoor swimming pools and wellness centers currently is growing, it is necessary to concern on parameters of their indoor environment. These parameters are necessary for the design of HVAC systems that operate in these premises. In indoor swimming pool facilities, the energy demand is large due to ventilation losses with the exhaust air. Since water is evaporated from the pool surface, the exhaust air has a high water content and specific enthalpy. In this publication measurements of indoor climate parameters and the comparison of indoor climate parameter during winter and summer operation period are described.

Keywords: swimming pool, measurements, water evaporation, air temperature, relative humidity, air velocity

1. Introduction

This paper deals with the topic of hygro-thermal

climate in indoor swimming pool. Ventilation in

these places ensures mainly the hygienic function. A

ventilation device provide internal environment for

people to feel comfortable in the swimming pool,

protecting their health by eliminating pollutants and

finally keep the technology in run and protects the

building structure. Indoor swimming pools belong

to premises with high moisture production,

respectively water vapor, where the relative

humidity in this area is usually between 60 to 80 %

and in rare cases even more.

Indoor swimming pools are water bodies

designed for recreational or competitive swimming,

diving and other water sports that require swimming

or aquatic exercise. Indoor swimming pools make

use artificial environment with technological

elements (filtration, ventilation equipments, pumps,

dosing of chemicals, etc.). Water temperature

depends on pool type. In table 1 are described

design water temperatures for different pool types.

The water temperature affects the heat and mass

transfer between water and human body. Because of

evaporation of the film of water on the unclothed

body additional heat is lost. Therefore to minimize

feel of cold, air temperature should be 2 K to 4 K

(min. 1 °C according to [6]) above the water

temperature, but not above 34 °C [4, 5]. Relative

humidity in swimming pool hall should be within

the range 40 ÷ 65 %. Air flow velocity in the zone

of stay should be below 0,2 m/s.

The water evaporation is a natural process and it

is a critical energy parameter in design and control

system. The forecast of water evaporation from

swimming pools by its reliable calculation is

required for accurate projection of HVAC systems.

In order to eliminate condensation on cold surfaces

in a swimming pool, water vapor has to be removed

by HVAC system and on the other hand water in the

pool has to heated to compensate the heat lost by

evaporation. According to statistics, 70 % of energy

loss in swimming pools goes to water evaporation.

Water evaporation rate to its complex and

stochastic nature is nearly impossible to predict. In

the literature is available wide variation in

correlations for predicting water evaporation and

energy consumption.

64

Table 1. Water temperatures in indoor swimming pool in °C [4, 5]

Basin Water temperature according to edict 72/2008 Water temperature according to VDI 2089

Swimming 18 ÷ 26 28

non-swimming 28 28

Relax 40 36

childrens up to 36 months

childrens older 36 months

30 ÷ 36

28 ÷ 32 32

2. Measurements

Measurements description

For performing experimental measurement was

selected the THERMAL CORVINUS in periphery of

Velky Meder, Slovakia. This facility is located in

Dunajská Streda County, 65 km from Bratislava.

Swimming pool uses thermal water from two sources.

THERMAL CORVINUS in Velky Meder is yearlong

open with nine pools with water temperature of 26-38

°C.

Measurements were carried out in the indoor

swimming pool (Fig. 1), which is yearlong open. The

hall serves as a small family water park, where beside

the indoor swimming pool with asymmetrical shape

with swimming and relaxing activities, is also a

whirlpool, children's pool with pool elements and

yearlong operated 2 waterslides. Declared properties

of the indoor swimming pool are water temperature 30

°C, water area 291.4 m2 and depth of 1.2 m, the

whirlpool water temperature 33 °C, water area 19.65 m2

and depth of 0.6 m, children's pool with water elements

water temperature 30 °C, water area 20.00 m2 and depth

0.4 m.

For long-term measurements of microclimate inside

the swimming pool hall and the outside air were used

data logger Comet S3541 (Fig. 2), thermo- and

hygrometer with temperature measuring range -30 ÷

+70 °C with an accuracy ± 0.4 °C, with a resolution of

0.1 °C. Relative humidity measuring range is 0 – 100

%, with an accuracy of ± 2.5 % (5-95%) and with a

resolution of 0.1 %. Also was used measuring

instruments Comet S0111 (Figure 2), thermometer with

extern probe, for measuring outside temperature.

Measuring temperature range is -30 ÷ +70 °C with an

accuracy of ± 0.2 °C and with a resolution of 0.1 °C.

Fig. 1. Indoor swimming pool, Velky Meder [7]

Fig. 2. Measuring instruments Comet S3541, S0111, Testo 451, 445 [8, 9]

For instant measurements of microclimate inside the

swimming pool hall were used measuring instruments

Testo 451 and 445 (Fig. 2). Measuring instrument

Testo 451 has the measurable range of air temperature

-40 ÷ +70 °C with an accuracy ±0,1 °C and resolution

0,1 °C, relative humidity range 0 ÷ 100 %, with an

accuracy ±2,0 % (2 ÷ 98 %), and resolution 0,1 %

and air flow velocity range 0,2 ÷ 60 m/s with an

accuracy ±0,1 °C and resolution 0,1 °C. Measuring

instrument Testo 445 has the measurable range of air

temperature of -50 ÷ +150 °C with an accuracy ±0,2 °C

and resolution 0,1 °C, relative humidity 0 ÷ 100 %,

with an accuracy ±2,0 % (2 ÷ 98 %) and resolution 0,1

% and air flow velocity 0,0 ÷ 10 m/s with an accuracy

±0,03 m/s and resolution 0,01 m/s.

Measurements of hygro - thermal microclimate

During the days 09. - 22.07.2013, 04.-08.08.2014

and 06.-13.02.2015 were made measurements of

temperature and humidity in the occupation zone (1 m

from ground) inside the swimming pool and outside air

temperature. Inside the hall was used data logger

Comet S3541 with the set of record interval every 5

min and outside data logger Comet S0111. With this

could be evaluated air temperature and relative

humidity values inside the covered swimming pool.

In the following figures (Fig. 3, 4) you can see the

behavior of hygro-thermal microclimate in swimming

pool. During summer period of 2013 the average inside

air temperature was 27,9 °C and the relative humidity

62,5 % and the average outside air temperature 23,1

°C. During summer period of 2014 the average inside



°C.

During winter period 2015 the average inside air

temperature was 26,05 ± 0,02 °C and the relative

humidity 56,01 ± 0,34 %, the average outside air

temperature 1,98 ± 0,09 °C and the relative humidity

68,20 ± 0,31 %.

Fig. 3. Time course of air temperature and relative humidity inside swimming pool during summer period 2013, 2014

and winter period 2015

Fig. 4. Time course of air temperature and relative humidity outside swimming pool during summer period 2013, 2014


65

Table 1. Water temperatures in indoor swimming pool in °C [4, 5]

Basin Water temperature according to edict 72/2008 Water temperature according to VDI 2089

Swimming 18 ÷ 26 28

non-swimming 28 28

Relax 40 36

childrens up to 36 months

childrens older 36 months

30 ÷ 36

28 ÷ 32 32

2. Measurements

Measurements description

For performing experimental measurement was

selected the THERMAL CORVINUS in periphery of

Velky Meder, Slovakia. This facility is located in

Dunajská Streda County, 65 km from Bratislava.

Swimming pool uses thermal water from two sources.

THERMAL CORVINUS in Velky Meder is yearlong

open with nine pools with water temperature of 26-38

°C.

Measurements were carried out in the indoor

swimming pool (Fig. 1), which is yearlong open. The

hall serves as a small family water park, where beside

the indoor swimming pool with asymmetrical shape

with swimming and relaxing activities, is also a

whirlpool, children's pool with pool elements and

yearlong operated 2 waterslides. Declared properties

of the indoor swimming pool are water temperature 30

°C, water area 291.4 m2 and depth of 1.2 m, the

whirlpool water temperature 33 °C, water area 19.65 m2

and depth of 0.6 m, children's pool with water elements

water temperature 30 °C, water area 20.00 m2 and depth

0.4 m.

For long-term measurements of microclimate inside

the swimming pool hall and the outside air were used

data logger Comet S3541 (Fig. 2), thermo- and

hygrometer with temperature measuring range -30 ÷

+70 °C with an accuracy ± 0.4 °C, with a resolution of

0.1 °C. Relative humidity measuring range is 0 – 100

%, with an accuracy of ± 2.5 % (5-95%) and with a

resolution of 0.1 %. Also was used measuring

instruments Comet S0111 (Figure 2), thermometer with

extern probe, for measuring outside temperature.

Measuring temperature range is -30 ÷ +70 °C with an

accuracy of ± 0.2 °C and with a resolution of 0.1 °C.

Fig. 1. Indoor swimming pool, Velky Meder [7]

Fig. 2. Measuring instruments Comet S3541, S0111, Testo 451, 445 [8, 9]

For instant measurements of microclimate inside the

swimming pool hall were used measuring instruments

Testo 451 and 445 (Fig. 2). Measuring instrument

Testo 451 has the measurable range of air temperature

-40 ÷ +70 °C with an accuracy ±0,1 °C and resolution

0,1 °C, relative humidity range 0 ÷ 100 %, with an

accuracy ±2,0 % (2 ÷ 98 %), and resolution 0,1 %

and air flow velocity range 0,2 ÷ 60 m/s with an

accuracy ±0,1 °C and resolution 0,1 °C. Measuring

instrument Testo 445 has the measurable range of air

temperature of -50 ÷ +150 °C with an accuracy ±0,2 °C

and resolution 0,1 °C, relative humidity 0 ÷ 100 %,

with an accuracy ±2,0 % (2 ÷ 98 %) and resolution 0,1

% and air flow velocity 0,0 ÷ 10 m/s with an accuracy

±0,03 m/s and resolution 0,01 m/s.

Measurements of hygro - thermal microclimate

During the days 09. - 22.07.2013, 04.-08.08.2014

and 06.-13.02.2015 were made measurements of

temperature and humidity in the occupation zone (1 m

from ground) inside the swimming pool and outside air

temperature. Inside the hall was used data logger

Comet S3541 with the set of record interval every 5

min and outside data logger Comet S0111. With this

could be evaluated air temperature and relative

humidity values inside the covered swimming pool.

In the following figures (Fig. 3, 4) you can see the

behavior of hygro-thermal microclimate in swimming

pool. During summer period of 2013 the average inside



°C. During summer period of 2014 the average inside



°C.

During winter period 2015 the average inside air

temperature was 26,05 ± 0,02 °C and the relative

humidity 56,01 ± 0,34 %, the average outside air

temperature 1,98 ± 0,09 °C and the relative humidity

68,20 ± 0,31 %.

Fig. 3. Time course of air temperature and relative humidity inside swimming pool during summer period 2013, 2014


Fig. 4. Time course of air temperature and relative humidity outside swimming pool during summer period 2013, 2014


66

123 Int. Rev. Appl. Sci. Eng. 7, 2016

From these measurements could be done

calculations for enthalpy and specific humidity of

air in and outside the swimming pool.

In the figure (Fig. 5) you can see the behavior of

specific humidity (water vapour) of air in and

outside the swimming pool during summer and

winter periods.

The average specific humidity in summer period

2013 of inside air was 14,04 ± 0,03 g/kg and of

outside air was 10,76 ± 0,03 g/kg. Enthalpy of

inside air was 66,08 ± 0,10 kJ/kg and of outside air

was 55,99 ± 0,18 kJ/kg. The average specific

humidity in summer period 2013 of inside air was

14,04 ± 0,03 g/kg and of outside air was 10,76 ±

0,03 g/kg. Enthalpy of inside air was 66,08 ± 0,10

kJ/kg and of outside air was 55,99 ± 0,18 kJ/kg.





was 51,76 ± 0,19 kJ/kg.

The average specific humidity in winter period


outside air was 3,03 ± 0,02 g/kg. Enthalpy of inside

air was 57,36 ± 0,24 kJ/kg and of outside air was

9,77 ± 0,15 kJ/kg.

Fig. 5. Time course of air specific humidity in- and outside swimming pool during summer period ‘13, ‘14 and winter period ‘16

Measurements of air flow velocity

During the days 4.-8.8.2014 and 6.-13.02.2015

were made measurements of air flow velocity.

Measurements were made just above the water level

(0,1m) and in the height of human upper body

(1,5m). For this was used measuring instrument

Testo 445.

Fig. . Time course of air stream velocity above water level in swimming pool during summer period ´14 and winter period ´15


air flow above the water level.

The average velocity in summer period in the

height of 0,1 m was 0,18 ± 0,02 m/s and in the

height of 1,5 m was 0,15 ± 0,01 m/s.

The average velocity in winter period 2015 in

the height of 0,1 m was 0,19 ± 0,01 m/s and in the

height of 1,5 m was 0,10 ± 0,01 m/s.

3. Water evaporation calculation

After these measurements was made also

calculations of water evaporation. Numerous empirical

correlations have been presented for unoccupied or

occupied swimming pools. I have chosen the formula

most used in Slovakia, which is according to [4].

The mass flow of evaporated water mw:

( ) ( )( ) ( )skgAppTR

m hpp

v

w iw/..

.θθ

β−′′= (1)

β=f (βx) (2)

βx=f (swimming pool type, air flow velocity) (3)

where:

β – coefficient of mass transfer (m/h),

Rv – specific gas constant for water vapor (J/(kg.K)),

T – arithmetic mean of water and air temperature (K),

p“v(θw) – saturation pressure of water vapors at water

temperature (Pa),

pv(θi) – water vapor pressure of tinside air (Pa),

Ah – water area (m2).

In the figure below (Fig. 7) is shown time course of

the mass flow of evaporated water from the pool.

During the summer period 2013 was the average

mass flow of evaporated water 198,66 ± 1,33 kg/h and

latent heat flow needed to vaporize this amount of

water was 496,65 ± 1,28 kJ.




water was 279,83 ± 4,08 kJ.

During the winter period 2015 was the average mass

flow of evaporated water 234,54 ± 1,33 kg/h and the

amount of latent heat needed to vaporize this amount of

water was 586,35 ± 3,32 kJ.

Fig. 7. Time course of evaporated water flow from the swimming pool during summer period ´13, ´14 and winter period´15

4. Conclusion

During the summer period 2013, 2014 and winter

period 2015 were made measurements of hydro-

thermal microclimate in the indoor swimming pool

in Thermal Corvinus Velky Meder. This paper

presents the results of these measurements. During

the measurements in summer period was also used

natural ventilation through open windows and

doors. In consequence of this, inside air temperature

depended on the temperature of the external

environment. Therefore it was not permanently

secured required level of air temperature, which

should be at least 2 °C higher from the water

temperature. Relative humidity in the swimming

pool was below the required level 65%. The

exception was side of the swimming pool with

toboggans, where the relative humidity was affected

by significant water spilling due to slipping on the

water slides. Solution of this could be elimination of

additional moisture by closing doors and windows

and running the HVAC system with better

regulation.

Air flow velocity above the water level was

met, i.e. below 0,2 m/s.

In this paper was presented also calculation

of water evaporation from water level according to

VDI 2089 methodology.

67

123 Int. Rev. Appl. Sci. Eng. 7, 2016

From these measurements could be done

calculations for enthalpy and specific humidity of

air in and outside the swimming pool.


specific humidity (water vapour) of air in and

outside the swimming pool during summer and

winter periods.





was 55,99 ± 0,18 kJ/kg. The average specific

humidity in summer period 2013 of inside air was

14,04 ± 0,03 g/kg and of outside air was 10,76 ±

0,03 g/kg. Enthalpy of inside air was 66,08 ± 0,10

kJ/kg and of outside air was 55,99 ± 0,18 kJ/kg.





was 51,76 ± 0,19 kJ/kg.

The average specific humidity in winter period


outside air was 3,03 ± 0,02 g/kg. Enthalpy of inside

air was 57,36 ± 0,24 kJ/kg and of outside air was

9,77 ± 0,15 kJ/kg.

Fig. 5. Time course of air specific humidity in- and outside swimming pool during summer period ‘13, ‘14 and winter period ‘16

Measurements of air flow velocity

During the days 4.-8.8.2014 and 6.-13.02.2015

were made measurements of air flow velocity.

Measurements were made just above the water level

(0,1m) and in the height of human upper body

(1,5m). For this was used measuring instrument

Testo 445.

Fig. . Time course of air stream velocity above water level in swimming pool during summer period ´14 and winter period ´15


air flow above the water level.

The average velocity in summer period in the

height of 0,1 m was 0,18 ± 0,02 m/s and in the

height of 1,5 m was 0,15 ± 0,01 m/s.

The average velocity in winter period 2015 in

the height of 0,1 m was 0,19 ± 0,01 m/s and in the

height of 1,5 m was 0,10 ± 0,01 m/s.

3. Water evaporation calculation

After these measurements was made also

calculations of water evaporation. Numerous empirical

correlations have been presented for unoccupied or

occupied swimming pools. I have chosen the formula

most used in Slovakia, which is according to [4].

The mass flow of evaporated water mw:

( ) ( )( ) ( )skgAppTR

m hpp

v

w iw/..

.θθ

β−′′= (1)

β=f (βx) (2)

βx=f (swimming pool type, air flow velocity) (3)

where:

β – coefficient of mass transfer (m/h),

Rv – specific gas constant for water vapor (J/(kg.K)),

T – arithmetic mean of water and air temperature (K),

p“v(θw) – saturation pressure of water vapors at water

temperature (Pa),

pv(θi) – water vapor pressure of tinside air (Pa),

Ah – water area (m2).

In the figure below (Fig. 7) is shown time course of

the mass flow of evaporated water from the pool.




water was 496,65 ± 1,28 kJ.




water was 279,83 ± 4,08 kJ.

During the winter period 2015 was the average mass

flow of evaporated water 234,54 ± 1,33 kg/h and the

amount of latent heat needed to vaporize this amount of

water was 586,35 ± 3,32 kJ.

Fig. 7. Time course of evaporated water flow from the swimming pool during summer period ´13, ´14 and winter period´15

4. Conclusion

During the summer period 2013, 2014 and winter

period 2015 were made measurements of hydro-

thermal microclimate in the indoor swimming pool

in Thermal Corvinus Velky Meder. This paper

presents the results of these measurements. During

the measurements in summer period was also used

natural ventilation through open windows and

doors. In consequence of this, inside air temperature

depended on the temperature of the external

environment. Therefore it was not permanently

secured required level of air temperature, which

should be at least 2 °C higher from the water

temperature. Relative humidity in the swimming

pool was below the required level 65%. The

exception was side of the swimming pool with

toboggans, where the relative humidity was affected

by significant water spilling due to slipping on the

water slides. Solution of this could be elimination of

additional moisture by closing doors and windows

and running the HVAC system with better

regulation.

Air flow velocity above the water level was

met, i.e. below 0,2 m/s.

In this paper was presented also calculation

of water evaporation from water level according to

VDI 2089 methodology.

68

References

[1] FERSTL, K., Vetranie a klimatizácia priestorov

s vyššou produkciou vlhkosti (Ventilation and air

conditioning in areas with higher humidity production),

SSTP, Bratislava, 2001

[2] FERSTL, K., MASARYK, M., Prenos tepla (Heat

transfer), STU, Bratislava, 2011, ISBN 978-80-227-

3534-6

[3] Turza, R., Teplovzdušné vetranie krytej plavárne

(Ventilation of indoor swimming pool), Diplomová

práca, STU, Bratislava, 2011

[4] VDI 2089, Building services in swimming baths –

Indoor pools

[5] Edict of Ministry of Health SK 72/2008 - requirements

for water quality, facilities for the natural and indoor

swimming pools


for indoor climate environment

[7] Thermal Corvinus, Veľký Meder,.

http://www.thermalcorvinus.sk

[8] Comet, http://www.cometsystem.cz

[9] Testo, http://www.testo.sk




International J. Energy. Vol. 106, pp.520 -527, 1. July

2016. doi:10.1016/j.energy.2016.03.008.

[11] Kajtar L., Nyers J., Szabo J.: Dynamic thermal

dimensioning of underground spaces, International J.

Energy. Vol. 87, pp. 361-368, 1 July 2015.

doi:10.1016/j.energy.2015.04.112.

EXPRES 2017

ISBN 978-86-919769-1-0

Optimal operating conditions for manure biogas plants in Serbia

P. KOVAČ a, S. KIRIN b, B. SAVKOVIĆ a, D. JESIC c, D. GOLUBOVIC d

a Department for Production Engineering, Faculty of Technical Sciences, University of Novi Sad

21000 Novi Sad, Trg D Obradovica 6, Serbia

E-mail:[email protected], [email protected] bInovative Centre of Faculty of Mecchanical Engineering, University of Belgrade

11000 Beograd Trg Kraljice Marije, Serbia

E-mail:[email protected] cInternational Technology and Management Academy – MTMA,

TrgD.Obradovića 7, 21000 Novi Sad, Serbia

E-mail:[email protected] dFaculty of Mechanical Engineering, University of East Sarajevo

71123East Sarajevo, Vuka Karadžića 30, Bosnia and Hercegovina

E-mail:[email protected]

Serbia has significant potential for renewable energy by using agriculture and forestry. Despite a high incidence of renewable raw

materials and residues from the agricultural industry, the biogas market in Serbia is still in the beginning phase. The paper gives

short overview of biogas production from organic waste and animal manure. First attempts to produce energy from anaerobic

digestion were made in the 1980s when several biogas plants had been built to digest manure and (sewage) sludge. None of these

plants has been operated beyond the 1990s due to commercial and technical problems. After a gap of almost 20 years biogas

technology today is new to Serbia and little experience exists. Between 2009 and 2012 a small number of biogas plants have been

built. Here is proposal for an additional income source for medium sized farms with small scale slurry biogas plants. Here is

project proposal for 50 kWel biogas plant for pig farm or cattle farm. This way is given contribution to renewable energy from

biogas sources in energy production in Serbia

Keywords:renewable energy, biogas, operating conditions

1. Introduction

Over the past decade, and particularly in recent years,

advances in renewable energy technologies, global

increases in capacity, and rapid cost reductions have

been due largely to policy support, which has

attracted significant investment and has further driven

down costs through economies of scale.

According to recently conducted studies there

are currently no CHP-plants fired with biomass from

agriculture. In the sector of heating of private

households wooden biomass is widely used in Serbia.

In 2010/2011 around 6.4 Mm3 wood were used for

heating purposes in households in Serbia [1]. The use

of biogas in Serbia is just at the beginning. There are

3 agricultural biogas plants online and two more,

using organic waste or by-products as substrate [2].

The biogas plants in Vrbas and Blace have been

visited in the course of the project.

The biogas plant in Vrbas uses around 27,000 t of

manure annually. The manure is provided by a farm

next to the biogas plant, which belongs to Mirotin-

Group as well. In addition to the manure also the use

of 10,000 t of maize silage was planned. Due to the

relatively high prizes for maize the substrate

consumption was switched to sugar beet pulp.

Currently half of the initially planned maize silage

consumption is replaced by around 15,000 t of sugar

beet pulp. In the moment there is no usage of the heat.

But in the course of the planned extension of biogas

production the usage of heat is envisaged.

69

References

[1] FERSTL, K., Vetranie a klimatizácia priestorov

s vyššou produkciou vlhkosti (Ventilation and air

conditioning in areas with higher humidity production),

SSTP, Bratislava, 2001

[2] FERSTL, K., MASARYK, M., Prenos tepla (Heat

transfer), STU, Bratislava, 2011, ISBN 978-80-227-

3534-6

[3] Turza, R., Teplovzdušné vetranie krytej plavárne

(Ventilation of indoor swimming pool), Diplomová

práca, STU, Bratislava, 2011

[4] VDI 2089, Building services in swimming baths –

Indoor pools


for water quality, facilities for the natural and indoor

swimming pools


for indoor climate environment

[7] Thermal Corvinus, Veľký Meder,.

http://www.thermalcorvinus.sk

[8] Comet, http://www.cometsystem.cz

[9] Testo, http://www.testo.sk




International J. Energy. Vol. 106, pp.520 -527, 1. July

2016. doi:10.1016/j.energy.2016.03.008.

[11] Kajtar L., Nyers J., Szabo J.: Dynamic thermal

dimensioning of underground spaces, International J.

Energy. Vol. 87, pp. 361-368, 1 July 2015.

doi:10.1016/j.energy.2015.04.112.

EXPRES 2017

ISBN 978-86-919769-1-0

Optimal operating conditions for manure biogas plants in Serbia

P. KOVAČ a, S. KIRIN b, B. SAVKOVIĆ a, D. JESIC c, D. GOLUBOVIC d

a Department for Production Engineering, Faculty of Technical Sciences, University of Novi Sad

21000 Novi Sad, Trg D Obradovica 6, Serbia

E-mail:[email protected], [email protected] bInovative Centre of Faculty of Mecchanical Engineering, University of Belgrade

11000 Beograd Trg Kraljice Marije, Serbia

E-mail:[email protected] cInternational Technology and Management Academy – MTMA,

TrgD.Obradovića 7, 21000 Novi Sad, Serbia

E-mail:[email protected] dFaculty of Mechanical Engineering, University of East Sarajevo

71123East Sarajevo, Vuka Karadžića 30, Bosnia and Hercegovina


Serbia has significant potential for renewable energy by using agriculture and forestry. Despite a high incidence of renewable raw

materials and residues from the agricultural industry, the biogas market in Serbia is still in the beginning phase. The paper gives

short overview of biogas production from organic waste and animal manure. First attempts to produce energy from anaerobic

digestion were made in the 1980s when several biogas plants had been built to digest manure and (sewage) sludge. None of these

plants has been operated beyond the 1990s due to commercial and technical problems. After a gap of almost 20 years biogas

technology today is new to Serbia and little experience exists. Between 2009 and 2012 a small number of biogas plants have been

built. Here is proposal for an additional income source for medium sized farms with small scale slurry biogas plants. Here is

project proposal for 50 kWel biogas plant for pig farm or cattle farm. This way is given contribution to renewable energy from

biogas sources in energy production in Serbia

Keywords:renewable energy, biogas, operating conditions

1. Introduction

Over the past decade, and particularly in recent years,

advances in renewable energy technologies, global

increases in capacity, and rapid cost reductions have

been due largely to policy support, which has

attracted significant investment and has further driven

down costs through economies of scale.

According to recently conducted studies there

are currently no CHP-plants fired with biomass from

agriculture. In the sector of heating of private

households wooden biomass is widely used in Serbia.

In 2010/2011 around 6.4 Mm3 wood were used for

heating purposes in households in Serbia [1]. The use

of biogas in Serbia is just at the beginning. There are

3 agricultural biogas plants online and two more,

using organic waste or by-products as substrate [2].

The biogas plants in Vrbas and Blace have been

visited in the course of the project.

The biogas plant in Vrbas uses around 27,000 t of

manure annually. The manure is provided by a farm

next to the biogas plant, which belongs to Mirotin-

Group as well. In addition to the manure also the use

of 10,000 t of maize silage was planned. Due to the

relatively high prizes for maize the substrate

consumption was switched to sugar beet pulp.

Currently half of the initially planned maize silage

consumption is replaced by around 15,000 t of sugar

beet pulp. In the moment there is no usage of the heat.

But in the course of the planned extension of biogas

production the usage of heat is envisaged.

70

OPTIMAL OPERATING CONDITIONS FORMANURE BIOGASPLANTS IN SERBIA

The biogas plant in Blace uses around 12,700 t

of manure annually. In addition 14,600 t/a of whey

from the dairy production is used, as well as 7,300 t/a

of maize silage. As maize silage is too expensive the

partial replacement with whole crop silage from

wheat or triticale is planned. For the use of heat a

dryer for digestate is under construction. It is planned

to use the dried digestate afterwards as fuel for heat

production at the dairy. Both visited biogas plants run

more than 8,000 operating hours annually.

2. Materialandmethods

Biogas is produced in the performance of

anaerobic digestion of organic matter. Due to the

different degree of processing biomass resources are

divided into:

– Landfill gas, obtained by the fermentation of

waste in landfills,

– Gas from sewage sludge, produced by anaerobic

digestion of sludge sewerage,

– Other biogas:

a) agricultural biogas obtained in anaerobic

digestion of biomass from energy crops, crop

residues and animal manure;

b) biogas obtained in anaerobic digestion of

biomass from wastes in abattoirs, breweries and

other food industries.

Biogas is a gas consisting mainly of methane

and carbon dioxide, obtained in the process of

anaerobic digestion of biomass. Building agricultural

biogas plants contribute in the longer term to the

environment, production of additional clean energy,

which will ensure energy security. Biogas plants are

highly efficient - producing four times more power

than wind power. Their construction will contribute

to reducing pollution, reducing the odor that

accompanies crop production and most importantly,

increase the share of RES in the energy balance.

All 6 plants that are in operation in Serbia were

built after the first version of the statutory feed-in

remuneration for biogas in 2009, whereby three of

these plants are fermenting industrial wastewater and

sewage sludge for their own power supply. The

remaining three biogas plants are mainly charged

with cattle manure and slurry, maize silage and beet

pulp. The latter is a raw material that exists in high

quantities in particular in the region of Vojvodina,

because there are numerous sugar beet processing

plants. According to the information provided by

operators of these plants, whose installed electrical

capacity ranges between 635 kW and 1.5 MW, they

have a capacity utilization rate of over 90%, which

figure indicates solid plant technology paired with

strong know-how of the operators. Also the

profitability of biogas plants under the remuneration

scheme from year 2009 seems to be convincing for

the operators - so all three agricultural plants are

planning to expand plant capacity plus to add as yet

non-existing heat utilization through construction of

new greenhouses and district heating networks.

Serbia has accepted the obligation to increase the

share of renewable energy sources in in total energy

consumption from 21.1% in 2009 to 27% in 2020.

Table 1 shows combined heat and power (CHP) plant

planned in year 2020 and achieved in 2015, [3].

Table1.Biomass and biogas plan in realization

Plan (2020) Achieved (2015)

MW MW

Biomas – CHP plant 100 0

Biogas – CHP plant 30 4,9

Serbia is above average rich in renewable energy,

in contrast to conventional and Serbia wants to develop

the energy use of its enormous potential of biomass

from agriculture and forestry. Agricultural residues

represent the greatest potential resource.

The estimated total of produced biomass in

Serbia, is around 12.5 million tons per year, of which 9

million tons is produced in Vojvodina (72%), [4].

Manure can be used for the commercial energy

production on and near farms without competing with

the supply needed for fertilization. According to

statistical data, published by the Statistical Office of

the Republic of Serbia for year 2014, [5], the total

livestock of the Republic is in Table 2. Manure can be

used for the commercial energy production on and near

farms without competing with the supply needed for

fertilization. According to statistical data, published by

the Statistical Office of the Republic of Serbia for year

2014, [5], the total livestock of the Republic is in Table

2.

Table 2.Total livestock of the Republic Serbia

Livestock in Serbia

Cattle 915 641

Horses 15 222

Sheep 1 789 144

Goats 202 828

Pigs 3 284 378

Poultry 17 449 938

However, the economics might not be beneficial

to all farmers, since the methane yield per mass unit of

manure is comparatively low. Therefore, co-digestion

with other substrates (e.g. energy crops, crop residues)

is common and their availability in the presented

hotspots should be included in future evaluations Table

3.

In addition to the feed-in tariffs, heat and steam

generation with biogas and CHP waste heat will play a

significant role for the profitability of biogas plants in


Serbia. Although cheap energy sources, such as coal

and firewood, are still in many regions and sectors

the main fuels, approximately 40% of public

buildings in Serbia are heated with fuel oil HEL,

which is currently with a heat price in average of

approximately 100€ per MWh of heat (approximately

1.05 € per litre net) exerting a massive impact on the

budgets of the municipalities. Particularly in the

agricultural and forestry regions of Serbia people are

looking into reasonably priced and available

bioenergy. In Figure 1 biogas plant model is shown

[6].

Table3.Estimated biogas production of livestock manure per head (m3/head*day) [4]

Livestock

Categories

Estimated fresch manure

(FM) (m3/head*year)

Methane yield in

(ml/m3 FM)

Net caloric

value biogas

Cattle 11.76 17.00

21.8 MJ/m3

= 6 kwh

Cattle 18.00 17.00

Pigs 2.20 12.00

Poultry 0.02 82.00

Fig.1.Biogas plant model





sewage sludge for their own power supply. Realized

biogas plant in Mirotin is shown in Figure 2. The

remaining three biogas plants are mainly charged with

cattle manure and slurry, maize silage and beet pulp.

There is no project for construction of a biomass plant

in Serbia yet, despite the favorable position that

biomass has with a 60% share of the total potential for

renewable energy in the country.

Fig.2.Mirotin/biogas plant

71


The biogas plant in Blace uses around 12,700 t

of manure annually. In addition 14,600 t/a of whey

from the dairy production is used, as well as 7,300 t/a

of maize silage. As maize silage is too expensive the

partial replacement with whole crop silage from

wheat or triticale is planned. For the use of heat a

dryer for digestate is under construction. It is planned

to use the dried digestate afterwards as fuel for heat

production at the dairy. Both visited biogas plants run

more than 8,000 operating hours annually.

2. Materialandmethods

Biogas is produced in the performance of

anaerobic digestion of organic matter. Due to the

different degree of processing biomass resources are

divided into:

– Landfill gas, obtained by the fermentation of

waste in landfills,

– Gas from sewage sludge, produced by anaerobic

digestion of sludge sewerage,

– Other biogas:

a) agricultural biogas obtained in anaerobic

digestion of biomass from energy crops, crop

residues and animal manure;

b) biogas obtained in anaerobic digestion of

biomass from wastes in abattoirs, breweries and

other food industries.

Biogas is a gas consisting mainly of methane

and carbon dioxide, obtained in the process of

anaerobic digestion of biomass. Building agricultural

biogas plants contribute in the longer term to the

environment, production of additional clean energy,

which will ensure energy security. Biogas plants are

highly efficient - producing four times more power

than wind power. Their construction will contribute

to reducing pollution, reducing the odor that

accompanies crop production and most importantly,

increase the share of RES in the energy balance.





sewage sludge for their own power supply. The

remaining three biogas plants are mainly charged

with cattle manure and slurry, maize silage and beet

pulp. The latter is a raw material that exists in high

quantities in particular in the region of Vojvodina,

because there are numerous sugar beet processing

plants. According to the information provided by

operators of these plants, whose installed electrical

capacity ranges between 635 kW and 1.5 MW, they

have a capacity utilization rate of over 90%, which

figure indicates solid plant technology paired with

strong know-how of the operators. Also the

profitability of biogas plants under the remuneration

scheme from year 2009 seems to be convincing for

the operators - so all three agricultural plants are

planning to expand plant capacity plus to add as yet

non-existing heat utilization through construction of

new greenhouses and district heating networks.

Serbia has accepted the obligation to increase the

share of renewable energy sources in in total energy

consumption from 21.1% in 2009 to 27% in 2020.

Table 1 shows combined heat and power (CHP) plant

planned in year 2020 and achieved in 2015, [3].

Table1.Biomass and biogas plan in realization

Plan (2020) Achieved (2015)

MW MW

Biomas – CHP plant 100 0

Biogas – CHP plant 30 4,9

Serbia is above average rich in renewable energy,

in contrast to conventional and Serbia wants to develop

the energy use of its enormous potential of biomass

from agriculture and forestry. Agricultural residues

represent the greatest potential resource.

The estimated total of produced biomass in

Serbia, is around 12.5 million tons per year, of which 9

million tons is produced in Vojvodina (72%), [4].

Manure can be used for the commercial energy

production on and near farms without competing with

the supply needed for fertilization. According to

statistical data, published by the Statistical Office of

the Republic of Serbia for year 2014, [5], the total

livestock of the Republic is in Table 2. Manure can be

used for the commercial energy production on and near

farms without competing with the supply needed for

fertilization. According to statistical data, published by

the Statistical Office of the Republic of Serbia for year

2014, [5], the total livestock of the Republic is in Table

2.

Table 2.Total livestock of the Republic Serbia

Livestock in Serbia

Cattle 915 641

Horses 15 222

Sheep 1 789 144

Goats 202 828

Pigs 3 284 378

Poultry 17 449 938

However, the economics might not be beneficial

to all farmers, since the methane yield per mass unit of

manure is comparatively low. Therefore, co-digestion

with other substrates (e.g. energy crops, crop residues)

is common and their availability in the presented

hotspots should be included in future evaluations Table

3.

In addition to the feed-in tariffs, heat and steam

generation with biogas and CHP waste heat will play a

significant role for the profitability of biogas plants in


Serbia. Although cheap energy sources, such as coal

and firewood, are still in many regions and sectors

the main fuels, approximately 40% of public

buildings in Serbia are heated with fuel oil HEL,

which is currently with a heat price in average of

approximately 100€ per MWh of heat (approximately

1.05 € per litre net) exerting a massive impact on the

budgets of the municipalities. Particularly in the

agricultural and forestry regions of Serbia people are

looking into reasonably priced and available

bioenergy. In Figure 1 biogas plant model is shown

[6].

Table3.Estimated biogas production of livestock manure per head (m3/head*day) [4]

Livestock

Categories

Estimated fresch manure

(FM) (m3/head*year)

Methane yield in

(ml/m3 FM)

Net caloric

value biogas

Cattle 11.76 17.00

21.8 MJ/m3

= 6 kwh

Cattle 18.00 17.00

Pigs 2.20 12.00

Poultry 0.02 82.00

Fig.1.Biogas plant model





sewage sludge for their own power supply. Realized

biogas plant in Mirotin is shown in Figure 2. The

remaining three biogas plants are mainly charged with

cattle manure and slurry, maize silage and beet pulp.

There is no project for construction of a biomass plant

in Serbia yet, despite the favorable position that

biomass has with a 60% share of the total potential for

renewable energy in the country.

Fig.2.Mirotin/biogas plant

72


3. Results and analyze

Table4.Project Proposal of 50 kWel Biogas plant in Serbia: Manure input– required quantity and quality

Biogas production of substrate

Substrate Fresh material DMS oDMS Production of CH4 Production of biogas

t/a m3/d % FM % DMS % m3/year l/kg oDMS m3/year

Liquid Pork Manure 31 928 87 2.0 % 75 % 60% 120 687 420.0 201 145

total 31 928 87 120 687 201 145

or




Liquid cattle manure 9445 26 7.0% 75% 55% 95 458.15 350.0 175 560

Solid cattle manure 730 2 18.0% 80% 60% 25 229 400.0 42 048

total 10.175 28 120 687 215 608

Pig farm of around 5.000 animal units or cattle

farm around 1.000 animal units can provide needed

amount for the proposed plant size analysis of

organic dry matter content and real quantity values

necessary for each individual farm and projectcosts

of biogas production, in cattle farming.

Ideal operating conditions for manure -based

small installations to 75 KW


small installations to 75 KW, domestic conditions

are:

• Significantly more than 4.000 m³ manure (> 200

GV), a part as solid manure

• No manure pit

• Slurry attack at a central location

• Large manure storage (new / with leakage film)

present or needed anyway for animal

husbandry, which can be gas-tight covered

• In silage economy oriented (cattle farming)

• Low cost upgrade the silo possible

• Transformer already exists (PV)

• Still additional space available

• Proper Location

• Heat demand in the house and / or shed.

1.1. Work Economic Aspects

• Time required (only plant care without transport

work): ca. 600 h / year, that is, on average 1.5

hours/day

• Routine work (monitoring, documentation,

feeding): 30 - 60 min / day

• Remaining time for maintenance works (for

example, oil changes), repairs, organization and

management

• Technical skills should be present (repairs,

maintenance), and a willingness to learn new

things (biology, plant care) and a certain nerve

strength is not disadvantageous.

1.2. Heat utilization

• For pure manure plants, during the winter months

no excess of heat. At low dry matter levels even

possibly too little heat for the fermenter heating

- Good thermal insulation of the tank, if

necessary, heat exchanger

• With fermentable of solid biomass, the heat

balance improved

- Heating residential house and possibly

stables conceivable

Reasons for implementation

• Additional cash-flow of over 378.000 € per

project without taxation in 15 years possible

around 25.200 € per year)

• Emission reduction of methane from manure

storage

• Environmental treatment of manure waste

• Renewable energy sources, energy independency

• Conditioning of fertilizer, nutrients stay in

effluents

• Upscale and multiplication possible

• Positive visibility

Are smaller plants useful?

• This is highly dependent on the construction

costs biogas plants are relatively expensive in

Serbia, as a high technical standard and many

statutory. Requirements must be observed.

• If the additional benefits (manure improvement,

etc.) or the autonomous power supply operation

(electricity + heat) is in the foreground.


Table5.Operating economics with cattle farming (EEG 2014, Remuneration: 23.53 ct / kWh )

30KW 50KW 75 KW

manure slurry manure slurry manure + silage manure slurry manure + silage

Investment cost € 270,000 € 400,000 € 480,000 € 450,000 €550,000

Current

production 240 000 kw 400 000 kw 600 000 kw

Revenue € 57 000 € 94 900 € 94 900 €142 000 € 142 400

Heat Proceeds € 2 500 € 2 500

cost without

Biomasse € 40 500 €59 500 € 70 200 € 68 900 € 81 800

Slurry (1 € / m³) € 4 400 € 7 200 € € 2 900 € 10 500 €4 150

total cost € 44 900 € 66 700 € 99 100 € 79 050 € 122 450

profit (excluding

labor costs) € 12 100 €28 200 € 1 700 € 63 350 € 22 450

biomass € 2600 € 36 500

profit rate 21. 2% 29,7% -0.2% 44.5 % 15.8%

working € 6 000 € 6 000 € 7 500 € 6 000 € 9 000

entrepreneurs

profit /loss kWh

€ 6 100

ct

€ 22 200

5.6 ct

€ 9 200

-2.3 ct

€ 57 350

9.6 ct

€ 13 450

2.2 ct

return on

investment 8.4 % 15.1 % 0.2 % 29.6 % 8.9%

Electricity production from renewable resources

in Serbia is still quite unfamiliar, except generated

electricity from hydro power. However, in the year

2013 the Statistical Office has started keeping track

of the electricity production from existing biogas

plants which is a step forward to a better oversight of

generated energy from renewables. There is no

official statistical document nor is report that can

validate how much electricity is actually produced

from all renewable energies. However, on the website

of the Ministry of Mining and Energy, there is a list

of all registered privileged electricity producers, as

well as the list of all submitted applications for

obtaining the status of privileged electricity produces

(http://mre.gov.rs/energetska-efikasnost-obnovljivi-

izvori.php). This list is updated every three months.

According to the Energy Law (2014), the records and

information of electricity and heat produced from the

renewable energy sources should be kept and up-dated

by the authorities on local level. Once a year, these

records should be submitted to the Ministry of Mining

and Energy.

Fig.3.Energetic use of biogas

73


3. Results and analyze

Table4.Project Proposal of 50 kWel Biogas plant in Serbia: Manure input– required quantity and quality




Liquid Pork Manure 31 928 87 2.0 % 75 % 60% 120 687 420.0 201 145

total 31 928 87 120 687 201 145

or




Liquid cattle manure 9445 26 7.0% 75% 55% 95 458.15 350.0 175 560

Solid cattle manure 730 2 18.0% 80% 60% 25 229 400.0 42 048

total 10.175 28 120 687 215 608

Pig farm of around 5.000 animal units or cattle

farm around 1.000 animal units can provide needed

amount for the proposed plant size analysis of

organic dry matter content and real quantity values

necessary for each individual farm and projectcosts

of biogas production, in cattle farming.


small installations to 75 KW


small installations to 75 KW, domestic conditions

are:

• Significantly more than 4.000 m³ manure (> 200

GV), a part as solid manure

• No manure pit

• Slurry attack at a central location

• Large manure storage (new / with leakage film)

present or needed anyway for animal

husbandry, which can be gas-tight covered

• In silage economy oriented (cattle farming)

• Low cost upgrade the silo possible

• Transformer already exists (PV)

• Still additional space available

• Proper Location

• Heat demand in the house and / or shed.

1.1. Work Economic Aspects

• Time required (only plant care without transport

work): ca. 600 h / year, that is, on average 1.5

hours/day

• Routine work (monitoring, documentation,

feeding): 30 - 60 min / day

• Remaining time for maintenance works (for

example, oil changes), repairs, organization and

management

• Technical skills should be present (repairs,

maintenance), and a willingness to learn new

things (biology, plant care) and a certain nerve

strength is not disadvantageous.

1.2. Heat utilization

• For pure manure plants, during the winter months

no excess of heat. At low dry matter levels even

possibly too little heat for the fermenter heating

- Good thermal insulation of the tank, if

necessary, heat exchanger

• With fermentable of solid biomass, the heat

balance improved

- Heating residential house and possibly

stables conceivable

Reasons for implementation

• Additional cash-flow of over 378.000 € per

project without taxation in 15 years possible

around 25.200 € per year)

• Emission reduction of methane from manure

storage

• Environmental treatment of manure waste

• Renewable energy sources, energy independency

• Conditioning of fertilizer, nutrients stay in

effluents

• Upscale and multiplication possible

• Positive visibility

Are smaller plants useful?

• This is highly dependent on the construction

costs biogas plants are relatively expensive in

Serbia, as a high technical standard and many

statutory. Requirements must be observed.

• If the additional benefits (manure improvement,

etc.) or the autonomous power supply operation

(electricity + heat) is in the foreground.


Table5.Operating economics with cattle farming (EEG 2014, Remuneration: 23.53 ct / kWh )

30KW 50KW 75 KW

manure slurry manure slurry manure + silage manure slurry manure + silage

Investment cost € 270,000 € 400,000 € 480,000 € 450,000 €550,000

Current

production 240 000 kw 400 000 kw 600 000 kw

Revenue € 57 000 € 94 900 € 94 900 €142 000 € 142 400

Heat Proceeds € 2 500 € 2 500

cost without

Biomasse € 40 500 €59 500 € 70 200 € 68 900 € 81 800

Slurry (1 € / m³) € 4 400 € 7 200 € € 2 900 € 10 500 €4 150

total cost € 44 900 € 66 700 € 99 100 € 79 050 € 122 450

profit (excluding

labor costs) € 12 100 €28 200 € 1 700 € 63 350 € 22 450

biomass € 2600 € 36 500

profit rate 21. 2% 29,7% -0.2% 44.5 % 15.8%

working € 6 000 € 6 000 € 7 500 € 6 000 € 9 000

entrepreneurs

profit /loss kWh

€ 6 100

ct

€ 22 200

5.6 ct

€ 9 200

-2.3 ct

€ 57 350

9.6 ct

€ 13 450

2.2 ct

return on

investment 8.4 % 15.1 % 0.2 % 29.6 % 8.9%

Electricity production from renewable resources

in Serbia is still quite unfamiliar, except generated

electricity from hydro power. However, in the year

2013 the Statistical Office has started keeping track

of the electricity production from existing biogas

plants which is a step forward to a better oversight of

generated energy from renewables. There is no

official statistical document nor is report that can

validate how much electricity is actually produced

from all renewable energies. However, on the website

of the Ministry of Mining and Energy, there is a list

of all registered privileged electricity producers, as

well as the list of all submitted applications for

obtaining the status of privileged electricity produces

(http://mre.gov.rs/energetska-efikasnost-obnovljivi-

izvori.php). This list is updated every three months.

According to the Energy Law (2014), the records and

information of electricity and heat produced from the

renewable energy sources should be kept and up-dated

by the authorities on local level. Once a year, these

records should be submitted to the Ministry of Mining

and Energy.

Fig.3.Energetic use of biogas

74


4. Conclusions

According to Directive 2009/28/EC, each

Member State shall ensure that its share of energy

from renewable sources in gross final energy

consumption in 2020 is at least its national overall

target for the share of renewable energy this year, as

specified in directive. In addition, each Member State

should ensure that the share of renewable energy in all

modes of transport in 2020 is at least 10% of final

energy consumption in transport in that Member State.

These mandatory national targets are consistent with

the overall goal on assumptions of 20% share of

energy from renewable sources in gross final energy

consumption in the Community in 2020, the fastest

growing sector of renewable energy sources is solar

energy. In 2007 the installed collector area has

increased almost to the level of 40% over the previous

year. The most effective and efficient because of the

attractiveness to investors in the long run, it may be

the energy production from wind and biogas.

References

[1] Glavonjić B., Vasiljević A., Petrović S., Pajović L.,

Sretenović P., Radović S. (2009), The economic

(macro-level) aspects of wood energy systems in

Serbia. University of Belgrade, Faculty of forestry.

[2] Köttner M., Kayser K.(2014), Assessment of the

framework conditions for biogas production in Serbia.

IBBK Fachgruppe Biogas GmbH.

[3] Ćosić B., Stanić Z., Duić N. (2011), Geographic

distribution of economic potential of agricultural and

forest biomass residual for energy use: Case study

Croatia.

[4] Dodic S., Zekic V., Rodic V., Tica N., Dodic J. (2010),

Situation and perspectives of waste biomass application

as energy source in Serbia. Renew. Sustain. Energy

Rev., 14, 3171–3177.

[5] Ericsson K., Nilsson L.J. (2006), Assessment of the

potential biomass supply in Europe using a resource-

focused approach. Biomass Bioenergy, 30, 1–15.

[6] Cvetković S., Kaluđerović-Radoičić T., Vukadinović B., Kijevčanin M. (2014),Potentials and status of

biogas as energy source in the Republic of Serbia,

Renewable and Sustainable Energy Reviews, 31, 407-

416.

[7] Wojtczak J. Bajda L. (2010), Biogas. ISBN-978-83-

911711-8-9.

[8] Kiedrowicz M., Palkova Z, Kovac P. (2013),

Renewable energy from biogas - status and prospects in

Poland relating to the european union, XIX TREND,

Pohorje, Slovenija, 18–21.02.

[9] Petrovic M., Petrovic P., Petrovic M. (2013), Biogas

production posibility of Agricultural and other organic

Wastebto secondary sustanable ecology and Tourism in

Rural and other Areas, Tractors and power machines,

18/3, 102–111.

[10] Cvetković S., Vukadinović B., Kijevčanin M.,

Radoičić-Kaludjerović T. (2013), Potentials and status

of biogas as energy source in the Republic of Serbia.

[11] Faasch R. J., Patenaude G. (2012), The economics of

short rotation coppice in Germany. Biomass Bioenergy

45, 27–40.

[12] Nyers J., Tomic S. (2013): Financial Optimum of

Thermal Insulating Layer for the Buildings of Bricket,

5rd International Symposium, EXPRES 2013.

Proceedings ISBN 978-86-85409-82-0, pp. 33-37,

Subotica, Serbia.

[13] Nyers J., Kajtar L., Tomic S., Nyers A. (2015):

Investment-savings method for energy-economic

optimization of external wall thermal insulation

thickness, International J. Energy and Buildings. Vol.

86, pp. 268–274, .

http://dx.doi.org/10.1016/j.enbuild.2014.10.023.

TEMPERATURE PARAMETERS CHANGING OF A SPACE HEATING ELEMENT AFTER HUMAN ACTION

1

Temperature parameters changing of a space heating element after human action

M. KURČOVÁ

Slovak University of Technology in Bratislava, Faculty of Civil Engineering, Department of Building Services

SK – 810 05 Bratislava, Radlinského 11, Slovakia


Assignment of space heating element is to deliver an amount of heat, what cover actually energy losses in interior. Emplacement

of space heating element, with design on the ground of heat losses, not yet guarantee his accurate function. Immediate

performance of space heating elements many time is affect human behavior of user in connection with space heating elements.

Keywords:heating element, heating system

1. Introduction

Space heating elements are integral part of living

interiors. Look of space heating elements emerge from

conditions of building constructions and material basis of

heating elements, appropriate his capacity and

dimension. Esthetical appearances of heating element

nevertheless fall behind to appearance of interiors. Hence

of times effort of architects, to cover over space heating

elements. 2. Design of space heating element

Main assignment of space heating elements is

supply such amount of heat to the space obtain

thermal comfort.

Fig.1.Distribution of ideal air flow in a room

with a heating elements

From this main requirement is outgoing for

design of space heating elements. Heat capacity of

space heating element outgoing from projected

incoming heat power (heat losses) of space, on

grounds choices of temperature decrease of circulated

heating water. Ideally emplacement of space heating

element to the mostly cooled construction – up to

windows, equivalent of windows length, i.e.

minimally 80 % of windows length. Solution of

heating element design like this, results ideal air flow

in heated space (Fig. 1).

3.Factors affecting fhe performance of the heating element

Heating element's heat output is transmitted into

the room by radiation and convection while the

proportion of the radiant component of heat transfer

can be between 30 and 50% depending on the type of

the heater.

Performance of heating element located in the

heated space is influenced by several factors according

to:

f.NΦΦ = (W)

pnoxm f.f.f.f.f.ffθ∆

= (-)

75


4. Conclusions

According to Directive 2009/28/EC, each

Member State shall ensure that its share of energy

from renewable sources in gross final energy

consumption in 2020 is at least its national overall

target for the share of renewable energy this year, as

specified in directive. In addition, each Member State

should ensure that the share of renewable energy in all

modes of transport in 2020 is at least 10% of final

energy consumption in transport in that Member State.

These mandatory national targets are consistent with

the overall goal on assumptions of 20% share of

energy from renewable sources in gross final energy

consumption in the Community in 2020, the fastest

growing sector of renewable energy sources is solar

energy. In 2007 the installed collector area has

increased almost to the level of 40% over the previous

year. The most effective and efficient because of the

attractiveness to investors in the long run, it may be

the energy production from wind and biogas.

References

[1] Glavonjić B., Vasiljević A., Petrović S., Pajović L.,

Sretenović P., Radović S. (2009), The economic

(macro-level) aspects of wood energy systems in

Serbia. University of Belgrade, Faculty of forestry.

[2] Köttner M., Kayser K.(2014), Assessment of the

framework conditions for biogas production in Serbia.

IBBK Fachgruppe Biogas GmbH.

[3] Ćosić B., Stanić Z., Duić N. (2011), Geographic

distribution of economic potential of agricultural and

forest biomass residual for energy use: Case study

Croatia.

[4] Dodic S., Zekic V., Rodic V., Tica N., Dodic J. (2010),

Situation and perspectives of waste biomass application

as energy source in Serbia. Renew. Sustain. Energy

Rev., 14, 3171–3177.

[5] Ericsson K., Nilsson L.J. (2006), Assessment of the

potential biomass supply in Europe using a resource-

focused approach. Biomass Bioenergy, 30, 1–15.

[6] Cvetković S., Kaluđerović-Radoičić T., Vukadinović B., Kijevčanin M. (2014),Potentials and status of

biogas as energy source in the Republic of Serbia,

Renewable and Sustainable Energy Reviews, 31, 407-

416.

[7] Wojtczak J. Bajda L. (2010), Biogas. ISBN-978-83-

911711-8-9.

[8] Kiedrowicz M., Palkova Z, Kovac P. (2013),

Renewable energy from biogas - status and prospects in

Poland relating to the european union, XIX TREND,

Pohorje, Slovenija, 18–21.02.

[9] Petrovic M., Petrovic P., Petrovic M. (2013), Biogas

production posibility of Agricultural and other organic

Wastebto secondary sustanable ecology and Tourism in

Rural and other Areas, Tractors and power machines,

18/3, 102–111.

[10] Cvetković S., Vukadinović B., Kijevčanin M.,

Radoičić-Kaludjerović T. (2013), Potentials and status

of biogas as energy source in the Republic of Serbia.

[11] Faasch R. J., Patenaude G. (2012), The economics of

short rotation coppice in Germany. Biomass Bioenergy

45, 27–40.

[12] Nyers J., Tomic S. (2013): Financial Optimum of

Thermal Insulating Layer for the Buildings of Bricket,

5rd International Symposium, EXPRES 2013.

Proceedings ISBN 978-86-85409-82-0, pp. 33-37,

Subotica, Serbia.

[13] Nyers J., Kajtar L., Tomic S., Nyers A. (2015):

Investment-savings method for energy-economic

optimization of external wall thermal insulation

thickness, International J. Energy and Buildings. Vol.

86, pp. 268–274, .

http://dx.doi.org/10.1016/j.enbuild.2014.10.023.


1

Temperature parameters changing of a space heating element after human action

M. KURČOVÁ

Slovak University of Technology in Bratislava, Faculty of Civil Engineering, Department of Building Services

SK – 810 05 Bratislava, Radlinského 11, Slovakia


Assignment of space heating element is to deliver an amount of heat, what cover actually energy losses in interior. Emplacement

of space heating element, with design on the ground of heat losses, not yet guarantee his accurate function. Immediate

performance of space heating elements many time is affect human behavior of user in connection with space heating elements.

Keywords:heating element, heating system

1. Introduction

Space heating elements are integral part of living

interiors. Look of space heating elements emerge from

conditions of building constructions and material basis of

heating elements, appropriate his capacity and

dimension. Esthetical appearances of heating element

nevertheless fall behind to appearance of interiors. Hence

of times effort of architects, to cover over space heating

elements. 2. Design of space heating element

Main assignment of space heating elements is

supply such amount of heat to the space obtain

thermal comfort.

Fig.1.Distribution of ideal air flow in a room

with a heating elements

From this main requirement is outgoing for

design of space heating elements. Heat capacity of

space heating element outgoing from projected

incoming heat power (heat losses) of space, on

grounds choices of temperature decrease of circulated

heating water. Ideally emplacement of space heating

element to the mostly cooled construction – up to

windows, equivalent of windows length, i.e.

minimally 80 % of windows length. Solution of

heating element design like this, results ideal air flow

in heated space (Fig. 1).

3.Factors affecting fhe performance of the heating element

Heating element's heat output is transmitted into

the room by radiation and convection while the

proportion of the radiant component of heat transfer

can be between 30 and 50% depending on the type of

the heater.

Performance of heating element located in the

heated space is influenced by several factors according

to:

f.NΦΦ = (W)

pnoxm f.f.f.f.f.ffθ∆

= (-)

76


where Φ is the actual heat output of the convector,

ΦN – rated heat output of the convector (W),

f∆θ- the correction factor for temperature

differences (-),

fm – the correction factor for the mass flow of heat

transfer medium (-),

fx – the correction factor for connecting

the convector (-),

fo – the correction factor to adjust the ambient

temperature (-),

fn – the correction factor for the number

of sections (-),

fp – the correction factor for the space location

of convector. [1, 2]

Planning engineer in the design of heating element

must determine his real performance according to the

formula above. Heat output's corrective factors are

given the positioning of the convector in space and it

does usually not change during the use.

4. Esthetic solutions to covering

heating element

Difficulty arises when heater does not fit into the

interior design. Then is the effort to get rid of view of

the heater in various ways of masking (Fig. 2).

Fig.2. An additional interior design solution

Covering the heating element is completely

suppress the radiant component of heat transfer while

the convention component is reduces, which reduces

the total power of the heating element. The fact is that

in the past was necessary not only aesthetic

considerations but more often was necessary to resort

to cover the heating elements, the correction factor to

adjust the ambient temperature dealt STN 06 1101

(currently canceled).

It should be understood that the covering of heating

element affects the flow direction of the thermal

convection flows. The heat output's impact of various

methods of masking heating element is shown in F


is the actual heat output of the convector,

rated heat output of the convector (W),

the correction factor for temperature

the correction factor for the mass flow of heat

the correction factor for connecting

the correction factor to adjust the ambient

the correction factor for the number

the correction factor for the space location



corrective factors are



effort to get rid of view of


. An additional interior design solution



reduces, which reduces





mperature dealt STN 06 1101



impact of various

methods of masking heating element is shown in Fig.3.

Fig.3. The correction factor to adjust the ambient temperature expressed in percentage [1]

Thus, when the area of the panel fitted with a the

heater 22K-800/500, the performance of the

temperature gradient of the heating system 90/70 ° C

and a desired internal temperature of 20 ° C, the

1498 W output heating element 22K

90/70/20 ° C is reduced:

• In the current state of the sliding it under the sill

of

60 W. It's a tiny part of performance,

unnoticeable to users.

• The covering of the heating element with the

prescribed maximum holes in the base of the

upper casing 150-195 W. The heat output of the

user is already appreciable.

• The complete covering of the perforated cover of

heating element 225 W or more depending upon

the ratio perforated. The heat output is

significantly reduced.

Another case occurs by using the front cover

heating element placed at a certain height above the

floor. In this case, there is an increased flow of air

around the heating element, and therefore increases

the power up to 150 W.

The correction factor affects only the performance

of heating element for calculation parameters.

Adaptation of the heat output of heating element to

heat loss are made through the room thermostat

control valve in front of the heating element, therefore,

in covering heating element must not forget the

principle of their operation.


2

. The correction factor to adjust the ambient temperature expressed in percentage [1]


800/500, the performance of the


desired internal temperature of 20 ° C, the

1498 W output heating element 22K-800/500 in the

In the current state of the sliding it under the sill


the heating element with the


195 W. The heat output of the

The complete covering of the perforated cover of


forated. The heat output is









ing element, therefore,



3

5. Human intervention and temperature

parameters of heating element

Monitoring human impacts on heating element

temperature parameters was carried out on the heating

element placed in a residential building. The heater is

on supply pipe valve with thermostat. The heater is

part of a two-pipe hydronic heating system of

residential building. The heating system is

hydraulically balanced.

Fig.4. Measurement of physical parameters

For monitoring temperature changes in radiator human

intervention was measured:

• Outside air temperature,

• Indoor air temperature in the middle of the room,

• Indoor air temperature 15 cm in front of the heater,

• the supply pipe temperature,

• the return pipe temperature.

As part of the measurements was studied human impact

on physical parameters:

a) in affecting the temperature performance of heating

element by turning the thermostat,

b) the covering of heating element by cover.

In the first stage is shown progress of temperatures at

the measurement starting position. The heater is freely

accessible to the thermostat to position 4. The difference

between inlet and return temperature of the heating

water temperature is 7 K. Indoor air measured in the

middle of the room and close to heating element is

about the same. The second phase of measurement is a

reduction of the mass flow of heating water to the

heating element by adjusting the thermostat from

position 4 to the position 2

Fig.5.Temperature of the heating element

This occurs slow temperature drop inlet and return

heating water. The temperature in the room and in

front of the heater remains due to the accumulation

of heat in the room at the same value. The third

phase is a measurement of a sudden increase in the

mass flow of heating water to the heating element.

After turning the thermostat to its original setting 4

occurring temperature increase inlet and return

water. At the same time inside air temperature

gentle rise near the heating element, while the air

temperature in the middle of the room does not

change. Gradual change of temperature on the

heater can be seen in images from the thermal

imaging camera

Fig. 6.

77


where Φ is the actual heat output of the convector,

ΦN – rated heat output of the convector (W),

f∆θ- the correction factor for temperature

differences (-),

fm – the correction factor for the mass flow of heat

transfer medium (-),

fx – the correction factor for connecting

the convector (-),

fo – the correction factor to adjust the ambient

temperature (-),

fn – the correction factor for the number

of sections (-),

fp – the correction factor for the space location

of convector. [1, 2]



formula above. Heat output's corrective factors are


does usually not change during the use.

4. Esthetic solutions to covering

heating element


interior design. Then is the effort to get rid of view of


Fig.2. An additional interior design solution



the convention component is reduces, which reduces





adjust the ambient temperature dealt STN 06 1101

(currently canceled).



convection flows. The heat output's impact of various

methods of masking heating element is shown in F


is the actual heat output of the convector,

rated heat output of the convector (W),

the correction factor for temperature

the correction factor for the mass flow of heat

the correction factor for connecting

the correction factor to adjust the ambient

the correction factor for the number

the correction factor for the space location



corrective factors are



effort to get rid of view of


. An additional interior design solution



reduces, which reduces





mperature dealt STN 06 1101



impact of various

methods of masking heating element is shown in Fig.3.

Fig.3. The correction factor to adjust the ambient temperature expressed in percentage [1]


heater 22K-800/500, the performance of the


and a desired internal temperature of 20 ° C, the

1498 W output heating element 22K

90/70/20 ° C is reduced:

• In the current state of the sliding it under the sill

of


unnoticeable to users.

• The covering of the heating element with the


upper casing 150-195 W. The heat output of the

user is already appreciable.

• The complete covering of the perforated cover of


the ratio perforated. The heat output is

significantly reduced.





the power up to 150 W.





control valve in front of the heating element, therefore,


principle of their operation.


2

. The correction factor to adjust the ambient temperature expressed in percentage [1]


800/500, the performance of the


desired internal temperature of 20 ° C, the

1498 W output heating element 22K-800/500 in the

In the current state of the sliding it under the sill


the heating element with the


195 W. The heat output of the

The complete covering of the perforated cover of


forated. The heat output is









ing element, therefore,



3

5. Human intervention and temperature

parameters of heating element

Monitoring human impacts on heating element

temperature parameters was carried out on the heating

element placed in a residential building. The heater is

on supply pipe valve with thermostat. The heater is

part of a two-pipe hydronic heating system of

residential building. The heating system is

hydraulically balanced.

Fig.4. Measurement of physical parameters

For monitoring temperature changes in radiator human

intervention was measured:

• Outside air temperature,

• Indoor air temperature in the middle of the room,

• Indoor air temperature 15 cm in front of the heater,

• the supply pipe temperature,

• the return pipe temperature.

As part of the measurements was studied human impact

on physical parameters:

a) in affecting the temperature performance of heating

element by turning the thermostat,

b) the covering of heating element by cover.

In the first stage is shown progress of temperatures at

the measurement starting position. The heater is freely

accessible to the thermostat to position 4. The difference

between inlet and return temperature of the heating

water temperature is 7 K. Indoor air measured in the

middle of the room and close to heating element is

about the same. The second phase of measurement is a

reduction of the mass flow of heating water to the

heating element by adjusting the thermostat from

position 4 to the position 2

Fig.5.Temperature of the heating element

This occurs slow temperature drop inlet and return

heating water. The temperature in the room and in

front of the heater remains due to the accumulation

of heat in the room at the same value. The third

phase is a measurement of a sudden increase in the

mass flow of heating water to the heating element.

After turning the thermostat to its original setting 4

occurring temperature increase inlet and return

water. At the same time inside air temperature

gentle rise near the heating element, while the air

temperature in the middle of the room does not

change. Gradual change of temperature on the

heater can be seen in images from the thermal

imaging camera

Fig. 6.

78


Fig.6. Images of a

The fourth phase of measurements show a change

of temperature in cover heating element. The

temperature of the air in the middle of the room

does not change the temperature of air near the

heating element will rise to about 3 K.

6. Conclusion

Heating element is the part of the heating system,

which gets into direct contact with users of heated

space. That's why the user thinks is his property

and he can do with it what he wants. The most

common problem of heating element is

appearance, which the user cannot control.

Therefore makes additional aesthetic solutions

covering different types of heating element covers

and do not realize that this will impoverish

himself of some of the heat that heat element can

provide.

References

[1] J. Bašta, Otopnéplochy, část 1 až 4 ( www.tzb

[2] D. Petráš, a kol.:Vykurovanie rodinných a bytovýchdomov, Jaga, Bratislava, 2005, ISBN 80-8076

[3] J. Cihelka, Vytápění, větrání a klimatizace, SNTL, Praha, 1985, ISBN 04-201-85.


. Images of a thermal imaging camera



mperature of the air in the middle of the room




s why the user thinks is his property





ng element covers



www.tzb-info.cz)

bytových 8076-012-8. J.

klimatizace, SNTL,

[4] STN 06 1101 Vykurovacie telesána vykurovanie, 1992.

[5] Kalmár, F. (2016), Interrelation betwesummer operative temperature in buildings, International Review of Applied Sciences and Engineering, 7 (2016) 1, pp. 51–60, DOI: 10.1556/1848.2016.7.1.7

[6] Kalmár, F., Csomós, Gy., Lakatos, Á. (2013),renewable energy (energy policy) —International Review of Applied Sciences and Engineering, 4 (1), 95-95 (2013)

[7] Kajtár, L., Kassai, M., Bánhidi, L. (2011), Computerized simulation of the energy consumption of air handling units. 2011, Energy and Buildings, ISSN 0378-7788, (45) pp. 54-59.

[8] Kassai, M., Ge, G., Simonson, C. J. Dehumidification performance investigation of to-air membrane energy exchanger system, Thermal Science, DOI: 10.2298/TSCI140816129K (2015).

[9] Nyers, J., Garbai, L., Nyers, A. (2015),mathematical model of heat pump's condenser for analytical optimization, International J. Energy, Vol. pp. 706-714, 1 February 2015.

DOI:10.1016/j.energy.2014.12.028

[10] Nyers, J., Nyers, A. (2013), Hydraulic Analysis of Heat Pump's Heating Circuit using Mathematical Model, 9ICCC International Conferenc, ProceedingsISBN 978-1-4799-0061-9, pp. 349Hungary, 2013

[11] Nyers, J., Nyers, A.(2011), COP of heatingsystem with heat pump, EXPRES 2011, 3rd IEEE International Symposium on Exploitation of Renewable Energy Sources, Subotica, Serbia; 2011, Proceedings, pp. 17-21, Article number 5741809


4

ústredné

nterrelation between glazing and summer operative temperature in buildings, International Review of Applied Sciences and

60, DOI:

Kalmár, F., Csomós, Gy., Lakatos, Á. (2013), Focus on — Editorial,

International Review of Applied Sciences and

sai, M., Bánhidi, L. (2011), Computerized simulation of the energy consumption of air handling units. 2011, Energy and Buildings, ISSN

Kassai, M., Ge, G., Simonson, C. J. (2015), Dehumidification performance investigation of liquid-

air membrane energy exchanger system, Thermal Science, DOI: 10.2298/TSCI140816129K (2015).

Nyers, A. (2015), A modified mathematical model of heat pump's condenser for analytical optimization, International J. Energy, Vol. 80,

Hydraulic Analysis of Heat Pump's Heating Circuit using Mathematical Model, 9th ICCC International Conferenc, Proceedings-USB,

9, pp. 349-353, Tihany,

COP of heating-cooling EXPRES 2011, 3rd IEEE

International Symposium on Exploitation of Renewable Energy Sources, Subotica, Serbia; 2011, Proceedings,

ISBN

EXPRES 2017

ISBN 978-86-919769-1-0

Modern cost accounting techniques for renewable energy and sustainable development

Đ. PETKOVIČ a, I. MEDVED b

University of Novi Sad, Faculty of Economics,

Subotica, Segedinski put 9-11, Serbia aE-mail:[email protected] bE-mail:[email protected]

Costing and modern cost accounting techniques are important for cost measurement of sustainable development. The aim of this

paper is to analyze the possible advantages and limitations of modern costing tools for renewable energy technologies and

sustainable development. This paper points out that the calculation of the costs in sustainable development in modern business

conditions necessarily requires the use of modern costing systems in purpose to provide a suitable basis for making business

decisions, better measurement of profitability, improving operations in terms of cost savings and ensuring information for

keeping or gaining a competitive advantage. The issue of costs is central to the question of how renewable energy technologies

will development and spread as energy sources instead of fossil fuels.

Keywords:cost accounting,sustainable development,renewable energy technologies,modern costing systems

1. Introduction

Limited natural resources and a wish to fulfill the

most favorable financial effects of the business, it

indicates the need for planning, organization and

implementation of activities of business entities

through preservation of the environment and

enhancing the quality of life of people, seen through

the interests of the present generation, but also for

the benefit of future generations. Sustainable

development is focused on long-term stable

production of quality products and services while

preserving and protecting the environment, energy

and natural resources but with the provision earning

capacity of the organization and for the welfare of

individuals and the wider community.

The last decades of the twentieth and beginning

of XXI century brought many changes in the

business management and environment management

because of increase of consumption, world

population, industrial activity, etc. The attitude

towards customers and suppliers is also changed, as

same as mode of production and people’s sense for

environmental problems and sustainable

development.

Environmental problems such as harmful

pollution of water, air and soil, waste disposal,

climate change, Stratospheric ozone depletion and

other environmental degradation are current issues

for theoretical and practical study of various

disciplines. Some potential solutions to the current

environmental problems associated with the harmful

pollutant emissions have evolved, including: [2]

− renewable energy technologies;

− energy conservation (efficient energy utilization);

− cogeneration and district heating;

− energy storage technologies;

− alternative energy dimensions for transport;

− energy source switching from fossil fuels to

environmentally benign energy forms;

− coal cleaning technologies;

− optimum monitoring and evaluation of energy

indicators;

− policy integration;

− recycling;

− process change and sectoral shiftment;

− acceleration of forestation;

− carbon or fuel taxes;

− materials substitution;

− promoting public transport;

− changing life styles;

− increasing public awareness;

− education and training.

79


Fig.6. Images of a



temperature of the air in the middle of the room


heating element will rise to about 3 K.

6. Conclusion



space. That's why the user thinks is his property





covering different types of heating element covers



provide.

References

[1] J. Bašta, Otopnéplochy, část 1 až 4 ( www.tzb

[2] D. Petráš, a kol.:Vykurovanie rodinných a bytovýchdomov, Jaga, Bratislava, 2005, ISBN 80-8076

[3] J. Cihelka, Vytápění, větrání a klimatizace, SNTL, Praha, 1985, ISBN 04-201-85.


. Images of a thermal imaging camera



mperature of the air in the middle of the room




s why the user thinks is his property





ng element covers



www.tzb-info.cz)

bytových 8076-012-8. J.

klimatizace, SNTL,

[4] STN 06 1101 Vykurovacie telesána vykurovanie, 1992.

[5] Kalmár, F. (2016), Interrelation betwesummer operative temperature in buildings, International Review of Applied Sciences and Engineering, 7 (2016) 1, pp. 51–60, DOI: 10.1556/1848.2016.7.1.7

[6] Kalmár, F., Csomós, Gy., Lakatos, Á. (2013),renewable energy (energy policy) —International Review of Applied Sciences and Engineering, 4 (1), 95-95 (2013)

[7] Kajtár, L., Kassai, M., Bánhidi, L. (2011), Computerized simulation of the energy consumption of air handling units. 2011, Energy and Buildings, ISSN 0378-7788, (45) pp. 54-59.

[8] Kassai, M., Ge, G., Simonson, C. J. Dehumidification performance investigation of to-air membrane energy exchanger system, Thermal Science, DOI: 10.2298/TSCI140816129K (2015).

[9] Nyers, J., Garbai, L., Nyers, A. (2015),mathematical model of heat pump's condenser for analytical optimization, International J. Energy, Vol. pp. 706-714, 1 February 2015.

DOI:10.1016/j.energy.2014.12.028

[10] Nyers, J., Nyers, A. (2013), Hydraulic Analysis of Heat Pump's Heating Circuit using Mathematical Model, 9ICCC International Conferenc, ProceedingsISBN 978-1-4799-0061-9, pp. 349Hungary, 2013

[11] Nyers, J., Nyers, A.(2011), COP of heatingsystem with heat pump, EXPRES 2011, 3rd IEEE International Symposium on Exploitation of Renewable Energy Sources, Subotica, Serbia; 2011, Proceedings, pp. 17-21, Article number 5741809


4

ústredné

nterrelation between glazing and summer operative temperature in buildings, International Review of Applied Sciences and

60, DOI:

Kalmár, F., Csomós, Gy., Lakatos, Á. (2013), Focus on — Editorial,

International Review of Applied Sciences and

sai, M., Bánhidi, L. (2011), Computerized simulation of the energy consumption of air handling units. 2011, Energy and Buildings, ISSN

Kassai, M., Ge, G., Simonson, C. J. (2015), Dehumidification performance investigation of liquid-

air membrane energy exchanger system, Thermal Science, DOI: 10.2298/TSCI140816129K (2015).

Nyers, A. (2015), A modified mathematical model of heat pump's condenser for analytical optimization, International J. Energy, Vol. 80,

Hydraulic Analysis of Heat Pump's Heating Circuit using Mathematical Model, 9th ICCC International Conferenc, Proceedings-USB,

9, pp. 349-353, Tihany,

COP of heating-cooling EXPRES 2011, 3rd IEEE

International Symposium on Exploitation of Renewable Energy Sources, Subotica, Serbia; 2011, Proceedings,

ISBN

EXPRES 2017

ISBN 978-86-919769-1-0

Modern cost accounting techniques for renewable energy and sustainable development

Đ. PETKOVIČ a, I. MEDVED b

University of Novi Sad, Faculty of Economics,

Subotica, Segedinski put 9-11, Serbia aE-mail:[email protected] bE-mail:[email protected]

Costing and modern cost accounting techniques are important for cost measurement of sustainable development. The aim of this

paper is to analyze the possible advantages and limitations of modern costing tools for renewable energy technologies and

sustainable development. This paper points out that the calculation of the costs in sustainable development in modern business

conditions necessarily requires the use of modern costing systems in purpose to provide a suitable basis for making business

decisions, better measurement of profitability, improving operations in terms of cost savings and ensuring information for

keeping or gaining a competitive advantage. The issue of costs is central to the question of how renewable energy technologies

will development and spread as energy sources instead of fossil fuels.

Keywords:cost accounting,sustainable development,renewable energy technologies,modern costing systems

1. Introduction

Limited natural resources and a wish to fulfill the

most favorable financial effects of the business, it

indicates the need for planning, organization and

implementation of activities of business entities

through preservation of the environment and

enhancing the quality of life of people, seen through

the interests of the present generation, but also for

the benefit of future generations. Sustainable

development is focused on long-term stable

production of quality products and services while

preserving and protecting the environment, energy

and natural resources but with the provision earning

capacity of the organization and for the welfare of

individuals and the wider community.

The last decades of the twentieth and beginning

of XXI century brought many changes in the

business management and environment management

because of increase of consumption, world

population, industrial activity, etc. The attitude

towards customers and suppliers is also changed, as

same as mode of production and people’s sense for

environmental problems and sustainable

development.

Environmental problems such as harmful

pollution of water, air and soil, waste disposal,

climate change, Stratospheric ozone depletion and

other environmental degradation are current issues

for theoretical and practical study of various

disciplines. Some potential solutions to the current

environmental problems associated with the harmful

pollutant emissions have evolved, including: [2]

− renewable energy technologies;

− energy conservation (efficient energy utilization);

− cogeneration and district heating;

− energy storage technologies;

− alternative energy dimensions for transport;

− energy source switching from fossil fuels to

environmentally benign energy forms;

− coal cleaning technologies;

− optimum monitoring and evaluation of energy

indicators;

− policy integration;

− recycling;

− process change and sectoral shiftment;

− acceleration of forestation;

− carbon or fuel taxes;

− materials substitution;

− promoting public transport;

− changing life styles;

− increasing public awareness;

− education and training.

80

ISBN

The renewable energy technologies are potential

very important solution for environmental problems.

A secure supply of energy resources is generally

agreed to be a necessary but not sufficient requirement

for development within a society. Furthermore,

sustainable development within a society demands a

sustainable supply of energy resources (that, in the

long term, is readily and sustainably available at

reasonable cost and can be utilized for all required

tasks without causing negative societal impacts) and

an effective and efficient utilization of energy

resources. In this regard, the connection between

renewable energy sources and sustainable

development comes out [2].

Renewable energy technologies produce marketable

energy by converting natural phenomena into useful

energy forms. These technologies use the energy

inherent in sunlight and its direct and indirect impacts

on the Earth

(photons, wind, falling water, heating effects, and

plant growth), gravitational forces (the tides), and the

heat of the Earth's core (geothermal) as the resources

from which they produce energy.[5]

Measuring sustainable development performance

and quantifying the benefits of sustainability progress

is more qualitative (non-monetary) then quantitative

(monetary) aspects. But, at different levels of

organizational systems (businesses, local government,

state, etc.) most important the question is - whether the

investment in green technologies is cost or

investment? – in context that good investment, in

future, will bring higher benefits than costs.

Investors and government representatives are

interested in:

a) amount of costs of pollution (environmental

damage) or amount of costs of reducing environmental

pollution;

b) amount of costs of prevention and protection of

environment; and

c) amount of eventual benefits of the (non) use

different ways to reduce pollution

which requires the provision of adequate data and

information [7].

Innovation in the sustainable management and

requirements in measuring costs of renewable energy

sources (RES) and sustainable development are

reflected in the Accounting Information System

(AIS) and Environmental Management Accounting

(EMA). Use of Cost Accounting techniques provide

decision making, budgeting, research and

development and control of some aspects of


development.

2. Importance of modern costing techniques

Chronologically speaking, the industrial revolution at

the end of the eighteenth and at the beginning of early

nineteenth century, with the large scale of

production, gives impetus to the development of

cost accounting. The period from the late nineteenth

century until the outbreak of World War II could be

called the period of establishing the principles,

methods and procedures of processing costs.

Traditional costing systems include Standard

Costing and Absorption Costing among other. New,

modern (contemporary) cost accounting systems are

developed from the middle of the last century. Cost

accounting systems, traditional or contemporary,

are, in the main, concepts of cost allocation by the

effects of the revenue generating organization.

Contemporary (modern) costing systems and

techniques attempts, compared to traditional

(classical) cost accounting systems, to enable

adequate deployment of costs, especially overhead

costs to cost centers.

We believe that the following main reasons

contributed to the necessity of creation,

development and application of modern techniques

of cost accounting:

a) increase of overhead costs in total costs - the

most important changes in the cost of operations

reflected in the increase in overhead costs and a

reduction of direct costs in relation to total costs;

b) change of types and structure of the organization

business management;

c) the international market (the emergence of

international corporations contributes to increasing

the complexity of calculating the cost, the growing

importance of transfer pricing and other);

d) the search for new ways to achieve sustainable

competitiveness (cost accounting should provide

information about products, but also on markets,

customers and competition); and

e) the creation and development of strategic cost

management and strategic management accounting

(business is unthinkable without the cost

management and focuses on the measurement of

financial and non-financial performance measures

of results achieved).

Costing (cost accounting), together with

management accounting, which is an integral part,

is trying to respond to the challenges of measuring

sustainable development performance through the

creation of new cost accounting techniques,

methods and concepts to be more informative.

Among them, we emphasize the following modern

cost accounting techniques: Activity based costing

(ABC) and modification of that system as Time-

Driven Activity based costing (TDABC); Flexible

cost planning - Marginal costing

(Grenzplankostenrechnung - GPK); Target

costing; Life- cycle costing; Value chain; Kaizen

costing; Cost of quality reporting, The Balanced

Scorecard, Benchmarking, strategic mapping, etc.

A brief overview of the importance of modern

costing systems is presented in Table 1.

3

Table 1. A brief overview of the importance of modern costing systems

The aim of this paper is to analyze the possible

advantages of different modern systems for

measuring costs of some aspects of renewable energy

sources and sustainable development. In order to

achieve the object and purpose of research, tested the

hypothesis that the calculation of the costs and results

of renewable energy technologies and sustainable

production in modern business conditions necessarily

requires the use of modern costing techniques in the

function of providing a suitable basis for making

business decisions, better measurement of

performance, improving business in terms of cost

savings, providing information to maintain or gain a

competitive advantage and more.

3. Advantages and limitations of costing

tools in sustainable development

measurement and limitations of costing


measurement

Possibilities of modern costing systems and techniques for information basis and performance measurement in sustainable production are:

a) the provision of accurate, timely and adequate information about costs - business decisions that are essential for sustainable production, above all, from the internal sphere of operations and necessary information on different cost structure which depends on the business decision nature,

b) modified techniques, concepts of modern costing systems and objectives of management accounting reports provide quality information support strategic

and operational business decisions in sustainable agricultural production;

c) changes in the level of costs and their behavior, changes in production volume and changes in production processes, changing the amount and structure of the cost of the product, which is particularly reflected in the increasing participation of overhead costs in total costs. Therefore, it is important that modern cost accounting systems generally do not use the same basis for allocation of costs as the traditional cost accounting systems;

d) the method of including general expenses unproductive functional areas eg. research and development costs, marketing and other (having increasing share of the total costs), may, with the appropriate methodological procedures using modern costing systems assign to renewable energy technologies or other sustainable development project in order to provide a suitable basis for making business decisions, better measurement of profitability, improvement of the business in terms of cost savings, providing information to maintain or gain a competitive advantage and more;

e) individual manufacturing costs may be excluded from the total cost of the sustainable development project - according to the modern systems costing, costs are allocated to project only if the product resulting from business decisions about the projects (activities, processes) caused costs.

Accountants are increasingly required to struggle with

issues of measuring sustainability performance. But

sustainable development as an interdisciplinary field of

examination and research incorporates insights from a

many academic disciplinesincluding the natural,

engineering and social sciences.[3]

As a result a number of different sustainability

assessment toolsthat have been developed to measure

Modern Costing Systems Concept basis

Activity-Based Costing – ABC Determining the cost driver of activity

Time-Driven Activity-Based

Costing – TDABC

Direct measurement of unused capacity

Marginal costing - GPK –

Grenzplankostenrechnung

Short-term orientation to variable costs, focus on cost

centers

Target Costing Manage cost reduction in the function of achieving

competitive advantages

Life-Cycle Costing – LCC Measurement of diferent investment alternatives

Value Chain The strategic orientation in order to achieve sustainable

competitive advantage

Kaizen Costing Measurement of continuous cost reduction and continuous

improvement

Cost of Quality Reporting Measuring the prevention costs and appraisal costs, focus

on cost centers

Balanced Scorecard – BSC The focus on the critical success factors - financial and

non-financial - in order to achieve strategic goals

Benchmarking Identifying and measuring competitive advantages through

analysis and comparison with best practices

Strategy Map Based on BSC with linking critical success factors through

cause-and-effect diagrams

81

ISBN

The renewable energy technologies are potential

very important solution for environmental problems.

A secure supply of energy resources is generally

agreed to be a necessary but not sufficient requirement

for development within a society. Furthermore,

sustainable development within a society demands a

sustainable supply of energy resources (that, in the

long term, is readily and sustainably available at

reasonable cost and can be utilized for all required

tasks without causing negative societal impacts) and

an effective and efficient utilization of energy

resources. In this regard, the connection between


development comes out [2].

Renewable energy technologies produce marketable

energy by converting natural phenomena into useful

energy forms. These technologies use the energy

inherent in sunlight and its direct and indirect impacts

on the Earth

(photons, wind, falling water, heating effects, and

plant growth), gravitational forces (the tides), and the

heat of the Earth's core (geothermal) as the resources

from which they produce energy.[5]

Measuring sustainable development performance

and quantifying the benefits of sustainability progress

is more qualitative (non-monetary) then quantitative

(monetary) aspects. But, at different levels of

organizational systems (businesses, local government,

state, etc.) most important the question is - whether the

investment in green technologies is cost or

investment? – in context that good investment, in

future, will bring higher benefits than costs.

Investors and government representatives are

interested in:

a) amount of costs of pollution (environmental

damage) or amount of costs of reducing environmental

pollution;

b) amount of costs of prevention and protection of

environment; and

c) amount of eventual benefits of the (non) use

different ways to reduce pollution

which requires the provision of adequate data and

information [7].

Innovation in the sustainable management and

requirements in measuring costs of renewable energy

sources (RES) and sustainable development are

reflected in the Accounting Information System

(AIS) and Environmental Management Accounting

(EMA). Use of Cost Accounting techniques provide

decision making, budgeting, research and

development and control of some aspects of


development.

2. Importance of modern costing techniques

Chronologically speaking, the industrial revolution at

the end of the eighteenth and at the beginning of early

nineteenth century, with the large scale of

production, gives impetus to the development of

cost accounting. The period from the late nineteenth

century until the outbreak of World War II could be

called the period of establishing the principles,

methods and procedures of processing costs.

Traditional costing systems include Standard

Costing and Absorption Costing among other. New,

modern (contemporary) cost accounting systems are

developed from the middle of the last century. Cost

accounting systems, traditional or contemporary,

are, in the main, concepts of cost allocation by the

effects of the revenue generating organization.

Contemporary (modern) costing systems and

techniques attempts, compared to traditional

(classical) cost accounting systems, to enable

adequate deployment of costs, especially overhead

costs to cost centers.

We believe that the following main reasons

contributed to the necessity of creation,

development and application of modern techniques

of cost accounting:

a) increase of overhead costs in total costs - the

most important changes in the cost of operations

reflected in the increase in overhead costs and a

reduction of direct costs in relation to total costs;

b) change of types and structure of the organization

business management;

c) the international market (the emergence of

international corporations contributes to increasing

the complexity of calculating the cost, the growing

importance of transfer pricing and other);

d) the search for new ways to achieve sustainable

competitiveness (cost accounting should provide

information about products, but also on markets,

customers and competition); and

e) the creation and development of strategic cost

management and strategic management accounting

(business is unthinkable without the cost

management and focuses on the measurement of

financial and non-financial performance measures

of results achieved).

Costing (cost accounting), together with

management accounting, which is an integral part,

is trying to respond to the challenges of measuring

sustainable development performance through the

creation of new cost accounting techniques,

methods and concepts to be more informative.

Among them, we emphasize the following modern

cost accounting techniques: Activity based costing

(ABC) and modification of that system as Time-

Driven Activity based costing (TDABC); Flexible

cost planning - Marginal costing

(Grenzplankostenrechnung - GPK); Target

costing; Life- cycle costing; Value chain; Kaizen

costing; Cost of quality reporting, The Balanced

Scorecard, Benchmarking, strategic mapping, etc.

A brief overview of the importance of modern

costing systems is presented in Table 1.

3

Table 1. A brief overview of the importance of modern costing systems

The aim of this paper is to analyze the possible

advantages of different modern systems for

measuring costs of some aspects of renewable energy

sources and sustainable development. In order to

achieve the object and purpose of research, tested the

hypothesis that the calculation of the costs and results

of renewable energy technologies and sustainable

production in modern business conditions necessarily

requires the use of modern costing techniques in the

function of providing a suitable basis for making

business decisions, better measurement of

performance, improving business in terms of cost

savings, providing information to maintain or gain a

competitive advantage and more.

3. Advantages and limitations of costing


measurement and limitations of costing


measurement

Possibilities of modern costing systems and techniques for information basis and performance measurement in sustainable production are:

a) the provision of accurate, timely and adequate information about costs - business decisions that are essential for sustainable production, above all, from the internal sphere of operations and necessary information on different cost structure which depends on the business decision nature,

b) modified techniques, concepts of modern costing systems and objectives of management accounting reports provide quality information support strategic

and operational business decisions in sustainable agricultural production;

c) changes in the level of costs and their behavior, changes in production volume and changes in production processes, changing the amount and structure of the cost of the product, which is particularly reflected in the increasing participation of overhead costs in total costs. Therefore, it is important that modern cost accounting systems generally do not use the same basis for allocation of costs as the traditional cost accounting systems;

d) the method of including general expenses unproductive functional areas eg. research and development costs, marketing and other (having increasing share of the total costs), may, with the appropriate methodological procedures using modern costing systems assign to renewable energy technologies or other sustainable development project in order to provide a suitable basis for making business decisions, better measurement of profitability, improvement of the business in terms of cost savings, providing information to maintain or gain a competitive advantage and more;

e) individual manufacturing costs may be excluded from the total cost of the sustainable development project - according to the modern systems costing, costs are allocated to project only if the product resulting from business decisions about the projects (activities, processes) caused costs.

Accountants are increasingly required to struggle with

issues of measuring sustainability performance. But

sustainable development as an interdisciplinary field of

examination and research incorporates insights from a

many academic disciplinesincluding the natural,

engineering and social sciences.[3]

As a result a number of different sustainability

assessment toolsthat have been developed to measure

Modern Costing Systems Concept basis

Activity-Based Costing – ABC Determining the cost driver of activity

Time-Driven Activity-Based

Costing – TDABC

Direct measurement of unused capacity

Marginal costing - GPK –

Grenzplankostenrechnung

Short-term orientation to variable costs, focus on cost

centers

Target Costing Manage cost reduction in the function of achieving

competitive advantages

Life-Cycle Costing – LCC Measurement of diferent investment alternatives

Value Chain The strategic orientation in order to achieve sustainable

competitive advantage

Kaizen Costing Measurement of continuous cost reduction and continuous

improvement

Cost of Quality Reporting Measuring the prevention costs and appraisal costs, focus

on cost centers

Balanced Scorecard – BSC The focus on the critical success factors - financial and

non-financial - in order to achieve strategic goals

Benchmarking Identifying and measuring competitive advantages through

analysis and comparison with best practices

Strategy Map Based on BSC with linking critical success factors through

cause-and-effect diagrams

82

4

sustainability performance have been published over

the past years. Sustainabilityassessment tools must be

accurate, robust and based on sound theoretical

foundationsbacked with empirical evidence if

misleading policy messages are to be avoided.[3] In practice, traditional costing systems are often used

more then modern costing tools because of long tradition of use or high costs of implementation of modern cost tools. Sometimes, traditional costing system are used with modern costing techniques as addition. Nevertheless, modern costing techniques give contribution to more accurate cost allocation.

Energy budget savings or reducing costs of energy are central issues of almost every project of sustainable development. Energy is crucial for the functioning of the economy. Mostly, fossil fuels (non-renewable) like oils, natural gas and coal are main energy sources. Costing systems and techniques are adequate for cost measurement of renewable energy technologies like biomass production, hydropower, wind power, solar or geothermal energy production.

The renewable energy technologies already exist (some renewable sources are used for centuries) but are not used in sufficient quantities.

The issue of costs is central to the question of how rapidly an energy transition will occur. Costs include energy infrastructure investment and the day-to-day operations. In analyzing costs, we should consider both the market costs of supply and the environmental costs of various energy sources.The costs of renewable energy resources are attributable in part to inherent characteristics, particularly their low net energy ratios, intermittent availability, and capital intensity. Development of new technology will reduce cost but may not make renewable energy cost competitive with market prices of fossil fuels in the near future unless fossil-fuel externalities are considered.[8]

However, at the moment, none of costing methodological proposals are able to encompass all considerations for proper measuring of sustainable development, especially future benefits. There are methodological limitations, different concepts of value, time, economic, environmental and social horizonts and objectives.

The future benefits are difficult to quantify, unlike costs, and this make difficult to express the usefulness of designing and usingrenewable energy technologies and other sustainable development projects.

4. CONCLUSIONS

Measuring sustainable development performance and quantifying the benefits of sustainability progress is more qualitative then quantitative perspective. Sustainable development is an interdisciplinary field. That is the reason why is not yet developed proper system for quantitative measuring of sustainable development and it’s benefits. This paper exposes some of the strengths and weaknesses of traditional and modern accounting tools that follow the measurement of sustainable development.

Atdifferent levels of organizational systems (businesses, local government, state, etc.) very important issue is - whether the investment in the renewable energy technology, in future, bring greater benefits than costs.The future benefits are difficult to quantify. That is the reason why projects of renewable energy technologies and other sustainable development projects seems to have higher costs than benefits. Because of that, often sustainable development is based on savings in energy and efficiency improvement instead of use of renewable sources.

The renewable sources already exist and some are used for centuries. At the moment, the renewable sources technologies aren’t used in satisfactory quantities to reduce the disappearance of fossil fuels.

Modern costing techniques give contribution to more accurate cost allocation of renewable energy technologies and other sustainable development projects.

References

[1] A. Ball, R. Craig, “Using neo-institutionalism to advance

social and environmental accounting“, Critical Perspectives on Accounting, vol. 21, pp. 283-293, 2010.

[2] I. Dincer, “Renewable energy and sustainable development: a crucial review“, Renewable and Sustainable Energy Reviews, vol. 4, pp. 157-175, 2000.

[3] A. Gasparatos, M. El-Haram, M. Horner, “The argument against a reductionist approach for measuring sustainable development performance and the need for methodological pluralism“, Accounting Forum, vol. 33, pp. 245-256, 2008.

[4] M. J. Jones, “Accounting for the environment: Towards a theoretical perspective for environmental accounting and reporting“, Accounting Forum, vol. 34, pp. 123-138, 2010.

[5] D. L. Hartley, “Perspectives on renewable energy and the environment”, in Energy and the Environment in the 21st Century J.W. Tester, D.O. Wood, N.A. Ferrari (Eds.), MIT, Massachusetts, 1990, from [2].

[6] H. Lund, “Renewable energy strategies for sustainable development“, Energy vol. 32, pp. 912-919, 2007.

[7] I. Medved, „Obračun troškova u projektima zaštite životne sredine“, („Costing in Projects of Environment Protection“ – in Serbian with English abstract), Subotica: Anali Ekonomskog fakulteta, vol. 20, pp. 167-178, 2008.

[8] D. Timmons, J. M. Harris, B. Roach, The Economics of Renewable Energy,A GDAE Teaching Module on Social and Environmental Issues in Economics, Global Development And Environment Institute, Tufts University, 2014.

EXPRES 2017

ISBN 978-86-919769-1-0

Environmentally sustainable tourist behaviour in the function of sustainable development

M. JELAČA STRUGAR a, A. BOLJEVIĆ b, S. BOLJEVIĆ c

Department of Management, Faculty of Economics in Subotica,

University of Novi Sad, 24000 Subotica, Segedinski put 9-11, Srbija a E-mail: [email protected] b E-mail: [email protected] c E-mail:

Rapid tourism growth, along with irrational use of natural resources, leads to negative effects and multiple-growing crisis in the

field of applying the principles of sustainable development and especially environmental preservation of tourist destinations.

Therefore, within this paper’s framework is the focus on future propagation of tourists’ environmentally responsible behavior in

order to minimize the destruction of the environment. The initiative for conducting research in this area stems from the present

gap between theoretical activities to be implemented in order to successfully realize this way of tourist behavior and the actual

actions being carried out, that are often completely absent or present just on a small scale. Previous theoretical base on this

subject had put its emphasis on planning phase of the concept of sustainable tourism development with some slight looking back

at its implementation. It should be noted that the topic was dealt with from a macro point of view more than from a point of view

of the role of individual participants, where tourists have the most important role as agents of environmental impacts on the

tourist destination and are also potential agents of change in the light of benefits of ecologically responsible behavior. As a result

of the paper, the proposal of activities to be implemented during all phases of tourists’ travel organization is pointed out, starting

from the analysis and selection of the tourist product to implementation of activities during realization of the selected travel

arrangement.

Keywords: sustainable development concept, sustainable tourism development, environmentally sustainable

behavior

1. Introduction

Given that tourism is described as the largest human migration

in history, which annually represents 10% of the world's

population [1, p. 499], one of the most important issues being

raised is the impact of such a large movement of people on the

cultural and historical heritage of a tourist destination and the

possibility of its long-term preservation. Therefore, it is

necessary to observe tourist destination through the prism of

sustainable development, in order to analyze strong effects of

tourists on all elements of sustainability, namely economic,

social and environmental, which can lead to preservation vs

erosion of a tourist destination. Emphasis is placed on the

ecological side, because previous researches indicate and prove

evident negative impact of tourism trends in the ecological

sphere [2, 3, 4]. The need for observing this problem with a

high degree of seriousness stems from the fact that travel

becomes more and more accessible and therefore more

common and can be seen as a social norm of modern life.

Studies indicate exponential growth in the number of tourists

in the future and therefore greater negative environmental

effects caused by irrational use of natural resources,

environmental pollution and endangering natural heritage.

Thus, popular tourist destinations are faced with water

shortage, high emissions of carbon dioxide, excessive amounts

of garbage, dirty coast and numerous other problems [5].

Research suggests that particular destinations around the

Mediterranean are already close to the ecological risks that

threaten natural environment and population, and finally the

entire society [6].

Negative effects of mass tourism developments on

environment can be classified as follows [7]:

• Mechanical effects, such as destruction of vegetation,

soil erosion, etc.;

• Impacts caused by intensive use of surfaces and

changing the landscapes;

• Impacts due to the increase of harmful substances in the

air, water and soil due to higher combustion of fuel, vapor

emissions and waste;

• Hindering effects, such as increased noise.

In the long run, uncontrolled tourism growth and

neither taking into consideration this problem nor resolving it

will lead to future decline in tourism demand and hence

tourism revenues, which currently record significant foreign

exchange effects. Therefore, timely planning tourism’s future

development and the need for increased environmental

awareness of tourists will minimize or completely eliminate

potential damage that destroys the environment of tourist

destinations crucial for its sustainable development.

The aim of this paper is to interpret ecologically

responsible tourist behavior and identify instructions for its

improvement. However, this is just one link on the path of

solving the diagnosed problem, since it is necessary to

involve all participants of the tourism industry. All actors in

tourism industry need to find a sustainable way of doing

business in order to achieve stable long-term development of

the tourism sector [8].

83

4

sustainability performance have been published over

the past years. Sustainabilityassessment tools must be

accurate, robust and based on sound theoretical

foundationsbacked with empirical evidence if

misleading policy messages are to be avoided.[3] In practice, traditional costing systems are often used

more then modern costing tools because of long tradition of use or high costs of implementation of modern cost tools. Sometimes, traditional costing system are used with modern costing techniques as addition. Nevertheless, modern costing techniques give contribution to more accurate cost allocation.

Energy budget savings or reducing costs of energy are central issues of almost every project of sustainable development. Energy is crucial for the functioning of the economy. Mostly, fossil fuels (non-renewable) like oils, natural gas and coal are main energy sources. Costing systems and techniques are adequate for cost measurement of renewable energy technologies like biomass production, hydropower, wind power, solar or geothermal energy production.

The renewable energy technologies already exist (some renewable sources are used for centuries) but are not used in sufficient quantities.

The issue of costs is central to the question of how rapidly an energy transition will occur. Costs include energy infrastructure investment and the day-to-day operations. In analyzing costs, we should consider both the market costs of supply and the environmental costs of various energy sources.The costs of renewable energy resources are attributable in part to inherent characteristics, particularly their low net energy ratios, intermittent availability, and capital intensity. Development of new technology will reduce cost but may not make renewable energy cost competitive with market prices of fossil fuels in the near future unless fossil-fuel externalities are considered.[8]

However, at the moment, none of costing methodological proposals are able to encompass all considerations for proper measuring of sustainable development, especially future benefits. There are methodological limitations, different concepts of value, time, economic, environmental and social horizonts and objectives.

The future benefits are difficult to quantify, unlike costs, and this make difficult to express the usefulness of designing and usingrenewable energy technologies and other sustainable development projects.

4. CONCLUSIONS

Measuring sustainable development performance and quantifying the benefits of sustainability progress is more qualitative then quantitative perspective. Sustainable development is an interdisciplinary field. That is the reason why is not yet developed proper system for quantitative measuring of sustainable development and it’s benefits. This paper exposes some of the strengths and weaknesses of traditional and modern accounting tools that follow the measurement of sustainable development.

Atdifferent levels of organizational systems (businesses, local government, state, etc.) very important issue is - whether the investment in the renewable energy technology, in future, bring greater benefits than costs.The future benefits are difficult to quantify. That is the reason why projects of renewable energy technologies and other sustainable development projects seems to have higher costs than benefits. Because of that, often sustainable development is based on savings in energy and efficiency improvement instead of use of renewable sources.

The renewable sources already exist and some are used for centuries. At the moment, the renewable sources technologies aren’t used in satisfactory quantities to reduce the disappearance of fossil fuels.

Modern costing techniques give contribution to more accurate cost allocation of renewable energy technologies and other sustainable development projects.

References

[1] A. Ball, R. Craig, “Using neo-institutionalism to advance

social and environmental accounting“, Critical Perspectives on Accounting, vol. 21, pp. 283-293, 2010.

[2] I. Dincer, “Renewable energy and sustainable development: a crucial review“, Renewable and Sustainable Energy Reviews, vol. 4, pp. 157-175, 2000.

[3] A. Gasparatos, M. El-Haram, M. Horner, “The argument against a reductionist approach for measuring sustainable development performance and the need for methodological pluralism“, Accounting Forum, vol. 33, pp. 245-256, 2008.

[4] M. J. Jones, “Accounting for the environment: Towards a theoretical perspective for environmental accounting and reporting“, Accounting Forum, vol. 34, pp. 123-138, 2010.

[5] D. L. Hartley, “Perspectives on renewable energy and the environment”, in Energy and the Environment in the 21st Century J.W. Tester, D.O. Wood, N.A. Ferrari (Eds.), MIT, Massachusetts, 1990, from [2].

[6] H. Lund, “Renewable energy strategies for sustainable development“, Energy vol. 32, pp. 912-919, 2007.

[7] I. Medved, „Obračun troškova u projektima zaštite životne sredine“, („Costing in Projects of Environment Protection“ – in Serbian with English abstract), Subotica: Anali Ekonomskog fakulteta, vol. 20, pp. 167-178, 2008.

[8] D. Timmons, J. M. Harris, B. Roach, The Economics of Renewable Energy,A GDAE Teaching Module on Social and Environmental Issues in Economics, Global Development And Environment Institute, Tufts University, 2014.

EXPRES 2017

ISBN 978-86-919769-1-0

Environmentally sustainable tourist behaviour in the function of sustainable development

M. JELAČA STRUGAR a, A. BOLJEVIĆ b, S. BOLJEVIĆ c

Department of Management, Faculty of Economics in Subotica,

University of Novi Sad, 24000 Subotica, Segedinski put 9-11, Srbija a E-mail: [email protected] b E-mail: [email protected] c E-mail:

Rapid tourism growth, along with irrational use of natural resources, leads to negative effects and multiple-growing crisis in the

field of applying the principles of sustainable development and especially environmental preservation of tourist destinations.

Therefore, within this paper’s framework is the focus on future propagation of tourists’ environmentally responsible behavior in

order to minimize the destruction of the environment. The initiative for conducting research in this area stems from the present

gap between theoretical activities to be implemented in order to successfully realize this way of tourist behavior and the actual

actions being carried out, that are often completely absent or present just on a small scale. Previous theoretical base on this

subject had put its emphasis on planning phase of the concept of sustainable tourism development with some slight looking back

at its implementation. It should be noted that the topic was dealt with from a macro point of view more than from a point of view

of the role of individual participants, where tourists have the most important role as agents of environmental impacts on the

tourist destination and are also potential agents of change in the light of benefits of ecologically responsible behavior. As a result

of the paper, the proposal of activities to be implemented during all phases of tourists’ travel organization is pointed out, starting

from the analysis and selection of the tourist product to implementation of activities during realization of the selected travel

arrangement.

Keywords: sustainable development concept, sustainable tourism development, environmentally sustainable

behavior

1. Introduction

Given that tourism is described as the largest human migration

in history, which annually represents 10% of the world's

population [1, p. 499], one of the most important issues being

raised is the impact of such a large movement of people on the

cultural and historical heritage of a tourist destination and the

possibility of its long-term preservation. Therefore, it is

necessary to observe tourist destination through the prism of

sustainable development, in order to analyze strong effects of

tourists on all elements of sustainability, namely economic,

social and environmental, which can lead to preservation vs

erosion of a tourist destination. Emphasis is placed on the

ecological side, because previous researches indicate and prove

evident negative impact of tourism trends in the ecological

sphere [2, 3, 4]. The need for observing this problem with a

high degree of seriousness stems from the fact that travel

becomes more and more accessible and therefore more

common and can be seen as a social norm of modern life.

Studies indicate exponential growth in the number of tourists

in the future and therefore greater negative environmental

effects caused by irrational use of natural resources,

environmental pollution and endangering natural heritage.

Thus, popular tourist destinations are faced with water

shortage, high emissions of carbon dioxide, excessive amounts

of garbage, dirty coast and numerous other problems [5].

Research suggests that particular destinations around the

Mediterranean are already close to the ecological risks that

threaten natural environment and population, and finally the

entire society [6].

Negative effects of mass tourism developments on

environment can be classified as follows [7]:

• Mechanical effects, such as destruction of vegetation,

soil erosion, etc.;

• Impacts caused by intensive use of surfaces and

changing the landscapes;

• Impacts due to the increase of harmful substances in the

air, water and soil due to higher combustion of fuel, vapor

emissions and waste;

• Hindering effects, such as increased noise.

In the long run, uncontrolled tourism growth and

neither taking into consideration this problem nor resolving it

will lead to future decline in tourism demand and hence

tourism revenues, which currently record significant foreign

exchange effects. Therefore, timely planning tourism’s future

development and the need for increased environmental

awareness of tourists will minimize or completely eliminate

potential damage that destroys the environment of tourist

destinations crucial for its sustainable development.

The aim of this paper is to interpret ecologically

responsible tourist behavior and identify instructions for its

improvement. However, this is just one link on the path of

solving the diagnosed problem, since it is necessary to

involve all participants of the tourism industry. All actors in

tourism industry need to find a sustainable way of doing

business in order to achieve stable long-term development of

the tourism sector [8].

84

2. The concept of sustainable tourism

development

Application of the principles of sustainability has been lately,

and in most cases by a large number of scholars, the topic in

the field of tourism that was dealt the most with. However,

despite the aforementioned statement there is no generally

accepted unique definition of the concept of sustainable

tourism development. According to Milenković [9],

sustainable development and sustainable tourism can be seen

through the balance of production and consumption of

environmental elements in all intervals. Thus, the principle of

sustainable development, if applied in a controlled tourist

activity, involves the development of from economic, social

and environmental angle followed by meeting the needs of

present tourists along with the preservation and improvement

of tourist potential for the future generations of tourists. In

order to explain the difference between unsustainable tourism

development as a source of accumulated environmental

problems of most tourist destinations and the concept of

sustainable tourism development, the table 1. lists the main

characteristics.

Crucial tourism potential that creates tourist offer is

nature of tourism activities, which should be protected and

intact in order to offer a unique experience and it was a

constant generator of income. Since the nature of tourist

destinations is characterized by non-renewable natural

resources, it is necessary to simultaneously focus on both

economic and environmental objectives and their mutual

alignment so that each additional night would result in less

energy consumption and lower environmental pollution [10].

Tourism potential in the form of natural landscapes of a tourist

destination is under direct influence of the largest mass

movements of tourists and therefore the most important area

for ecological principles.

However, current practice has put more emphasis on the

application of this principle on a macro level - by the state, in

creating tourism development policy; while at the micro level

it was applied only by tourist organizations which have

drawn up plans for the development of sustainable tourism

and the principles on which the same should be based [11]

without taking into account tourists as an important category

in the process. To date, this issue is being considered

theoretically, but in practice the positive effects are often

absent. Emphasis is placed on planning how to implement

sustainable development of tourism activities, but the

proposed actions have still not been transformed into practical

realization. Thus, one can say that in most cases actual

implementation of previously formulated plans for sustainable

tourism development is missing. Therefore, the following

practice of all participants in the tourism industry should be

minimizing the gap between the proposed theoretical and

practical criteria of conduct. Also, little accent has been placed

on environmentally responsible tourist behavior, as they are

the main stakeholders in tourism movement that produce the

actual environmental impact on tourist destinations. There are

indications that travel behavior can be improved from the

perspective of ecological principles in the use of tourism

resources, management of waste which remains at the tourist

destination after mass tourist visits and optimizing transport

[12, 13]. However, when analyzing this topic, tourists as an

interest category are less interested in application of

environmentally responsible behavior because it limits them to

a smaller number of tourist destinations to visit as well as the

use of a smaller range of tourist services during the journey

than in case of other participants, such as public authorities

and tourism organizations. The above statement is confirmed

also by the author Martens and Spaargaren, [14], indicating

that tourists’ response to the required application of

environmentally sustainable behavior is still small and does

not lead to matching their goals with the goals of tourism for

further development.

In order to ensure general acceptance of the concept of

sustainable tourism development one should apply a holistic

approach, which advocates inclusion of direct and indirect

participants in the tourism sector at micro and macro level.

Previously mentioned speaks in favor of developing initiatives

to create partnerships in this area at both national and global

levels in order to achieve positive results and multiply their

influence as soon as possible.

Table 1. Characteristics of sustainable and unsustainable tourist development [15]

Characteristics Unsustainable tourist development Sustainable tourist development

Basic elements Focuses on economic factors of tourism

trends

Emphasizes three key elements of

tourism development, such as

economic, social and ecologic

development

Speed of development

Aggressive and rapid development,

which often leads to uncontrolled

growth

Cautious, slower development based on

spatial planning and controlled growth

Result time determinants Short-term results Long term results

Result type Focuses exclusively on quantitative

results

Focus is given to qualitative results,

based on the principle of balancing

qualitative and quantitative observation

Spatial observation The emphasis is on the local access to

tourism

Global impact of tourism is gaining in

significance

Tourism product Focus on the price of the tourism

product

Focus on the quality of the tourism

product based on the principle of the

true value for money

Tourists’ profile

Mass tourists who have no sense of

sustainable development and the need

to preserve natural sites for future

generations

Tourists who are educated and aware of

the importance of tourism’s sustainable

development

3. Environmental dimension of tourist

behaviour

Environmentally responsible behavior of tourists is

considered that "behavior that does not adversely affect the

environment or even leads to positive effects globally and

locally viewed through tourist destination" [16, p. 31]. In

order to promote previously explained behavior, a significant

step is recognized in adequate education of tourists and

establishment of ethical and eco-system values that

determine their behavior. Norms of his behavior, in terms of

whether or not to behave environmentally responsible, derive

from the system of values adopted by the tourists [17]. Their

ecological awareness derives from the existing problems

caused by current tourist activities as well as their sense of

responsibility that they should affect the reduction of this

problem [16]. Tourists who have developed environmental

awareness and responsibility aimed at ecologically

acceptable behavior belong to the group of so-called "green"

or eco-tourists. However, in order to be categorized as a

"green" or eco-tourist, it is not enough just to have a correct

belief and sense of responsibility - it is a precondition - but in

addition, to practically transform ecologically desired norms

of behavior into actual behavior. In environmentally

responsible behavior of tourists we categorize those tourists

who have intentions to act in this way and who conduct such

actions during vacation, affecting the environment in a

minimized way or even have a positive impact on the

environment of the tourist destination.

The following table summarizes definitions of various

authors who have dealt with the environmental dimension of

tourists’ behavior. In order to implement the analysis of the

existence of the above mentioned categories of tourists in

practice, empirical research was conducted by the authors

Juvan and Dolnicar [16]. The results indicate that 31% of

respondents possessed only good intention to behave

environmentally responsible, but such behavior was absent;

also the same percentage of respondents (31%) stated that they

possess pro-environmental values and standards, but still do

not behave environmentally responsibly as tourists. Thus, 62%

of tourists does not behave environmentally responsibly in

practice. The remaining 38% emphasizes application of such

behavior in practice, so that 22% of them did not have

intention to behave environmentally responsibly, but they still

acted this way, while only 15% of tourists identified intention

and real environmental responsibility during the trip. It is

pointed out that tourists who are environmentally responsible,

as shown in paying the registration fee for carbon dioxide,

choosing transport which is more environmentally friendly,

they were housed in environmentally responsible hotels and

used services of providers that operated by the principle of

ecological sustainability [16, p. 36]. A small percentage of

tourists who identified the desired environmental

responsibility can be attributed to mass tourists’ lower

awareness of the importance of it, as well as the result of

application of such behavior that leads to narrowing tourist

choice onto using only those services that are not inconsistent

with ecological principles. On the other hand, research

conducted by the author Martin (2001), which deals with the

tourists from Great Britain only, showed that majority of about

90% of tourists said it was very important to behave in an

environmentally responsible while traveling. However,

contrary to these empirical results, authors Goodwin and

Francis [18] point out that there is a difference in intent of

British tourists and their actual behavior during their visit to a

tourist destination, noting that only 32% of tourists from the

UK choose package tours which are especially formed for the

purpose of minimizing harmful effects of tourism on the

environment destination.

Table 2. Environmentally responsible tourist [16, p. 33-34]

Number Author Definition

1. Poon (1993)

Dolnicar (2004)

A group of new tourists includes those tourists that take into account

natural environment and tend to its preservation in a tourist destination.

2.

Swarbrooke &

Horner (1999)

There are three groups of "green tourists":

1) completely "green" tourists are those who do not go on tourist trips

because they do not want to destroy the environment of the tourist

destination in any way;

2) "Green tourist" is a tourist who does not accept and does not visit

hotels that do not point to the importance of preserving the

environment from the perspective of tourists;

3) Partially "green tourist" considers environmental issues of tourism

activities and strives to minimize negative effects.

3.

Dinan &

Sargeant

(2000)

Sustainable tourist is understood to be the one who appreciates the

possibilities of visits to certain tourist destinations with respect to

85

2. The concept of sustainable tourism

development

Application of the principles of sustainability has been lately,

and in most cases by a large number of scholars, the topic in

the field of tourism that was dealt the most with. However,

despite the aforementioned statement there is no generally

accepted unique definition of the concept of sustainable

tourism development. According to Milenković [9],

sustainable development and sustainable tourism can be seen

through the balance of production and consumption of

environmental elements in all intervals. Thus, the principle of

sustainable development, if applied in a controlled tourist

activity, involves the development of from economic, social

and environmental angle followed by meeting the needs of

present tourists along with the preservation and improvement

of tourist potential for the future generations of tourists. In

order to explain the difference between unsustainable tourism

development as a source of accumulated environmental

problems of most tourist destinations and the concept of

sustainable tourism development, the table 1. lists the main

characteristics.

Crucial tourism potential that creates tourist offer is

nature of tourism activities, which should be protected and

intact in order to offer a unique experience and it was a

constant generator of income. Since the nature of tourist

destinations is characterized by non-renewable natural

resources, it is necessary to simultaneously focus on both

economic and environmental objectives and their mutual

alignment so that each additional night would result in less

energy consumption and lower environmental pollution [10].

Tourism potential in the form of natural landscapes of a tourist

destination is under direct influence of the largest mass

movements of tourists and therefore the most important area

for ecological principles.

However, current practice has put more emphasis on the

application of this principle on a macro level - by the state, in

creating tourism development policy; while at the micro level

it was applied only by tourist organizations which have

drawn up plans for the development of sustainable tourism

and the principles on which the same should be based [11]

without taking into account tourists as an important category

in the process. To date, this issue is being considered

theoretically, but in practice the positive effects are often

absent. Emphasis is placed on planning how to implement

sustainable development of tourism activities, but the

proposed actions have still not been transformed into practical

realization. Thus, one can say that in most cases actual

implementation of previously formulated plans for sustainable

tourism development is missing. Therefore, the following

practice of all participants in the tourism industry should be

minimizing the gap between the proposed theoretical and

practical criteria of conduct. Also, little accent has been placed

on environmentally responsible tourist behavior, as they are

the main stakeholders in tourism movement that produce the

actual environmental impact on tourist destinations. There are

indications that travel behavior can be improved from the

perspective of ecological principles in the use of tourism

resources, management of waste which remains at the tourist

destination after mass tourist visits and optimizing transport

[12, 13]. However, when analyzing this topic, tourists as an

interest category are less interested in application of

environmentally responsible behavior because it limits them to

a smaller number of tourist destinations to visit as well as the

use of a smaller range of tourist services during the journey

than in case of other participants, such as public authorities

and tourism organizations. The above statement is confirmed

also by the author Martens and Spaargaren, [14], indicating

that tourists’ response to the required application of

environmentally sustainable behavior is still small and does

not lead to matching their goals with the goals of tourism for

further development.

In order to ensure general acceptance of the concept of

sustainable tourism development one should apply a holistic

approach, which advocates inclusion of direct and indirect

participants in the tourism sector at micro and macro level.

Previously mentioned speaks in favor of developing initiatives

to create partnerships in this area at both national and global

levels in order to achieve positive results and multiply their

influence as soon as possible.

Table 1. Characteristics of sustainable and unsustainable tourist development [15]

Characteristics Unsustainable tourist development Sustainable tourist development

Basic elements Focuses on economic factors of tourism

trends

Emphasizes three key elements of

tourism development, such as

economic, social and ecologic

development

Speed of development

Aggressive and rapid development,

which often leads to uncontrolled

growth

Cautious, slower development based on

spatial planning and controlled growth

Result time determinants Short-term results Long term results

Result type Focuses exclusively on quantitative

results

Focus is given to qualitative results,

based on the principle of balancing

qualitative and quantitative observation

Spatial observation The emphasis is on the local access to

tourism

Global impact of tourism is gaining in

significance

Tourism product Focus on the price of the tourism

product

Focus on the quality of the tourism

product based on the principle of the

true value for money

Tourists’ profile

Mass tourists who have no sense of

sustainable development and the need

to preserve natural sites for future

generations

Tourists who are educated and aware of

the importance of tourism’s sustainable

development

3. Environmental dimension of tourist

behaviour

Environmentally responsible behavior of tourists is

considered that "behavior that does not adversely affect the

environment or even leads to positive effects globally and

locally viewed through tourist destination" [16, p. 31]. In

order to promote previously explained behavior, a significant

step is recognized in adequate education of tourists and

establishment of ethical and eco-system values that

determine their behavior. Norms of his behavior, in terms of

whether or not to behave environmentally responsible, derive

from the system of values adopted by the tourists [17]. Their

ecological awareness derives from the existing problems

caused by current tourist activities as well as their sense of

responsibility that they should affect the reduction of this

problem [16]. Tourists who have developed environmental

awareness and responsibility aimed at ecologically

acceptable behavior belong to the group of so-called "green"

or eco-tourists. However, in order to be categorized as a

"green" or eco-tourist, it is not enough just to have a correct

belief and sense of responsibility - it is a precondition - but in

addition, to practically transform ecologically desired norms

of behavior into actual behavior. In environmentally

responsible behavior of tourists we categorize those tourists

who have intentions to act in this way and who conduct such

actions during vacation, affecting the environment in a

minimized way or even have a positive impact on the

environment of the tourist destination.

The following table summarizes definitions of various

authors who have dealt with the environmental dimension of

tourists’ behavior. In order to implement the analysis of the

existence of the above mentioned categories of tourists in

practice, empirical research was conducted by the authors

Juvan and Dolnicar [16]. The results indicate that 31% of

respondents possessed only good intention to behave

environmentally responsible, but such behavior was absent;

also the same percentage of respondents (31%) stated that they

possess pro-environmental values and standards, but still do

not behave environmentally responsibly as tourists. Thus, 62%

of tourists does not behave environmentally responsibly in

practice. The remaining 38% emphasizes application of such

behavior in practice, so that 22% of them did not have

intention to behave environmentally responsibly, but they still

acted this way, while only 15% of tourists identified intention

and real environmental responsibility during the trip. It is

pointed out that tourists who are environmentally responsible,

as shown in paying the registration fee for carbon dioxide,

choosing transport which is more environmentally friendly,

they were housed in environmentally responsible hotels and

used services of providers that operated by the principle of

ecological sustainability [16, p. 36]. A small percentage of

tourists who identified the desired environmental

responsibility can be attributed to mass tourists’ lower

awareness of the importance of it, as well as the result of

application of such behavior that leads to narrowing tourist

choice onto using only those services that are not inconsistent

with ecological principles. On the other hand, research

conducted by the author Martin (2001), which deals with the

tourists from Great Britain only, showed that majority of about

90% of tourists said it was very important to behave in an

environmentally responsible while traveling. However,

contrary to these empirical results, authors Goodwin and

Francis [18] point out that there is a difference in intent of

British tourists and their actual behavior during their visit to a

tourist destination, noting that only 32% of tourists from the

UK choose package tours which are especially formed for the

purpose of minimizing harmful effects of tourism on the

environment destination.

Table 2. Environmentally responsible tourist [16, p. 33-34]

Number Author Definition

1. Poon (1993)

Dolnicar (2004)

A group of new tourists includes those tourists that take into account

natural environment and tend to its preservation in a tourist destination.

2.

Swarbrooke &

Horner (1999)

There are three groups of "green tourists":

1) completely "green" tourists are those who do not go on tourist trips

because they do not want to destroy the environment of the tourist

destination in any way;

2) "Green tourist" is a tourist who does not accept and does not visit

hotels that do not point to the importance of preserving the

environment from the perspective of tourists;

3) Partially "green tourist" considers environmental issues of tourism

activities and strives to minimize negative effects.

3.

Dinan &

Sargeant

(2000)

Sustainable tourist is understood to be the one who appreciates the

possibilities of visits to certain tourist destinations with respect to

86

cultural, social and environmental norms and the uniqueness of a

destination.

4. Dolnicar &

Matus (2008)

"Green tourists" behave environmentally responsible while traveling and

during implementation of all activities that are associated with tourism

context.

5. Stanford (2008, str. 270)

Responsible tourists should have the following dimensions:

• respect,

• awareness;

• involvement;

• excellence and reciprocity.

6.

Bergin-Seers &

Mair (2009, str. 117)

"Green tourist" is interested in behaving environmentally responsibly

towards the environment while on vacation. Also, one is ready to pay a

higher price in order to be the user of goods and services obtained by

environmentally responsible tourist agency.

7. Mehmetoglu

(2010)

A tourist who advocates the principle of sustainable development and is

concerned with the issues of sustainability and economic benefits for the

local population of the tourist destination.

8.

Wehrli and others

(2011)

A tourist who is aware of the importance of tourist destinations’

sustainable development and when booking a holiday takes into account

sustainability factor.

9.

Perkins &

Brown (2012)

The real eco-tourist travels guided by the values of the biosphere, on

one’s way supports environmental responsibility and avoids the use of

resources just for entertainment, while taking into account the impact of

that usege on the environment.

4. Proposal for action in implementation of

environmentally responsible tourist

behavior

The impact of tourist behavior on social, economic and

ecological system is essential for tourist destination and

follows all the stages of tourist travel - from its planning,

through selection and realization of the selected packages, as

shown in the Figure 1.

While planning a tourist travel, tourists choose individual

elements of the tourist package tour, such as travel itinerary, or

the path to arrive to the selected travel destinations and

accommodation capacities. Decisions about the elements

mentioned should be based on principles of environmentally

responsible behavior, so that the tourists choose:

• such a product of a tourist agency or a package deal,

consisting of a set of tourist services that are in line with the

concept of sustainable development of tourism in a chosen

tourist destination. This criterion may reduce available tourist

offer and narrow the choice. Since the demand for these

packages is still not large and massive, they cannot be

considered the usual tourist outfit, so agencies often do not

have them in mind when forming advertised arrangements, but

only order and create those individually, if there are interested

tourists. The above situation leads to differentiation and

individualization of tourist offer, which carries a higher price;

• transport by railways, since it has the smallest contribution to

the greenhouse effect compared to road and air transport [19],

which are, when observing the European Union, the most

common choices of tourists. Selection of rail transport reduces

the possibility of going to destinations that are not connected

by rails, as well as tourist destinations that are spatially very

far from the potential tourists’ place of residence;

• accommodation in such facilities which have lower

consumption of water and energy, the so-called eco-efficient

accommodation facilities. The attractiveness to these

properties is present with tourists from Denmark, who are even

willing to allocate more funds for such accommodation. Most

Italian tourists also prefer this type of accommodation, while

tourists from Germany are minority here [1, p. 500]. Observing

from the perspective of mass tourists who focus on the cost of

the service provided, it is unlikely that they will choose such

accommodation facilities, which are often offered at a higher

price.

Also, tourists and their stay at the selected tourist destination

must be accompanied by preservation of the welfare of local

population and the existing ecosystem, from the point of

activity to be performed [1]:

• natural area should not be over-used, in order to avoid the

crowds (skiing in the Alps)

• activities targeted towards party, that lead to consumption of

high amount of energy, such as diving, should be carried out to

a lesser extent;

• use of alcohol should be limited in order not to upset local

population and infringe upon their well-being;

• the differences in culture, social values and religion should

not be highlighted, in order to reduce tensions between the

tourists and residents.

Fig. 1. The impact of the choice of tourism product on environment [1, p. 501]

5. Final consideration

Placing emphasis on the environmental dimension of tourist

trips will allow better control of negative impacts of

aggressive growth of mass tourism trends which they have on

the environment. Further growth in the tourism activities

should be followed by the course of transformation of the

traditional economic Trinity, such as profit, power and prestige

into elements of sustainable economic Trinity - efficiency,

economy and ecology. In order to implement the

aforementioned transformation into practice and lead to

tangible results, it is necessary to include not only participants

of the tourism supply, but also those on the side of tourist

demand, it est tourists. Today there is a mismatch between the

preferences of modern tourists and their motivation for

selecting certain tourism products and services, as well as

expectations from them on one hand and environmental

principles on the other. Therefore, it is necessary to develop

awareness on tourists’ side of the need for ecologically

responsible behavior during tourist visits. However, in

addition, it is necessary and direct tourists to form a group of

eco-tourists, or so-called green tourists who apply such tourist

behavior. Parallel support and implementation of such

behavior will lead to positive long-term effects, both in terms

of natural resources of tourist destinations and their residents,

through minimizing tensions and other social problems. With

regard to environmental and social problems accumulated at

the most famous and most visited tourist destinations, it is

necessary to implement the proposed course of action in a

short period of time, which is possible only through radical

changes on the demand and supply side. It is necessary to

correct common tourist behavior through application of more

rigorous criteria and initiatives in favor of ecology

preservation (such as introduction of taxes, fees, etc.), as well

as the expansion of the tourist offer in terms of a large number

of variants of tourist services, along with satisfying principles

of economy. In this way, obligation for environmentally

responsible behavior will be created for all the tourists, who

will be able to find pro-ecological tourist services in

accordance with their preferences, expectations and purchase

power.

References

[1] Budeanu A. (2007), Sustainable tourist behaviour – a

discussion of opportunities for change. International

Journal of Consumer Studies, 31, 499-508.

[2] Gössling S. (2002), Global environmental consequences

of tourism. Global Environmental Change, 12(4), 283–

302.

[3] UNWTO & UNEP (2008): Climate change and tourism:

Responding to global challenges.

http://www.unwto.org/sustainable/doc/climate2008.pdf,

last accessed: Decembre 20, 2016.

[4] World Wide Fund For Nature (2012). Living Planet

Report. Switzerland, WWF.

[5] European Commission (2004), Feasibility and

Preparatory Study Regarding Multi-stakeholder European

Targeted Action Sustainable Tourism and Transport.

European Commission, DG Enterprise, Hague.

[6] Schmidt H.W. (2002), How Europeans go on holiday,

Eurostat.

[7] Hahn P. (1989), Analyse des Konflikts umwelt, Tu

Berlin, Berlin.

[8] Štetić S. (2009), Značaj I uloga turoperatora za razvoj

održivog turizma, Zbornik radova naučnog skupa:

Savremene tendencije u turizmu, hotelijerstvu i

gastronomiji, Novi Sad: Univerzitet u Novom Sadu,

PMF.

[9] Milenković S. (2009), Monografija: Turizam i ekonomija,

Kragujevac: Univerzitet u Kragujevcu, Ekonomski

fakultet.

[10] Daly E. H. (1999), Beyond growth: the economics of

sustainable development, Beacon Press.

[11] Sharpley R. (2000), Tourism and Sustainable

Development: Exploring the Theoretical Divide. Journal

of Sustainable Tourism, 8(1), 1-19.

[12] Upham P. (2001), A comparison of sustainability theory

87

cultural, social and environmental norms and the uniqueness of a

destination.

4. Dolnicar &

Matus (2008)

"Green tourists" behave environmentally responsible while traveling and

during implementation of all activities that are associated with tourism

context.

5. Stanford (2008, str. 270)

Responsible tourists should have the following dimensions:

• respect,

• awareness;

• involvement;

• excellence and reciprocity.

6.

Bergin-Seers &

Mair (2009, str. 117)

"Green tourist" is interested in behaving environmentally responsibly

towards the environment while on vacation. Also, one is ready to pay a

higher price in order to be the user of goods and services obtained by

environmentally responsible tourist agency.

7. Mehmetoglu

(2010)

A tourist who advocates the principle of sustainable development and is

concerned with the issues of sustainability and economic benefits for the

local population of the tourist destination.

8.

Wehrli and others

(2011)

A tourist who is aware of the importance of tourist destinations’

sustainable development and when booking a holiday takes into account

sustainability factor.

9.

Perkins &

Brown (2012)

The real eco-tourist travels guided by the values of the biosphere, on

one’s way supports environmental responsibility and avoids the use of

resources just for entertainment, while taking into account the impact of

that usege on the environment.

4. Proposal for action in implementation of

environmentally responsible tourist

behavior

The impact of tourist behavior on social, economic and

ecological system is essential for tourist destination and

follows all the stages of tourist travel - from its planning,

through selection and realization of the selected packages, as

shown in the Figure 1.

While planning a tourist travel, tourists choose individual

elements of the tourist package tour, such as travel itinerary, or

the path to arrive to the selected travel destinations and

accommodation capacities. Decisions about the elements

mentioned should be based on principles of environmentally

responsible behavior, so that the tourists choose:

• such a product of a tourist agency or a package deal,

consisting of a set of tourist services that are in line with the

concept of sustainable development of tourism in a chosen

tourist destination. This criterion may reduce available tourist

offer and narrow the choice. Since the demand for these

packages is still not large and massive, they cannot be

considered the usual tourist outfit, so agencies often do not

have them in mind when forming advertised arrangements, but

only order and create those individually, if there are interested

tourists. The above situation leads to differentiation and

individualization of tourist offer, which carries a higher price;

• transport by railways, since it has the smallest contribution to

the greenhouse effect compared to road and air transport [19],

which are, when observing the European Union, the most

common choices of tourists. Selection of rail transport reduces

the possibility of going to destinations that are not connected

by rails, as well as tourist destinations that are spatially very

far from the potential tourists’ place of residence;

• accommodation in such facilities which have lower

consumption of water and energy, the so-called eco-efficient

accommodation facilities. The attractiveness to these

properties is present with tourists from Denmark, who are even

willing to allocate more funds for such accommodation. Most

Italian tourists also prefer this type of accommodation, while

tourists from Germany are minority here [1, p. 500]. Observing

from the perspective of mass tourists who focus on the cost of

the service provided, it is unlikely that they will choose such

accommodation facilities, which are often offered at a higher

price.

Also, tourists and their stay at the selected tourist destination

must be accompanied by preservation of the welfare of local

population and the existing ecosystem, from the point of

activity to be performed [1]:

• natural area should not be over-used, in order to avoid the

crowds (skiing in the Alps)

• activities targeted towards party, that lead to consumption of

high amount of energy, such as diving, should be carried out to

a lesser extent;

• use of alcohol should be limited in order not to upset local

population and infringe upon their well-being;

• the differences in culture, social values and religion should

not be highlighted, in order to reduce tensions between the

tourists and residents.

Fig. 1. The impact of the choice of tourism product on environment [1, p. 501]

5. Final consideration

Placing emphasis on the environmental dimension of tourist

trips will allow better control of negative impacts of

aggressive growth of mass tourism trends which they have on

the environment. Further growth in the tourism activities

should be followed by the course of transformation of the

traditional economic Trinity, such as profit, power and prestige

into elements of sustainable economic Trinity - efficiency,

economy and ecology. In order to implement the

aforementioned transformation into practice and lead to

tangible results, it is necessary to include not only participants

of the tourism supply, but also those on the side of tourist

demand, it est tourists. Today there is a mismatch between the

preferences of modern tourists and their motivation for

selecting certain tourism products and services, as well as

expectations from them on one hand and environmental

principles on the other. Therefore, it is necessary to develop

awareness on tourists’ side of the need for ecologically

responsible behavior during tourist visits. However, in

addition, it is necessary and direct tourists to form a group of

eco-tourists, or so-called green tourists who apply such tourist

behavior. Parallel support and implementation of such

behavior will lead to positive long-term effects, both in terms

of natural resources of tourist destinations and their residents,

through minimizing tensions and other social problems. With

regard to environmental and social problems accumulated at

the most famous and most visited tourist destinations, it is

necessary to implement the proposed course of action in a

short period of time, which is possible only through radical

changes on the demand and supply side. It is necessary to

correct common tourist behavior through application of more

rigorous criteria and initiatives in favor of ecology

preservation (such as introduction of taxes, fees, etc.), as well

as the expansion of the tourist offer in terms of a large number

of variants of tourist services, along with satisfying principles

of economy. In this way, obligation for environmentally

responsible behavior will be created for all the tourists, who

will be able to find pro-ecological tourist services in

accordance with their preferences, expectations and purchase

power.

References

[1] Budeanu A. (2007), Sustainable tourist behaviour – a

discussion of opportunities for change. International

Journal of Consumer Studies, 31, 499-508.

[2] Gössling S. (2002), Global environmental consequences

of tourism. Global Environmental Change, 12(4), 283–

302.

[3] UNWTO & UNEP (2008): Climate change and tourism:

Responding to global challenges.

http://www.unwto.org/sustainable/doc/climate2008.pdf,

last accessed: Decembre 20, 2016.

[4] World Wide Fund For Nature (2012). Living Planet

Report. Switzerland, WWF.

[5] European Commission (2004), Feasibility and

Preparatory Study Regarding Multi-stakeholder European

Targeted Action Sustainable Tourism and Transport.

European Commission, DG Enterprise, Hague.

[6] Schmidt H.W. (2002), How Europeans go on holiday,

Eurostat.

[7] Hahn P. (1989), Analyse des Konflikts umwelt, Tu

Berlin, Berlin.

[8] Štetić S. (2009), Značaj I uloga turoperatora za razvoj

održivog turizma, Zbornik radova naučnog skupa:

Savremene tendencije u turizmu, hotelijerstvu i

gastronomiji, Novi Sad: Univerzitet u Novom Sadu,

PMF.

[9] Milenković S. (2009), Monografija: Turizam i ekonomija,

Kragujevac: Univerzitet u Kragujevcu, Ekonomski

fakultet.

[10] Daly E. H. (1999), Beyond growth: the economics of

sustainable development, Beacon Press.

[11] Sharpley R. (2000), Tourism and Sustainable

Development: Exploring the Theoretical Divide. Journal

of Sustainable Tourism, 8(1), 1-19.

[12] Upham P. (2001), A comparison of sustainability theory

88

with UK and European airports policy and practice.

Journal of Environmental Management, 63, 237–248.

[13] Götz K., Loose W., Schmied M., Schubert S. (2002),

Mobility Styles in Leisure Time: Reducing the

Environmental Impacts of Leisure and Tourism Travel.

Öko-Institut e.V, Freiburg.

[14] Martens S., Spaargaren G. (2005), The politics of

sustainable consumption: the case of the Netherlands.

Sustainability: Science, Practice and Policy, 1, 29–42.

[15] Krippendorf J. (1999), Reconciling tourist activities with

nature conservation, Strasbourg: Council of Europe

[16] Juvan E., Dolnicar S. (2016), Measuring

environmentally sustainable tourist behavior, Annals of

Tourism Research, 59, 30-44

[17] Stern P. C. (2000), Toward a coherent theory of

environmentally significant behavior. Journal of Social

Issues, 56(3), 407–424.

[18] Goodwin H., Francis J. (2003), Ethical and responsible

tourism: Consumer trends in UK, Journal of Vacation

Marketing, 9 (3), 271-284

[19] European Commission (2003), Basic Orientations for the

Sustainability of European Tourism. European

Commission, Brussels.

EXPRES 2017 ISBN 978-86-919769-1-0

Seasonal savings of transpired solar collectors B. BOKOR a, L. KAJTÁR a, D. ERYENER b, H. AKHAN b

aBudapest University of Technology and Economics, Department of Building Service and Process Engineering

H-1111 Budapest, Műegyetemrkp. 3-9, Hungary


bTrakya University, Engineering Faculty, Department of Mechanical Engineering

TR-22030 Edirne, Ahmet Karadeniz Campus

Abstract

The integration of renewable energy sources into building heat supply systems has been a key target of science for the

past decades. In many cases high set-up costs make payback periods so long that investors lose motivation to build

environmentally friendly HVAC systems. Transpired solar collectors heat up air directly by solar energy, which can

offset a remarkable proportion of ventilation heat demand. Their simple construction results in low first costs and

makes them practically maintenance-free. However, their suitability to certain building types has to be examined to

maximise their effect. Industrial buildings with large empty facades and high fresh air demand are well suitable for the

efficient TSC operation. The aim of the current article is to sum up the energy benefits of TSC systems both in winter

and in summer operation. In winter, alongside with the air heating itself, the TSC reduces the energy consumption by

wall heat recapture and building air destratification, too. In summer, when there is no heating demand in ventilation,

domestic hot water can be preheated with the use of an air-to-water heat exchanger. Moreover, the TSC is useful to

reduce cooling loads from solar radiation, both by daytime passive cooling (roof ventilation) and nocturnal radiant

cooling.

Nomenclature

Abbreviations

DHW domestic hot water

HVAC heating, ventilation, air condition

TSC transpired solar collector

Latin letters

As surface area [m2]

cp,air specific heat capacity of air [kJ/(kg·K)]

IT solar radiation incident on the collector [W/m2]

m˙air,out outgoing airmass flow [kg/s]

Tair,plen plenum air temperature [°C]

Tamb ambient temperature [°C]

Tair,out outgoing air temperature [°C]

Tcol collector temperature [°C]

Greek letters

εhx heat exchange effectiveness [-]

ηcol collector efficiency [-]

Keywords:solar air heating, transpired solar collector, passive cooling, nocturnal radiation, free cooling

1. Introduction Replacing the use of fossil fuels with renewable

energy is one of the most commonplace targets of

today’s energy policy. This process has created a

turnaround in the HVAC equipment market, as

products emerged which stand out with providing

great performance with lower needs of primary

energy. Engineers, builders and end-users face new

developments every year when attending international

fairs, which are often entirely dedicated to systems

based on renewable energy use. Unfortunately, in

many cases, high capital costs and the lack of stately

funding prevent several investors from sustainable

systems. For every green HVAC system predicted

payback periods therefore are crucially important, as

investors tend to consider these as the basis of

decision. Low capital costs and reliable energy

production at the same time are the key factors in the

89

with UK and European airports policy and practice.

Journal of Environmental Management, 63, 237–248.

[13] Götz K., Loose W., Schmied M., Schubert S. (2002),

Mobility Styles in Leisure Time: Reducing the

Environmental Impacts of Leisure and Tourism Travel.

Öko-Institut e.V, Freiburg.

[14] Martens S., Spaargaren G. (2005), The politics of

sustainable consumption: the case of the Netherlands.

Sustainability: Science, Practice and Policy, 1, 29–42.

[15] Krippendorf J. (1999), Reconciling tourist activities with

nature conservation, Strasbourg: Council of Europe

[16] Juvan E., Dolnicar S. (2016), Measuring

environmentally sustainable tourist behavior, Annals of

Tourism Research, 59, 30-44

[17] Stern P. C. (2000), Toward a coherent theory of

environmentally significant behavior. Journal of Social

Issues, 56(3), 407–424.

[18] Goodwin H., Francis J. (2003), Ethical and responsible

tourism: Consumer trends in UK, Journal of Vacation

Marketing, 9 (3), 271-284

[19] European Commission (2003), Basic Orientations for the

Sustainability of European Tourism. European

Commission, Brussels.

EXPRES 2017 ISBN 978-86-919769-1-0

Seasonal savings of transpired solar collectors B. BOKOR a, L. KAJTÁR a, D. ERYENER b, H. AKHAN b

aBudapest University of Technology and Economics, Department of Building Service and Process Engineering

H-1111 Budapest, Műegyetemrkp. 3-9, Hungary


bTrakya University, Engineering Faculty, Department of Mechanical Engineering

TR-22030 Edirne, Ahmet Karadeniz Campus

Abstract

The integration of renewable energy sources into building heat supply systems has been a key target of science for the

past decades. In many cases high set-up costs make payback periods so long that investors lose motivation to build

environmentally friendly HVAC systems. Transpired solar collectors heat up air directly by solar energy, which can

offset a remarkable proportion of ventilation heat demand. Their simple construction results in low first costs and

makes them practically maintenance-free. However, their suitability to certain building types has to be examined to

maximise their effect. Industrial buildings with large empty facades and high fresh air demand are well suitable for the

efficient TSC operation. The aim of the current article is to sum up the energy benefits of TSC systems both in winter

and in summer operation. In winter, alongside with the air heating itself, the TSC reduces the energy consumption by

wall heat recapture and building air destratification, too. In summer, when there is no heating demand in ventilation,

domestic hot water can be preheated with the use of an air-to-water heat exchanger. Moreover, the TSC is useful to

reduce cooling loads from solar radiation, both by daytime passive cooling (roof ventilation) and nocturnal radiant

cooling.

Nomenclature

Abbreviations

DHW domestic hot water

HVAC heating, ventilation, air condition

TSC transpired solar collector

Latin letters

As surface area [m2]

cp,air specific heat capacity of air [kJ/(kg·K)]

IT solar radiation incident on the collector [W/m2]

m˙air,out outgoing airmass flow [kg/s]

Tair,plen plenum air temperature [°C]

Tamb ambient temperature [°C]

Tair,out outgoing air temperature [°C]

Tcol collector temperature [°C]

Greek letters

εhx heat exchange effectiveness [-]

ηcol collector efficiency [-]

Keywords:solar air heating, transpired solar collector, passive cooling, nocturnal radiation, free cooling

1. Introduction Replacing the use of fossil fuels with renewable

energy is one of the most commonplace targets of

today’s energy policy. This process has created a

turnaround in the HVAC equipment market, as

products emerged which stand out with providing

great performance with lower needs of primary

energy. Engineers, builders and end-users face new

developments every year when attending international

fairs, which are often entirely dedicated to systems

based on renewable energy use. Unfortunately, in

many cases, high capital costs and the lack of stately

funding prevent several investors from sustainable

systems. For every green HVAC system predicted

payback periods therefore are crucially important, as

investors tend to consider these as the basis of

decision. Low capital costs and reliable energy

production at the same time are the key factors in the

90

SEASONAL SAVINGS OF TRANSPIRED SOLAR COLLECTORS

2

calculation of payback.

In the solar thermal industry besides the widely-

known solar water heating systems, solar air heating

represents a remarkable segment, too. Transpired

solar collectors (TSC) preheat fresh outside air for

ventilation systems by a very simple mechanism. A

TSC is a dark, corrugated perforated metal plate

which is installed onto a building’s façade in a given

distance. Under solar radiation, the metal plate heats

up and as the air transpires it, a heat exchange takes

place between the absorber and the air. The research

of the TSC dates back to the 1990s. Canadian

engineer John Hollick invented the TSC which has

been developed from glazed solar air heaters.

[1]Glazing protects the absorber against convective

heat losses to the ambiance, but at the same time it

doesn’t only increase optical losses, but when applied

on larger surfaces, it can influence a building’s

aesthetics in a negative way. Therefore, the transpired

design has been developed, which can maintain low

convective losses while having optical ones

minimised. As the performance strongly depends on

operational parameters, extensive research has been

carried out since the 1990s to optimise the TSC’s

solar air heating benefits. Kutscher [2]Error!

Reference source not found. presented the basic

heat loss theory of the TSC, underlining the stable

boundary layer on the perforated absorber’s external

side, which comes to be due suction. Kutscher’s

investigation considered a flat absorber plate with

circular perforations. Hollands et al. [3]developed a

model for the determination of the collector

efficiency and heat exchange effectiveness, in which

the absorber plate’s total heat transfer is broken down

into contributions from the front, the hole and the

back. Collins and Abulkhair[4]carried out a

numerical investigation on the modern TSC’s

performance, which – like most commercial products

– has different features from the models used to

produce heat loss and effectiveness correlations. The

target of research was to find out the effect of

corrugation and slit-like perforations. Croitoruet. al.

[5]carried out an analysis on the importance of the

shape of the perforations, as a heat transfer

influencing parameter. It has been found that the

increasing perimeter generates complex fluid

dynamics, which results in higher efficiency of heat

recovery. Fleck et al. [6]carried out an experimental

study on a working TSC installation to determine the

effect of wind on the thermal performance. Hall and

Blower [7]investigated the effect of low-emissivity

coatings to minimise radiative losses from the

absorber. As the literature shows, the TSC’s optimisation has

been a research target for more than two decades,

underlining its great potential among solar thermal

systems. The aim of the current article is to point out

the TSC’s flexibility as it can not only preheat

ventilation air by solar energy, but it can also reduce a

building’s cooling demand in summer operation.

2. Transpired Solar Collectors

Solar air heating has been a remarkable segment of

the solar thermal market with several different

collector constructions which heat up either fresh, or

recirculated air. Difference can be made among

products by the process of air heating, as air can

stream along a non-perforated or transpire a

perforated absorber. Several designs include a

transparent glazing to reduce the convectional losses

to the ambiance, which is necessary for collectors

with a non-transpired absorber construction. The heat

transfer mechanism of the unglazed, transpired solar

collector is fundamentally different from that of the

non-transpired collector, making it possible to leave

the glazing and reduce optical losses without the

increase of convective thermal losses from the

absorber.

TSC Construction and Operational Principle

The potential of the transpired solar collector lays in

its simple construction and thus reliable and almost

maintenance-free operation. The absorber, which is

made of conventional building cladding material can

be included in the architectural conception of new

buildings, and also it can be added to existing

facades. It is mounted in 15-20 cm distance onto the

building’s original façade, creating an air gap, or plenum. This is closed from the sides, so air can enter

it only through the perforations of the absorber plate.

As Fig. 1shows, the air passes the absorber as AHU

fans withdraw fresh air from the plenum. The

transpiration of the absorber ensures the transfer of

the solar heat to the fresh air.

Seeing Fig. 1, one could think that in the lack of

transparent glazing, the TSC has remarkable thermal

losses due to convection to the exterior. According to

Kutscher et al. [8], assuming homogenous suction on

the surface of the absorber, one can state that the

suction stabilizes the boundary layers on the external

side of the absorber, reducing the effect of convective

losses solely to the collector edges. This means that

for large collector surfaces the convective losses are

negligible and wind losses remain small, too.

Fig. 1. Construction of the transpired solar collector[9][10]


3

Parameters for Reliable Operation

However, significant convective and wind heat

losses can occur, if the collector is not designed or

operated optimally. Kutscher et al. [11]describe that

to ensure little impact of wind:

• the suction face velocity should be

preferably 0.04-0.05 m/s, but at least 0.02

m/s,

• at least 25 Pa pressure drop is to be obtained

across the perforated plate, and

• the wall should be designed to have uniform

flow through itself.

Fig.2.Temperature rise at different flow rates with variance

of minimal, low and medium wind speeds[13]

Generally speaking, high-flow TSC systems

perform much better than low flow ones, as the

efficiency can reach its highest values when high

flow is cooling the absorber, utilising the most of its

heat. Kumar and Leon [12]laid down a

mathematical model for the description of a TSC’s

thermal performance, in which collector efficiency

is defined as

, ∙ , ∙ ,

∙ (1)

whereas the heat exchange effectiveness is

, (2)

With rising flow the heat exchange effectiveness

drops, as the air cannot reach as high temperatures,

as if lower heat flow would transpire the plate. This

is illustrated inFig.2. However, the collector’s

efficiency increases with rising air flow, because the

absorber is being kept at a lower temperature, reducing all kinds of thermal losses.

In Fig.3 one can see that for a given wind speed the

collector efficiency only depends on the air flow

rate, which underlines the negligible impact of

convective losses depending on ambient

temperature.

A minimum of 25 Pa pressure drop is necessary

across the absorber to avoid the solar heated air

flowing out at regions with negative wind pressure.

So one can reach that the absorber is transpired

evenly and local hot regions do not come to be which

would worsen the collector’s efficiency. Ensuring

this minimal pressure drop speaks for keeping away

from low air-flow rates, too.

Fig.3. Efficiency versus air flow rates for various wind

speeds[13]

Considering these design aspects, it can be stated that

the TSC is generally a system for the preheating of

fresh ventilation air and not a heating system which

has to produce “ready-to-use” end temperatures itself.

Yet preheating reduces the heating demand

remarkably and shrinks the heating period of the

building. After careful design attention is to be paid

on the operation too, as the collector surface has been

defined for a certain fresh air demand, which resulted

in the exact definition of the aforementioned flow

rate in [m3/(m

2·h)]. The system operator has to be

aware of this, as eliminating air handling units or

reducing their air flow leads to the design criteria of

the TSC’s reliable operation not being fulfilled. In

contrast to a solar thermal system with liquid heat

transfer medium circulating in a closed primary

system, in which oversizing leads to higher solar

coverage and lower system efficiency, the beneficial

operation of a TSC system can be quickly made

impossible by oversizing.

3. Sources of TSC Benefits in Winter

For exploiting all the energy benefits a TSC system

can offer one has to know what building type it suits

the most. As due to the transpiration of the absorber,

the TSC heats up fresh ventilation air only, buildings

with high fresh air demand can benefit the most.

Industrial buildings offer large facades with low

glazing proportion, so vast surfaces are available for

TSC setup. The low glazing proportion would result

in low solar heat gain without the use of TSC. Some

technologies such as chemical, automotive and

rubber industries require very high amounts of fresh

ventilation air, which ensure the utilisation of the

solar heated fresh air. Eryener and Akhan [14]

reported on the performance analysis of the first

transpired solar collector installation in Turkey,

which was set up in 2012 on the south-facing wall of

an automotive manufacturing building with a total

91


2

calculation of payback.

In the solar thermal industry besides the widely-

known solar water heating systems, solar air heating

represents a remarkable segment, too. Transpired

solar collectors (TSC) preheat fresh outside air for

ventilation systems by a very simple mechanism. A

TSC is a dark, corrugated perforated metal plate

which is installed onto a building’s façade in a given

distance. Under solar radiation, the metal plate heats

up and as the air transpires it, a heat exchange takes

place between the absorber and the air. The research

of the TSC dates back to the 1990s. Canadian

engineer John Hollick invented the TSC which has

been developed from glazed solar air heaters.

[1]Glazing protects the absorber against convective

heat losses to the ambiance, but at the same time it

doesn’t only increase optical losses, but when applied

on larger surfaces, it can influence a building’s

aesthetics in a negative way. Therefore, the transpired

design has been developed, which can maintain low

convective losses while having optical ones

minimised. As the performance strongly depends on

operational parameters, extensive research has been

carried out since the 1990s to optimise the TSC’s

solar air heating benefits. Kutscher [2]Error!

Reference source not found. presented the basic

heat loss theory of the TSC, underlining the stable

boundary layer on the perforated absorber’s external

side, which comes to be due suction. Kutscher’s

investigation considered a flat absorber plate with

circular perforations. Hollands et al. [3]developed a

model for the determination of the collector

efficiency and heat exchange effectiveness, in which

the absorber plate’s total heat transfer is broken down

into contributions from the front, the hole and the

back. Collins and Abulkhair[4]carried out a

numerical investigation on the modern TSC’s

performance, which – like most commercial products

– has different features from the models used to

produce heat loss and effectiveness correlations. The

target of research was to find out the effect of

corrugation and slit-like perforations. Croitoruet. al.

[5]carried out an analysis on the importance of the

shape of the perforations, as a heat transfer

influencing parameter. It has been found that the

increasing perimeter generates complex fluid

dynamics, which results in higher efficiency of heat

recovery. Fleck et al. [6]carried out an experimental

study on a working TSC installation to determine the

effect of wind on the thermal performance. Hall and

Blower [7]investigated the effect of low-emissivity

coatings to minimise radiative losses from the

absorber. As the literature shows, the TSC’s optimisation has

been a research target for more than two decades,

underlining its great potential among solar thermal

systems. The aim of the current article is to point out

the TSC’s flexibility as it can not only preheat

ventilation air by solar energy, but it can also reduce a

building’s cooling demand in summer operation.

2. Transpired Solar Collectors

Solar air heating has been a remarkable segment of

the solar thermal market with several different

collector constructions which heat up either fresh, or

recirculated air. Difference can be made among

products by the process of air heating, as air can

stream along a non-perforated or transpire a

perforated absorber. Several designs include a

transparent glazing to reduce the convectional losses

to the ambiance, which is necessary for collectors

with a non-transpired absorber construction. The heat

transfer mechanism of the unglazed, transpired solar

collector is fundamentally different from that of the

non-transpired collector, making it possible to leave

the glazing and reduce optical losses without the

increase of convective thermal losses from the

absorber.

TSC Construction and Operational Principle

The potential of the transpired solar collector lays in

its simple construction and thus reliable and almost

maintenance-free operation. The absorber, which is

made of conventional building cladding material can

be included in the architectural conception of new

buildings, and also it can be added to existing

facades. It is mounted in 15-20 cm distance onto the

building’s original façade, creating an air gap, or plenum. This is closed from the sides, so air can enter

it only through the perforations of the absorber plate.

As Fig. 1shows, the air passes the absorber as AHU

fans withdraw fresh air from the plenum. The

transpiration of the absorber ensures the transfer of

the solar heat to the fresh air.

Seeing Fig. 1, one could think that in the lack of

transparent glazing, the TSC has remarkable thermal

losses due to convection to the exterior. According to

Kutscher et al. [8], assuming homogenous suction on

the surface of the absorber, one can state that the

suction stabilizes the boundary layers on the external

side of the absorber, reducing the effect of convective

losses solely to the collector edges. This means that

for large collector surfaces the convective losses are

negligible and wind losses remain small, too.

Fig. 1. Construction of the transpired solar collector[9][10]


3

Parameters for Reliable Operation

However, significant convective and wind heat

losses can occur, if the collector is not designed or

operated optimally. Kutscher et al. [11]describe that

to ensure little impact of wind:

• the suction face velocity should be

preferably 0.04-0.05 m/s, but at least 0.02

m/s,

• at least 25 Pa pressure drop is to be obtained

across the perforated plate, and

• the wall should be designed to have uniform

flow through itself.

Fig.2.Temperature rise at different flow rates with variance

of minimal, low and medium wind speeds[13]

Generally speaking, high-flow TSC systems

perform much better than low flow ones, as the

efficiency can reach its highest values when high

flow is cooling the absorber, utilising the most of its

heat. Kumar and Leon [12]laid down a

mathematical model for the description of a TSC’s

thermal performance, in which collector efficiency

is defined as

, ∙ , ∙ ,

∙ (1)

whereas the heat exchange effectiveness is

, (2)

With rising flow the heat exchange effectiveness

drops, as the air cannot reach as high temperatures,

as if lower heat flow would transpire the plate. This

is illustrated inFig.2. However, the collector’s

efficiency increases with rising air flow, because the

absorber is being kept at a lower temperature, reducing all kinds of thermal losses.

In Fig.3 one can see that for a given wind speed the

collector efficiency only depends on the air flow

rate, which underlines the negligible impact of

convective losses depending on ambient

temperature.

A minimum of 25 Pa pressure drop is necessary

across the absorber to avoid the solar heated air

flowing out at regions with negative wind pressure.

So one can reach that the absorber is transpired

evenly and local hot regions do not come to be which

would worsen the collector’s efficiency. Ensuring

this minimal pressure drop speaks for keeping away

from low air-flow rates, too.

Fig.3. Efficiency versus air flow rates for various wind

speeds[13]

Considering these design aspects, it can be stated that

the TSC is generally a system for the preheating of

fresh ventilation air and not a heating system which

has to produce “ready-to-use” end temperatures itself.

Yet preheating reduces the heating demand

remarkably and shrinks the heating period of the

building. After careful design attention is to be paid

on the operation too, as the collector surface has been

defined for a certain fresh air demand, which resulted

in the exact definition of the aforementioned flow

rate in [m3/(m

2·h)]. The system operator has to be

aware of this, as eliminating air handling units or

reducing their air flow leads to the design criteria of

the TSC’s reliable operation not being fulfilled. In

contrast to a solar thermal system with liquid heat

transfer medium circulating in a closed primary

system, in which oversizing leads to higher solar

coverage and lower system efficiency, the beneficial

operation of a TSC system can be quickly made

impossible by oversizing.

3. Sources of TSC Benefits in Winter

For exploiting all the energy benefits a TSC system

can offer one has to know what building type it suits

the most. As due to the transpiration of the absorber,

the TSC heats up fresh ventilation air only, buildings

with high fresh air demand can benefit the most.

Industrial buildings offer large facades with low

glazing proportion, so vast surfaces are available for

TSC setup. The low glazing proportion would result

in low solar heat gain without the use of TSC. Some

technologies such as chemical, automotive and

rubber industries require very high amounts of fresh

ventilation air, which ensure the utilisation of the

solar heated fresh air. Eryener and Akhan [14]

reported on the performance analysis of the first

transpired solar collector installation in Turkey,

which was set up in 2012 on the south-facing wall of

an automotive manufacturing building with a total

92


area of 770 m2. Estimated energy savings have bee

calculated using RETScreen, a feasibility analysis

software developed by the Canadian Government.

According to simulation, the system delivers

521557 kWh/a renewable energy. Results have been

validated by real monitoring data. Brown et al.

[15]presented a review on the TSC installations in

England and Wales, in which it was underlined that

the majority of the systems had been installed on

industrial or warehouse systems.

Fig. 4.Integration of a TSC system into an industrial building

As the TSC can be provided with optimal

operational conditions when working on industrial

buildings, Fig. 4shows a possible integration into an

imaginary industrial building to illustrate the

multiple energy saving opportunities of the TSC.

Solar Air Heating

As depicted inFig. 4, in buildings with no

distribution system, the solar heated air can be

distributed under the ceiling by fabric ducts. It is

important to note that the air distribution system of

the TSC has to be designed with the lowest pressure

drop possible and heat losses are

minimised. This is why air ducts with a round cross

section are preferable, led in the building’s interior.

In summer, when there is no need for any air heating,

the TSC can be bypassed by a damper, and the

ventilation system can withdraw fresh

temperature. In this case a natural stack effect comes

to be in the air gap between the absorber and the back

plate, which ventilates the plenum, reducing the

unwanted summer heat gain on the wall section

behind the TSC.

Wall Heat Recapture

The TSC is able to reduce the building’s

transmission heat losses, as it recaptures an amount

of the heat flow on the wall section where it has

been installed. In this way a part of the heat loss is

collected by the airflow and returned into the

building. This process is independent from the solar

radiation, so if ventilation air is collected through

the TSC at night, a certain amount of the

transmission heat losses can be recaptured, which

also has a preheating effect on the airflow.


. Estimated energy savings have been

feasibility analysis



a renewable energy. Results have been


presented a review on the TSC installations in

it was underlined that


Integration of a TSC system into an industrial building



shows a possible integration into an

ry industrial building to illustrate the


, in buildings with no existing air





drop possible and heat losses are also to be





ventilation system can withdraw fresh air of ambient










This process is independent from the solar





Building Air Destratification

Industrial processes are often bound to heat

production. As heat rises to the top of the building, it

can accumulate under the high ceiling which results

in a remarkable vertical temperature difference in the

heated space. This means high heat losses close to the

ceiling whereas the occupied areas (parts at the

lowest) still require heating performance. The

stratification (vertical temperature difference) can be

reduced by the TSC system, if the fresh solar

air, which has still lower temperature than the hot air

under the ceiling, is directed upwards to mix with the

hot air. This way, differences in the vertical

temperature profile can be minimised, reducing both

heat losses and heating requirement

4. Sources of TSC Benefits in Summer

In paragraph 3 it has been reflected on the benefits of

a transpired solar collector system in winter, when

the vast majority of a building’s heating demand

comes to be. However, as for every solar thermal

system, it is necessary to discuss the summer

operation of the TSC to see what impact it has on a

building’s thermal balance. In contrast to

thermal systems with liquid heat transfer medium,

solar air heaters do not get damaged when surplus

heat remains unused. Still, in order to increase the

utilisation of the system, several

opportunities are available to reduce primary energy

needs by the TSC.

DHW Preheating

The use of solar energy in DHW production is one of

the most common targets of solar collector

installations. For systems with liquid heat transfer

medium Horváth and Csoknyai[16]

[17] have presented results regarding the solar

contribution in DHW production energy needs.

the insertion of an air-to-water heat exchanger

the air duct just after the TSC, it can contribute in the

domestic hot water production, too. The Department

of Building Service and Process Engineering of

Budapest University of Technology and Economics

have been monitoring the TSC system of a

centre near Budapest, in which a part of the summer

heat is used for preheating DHW. For

thedetermination of preheating needs and the sizing

of the heat exchanger, results of Némethi and

Szánthó[18] and Garbai et al.[19]

a basis.

Roof Ventilation

In summer, when there is no heating demand

ventilation, the transpired solar collector

and fresh air is taken through a separate damper

directly from the exterior. In this case one may think 4





heat losses close to the




reduced by the TSC system, if the fresh solar-heated

temperature than the hot air




losses and heating requirement.

Sources of TSC Benefits in Summer

it has been reflected on the benefits of



o be. However, as for every solar thermal

necessary to discuss the summer-time


In contrast to solar


aters do not get damaged when surplus


utilisation of the system, several summer-time

available to reduce primary energy

production is one of


For systems with liquid heat transfer

[16] and Horváthet. al.

have presented results regarding the solar

contribution in DHW production energy needs.With

water heat exchanger into

can contribute in the

r production, too. The Department



been monitoring the TSC system of a shopping

Budapest, in which a part of the summer

ating DHW. For

determination of preheating needs and the sizing


can be regarded as

In summer, when there is no heating demand in

transpired solar collector is bypassed


directly from the exterior. In this case one may think


5

that the TSC means extra cooling loads through the

building envelope, as it gets hot under solar

radiation. However, this is not the case, as natural

ventilation develops in the air gap between the

perforated absorber and the actual building wall,

decoupling the solar loads from the interior. This

way the TSC significantly reduces the thermal loads

in summer, minimising the cooling energy demand.

In industrial buildings with large roof areas of low

inclination a remarkable amount of the summer

cooling load is solar gain through the roof. Roof

temperatures can reach up to 70-75°C under solar

radiation, if Central-Eastern European conditions

are considered. By applying TSC on the roof, the

natural ventilation through the perforations and in

the plenum can reduce this load significantly by

minimising the heating up of the actual building

roof. To find out its extent, joint co-operation

between Trakya University and Budapest University

of Technology and Economics have been

established. A mathematical model describing the

phenomenon is being developed. To validate this, a

measurement setup of 5 m2 commercially available

TSC is used.

Nocturnal Radiant Cooling

In buildings with heavy structure mass cooling load

can be moderated by night ventilation. In the course

of this, outdoor air is made stream in the building

either in mechanical or natural way. The cooler

outdoor air cools down the building mass to some

extent, reducing the peak air conditioning load of

the following day. However, the highest air-

conditioning loads are to be obtained at locations

where temperatures do not drop enough at night to

realise efficient night ventilation. Hollick[20]

reported on the cooling down of sky-facing TSC

surfaces due to longwave radiation to the sky.

Depending on location and weather conditions, the

surface can cool down 6-20 K below ambient [20].

Low-pitch roofs with TSC can increase the effect of

night ventilation if ambient air is further cooled

when transpiring the cold perforated plate. The

more exact characterisation of this effect is a target

of the co-operation between Trakya University and


too.

5. Conclusions

Transpired solar collectors represent a cost-

effective alternative in solar air heating technology,

due to their low capital costs and almost

maintenance-free operation. To reach optimal

operation and thus low payback periods, it is

essential to design and operate the system in a

conceived manner. This way, the system offers

multiple sources of energy savings, which can make

it particularly attractive for building service

designers, operators and investors.

References

[1] Hollick, JC: Unglazed Solar Wall Air Heaters. Renewable Energy, Vol. 5. Part I. pp. 415-421, 1994

[2] Kutscher CF: An Investigation of Heat Transfer for Air Flow through Low Porosity Perforated Plates. Doctoral thesis, University of Colorado, 1992

[3] Hollands KGT, Van Decker GWE, Brunger AP: Heat-exchange Relations for Unglazed Transpired Solar Collectors with Circular Holes on a Square or Triangular Pitch. Solar Energy Vol.71, No. 1, pp. 33-45, 2001

[4] Collins MR, Abulkhair H: An Evaluation of Heat Transfer and Effectiveness for Unglazed Transpired Solar Air Heaters. Solar Energy 99 (2014) 231-245.

[5] Croitoru CV, Nastase A, Bode FI, Meslem A: Thermodynamic Investigation on an Innovative Unglazed Transpired Solar Collector. Solar Energy 131 (2016) 21-29.

[6] Fleck BA, Meier RM, Matovic MD: A Field Study of the Wind Effects on the Performance of an Unglazed Transpired Solar Collector. Solar Energy Vol. 73, No. 3, pp. 209-216, 2002.

[7] Hall R, Blower J: Low-Emissivity Transpired Solar Collectors. Energy Procedia 91, June 2016, pp 56-63

[8] Kutscher CF, Christensen CB, Barker GM: Unglazed Transpired Solar Collectors: Heat Loss Theory. Journal of Solar Energy Engineering, Vol. 115, August 1993, pp. 182-188.

[9] http://tatproddel.tat.cloud.opentext.com/static_files/Images_new/Construction/about_us/new_panels/envelope/trsiomet-sc-solar-collector-build-up.jpg

[10] http://solarairheating.org/media/transpired-collector.gif

[11] Kutscher CF, Christensen CB, Gawlik K: Letter to the Editor of Solar Energy in response to “A Field Study of the Wind Effects on the Performance of an Unglazed Transpired Solar Collector. Solar Energy 74 (2003) 353-354.

[12] Kumar S, Leon MA: Mathematical Modelling and Thermal Performance Analysis of Unglazed Transpired Solar Collectors. Solar Energy 81 (2007) 62-75.

[13] http://sahwia.org/wp-content/uploads/2013/02/1001-SolarAMark_Conserval_Solar Wall.pdf

[14] Eryener D, Akhan H: The Performance of the First Transpired Solar Collector Installation in Turkey. Energy Procedia 91 (2016) 442-449

[15] Brown C, Perisoglou E, Hall R, Stevenson V: Transpired Solar Collector Installations in Wales and England. Energy Procedia 48 (2014) 18-27.

[16] Horváth M, Csoknyai T: Maximal and Optimal DHW Production with Solar Collectors for Single Family Houses. EXPRES 2015 Subotica, 7th International Symposium on Exploitation of Renewable Energy Sources and Efficiency. Subotica, Serbia, 2015

[17] Horváth M, Hrabovszky-Horváth S, Csoknyai T: Parametric Analysis of Solar Hot Water Production in “Commie-block” Buildings. Energy (IYCE), 2015 5th International Youth Conference on. Pisa, Italy, 2015

[18] Némethi B, Szánthó Z: Measurement Study on Demand of Domestic Hot Water in Residential Buildings; Proceedings of the 2nd IASME/WSEAS International Conference on Energy & Environment, p68-73.; Portorose, Slovenia, 15-17.05.2007.; ISSN:1790-5095

[19] Garbai L, Jasper A, Magyar Z: Probability theory description of domestic hot water and heating demands; Energy and Buildings 75 (2014) p.483-492

[20] Hollick J: Nocturnal Radiation Cooling Tests. Energy Procedia 30 (2012) 930-936.

[21] Petráš D, Lulkovičová O, Takács J, Füri B.: Obnoviteľ nézdroje energiena vykurovanie. In: Vykurovanie rodinných a bytových domov. Bratislava: Jaga, 2005. p. 193 – 217, ISBN 80-8076-012-8.

93


area of 770 m2. Estimated energy savings have bee

calculated using RETScreen, a feasibility analysis



521557 kWh/a renewable energy. Results have been


[15]presented a review on the TSC installations in

England and Wales, in which it was underlined that


industrial or warehouse systems.

Fig. 4.Integration of a TSC system into an industrial building



buildings, Fig. 4shows a possible integration into an

imaginary industrial building to illustrate the


Solar Air Heating

As depicted inFig. 4, in buildings with no





drop possible and heat losses are





ventilation system can withdraw fresh





behind the TSC.

Wall Heat Recapture






building. This process is independent from the solar






. Estimated energy savings have been

feasibility analysis



a renewable energy. Results have been


presented a review on the TSC installations in

it was underlined that


Integration of a TSC system into an industrial building



shows a possible integration into an

ry industrial building to illustrate the


, in buildings with no existing air





drop possible and heat losses are also to be





ventilation system can withdraw fresh air of ambient










This process is independent from the solar





Building Air Destratification





heated space. This means high heat losses close to the




reduced by the TSC system, if the fresh solar

air, which has still lower temperature than the hot air




heat losses and heating requirement

4. Sources of TSC Benefits in Summer

In paragraph 3 it has been reflected on the benefits of



comes to be. However, as for every solar thermal

system, it is necessary to discuss the summer


building’s thermal balance. In contrast to


solar air heaters do not get damaged when surplus


utilisation of the system, several

opportunities are available to reduce primary energy

needs by the TSC.

DHW Preheating

The use of solar energy in DHW production is one of


installations. For systems with liquid heat transfer

medium Horváth and Csoknyai[16]

[17] have presented results regarding the solar

contribution in DHW production energy needs.

the insertion of an air-to-water heat exchanger

the air duct just after the TSC, it can contribute in the

domestic hot water production, too. The Department



have been monitoring the TSC system of a

centre near Budapest, in which a part of the summer

heat is used for preheating DHW. For

thedetermination of preheating needs and the sizing


Szánthó[18] and Garbai et al.[19]

a basis.

Roof Ventilation

In summer, when there is no heating demand

ventilation, the transpired solar collector


directly from the exterior. In this case one may think 4





heat losses close to the




reduced by the TSC system, if the fresh solar-heated

temperature than the hot air




losses and heating requirement.

Sources of TSC Benefits in Summer

it has been reflected on the benefits of



o be. However, as for every solar thermal

necessary to discuss the summer-time


In contrast to solar


aters do not get damaged when surplus


utilisation of the system, several summer-time

available to reduce primary energy

production is one of


For systems with liquid heat transfer

[16] and Horváthet. al.

have presented results regarding the solar

contribution in DHW production energy needs.With

water heat exchanger into

can contribute in the

r production, too. The Department



been monitoring the TSC system of a shopping

Budapest, in which a part of the summer

ating DHW. For

determination of preheating needs and the sizing


can be regarded as

In summer, when there is no heating demand in

transpired solar collector is bypassed


directly from the exterior. In this case one may think


5

that the TSC means extra cooling loads through the

building envelope, as it gets hot under solar

radiation. However, this is not the case, as natural

ventilation develops in the air gap between the

perforated absorber and the actual building wall,

decoupling the solar loads from the interior. This

way the TSC significantly reduces the thermal loads

in summer, minimising the cooling energy demand.

In industrial buildings with large roof areas of low

inclination a remarkable amount of the summer

cooling load is solar gain through the roof. Roof

temperatures can reach up to 70-75°C under solar

radiation, if Central-Eastern European conditions

are considered. By applying TSC on the roof, the

natural ventilation through the perforations and in

the plenum can reduce this load significantly by

minimising the heating up of the actual building

roof. To find out its extent, joint co-operation

between Trakya University and Budapest University

of Technology and Economics have been

established. A mathematical model describing the

phenomenon is being developed. To validate this, a

measurement setup of 5 m2 commercially available

TSC is used.

Nocturnal Radiant Cooling

In buildings with heavy structure mass cooling load

can be moderated by night ventilation. In the course

of this, outdoor air is made stream in the building

either in mechanical or natural way. The cooler

outdoor air cools down the building mass to some

extent, reducing the peak air conditioning load of

the following day. However, the highest air-

conditioning loads are to be obtained at locations

where temperatures do not drop enough at night to

realise efficient night ventilation. Hollick[20]

reported on the cooling down of sky-facing TSC

surfaces due to longwave radiation to the sky.

Depending on location and weather conditions, the

surface can cool down 6-20 K below ambient [20].

Low-pitch roofs with TSC can increase the effect of

night ventilation if ambient air is further cooled

when transpiring the cold perforated plate. The

more exact characterisation of this effect is a target

of the co-operation between Trakya University and


too.

5. Conclusions

Transpired solar collectors represent a cost-

effective alternative in solar air heating technology,

due to their low capital costs and almost

maintenance-free operation. To reach optimal

operation and thus low payback periods, it is

essential to design and operate the system in a

conceived manner. This way, the system offers

multiple sources of energy savings, which can make

it particularly attractive for building service

designers, operators and investors.

References

[1] Hollick, JC: Unglazed Solar Wall Air Heaters. Renewable Energy, Vol. 5. Part I. pp. 415-421, 1994

[2] Kutscher CF: An Investigation of Heat Transfer for Air Flow through Low Porosity Perforated Plates. Doctoral thesis, University of Colorado, 1992

[3] Hollands KGT, Van Decker GWE, Brunger AP: Heat-exchange Relations for Unglazed Transpired Solar Collectors with Circular Holes on a Square or Triangular Pitch. Solar Energy Vol.71, No. 1, pp. 33-45, 2001

[4] Collins MR, Abulkhair H: An Evaluation of Heat Transfer and Effectiveness for Unglazed Transpired Solar Air Heaters. Solar Energy 99 (2014) 231-245.

[5] Croitoru CV, Nastase A, Bode FI, Meslem A: Thermodynamic Investigation on an Innovative Unglazed Transpired Solar Collector. Solar Energy 131 (2016) 21-29.

[6] Fleck BA, Meier RM, Matovic MD: A Field Study of the Wind Effects on the Performance of an Unglazed Transpired Solar Collector. Solar Energy Vol. 73, No. 3, pp. 209-216, 2002.

[7] Hall R, Blower J: Low-Emissivity Transpired Solar Collectors. Energy Procedia 91, June 2016, pp 56-63

[8] Kutscher CF, Christensen CB, Barker GM: Unglazed Transpired Solar Collectors: Heat Loss Theory. Journal of Solar Energy Engineering, Vol. 115, August 1993, pp. 182-188.

[9] http://tatproddel.tat.cloud.opentext.com/static_files/Images_new/Construction/about_us/new_panels/envelope/trsiomet-sc-solar-collector-build-up.jpg

[10] http://solarairheating.org/media/transpired-collector.gif

[11] Kutscher CF, Christensen CB, Gawlik K: Letter to the Editor of Solar Energy in response to “A Field Study of the Wind Effects on the Performance of an Unglazed Transpired Solar Collector. Solar Energy 74 (2003) 353-354.

[12] Kumar S, Leon MA: Mathematical Modelling and Thermal Performance Analysis of Unglazed Transpired Solar Collectors. Solar Energy 81 (2007) 62-75.

[13] http://sahwia.org/wp-content/uploads/2013/02/1001-SolarAMark_Conserval_Solar Wall.pdf

[14] Eryener D, Akhan H: The Performance of the First Transpired Solar Collector Installation in Turkey. Energy Procedia 91 (2016) 442-449

[15] Brown C, Perisoglou E, Hall R, Stevenson V: Transpired Solar Collector Installations in Wales and England. Energy Procedia 48 (2014) 18-27.

[16] Horváth M, Csoknyai T: Maximal and Optimal DHW Production with Solar Collectors for Single Family Houses. EXPRES 2015 Subotica, 7th International Symposium on Exploitation of Renewable Energy Sources and Efficiency. Subotica, Serbia, 2015

[17] Horváth M, Hrabovszky-Horváth S, Csoknyai T: Parametric Analysis of Solar Hot Water Production in “Commie-block” Buildings. Energy (IYCE), 2015 5th International Youth Conference on. Pisa, Italy, 2015

[18] Némethi B, Szánthó Z: Measurement Study on Demand of Domestic Hot Water in Residential Buildings; Proceedings of the 2nd IASME/WSEAS International Conference on Energy & Environment, p68-73.; Portorose, Slovenia, 15-17.05.2007.; ISSN:1790-5095

[19] Garbai L, Jasper A, Magyar Z: Probability theory description of domestic hot water and heating demands; Energy and Buildings 75 (2014) p.483-492

[20] Hollick J: Nocturnal Radiation Cooling Tests. Energy Procedia 30 (2012) 930-936.

[21] Petráš D, Lulkovičová O, Takács J, Füri B.: Obnoviteľ nézdroje energiena vykurovanie. In: Vykurovanie rodinných a bytových domov. Bratislava: Jaga, 2005. p. 193 – 217, ISBN 80-8076-012-8.

94


6

[22] Petráš D, Lulkovičová O, Takács J, Füri B: Obnoviteľ nézdroje energie pre nízkoteplotné systémy. Bratislava: Jaga Group, s.r.o., 2009. 221 s. ISBN 978-80-8076-075-5

[23] Takács J, Lulkovičová O, Füri B: Helyzetkép a megújuló energiaforrások hasznosítasi lehetöségeiről Szlovákiában In: Magyar Épületgépészet. - ISSN 1215-9913. – vol. 57, 12 (2008), s. 24-27

[24] Nyers J, Tomic S, Nyers Á: Economic Optimum of Thermal Insulating Layer for External Wall of Brick, Acta Polytechnica Hungarica 11: (7) pp. 209-222.

[25] Nyers J., Nyers A.: Hydraulic Analysis of Heat Pump's Heating Circuit using Mathematical Model, 9rd ICCC International Conference, Proceedings-USB, ISBN 978-1-4799-0061-9 pp 349-353, Tihany, Hungary. 04-08. 07. 2013.

Acknowledgements

An international co-operation between Trakya

University and Budapest University of Technology

and Economics to investigate TSC behaviour has

been funded by the “National Talent Program” of the

Hungarian Human Capacities Fund. For the support

that made a research semester at Trakya University

possible, author B. Bokor would thereby like to give

thanks to the Hungarian Ministry of Human

Capacities.

EXPRES 2017

ISBN 978-86-919769-1-0

Circular business model – effects on company’s energy efficiency and renewable energy use

S. TOMIĆ a, D. DELIĆ b, A. STOILJKOVIĆ c

Faculty of Economics, Universityof Novi Sad

24000 Subotica, Segedinski put 9-11, Serbia aE-mail:[email protected] bE-mail:[email protected]

cE-mail:[email protected]

In essence, a circular business model represents a fundamental alternative to linear business model.Circular business model

incorporate circular economy principles. In circular business models resources do not get lost or the loss is minimised. In this

paper, through the explanation of what are circular economy, sustainable business model and subsequently the circular business

model, weindicate how different approaches, archetypes or business model can affects company’s energy efficiency and

renewable energy use.

Key words: linear busiess model, circular business model, waste, energy

1. Introduction

Circularity is an approach which stands in contrast

to the linear, traditional production and consumption

(take – make – consume - dispose) pattern.

Circularity involves the joining up of the value

chain so that end-of-life products are reused as

inputs, and waste is utilized as a resource (material

or energy) wherever possible. Unlike the traditional

linear approach, a circular models (closed-loop,

cradle-to-cradle and similar) seek to respect

planetary boundaries through increasing the share of

renewable or recyclable resources while reducing

the consumption of raw materials and energy.At the

same time, circular models contribute to cutting

emissions and material losses. In order to better

understand circular business models and its effects

on company's resource efficiency, energy efficiency

and renewable energy use, it is necessary to explain

characteristics of linear and circular economy.

Lineareconomy currently predominates. It

is material and energy intensive way of

production; it relies on economies of scale and it

is based on the assumption that natural resources

are available, abundant, easy to source and

cheap to dispose of. But, it is not sustainable,

and in some cases exceeding planetary

boundaries [1].

In the current linear system, around 80%of

materials extracted and used for the production

end up in incinerators, landfill or wastewater [2].

Another financial and economic impact of note

in the linear economy is the associatedenergy

loss whenever materials are discarded

somewhere in the value chain [3].

Opportunities to increase resource effciency

in modern manufacturing processes still exist.

But the gains are largely incremental and

95


6

[22] Petráš D, Lulkovičová O, Takács J, Füri B: Obnoviteľ nézdroje energie pre nízkoteplotné systémy. Bratislava: Jaga Group, s.r.o., 2009. 221 s. ISBN 978-80-8076-075-5

[23] Takács J, Lulkovičová O, Füri B: Helyzetkép a megújuló energiaforrások hasznosítasi lehetöségeiről Szlovákiában In: Magyar Épületgépészet. - ISSN 1215-9913. – vol. 57, 12 (2008), s. 24-27



Acknowledgements

An international co-operation between Trakya

University and Budapest University of Technology

and Economics to investigate TSC behaviour has

been funded by the “National Talent Program” of the

Hungarian Human Capacities Fund. For the support

that made a research semester at Trakya University

possible, author B. Bokor would thereby like to give

thanks to the Hungarian Ministry of Human

Capacities.

EXPRES 2017

ISBN 978-86-919769-1-0

Circular business model – effects on company’s energy efficiency and renewable energy use

S. TOMIĆ a, D. DELIĆ b, A. STOILJKOVIĆ c

Faculty of Economics, Universityof Novi Sad

24000 Subotica, Segedinski put 9-11, Serbia aE-mail:[email protected] bE-mail:[email protected]

cE-mail:[email protected]

In essence, a circular business model represents a fundamental alternative to linear business model.Circular business model

incorporate circular economy principles. In circular business models resources do not get lost or the loss is minimised. In this

paper, through the explanation of what are circular economy, sustainable business model and subsequently the circular business

model, weindicate how different approaches, archetypes or business model can affects company’s energy efficiency and

renewable energy use.

Key words: linear busiess model, circular business model, waste, energy

1. Introduction

Circularity is an approach which stands in contrast

to the linear, traditional production and consumption

(take – make – consume - dispose) pattern.

Circularity involves the joining up of the value

chain so that end-of-life products are reused as

inputs, and waste is utilized as a resource (material

or energy) wherever possible. Unlike the traditional

linear approach, a circular models (closed-loop,

cradle-to-cradle and similar) seek to respect

planetary boundaries through increasing the share of

renewable or recyclable resources while reducing

the consumption of raw materials and energy.At the

same time, circular models contribute to cutting

emissions and material losses. In order to better

understand circular business models and its effects

on company's resource efficiency, energy efficiency

and renewable energy use, it is necessary to explain

characteristics of linear and circular economy.

Lineareconomy currently predominates. It

is material and energy intensive way of

production; it relies on economies of scale and it

is based on the assumption that natural resources

are available, abundant, easy to source and

cheap to dispose of. But, it is not sustainable,

and in some cases exceeding planetary

boundaries [1].

In the current linear system, around 80%of

materials extracted and used for the production

end up in incinerators, landfill or wastewater [2].

Another financial and economic impact of note

in the linear economy is the associatedenergy

loss whenever materials are discarded

somewhere in the value chain [3].

Opportunities to increase resource effciency

in modern manufacturing processes still exist.

But the gains are largely incremental and

96

EXPRES 2017

ISBN 978-86-919769-1-0

insufficient to generate real competitive advantage

for companies. Manufacturers’ margins are being

compressed by slow growth in demand, increasing

costs, and higher price volatility for resources.

Alternative models of productionand

consumption based on ‘circular’ sources of

value,resource reusing and regenerating natural

capital have drawn the attention of businesses around

the world.

The concept of circular economy describes an

economy with closed material loop. The circular

economy refers to an industrial economy that is

restorative, by intention and aims to maintain the

utility of products, components and materials and

retain their value, treating everything (in the

economy) as a valuable resource.

Based on natural principles, the circular

economy takes its insights from living systems as

these have proved adaptable and resilient, and model

the ‘waste is food’ relationship very well. A major

outcome of taking insights from living systems and

applying them to the economy is the notion of

optimising systems rather than components. Circular

economy, and business models within it, seeks to

reduce energy use per unit of output and accelerate

the shift to renewable energy, improving total energy

efficiency and the share of renewables, which should

both increase compared with the linear model [4].

Circular economy can also facilitate business

(companies) to benefit from higher levels of

collaboration throughout the supply chain and new

ways of creating value. Implementation of circular

economy concept may reveal new sources for

revenue generation in companies or result in

innovations which create new business opportunities.

According to European Environment Agency,

key characteristics of a circular economy are: less

input and use of natural resources, increased share of

renewable and recyclable resources and energy,

reduced emissions, fewer material losses/residual. On

the other hand, the enabling factors of a circular

economy are: eco-design, repair, refurbishment and

remanufacture, recycling, economic incentives and

finance, eco-innovation and business models

including for example collaborative consumption,

collaboration and transparency along the value chain

and collaboration between companies whereby the

wastes or by-products of one become a resource for

another(industrial symbiosis).One of the most

powerful enablers of a circular economy is business

model innovation e.g. circular business models that

successfully incorporate circular economy principles

and have direct and lasting effects on the economic

system and environment [5].

The concept of a circular economy is

relatively new, and its overall economic,

environmental and social effects have yet to be

fully assessed. The transition to a circular

economy is a complex process involving

fundamental changes to production-consumption

systems that affect the environment. These

include financing mechanisms, consumer

behaviour, government intervention,

technological, social and business innovation,

and very important – newbusiness models.

2. Sustainable business model

Business model can be defined as a conceptual

tool containing a set of objects, concepts and their

relationships with the objective to express the

business logic of a specific firm[6]or, as a

conceptual tool which can help understand how

firm does business and therefore can be used for

analysis, comparison and performance

assessment, management, and innovation[7].

Many other descriptions and explanations of a

business model could be found in the literature.

For example, business model can be regarded as a

holistic description on how a firm does business,

or how company convert resources and

capabilities into economic value. Also, business

model can be defined as organisational and

financial 'architecture' of a business or the

rationale of how an organization creates, delivers

and captures value. As it is mentioned at the begging, linear

business model is not sustainable. Therefore, the

short explanation on what sustainable business

model is, will be given. Sustainable business

models capture economic, social and

environmental value for a wide range of

stakeholders or aim to balance economic, social

and ecological needs. Sustainable business model

is a 'business model that creates competitive

advantage through superior customer value and

contributes to a sustainable development of the

company and society' [8]. Sustainable business

model can help embed sustainability into business

purpose and processes (existing industrial models),

and serve as a key driver of competitive

advantage.There are eight sustainable business

model archetypes, divided into three groups:

EXPRES 2017

ISBN 978-86-919769-1-0

Fig.1 Sustainable business model archetype[9]

Giving the context of the title, the focus of this

paper, will be on the first (technological) group and

three archetypes: (1) maximise material and energy

efficiency, (2) create value from ‘waste’ and (3)

substitute with renewables and natural processes.

(1) Sustainable business model archetype

maximise material and energy efficiency means’ do

more with fewer resources’, generate less waste,

emissions and pollution and reduce costs through the

optimised use of resources - material and energy.

Sustainable business model archetype ’maximise

material and energy efficiency’ includes: low carbon

manufacturing solutions, lean manufacturing, additive

manufacturing, dematerialisation (of

products/packaging), increased funcionality of

products, etc. [10].

Maximizing material productivity, resource

efficiency and waste reduction is a response to acute

resource constraints and energy price increase. This

archetype seeks to mitigate environmental impact of

industry by reducing the demand for energy and other

resources, reducing waste and emissions and

contributing to system-wide reduction of resource

consumption.Positive contribution to society and

environment, is achieved through a minimised

environmental footprint.


create value from ‘waste’ includes circular

economy, closed loop model, cradle-to-cradle

approach, industrial symbiosis, reuse,

remanufacture, recycle, extended producer

responsibility,etc. Within this model archetype the

concept of ’waste’ is eliminated by turning

existing waste streams into useful and valuable

input (to other production) [11].

Economic and environmental costs are

reduced through reusing material, and turning

waste into value – waste valorization either as a

material input or energy. Positive contribution to

society and environment is accomplished through

reduced footprint, reduced waste and reduced

virgin material use.

This second archetype is distinct from the first

efficiency archetype, in a sense that it seeks to

identify and create new value from what is

currently perceived as wasterather than seeking to

reduce waste to minimum. This approach is based

on similarities with the natural world where all

’waste’ products become food for another species.

One of the examplesfor sustainable business

model archetype create value from 'waste' is

industrial symbiosis which is process orientated

solution turning waste outputs from one process

into inputs for another process or product line.

Through industrial symbiosis, companies could

Sustainable business model

archetypes

Technological group

3.substitute with renewables and

natural processes

2. create value from 'waste'

1. maximise material and

energy efficiency

Social group

4. deliver functionality,

rather than ownership

5. adopt a stewardship role

6. encourage sufficiency

Organisational group

7. re-purpose the business for

society/environment

8. develop scale-up solutions

97

EXPRES 2017

ISBN 978-86-919769-1-0

insufficient to generate real competitive advantage

for companies. Manufacturers’ margins are being

compressed by slow growth in demand, increasing

costs, and higher price volatility for resources.

Alternative models of productionand

consumption based on ‘circular’ sources of

value,resource reusing and regenerating natural

capital have drawn the attention of businesses around

the world.

The concept of circular economy describes an

economy with closed material loop. The circular

economy refers to an industrial economy that is

restorative, by intention and aims to maintain the

utility of products, components and materials and

retain their value, treating everything (in the

economy) as a valuable resource.

Based on natural principles, the circular

economy takes its insights from living systems as

these have proved adaptable and resilient, and model

the ‘waste is food’ relationship very well. A major

outcome of taking insights from living systems and

applying them to the economy is the notion of

optimising systems rather than components. Circular

economy, and business models within it, seeks to

reduce energy use per unit of output and accelerate

the shift to renewable energy, improving total energy

efficiency and the share of renewables, which should

both increase compared with the linear model [4].

Circular economy can also facilitate business

(companies) to benefit from higher levels of

collaboration throughout the supply chain and new

ways of creating value. Implementation of circular

economy concept may reveal new sources for

revenue generation in companies or result in

innovations which create new business opportunities.

According to European Environment Agency,

key characteristics of a circular economy are: less

input and use of natural resources, increased share of

renewable and recyclable resources and energy,

reduced emissions, fewer material losses/residual. On

the other hand, the enabling factors of a circular

economy are: eco-design, repair, refurbishment and

remanufacture, recycling, economic incentives and

finance, eco-innovation and business models

including for example collaborative consumption,

collaboration and transparency along the value chain

and collaboration between companies whereby the

wastes or by-products of one become a resource for

another(industrial symbiosis).One of the most

powerful enablers of a circular economy is business

model innovation e.g. circular business models that

successfully incorporate circular economy principles

and have direct and lasting effects on the economic

system and environment [5].

The concept of a circular economy is

relatively new, and its overall economic,

environmental and social effects have yet to be

fully assessed. The transition to a circular

economy is a complex process involving

fundamental changes to production-consumption

systems that affect the environment. These

include financing mechanisms, consumer

behaviour, government intervention,

technological, social and business innovation,

and very important – newbusiness models.

2. Sustainable business model

Business model can be defined as a conceptual

tool containing a set of objects, concepts and their

relationships with the objective to express the

business logic of a specific firm[6]or, as a

conceptual tool which can help understand how

firm does business and therefore can be used for

analysis, comparison and performance

assessment, management, and innovation[7].

Many other descriptions and explanations of a

business model could be found in the literature.

For example, business model can be regarded as a

holistic description on how a firm does business,

or how company convert resources and

capabilities into economic value. Also, business

model can be defined as organisational and

financial 'architecture' of a business or the

rationale of how an organization creates, delivers

and captures value. As it is mentioned at the begging, linear

business model is not sustainable. Therefore, the

short explanation on what sustainable business

model is, will be given. Sustainable business

models capture economic, social and

environmental value for a wide range of

stakeholders or aim to balance economic, social

and ecological needs. Sustainable business model

is a 'business model that creates competitive

advantage through superior customer value and

contributes to a sustainable development of the

company and society' [8]. Sustainable business

model can help embed sustainability into business

purpose and processes (existing industrial models),

and serve as a key driver of competitive

advantage.There are eight sustainable business

model archetypes, divided into three groups:

EXPRES 2017

ISBN 978-86-919769-1-0

Fig.1 Sustainable business model archetype[9]

Giving the context of the title, the focus of this

paper, will be on the first (technological) group and

three archetypes: (1) maximise material and energy

efficiency, (2) create value from ‘waste’ and (3)

substitute with renewables and natural processes.


maximise material and energy efficiency means’ do

more with fewer resources’, generate less waste,

emissions and pollution and reduce costs through the

optimised use of resources - material and energy.

Sustainable business model archetype ’maximise

material and energy efficiency’ includes: low carbon

manufacturing solutions, lean manufacturing, additive

manufacturing, dematerialisation (of

products/packaging), increased funcionality of

products, etc. [10].

Maximizing material productivity, resource

efficiency and waste reduction is a response to acute

resource constraints and energy price increase. This

archetype seeks to mitigate environmental impact of

industry by reducing the demand for energy and other

resources, reducing waste and emissions and

contributing to system-wide reduction of resource

consumption.Positive contribution to society and

environment, is achieved through a minimised

environmental footprint.


create value from ‘waste’ includes circular

economy, closed loop model, cradle-to-cradle

approach, industrial symbiosis, reuse,

remanufacture, recycle, extended producer

responsibility,etc. Within this model archetype the

concept of ’waste’ is eliminated by turning

existing waste streams into useful and valuable

input (to other production) [11].

Economic and environmental costs are

reduced through reusing material, and turning

waste into value – waste valorization either as a

material input or energy. Positive contribution to

society and environment is accomplished through

reduced footprint, reduced waste and reduced

virgin material use.

This second archetype is distinct from the first

efficiency archetype, in a sense that it seeks to

identify and create new value from what is

currently perceived as wasterather than seeking to

reduce waste to minimum. This approach is based

on similarities with the natural world where all

’waste’ products become food for another species.

One of the examplesfor sustainable business

model archetype create value from 'waste' is

industrial symbiosis which is process orientated

solution turning waste outputs from one process

into inputs for another process or product line.

Through industrial symbiosis, companies could

Sustainable business model

archetypes

Technological group

3.substitute with renewables and

natural processes

2. create value from 'waste'

1. maximise material and

energy efficiency

Social group

4. deliver functionality,

rather than ownership

5. adopt a stewardship role

6. encourage sufficiency

Organisational group

7. re-purpose the business for

society/environment

8. develop scale-up solutions

98

EXPRES 2017

ISBN 978-86-919769-1-0

improve energy efficiency and/or renewable energy

use by turning by-products and production waste

(leftovers) into energy. For example, coffee chaf,

which has always been treated as a waste, could be

used as a biomass for energy production; chocolate

and sugar confectionary waste, through anaerobic

digestion could be turned into biogas. The same

applies to wastewaters and by-products from the

brewing process, sugar, oil production, etc. [12].

Known as waste-as-a-resource business model,

industrial symbiosis isaiming to use waste as a

resource in order to promote cross-sector and cross-

cycle links by creating markets for secondary raw

materials. These can reduce the use of energy and

materials during production and use, and also

facilitate locally clustered activities to prevent by-

products from becoming wastes. Positive economic

effects can arise from the availability of cheaper

materials diverted from waste as an alternative to

virgin materials, including avoiding the costs of

waste disposal and capturing the residual economic

value of existing material streams. Positive

environmental effects can be measured as a net

reduction in environmental pressure from waste

disposal and the production of virgin materials [13].

Also, closed-loop business models are the

representatives of the above mention archetype, and

include products and processes designed in a manner

that enables waste at the end of the use phase of a

product to be used to create new value. Cradle-to-

cradle approach is based on the idea of a closed loop

technical nutrient cycle with a biological open-loop

cycle.


substitute with renewables and natural processes

includes, among others, move from non-renewable to

renewable energy sources, solar and wind-power based

energy innovations, blue economy, biomimicry, slow

manufacturing, etc. Value creation and delivery within

this archetype is achieved by innovation in products

and production process design by introducing

renewable resources and energy and conceiving new

solutions by mimicking natural systems. New value

networks are based on renewable resource supply and

energy systems, new partnership to deliver holistic

’nature inspired’ solutions. This archetype seeks to

reduce environmental impact of industry by

substitution with renewable resources and natural

processes to create significantly more environmentally

benign materials and industrial (production) processes,

local renewable energy solutions, etc [14].

3. Circular business model

The special attention in this paper will be given to

circular business model as a subcategory of

sustainable business models which fit in an

economic system of restorative or closed material

loops. Circular business model does not need to

close material loops by itself (within its internal

system boundaries), but can also be part of a

system of business models which together close a

material loop in order to be called circular.Circular

business model is the rationale of how an

organization creates, delivers and captures value

with and within closed material loops.

Within circular business model, companies

utilize (internally and/or externally) material and

energy flows including waste and by-products to

reduce the systems virgin material and energy

input as well as the waste emission output from

the system as a whole.To implement circular

economy approach, companies often require new

business models. Closing material loops often

affects multiple, if not all aspects of their current

business models. Notable changes include

different products or services, different

(relationships with) customers, different

production processes and different revenue

models, sometimes including other types of

values than profit.

Fig. 2 Circular business models [15]

Circular business modelsinclude[16]:

EXPRES 2017

ISBN 978-86-919769-1-0

1. Closed loop recycling - using recycled

products as raw materials to manufacture new

products;

2. Downcycling - turning materials from one or

more used products into a new product with lower

quality;

3. Upcycling - turning materials from one or

more used products into a new product, implying an

improvement in quality;

4. Industrial symbiosis - sharing services,

utilities and by-products among industries to improve

resource efficiency;

5. Collection services - Providing a service to

collect old or used products.

On a general level, the most important identified

drivers for business to consider circular business

models are[17]:

1. Economic losses and structural waste. The current

economy is surprisingly wasteful in its model of

value creation. In Europe, material recycling and

waste-based energy recovery captures only 5 percent

of the original raw material value;

2. Price and supply risks. Recently, many companies

have begun to notice that a linear system increases

their exposure to risks, most notably volatile resource

prices and supply disruptions;

3. Natural systems degradation;

4. Regulatory trends;

5. Advances in technology;

6. Acceptance of alternative business models. Circular business model aims to link up all

material and energy flows in an infinite process circle

in order to use resources most efficiently and ideally

don’t create any waste. Through this circular approach,

the sustainability of a whole business network can be

driven. Circular business model offers business

opportunities in terms of cost benefits, brand value,

resource efficiency, strategic opportunities or new

revenue streams, supports the idea of a circular

economy by driving a system level design shift from a

linear to a circular system, reduces environmental

externalities, balancing out the value creation for

business, society and environment [18].

Implementation of circular business model can

prevent value loss in processing. For example, in the

production of consumer goods, significant volumes

of materials are commonly lost during processing.

The Food and Agriculture Organisation estimates

that 8-12% of total food inputs are lost in the

processing stage. There is further potential for

circularity in industrial food processing, where waste

is mostly created as a by-product, such as brewer’s

spent grains in beer-making or orange peel in

juice production [19].

However, it is important to mention that

linear model remains to have other strengths in

today’s business environment and changing to a

circular economy also comes with barriers,

obstacles and costs which should be regarded as

weaknesses or threats. Before starting to design

circular business model, it is importanat to take

into account several things. Due to practical

reasons (limitations), both 100% linear and 100%

circular economies or business models do not

exist. No matters how efficient companies

(industries) can be, there will always be a need

for a minimum amount of natural resources and a

minimum level of waste too. Also, many risks or

barriers to implement a circular business model

should not be neglected and underestimated.

Transition to circular business model often

increase complexity of company’s organisation

and management, ‘creates’ a need for new

information on materials, components, products,

processes, for new ways of collaboration within

company’s units or with other partners.

4. Conclusion

Today’s resource-intensive economies and

companies are confronted with an uncertain supply

of (critical) resources, due to scarcities on the

market, increased governmental intervention,

increased damage to global ecosystems. Responses

to environmental megatrends will necessarily need

to be in parallel with economic and social change.

One of the features of a route to a sustainable

economy might be a closed-loop, circularbusiness

model where nothing is allowed to be wasted or

discarded into environment (waste is treated as

resource).

Linear business models have proven to have

limited potential. Current linear economic model

of take – make – consume-dispose, relies on large

quantities of easily accessible resources and energy

is opposite to a circular model in which planetary

boundaries are respected through resource

conservation and by maximising the use of

resources already available within the economy.

Companies are rethinking and redesigning

their products and employing new design, new

materials and new circular business models.

Circular business models keep materials in the

economy and also enable companies to do so.The

term ‘circular economy’ denotes an industrial

99

EXPRES 2017

ISBN 978-86-919769-1-0

improve energy efficiency and/or renewable energy

use by turning by-products and production waste

(leftovers) into energy. For example, coffee chaf,

which has always been treated as a waste, could be

used as a biomass for energy production; chocolate

and sugar confectionary waste, through anaerobic

digestion could be turned into biogas. The same

applies to wastewaters and by-products from the

brewing process, sugar, oil production, etc. [12].

Known as waste-as-a-resource business model,

industrial symbiosis isaiming to use waste as a

resource in order to promote cross-sector and cross-

cycle links by creating markets for secondary raw

materials. These can reduce the use of energy and

materials during production and use, and also

facilitate locally clustered activities to prevent by-

products from becoming wastes. Positive economic

effects can arise from the availability of cheaper

materials diverted from waste as an alternative to

virgin materials, including avoiding the costs of

waste disposal and capturing the residual economic

value of existing material streams. Positive

environmental effects can be measured as a net

reduction in environmental pressure from waste

disposal and the production of virgin materials [13].

Also, closed-loop business models are the

representatives of the above mention archetype, and

include products and processes designed in a manner

that enables waste at the end of the use phase of a

product to be used to create new value. Cradle-to-

cradle approach is based on the idea of a closed loop

technical nutrient cycle with a biological open-loop

cycle.


substitute with renewables and natural processes

includes, among others, move from non-renewable to

renewable energy sources, solar and wind-power based

energy innovations, blue economy, biomimicry, slow

manufacturing, etc. Value creation and delivery within

this archetype is achieved by innovation in products

and production process design by introducing

renewable resources and energy and conceiving new

solutions by mimicking natural systems. New value

networks are based on renewable resource supply and

energy systems, new partnership to deliver holistic

’nature inspired’ solutions. This archetype seeks to

reduce environmental impact of industry by

substitution with renewable resources and natural

processes to create significantly more environmentally

benign materials and industrial (production) processes,

local renewable energy solutions, etc [14].

3. Circular business model

The special attention in this paper will be given to

circular business model as a subcategory of

sustainable business models which fit in an

economic system of restorative or closed material

loops. Circular business model does not need to

close material loops by itself (within its internal

system boundaries), but can also be part of a

system of business models which together close a

material loop in order to be called circular.Circular

business model is the rationale of how an

organization creates, delivers and captures value

with and within closed material loops.

Within circular business model, companies

utilize (internally and/or externally) material and

energy flows including waste and by-products to

reduce the systems virgin material and energy

input as well as the waste emission output from

the system as a whole.To implement circular

economy approach, companies often require new

business models. Closing material loops often

affects multiple, if not all aspects of their current

business models. Notable changes include

different products or services, different

(relationships with) customers, different

production processes and different revenue

models, sometimes including other types of

values than profit.

Fig. 2 Circular business models [15]

Circular business modelsinclude[16]:

EXPRES 2017

ISBN 978-86-919769-1-0

1. Closed loop recycling - using recycled

products as raw materials to manufacture new

products;

2. Downcycling - turning materials from one or

more used products into a new product with lower

quality;

3. Upcycling - turning materials from one or

more used products into a new product, implying an

improvement in quality;

4. Industrial symbiosis - sharing services,

utilities and by-products among industries to improve

resource efficiency;

5. Collection services - Providing a service to

collect old or used products.

On a general level, the most important identified

drivers for business to consider circular business

models are[17]:

1. Economic losses and structural waste. The current

economy is surprisingly wasteful in its model of

value creation. In Europe, material recycling and

waste-based energy recovery captures only 5 percent

of the original raw material value;

2. Price and supply risks. Recently, many companies

have begun to notice that a linear system increases

their exposure to risks, most notably volatile resource

prices and supply disruptions;

3. Natural systems degradation;

4. Regulatory trends;

5. Advances in technology;

6. Acceptance of alternative business models. Circular business model aims to link up all

material and energy flows in an infinite process circle

in order to use resources most efficiently and ideally

don’t create any waste. Through this circular approach,

the sustainability of a whole business network can be

driven. Circular business model offers business

opportunities in terms of cost benefits, brand value,

resource efficiency, strategic opportunities or new

revenue streams, supports the idea of a circular

economy by driving a system level design shift from a

linear to a circular system, reduces environmental

externalities, balancing out the value creation for

business, society and environment [18].

Implementation of circular business model can

prevent value loss in processing. For example, in the

production of consumer goods, significant volumes

of materials are commonly lost during processing.

The Food and Agriculture Organisation estimates

that 8-12% of total food inputs are lost in the

processing stage. There is further potential for

circularity in industrial food processing, where waste

is mostly created as a by-product, such as brewer’s

spent grains in beer-making or orange peel in

juice production [19].

However, it is important to mention that

linear model remains to have other strengths in

today’s business environment and changing to a

circular economy also comes with barriers,

obstacles and costs which should be regarded as

weaknesses or threats. Before starting to design

circular business model, it is importanat to take

into account several things. Due to practical

reasons (limitations), both 100% linear and 100%

circular economies or business models do not

exist. No matters how efficient companies

(industries) can be, there will always be a need

for a minimum amount of natural resources and a

minimum level of waste too. Also, many risks or

barriers to implement a circular business model

should not be neglected and underestimated.

Transition to circular business model often

increase complexity of company’s organisation

and management, ‘creates’ a need for new

information on materials, components, products,

processes, for new ways of collaboration within

company’s units or with other partners.

4. Conclusion

Today’s resource-intensive economies and

companies are confronted with an uncertain supply

of (critical) resources, due to scarcities on the

market, increased governmental intervention,

increased damage to global ecosystems. Responses

to environmental megatrends will necessarily need

to be in parallel with economic and social change.

One of the features of a route to a sustainable

economy might be a closed-loop, circularbusiness

model where nothing is allowed to be wasted or

discarded into environment (waste is treated as

resource).

Linear business models have proven to have

limited potential. Current linear economic model

of take – make – consume-dispose, relies on large

quantities of easily accessible resources and energy

is opposite to a circular model in which planetary

boundaries are respected through resource

conservation and by maximising the use of

resources already available within the economy.

Companies are rethinking and redesigning

their products and employing new design, new

materials and new circular business models.

Circular business models keep materials in the

economy and also enable companies to do so.The

term ‘circular economy’ denotes an industrial

100

EXPRES 2017

ISBN 978-86-919769-1-0

economy that is restorative by intention and design.

Because it extracts value, in form of material or

energy, from what are otherwise wasted resources,

modern circular business models are inherently more

productive than linear.

A circular economycould offer a platform for

innovative approaches, such as technologies and new

business models to create more economic value from

fewer natural resources.

References

[1] European Environment Agency (2016): Circular

economy in Europe - Developing the knowledge base.

http://www.eea.europa.eu/publications/circular-

economy-in-europe/at_download/file

[2] Ellen McArthur Foundation (2013) Towards Circular

Economy 2 – Opportunities for the consumer goods

sector.

https://www.ellenmacarthurfoundation.org/assets/downloads

/publications/TCE_Report-2013.pdf



sector.





sector.







[6]http://aisel.aisnet.org/cgi/viewcontent.cgi?article=3016&c

ontext=cais

[7] Bocken N.M.P., Short S.W., Rana P., Evans S. (2014), A

literature and practice review to develop sustainable

business model archetypes. Journal of Cleaner

Production, 65, 42-56

[8] Lüdeke-Freund, F. (2010). Towards a conceptual

framework of ‘business models for sustainability’ Paper

presented at theERSCP-EMSU conference, Delft

[9] Bocken N.M.P., Short S.W., Rana P., Evans S. (2014),

A literature and practice review to develop sustainable







[11] Bocken N.M.P., Short S.W., Rana P., Evans S.

(2014), A literature and practice review to develop

sustainable business model archetypes. Journal of

Cleaner Production, 65, 42-56

[12] Tomić S., Delić D. (2016), Effects of Industrial

Symbiosis on Company’s Energy Efficiency and

Renewable Energy Use, Proceedings of the 8th

International Symposium on Exploitation of

Renewable Energy Sources, 96-100


economy in Europe - Developing the knowledge

base.







[15]https://www.forumforthefuture.org/sites/default/file

s/Card%20deck.pdf


s/Infographic.pdf

[17] Ellen McArthur Foundation (2015) Towards

Circular Economy: Business rationale for an

Accelerated Transition

https://www.ellenmacarthurfoundation.org/assets/downl

oads/TCE_Ellen-MacArthur-Foundation_9-Dec-

2015.pdf


s/Infographic.pdf


Circular Economy 2 – Opportunities for the

consumer goods sector.

https://www.ellenmacarthurfoundation.org/assets/d

ownloads/publications/TCE_Report-2013.pdf

[20] Nyers J.: COP and Economic Analysis of the Heat

Recovery from Waste Water using Heat Pumps,

International J. Acta Polytechnica Hungarica Vol.

13, No. 5, 2016.

DOI: 10.12700/APH.13.5.2016.5.8.

EXPRES 2017 ISBN 978-86-919769-1-0

The development of plastic rainwater tank by creating a construction which can be economically produced under domestic circumstances

A. NAGY a, B. DUDINSZKY b , A. SZEKRÉNYES c


Budapest University of Technology and Economics, Budapest, Hungary aE-mail: [email protected] bE-mail: [email protected]

Calculations and analysis have been made concerning a rainwater storage tank family scheduled for approximately a 50 years

lifespan. These tanks bear 4, 5 and 6 m3 nominal cubic capacity, they are of standing cylindric make lowered under the

surface and inside under atmospheric pressure they are loaded.

Keywords: Plastic tank, strength and stability, reinforcement of plastic tank

1. Introduction

The aim is to manufacture economically an

average series of a rainwater storage tank family

expected to be operating reliably for

approximately a 50 years lifespan. These tanks

bear 4, 5 and 6 m3 nominal cubic capacity, they

are of standing cylindric make lowered under the

surface and inside they are under atmospheric

pressure [1].

2. Examining the strength and the

stiffness of a plastic rainwater storage

tank located under the surface The constructional sketch of the rainwater

storage tank under the surface constituting the

subject of our examination can be seen on figure 1. together with the operating external loadings

and the geometric characteristics in use and their

marks.Influential bearing forces:

• The hydrostatic test pressure preceding the placement of the tank under the ground in case of a cylinder with D = 1900 mm

diameter and H = 1600; 1900; 2300 mm

height ;

• The external pressure of the ground

occurring in radial direction in the empty

condition of the tank following the

lowering of the tank under the ground;

• The hydrostatic pressure caused by the

ground water effecting the bottom of the

tank in empty condition;

• In case of the lid the loading caused by the

concentrated force mog effecting the lid of

the man-hole and by the ground (ptf) over

it;

• In empty condition the drifting of the tank

to the surface caused by ground water.

2.1. Examining the stability of the

cylindric shell

In the empty condition of the tank the external

dividing loading (deriving from ground pressure)

effecting the shell of the spherical cylinder

having DdiameterH high SH thickness of its wall

changes according to figure 2.

As figure 2. shows the ground pressure having

radial direction and making an effect along the

length of the shell indicates a change of linear

characteristic. When making calculations we

used the average value of the radial pressure.

Assuming only radial pressure (N1 = 0) the

numerical value of the critical external pressure

(pkrit) which results in losing the stability of the

shell of the cylinder having H = 1600 mm;

1900 mm; 2300 mm height; D = 1900 mm

diameter, SH = 10 mm thickness of the wall,

MPaE 247=∞

characteristic of elasticity, is

given by the Windenburg-Trilling-theory

outlined below:

101

EXPRES 2017

ISBN 978-86-919769-1-0

economy that is restorative by intention and design.

Because it extracts value, in form of material or

energy, from what are otherwise wasted resources,

modern circular business models are inherently more

productive than linear.

A circular economycould offer a platform for

innovative approaches, such as technologies and new

business models to create more economic value from

fewer natural resources.

References







sector.





sector.





sector.







[6]http://aisel.aisnet.org/cgi/viewcontent.cgi?article=3016&c

ontext=cais

[7] Bocken N.M.P., Short S.W., Rana P., Evans S. (2014), A

literature and practice review to develop sustainable



[8] Lüdeke-Freund, F. (2010). Towards a conceptual

framework of ‘business models for sustainability’ Paper

presented at theERSCP-EMSU conference, Delft













[12] Tomić S., Delić D. (2016), Effects of Industrial

Symbiosis on Company’s Energy Efficiency and

Renewable Energy Use, Proceedings of the 8th

International Symposium on Exploitation of

Renewable Energy Sources, 96-100


economy in Europe - Developing the knowledge

base.








s/Card%20deck.pdf


s/Infographic.pdf


Circular Economy: Business rationale for an

Accelerated Transition

https://www.ellenmacarthurfoundation.org/assets/downl

oads/TCE_Ellen-MacArthur-Foundation_9-Dec-

2015.pdf


s/Infographic.pdf


Circular Economy 2 – Opportunities for the

consumer goods sector.

https://www.ellenmacarthurfoundation.org/assets/d

ownloads/publications/TCE_Report-2013.pdf



International J. Acta Polytechnica Hungarica Vol.

13, No. 5, 2016.

DOI: 10.12700/APH.13.5.2016.5.8.

EXPRES 2017 ISBN 978-86-919769-1-0

The development of plastic rainwater tank by creating a construction which can be economically produced under domestic circumstances

A. NAGY a, B. DUDINSZKY b , A. SZEKRÉNYES c


Budapest University of Technology and Economics, Budapest, Hungary aE-mail: [email protected] bE-mail: [email protected]

Calculations and analysis have been made concerning a rainwater storage tank family scheduled for approximately a 50 years

lifespan. These tanks bear 4, 5 and 6 m3 nominal cubic capacity, they are of standing cylindric make lowered under the

surface and inside under atmospheric pressure they are loaded.

Keywords: Plastic tank, strength and stability, reinforcement of plastic tank

1. Introduction

The aim is to manufacture economically an

average series of a rainwater storage tank family

expected to be operating reliably for

approximately a 50 years lifespan. These tanks

bear 4, 5 and 6 m3 nominal cubic capacity, they

are of standing cylindric make lowered under the

surface and inside they are under atmospheric

pressure [1].

2. Examining the strength and the

stiffness of a plastic rainwater storage

tank located under the surface The constructional sketch of the rainwater

storage tank under the surface constituting the

subject of our examination can be seen on figure 1. together with the operating external loadings

and the geometric characteristics in use and their

marks.Influential bearing forces:

• The hydrostatic test pressure preceding the placement of the tank under the ground in case of a cylinder with D = 1900 mm

diameter and H = 1600; 1900; 2300 mm

height ;

• The external pressure of the ground

occurring in radial direction in the empty

condition of the tank following the

lowering of the tank under the ground;

• The hydrostatic pressure caused by the

ground water effecting the bottom of the

tank in empty condition;

• In case of the lid the loading caused by the

concentrated force mog effecting the lid of

the man-hole and by the ground (ptf) over

it;

• In empty condition the drifting of the tank

to the surface caused by ground water.

2.1. Examining the stability of the

cylindric shell

In the empty condition of the tank the external

dividing loading (deriving from ground pressure)

effecting the shell of the spherical cylinder

having DdiameterH high SH thickness of its wall

changes according to figure 2.

As figure 2. shows the ground pressure having

radial direction and making an effect along the

length of the shell indicates a change of linear

characteristic. When making calculations we

used the average value of the radial pressure.

Assuming only radial pressure (N1 = 0) the

numerical value of the critical external pressure

(pkrit) which results in losing the stability of the

shell of the cylinder having H = 1600 mm;

1900 mm; 2300 mm height; D = 1900 mm

diameter, SH = 10 mm thickness of the wall,

MPaE 247=∞

characteristic of elasticity, is

given by the Windenburg-Trilling-theory

outlined below:

102

THE DEVELOPMENT OF PLASTIC RAINWATER TANK BY CREATING A CONSTRUCTION WHICH CAN BE ECONOMICALLY

PRODUCED UNDER DOMESTIC CIRCUMSTANCES

Fig. 2. Stability model

Fig. 1. The external loadings affecting the tank



2

1

2

5

45,0

6,2

−

=

∞

D

S

D

H

D

SE

p

H

H

krit

(1)

Assuming only hydrostatic external pressure (N1

≠ 0) the value of the critical external pressure can

be determined by the Ebner-theory shown below

[2,3].

2

5

6,2

=∞

D

S

H

DEp H

krit (2)

The calculations made based onthe above

relations indicate that the examined cylindric

shells having SH = 10 mm thickness of the wall

are not suitable for bearing the externalgauge

pressure (the horizontal component of the ground

pressure).

A possible reinforcing method of the examined

plastic(PP)cylindric shell can be seen on Figure

3., here the cylinder having Vh = 4 m3 useful

capacity, H = 1600 mm height, D = 1900 mm

diameter is stiffened by 8 radial trusses having

12=bs mm thickness of the wall, 200=fb

mm width and also by four annuli (Z = 4 pieces)

which are 320=∆H mm far from each other,

sized Z = Ø 1900 / Ø 1300 mm, being 12=bs

mm thick. The advantage of the above mentioned

stiffening frame is that it fulfills its duty by being

joined loosely to the shell of the cylinder to be

stiffened without welding, too.

2.2.Examining the whole construction by

finite element method Based on the previous calculations the permanent

geometry of the tank took shape, and by using it

we completed the entire finite element model

which isdemonstrated on Figure 4. In the solving

process we covered the tank being stiffened from

inside and outside with 5335 pieces of SHELL

type finite element. During the calculations we

took into considerations the ground pressure

which effects the shell of the tank in horizontal

direction as well as the load of the ground over

the lid and the central positioned, concentrated

mass powerm0g effecting the man-hole. The

results of the calculations concerning the tank

having Vh= 4 m3useful capacity are demonstrated

on Figures 5. and 6. In case ofh0 = 500 mm

ground covering the influential deformation of

the tank arises on the lid between the stiffening

and supporting trusses , of which numerical value

is f fmax = 15 mm independent of the useful

capacity . While the maximum reduced strain

arises at the junction of the radial external

stiffening truss on the lid and the edge of the

plate, of which value is 8max ≅redσ MPa

independent of the useful capacity. Thus the

calculated values of the influential move and

strain correspond to the relevant specifications

regarding stiffness and strength.

Fig 3. The sketch of the stiffening frame

103



Fig. 2. Stability model

Fig. 1. The external loadings affecting the tank



2

1

2

5

45,0

6,2

−

=

∞

D

S

D

H

D

SE

p

H

H

krit

(1)

Assuming only hydrostatic external pressure (N1

≠ 0) the value of the critical external pressure can

be determined by the Ebner-theory shown below

[2,3].

2

5

6,2

=∞

D

S

H

DEp H

krit (2)

The calculations made based onthe above

relations indicate that the examined cylindric

shells having SH = 10 mm thickness of the wall

are not suitable for bearing the externalgauge

pressure (the horizontal component of the ground

pressure).

A possible reinforcing method of the examined

plastic(PP)cylindric shell can be seen on Figure

3., here the cylinder having Vh = 4 m3 useful

capacity, H = 1600 mm height, D = 1900 mm

diameter is stiffened by 8 radial trusses having

12=bs mm thickness of the wall, 200=fb

mm width and also by four annuli (Z = 4 pieces)

which are 320=∆H mm far from each other,

sized Z = Ø 1900 / Ø 1300 mm, being 12=bs

mm thick. The advantage of the above mentioned

stiffening frame is that it fulfills its duty by being

joined loosely to the shell of the cylinder to be

stiffened without welding, too.

2.2.Examining the whole construction by

finite element method Based on the previous calculations the permanent

geometry of the tank took shape, and by using it

we completed the entire finite element model

which isdemonstrated on Figure 4. In the solving

process we covered the tank being stiffened from

inside and outside with 5335 pieces of SHELL

type finite element. During the calculations we

took into considerations the ground pressure

which effects the shell of the tank in horizontal

direction as well as the load of the ground over

the lid and the central positioned, concentrated

mass powerm0g effecting the man-hole. The

results of the calculations concerning the tank

having Vh= 4 m3useful capacity are demonstrated

on Figures 5. and 6. In case ofh0 = 500 mm

ground covering the influential deformation of

the tank arises on the lid between the stiffening

and supporting trusses , of which numerical value

is f fmax = 15 mm independent of the useful

capacity . While the maximum reduced strain

arises at the junction of the radial external

stiffening truss on the lid and the edge of the

plate, of which value is 8max ≅redσ MPa

independent of the useful capacity. Thus the

calculated values of the influential move and

strain correspond to the relevant specifications

regarding stiffness and strength.

Fig 3. The sketch of the stiffening frame

104



H=1600 mm

Loads:

On thelidofthe tank:

ptf=0.010791 MPa

h0=500 mm

On the shell: ptv=0.010791⋅10-3⋅h MPa,

where h means height

On the edge of the upper nozzle:

p0=0.5204 MPa⋅mm

Fig. 5. The distribution of the resultant displacement in the tank [mm].

Fig. 4. The finite element model of the plastic (PP) tank, inner view (SHELL63 shell part with thin wall).



3. Conclusion

Calculations and analysis have been made

concerning a rainwater storage tank family

scheduled for approximately a 50 yearslifespan.

These tanks bear 4, 5 and 6 m3 nominal cubic

capacity, they are of standing cylindric make

lowered under the surface and inside under

atmospheric pressure they are dynamically

loaded.

Examinations have shown that it is needed to

increase the thickness of the wall significantly

compared to the earlier applied solution so that

the tank in its most dangerous condition (without

water, empty condition) could endure the

external loading caused by surrounding soil.

However, this increase of the thickness of the

wall puts the cost-efficiency and the salebility of

the product at risk. In order to solve the problem

we have prepared a simulation on computer, we

have completed a finite element model and by

using it we have managed to develop in several

steps a material-saving, stiffening construction.

The most essential element of the solution is the

internal stiffening basket structure, which is

suitable to support radially the cylindric shell as

well as to reinforce the lid of the tank further.

The developed basket structure can be

manufactured economically and relatively simply

and it makes its stiffening effect while put in the

inner space before the lid of the tank is

permanently welded on the tank. Calculations

have proved that by applying the stiffening

basket we can save approximately 50 % of the

material used compared to the traditional

construction.

We have not found any solution in the technical

literature for stiffening plastic tanks operating

under the ground with basket structure, which

indicates the originality of our developed

solution

In the process of planning we modeled the

hydrostatic test pressure as well which precedes

the placement of the tank in the ground. We

specified the change of the form and the strain

which develop at the dangerous intersection of

the tank (at the junction of the cylindric shell and

the bottom of the tank) deriving from the

hydrostatic loading. . When calculating the

changes of forms and strains in specifying the

allowable values we took into account the time

dependent processes and their effects which

occur during the prescribed 50 years’ lifespan.

In the process of planning we also examined the

effect of the humidity of the ground on stability.

It was decided that independent of the useful

capacity during the building in a special concrete

base was needed in order to avoid the danger of

H=1600 mm

Loads:


ptf=0.010791 MPa

h0=500 mm

On the shell:

ptv=0.010791⋅10-3⋅h

MPa, where h means height


p0=0.5204 MPa⋅mm

Fig. 6. The distribution of the HMH-type equivalentstress in the tank [MPa].

105



H=1600 mm

Loads:


ptf=0.010791 MPa

h0=500 mm

On the shell: ptv=0.010791⋅10-3⋅h MPa,

where h means height


p0=0.5204 MPa⋅mm

Fig. 5. The distribution of the resultant displacement in the tank [mm].

Fig. 4. The finite element model of the plastic (PP) tank, inner view (SHELL63 shell part with thin wall).



3. Conclusion

Calculations and analysis have been made

concerning a rainwater storage tank family

scheduled for approximately a 50 yearslifespan.

These tanks bear 4, 5 and 6 m3 nominal cubic

capacity, they are of standing cylindric make

lowered under the surface and inside under

atmospheric pressure they are dynamically

loaded.

Examinations have shown that it is needed to

increase the thickness of the wall significantly

compared to the earlier applied solution so that

the tank in its most dangerous condition (without

water, empty condition) could endure the

external loading caused by surrounding soil.

However, this increase of the thickness of the

wall puts the cost-efficiency and the salebility of

the product at risk. In order to solve the problem

we have prepared a simulation on computer, we

have completed a finite element model and by

using it we have managed to develop in several

steps a material-saving, stiffening construction.

The most essential element of the solution is the

internal stiffening basket structure, which is

suitable to support radially the cylindric shell as

well as to reinforce the lid of the tank further.

The developed basket structure can be

manufactured economically and relatively simply

and it makes its stiffening effect while put in the

inner space before the lid of the tank is

permanently welded on the tank. Calculations

have proved that by applying the stiffening

basket we can save approximately 50 % of the

material used compared to the traditional

construction.

We have not found any solution in the technical

literature for stiffening plastic tanks operating

under the ground with basket structure, which

indicates the originality of our developed

solution

In the process of planning we modeled the

hydrostatic test pressure as well which precedes

the placement of the tank in the ground. We

specified the change of the form and the strain

which develop at the dangerous intersection of

the tank (at the junction of the cylindric shell and

the bottom of the tank) deriving from the

hydrostatic loading. . When calculating the

changes of forms and strains in specifying the

allowable values we took into account the time

dependent processes and their effects which

occur during the prescribed 50 years’ lifespan.

In the process of planning we also examined the

effect of the humidity of the ground on stability.

It was decided that independent of the useful

capacity during the building in a special concrete

base was needed in order to avoid the danger of

H=1600 mm

Loads:


ptf=0.010791 MPa

h0=500 mm

On the shell:

ptv=0.010791⋅10-3⋅h

MPa, where h means height


p0=0.5204 MPa⋅mm

Fig. 6. The distribution of the HMH-type equivalentstress in the tank [MPa].

106



the possible drifting up and to be able to load the

bottom of the tank further.

The finished so-called inner stiffening basket

construction, now being suitable as for strength

as well meets the relevant specifications of the

DIN 1989-3 norm in every aspect.

The joinings of the tanks fit in to the connecting

demands of the other parts of the systems (that

are the reduced bringing in of the rainwater from

the filter, the drainage towards the utilization

under pressure, the installation of the electric

energy cables of the cistern pump, the installation

of the replenishment of drinking water, the

installation of a level measuring instrument and

sensors, overflow drainage) which make use of

rainwater.

References [1] J. Powell: Engineering with Polymers AGRU

Kunststofftechnik GmbH Austria, Bad Hall, (2009).

[2] Girkman, K: Flachentragwerke . Springer-Verlag, Wien (1974)

[3] Ebner, H.: Theoretische und experimentelle Untersuchungüber das Einbeulen Zylindrischen Tanks durch Unterdruck. Stahlbau 21, 153 (1952)



EXPRES 2017 ISBN 978-86-919769-1-0

Geothermal heating of public buildings in downtown Zalaegerszeg

J. KONTRA

a, L. GARBAI

a, J. SZANYI

b

aBudapest University of Technology and Economics, Műegyetemrakpart 3., 1111 Budapest


bUniversity of Szeged, Hungary

In Hungary, district heating works on gas basis unbalanced; thermal water is rarely used in town heating. In Zalaegerszeg, there is

no district heating grid at all. Public buildings of the town are heated with individual gas boilers being rather outdated. After

scrapping, it is advisable to switch over to a new geothermal district heating system in public buildings – in the first stage. The

thermal water basis is available, we plan to deepen new thermal wells and a district heating grid shall be constructed. Low-level of

operational costs of heat supply can be guaranteed.

Keywords: district heating, geothermal district heating system, public buildings, thermal wells

1. Present thermal energy consumption of

the institutions of the downtown local

government

Condition of heat generating sources

The local government has defined the institutions

having heat supply systems with individual centers at

present. These institutions apply exclusively gas as

energy carrier for covering their thermal needs.

Location of these institutions can be seen on map no.

1. Typically, these institutions are situated in

downtown, but some lie relatively far away, yet, they

are major consumers.

These institutions include:

• educational establishments including also

nursery schools and kindergartens,

• social and health care establishments,

• cultural institutions.

Gas heating evaluation (boilers)

On the heat source side of the building heating

systems operating currently, we find outdated gas

boilers.

Heating appliances are obsolete.

They are evaluated in terms of the following two main

aspects:

a.) modernity status,

b.) wear and tear, physical aging.

Modernity status

Considering present state of gas heating, only

condensing heating technology can be regarded as

modern where heating technological efficiency may

reach 108-109%. Boilers with efficiency lower than

this are not suitable (FÉG-VESTALE, KOMFORT,

ÉTI). Among the public buildings reviewed, only the

headquarters of the municipality has a modern boiler.

Consumption of all the others is disproportionately

high; they do not meet the Hungarian energy-political

targets as they operate with expensive imported gas,

just for quoting a reason (see the images attached).

Wear and tear, physical aging

All boilers – except for two pieces – are in worn out

condition also physically. Some appliances have been

operating for 25-35 years, they often need cost-

intensive repairs, and their low efficiency goes with

high consumption. Their estimated remaining useful

life is 0 to 1 year. All this justifies their disassembly.

As high-rank energy-political target, a renewable

energy based reconstruction, namely geothermics shall

be realized.

Present state of heat generators of these

institutions

A characteristic feature of heat generators of some

heat consumers is a gas-burning boiler house, one in

each institution. In the only case of the cinema,

heating is provided by outdated steam boilers aged

over 30 years and working with light fuel oil or gas

oil.

107



the possible drifting up and to be able to load the

bottom of the tank further.

The finished so-called inner stiffening basket

construction, now being suitable as for strength

as well meets the relevant specifications of the

DIN 1989-3 norm in every aspect.

The joinings of the tanks fit in to the connecting

demands of the other parts of the systems (that

are the reduced bringing in of the rainwater from

the filter, the drainage towards the utilization

under pressure, the installation of the electric

energy cables of the cistern pump, the installation

of the replenishment of drinking water, the

installation of a level measuring instrument and

sensors, overflow drainage) which make use of

rainwater.

References [1] J. Powell: Engineering with Polymers AGRU

Kunststofftechnik GmbH Austria, Bad Hall, (2009).

[2] Girkman, K: Flachentragwerke . Springer-Verlag, Wien (1974)

[3] Ebner, H.: Theoretische und experimentelle Untersuchungüber das Einbeulen Zylindrischen Tanks durch Unterdruck. Stahlbau 21, 153 (1952)



EXPRES 2017 ISBN 978-86-919769-1-0

Geothermal heating of public buildings in downtown Zalaegerszeg

J. KONTRA

a, L. GARBAI

a, J. SZANYI

b

aBudapest University of Technology and Economics, Műegyetemrakpart 3., 1111 Budapest


bUniversity of Szeged, Hungary

In Hungary, district heating works on gas basis unbalanced; thermal water is rarely used in town heating. In Zalaegerszeg, there is

no district heating grid at all. Public buildings of the town are heated with individual gas boilers being rather outdated. After

scrapping, it is advisable to switch over to a new geothermal district heating system in public buildings – in the first stage. The

thermal water basis is available, we plan to deepen new thermal wells and a district heating grid shall be constructed. Low-level of

operational costs of heat supply can be guaranteed.

Keywords: district heating, geothermal district heating system, public buildings, thermal wells

1. Present thermal energy consumption of

the institutions of the downtown local

government

Condition of heat generating sources

The local government has defined the institutions

having heat supply systems with individual centers at

present. These institutions apply exclusively gas as

energy carrier for covering their thermal needs.

Location of these institutions can be seen on map no.

1. Typically, these institutions are situated in

downtown, but some lie relatively far away, yet, they

are major consumers.

These institutions include:

• educational establishments including also

nursery schools and kindergartens,

• social and health care establishments,

• cultural institutions.

Gas heating evaluation (boilers)

On the heat source side of the building heating

systems operating currently, we find outdated gas

boilers.

Heating appliances are obsolete.

They are evaluated in terms of the following two main

aspects:

a.) modernity status,

b.) wear and tear, physical aging.

Modernity status

Considering present state of gas heating, only

condensing heating technology can be regarded as

modern where heating technological efficiency may

reach 108-109%. Boilers with efficiency lower than

this are not suitable (FÉG-VESTALE, KOMFORT,

ÉTI). Among the public buildings reviewed, only the

headquarters of the municipality has a modern boiler.

Consumption of all the others is disproportionately

high; they do not meet the Hungarian energy-political

targets as they operate with expensive imported gas,

just for quoting a reason (see the images attached).

Wear and tear, physical aging

All boilers – except for two pieces – are in worn out

condition also physically. Some appliances have been

operating for 25-35 years, they often need cost-

intensive repairs, and their low efficiency goes with

high consumption. Their estimated remaining useful

life is 0 to 1 year. All this justifies their disassembly.

As high-rank energy-political target, a renewable

energy based reconstruction, namely geothermics shall

be realized.

Present state of heat generators of these

institutions

A characteristic feature of heat generators of some

heat consumers is a gas-burning boiler house, one in

each institution. In the only case of the cinema,

heating is provided by outdated steam boilers aged

over 30 years and working with light fuel oil or gas

oil.

108

GEOTHERMAL HEATING OF PUBLIC BUILDINGS IN DOWNTOWN ZALAEGERSZEG

2. Foreseeable design of the proposed new

geothermal heat source

In the first stage of the development, public buildings

marked red on the map (ones defined by the

municipality) are designated for geothermal heat

supply. Additional buildings identified by us during

our on-site review (marked blue) will also join the

geothermal heat supply.

The district heat supply system is radially arranged.

On the heat source side, there are 3 wells (marked T1,

T2, T3) from where thermal water is transferred to the

thermal water complex [primary side]. Here starts the

district heat supply grid, filled up with soft water of

varying mass flow, and goes to the individual

buildings. The recipient thermal centers may be

designed as direct thermal centers during the future

design process.

The cooled down thermal water comes to the injection

well, while also the heat supply of the nearby two

secondary schools can be solved by the cooled down

water using heat pumps.

3. Proposal for thermal water supply of

the swimming pool of the town

For heat supply and thermal water supply of the

swimming pool of the town we suggest boring a new

thermal well – independently of the geothermal

district heat supply of the town. Practically, this

thermal well would utilize the thermal water of the

Upper Pannon layer, just like to the well at Aqua-Park

marked ZG-3. This means that expectedly it would

yield 40 to 45°C thermal water with a bottom

deepness of about 900 to 950 m. This thermal water

may be suitable to heat the sports and leisure pools

and maintain their temperature as well as to supply the

fill–discharge system of the warm water pools

directly. Of course, this thermal water can be used

also for heating the swimming pool building and for

domestic hot water supply – possibly supported by

heat pump.

Usage of CH-dry wells

Based on the experience obtained in thermal water

utilization in Hungary, transformation of dry

hydrocarbon wells into thermal water production is

not successful and economical in all cases because

state and tubing of the well may cause

problems;

subsequent filter tubing results in strong

choking;

production is possible with compressor-

supported artificial exploitation only (e.g. in

Kiskunmajsa), diving pumps cannot be

applied.

Due to these risk factors, usage of abandoned

hydrocarbon wells is not recommended.

Locations of the new thermal wells proposed

On the map, we propose two locations for establishing

new wells:

- Békeliget and

- the area between the shopping center and

railways.

Optimum distance of these well locations and

convenient situation of the thermal water complex

justify this selection. However, the precise well

locations will be defined based on deep-going

thermal water geological, seismological and other.

4. Estimated investment costs of stage I

Decrease of expenses (cost reduction)

Heating demand of consumers varies with weather

and time within a day. These variations can be

controlled. Outdated equipment pieces are manually

controlled, but changes in heat demand can be

controlled manually with considerable inaccuracy

only, leading to wasting operation. Expenses can only

be reduced by controllability of the internal

temperature of consumers. Control of internal

temperature depending on weather and time of day

can be realized with central control valves or

thermostatic valves mounted to the heating panels. Via

control on the consumer side, the circulated thermal

water quantity can be changed, and this way, a

thermal water consumption corresponding to changes

of weather and times of day can be realized. Instead of

choke and mix control of pumps used for thermal

water transport, significant energy saving can be

attained by changing revolutions controlled by

frequency changer.

After optimizing internal temperature and thermal

water quantity circulated, control of water quantity

exploited from the thermal well is the next task. In the

case of a positive well, it can be solved by a control

valve while in the case of mechanical exploitation, it

is possible by changing number of revolutions of the

drowned pump. In this case, we propose control of

revolutions of drowned pumps.


Heating with varying volume flow instead of constant

volume flow results in reduction of thermal water and

energy consumption. For comparison, we give here

annual water quantity circulated in a 90/70°C system

controlled alone by quality (constant volume flow)

and controlled alone by quantity (varying volume

flow) for one unit of heat output demand (1,000 kW)

when thermal water temperature is 95°C. While in a

system of constant volume flow, the circulated water

quantity is annually 47,300 cubic meters, in a system

of varying volume flow, 33,800 cubic meters pro year

are sufficient, and this means almost 30% saving.

For performing control tasks, freely programmable

controllers (PLCs, DDCs) can be applied, enabling

implementation of monitoring systems.

Fig. 1.Plannedgridtrack and wellschema

5. Design of a district heating grid based on

geothermal energy

District heat supply is an important sector of

energetics industry both in Europe and in Hungary.

650 thousand flats constructed with prefabricated

technology in the past decades are heated with

district heat. Grid-based utilities play essential role in

settlements. Among utility grids, district heating

systems represent the most complex technology.

They are equipment-intensive, their investments and

operation are expensive, while their role is important

in energetics because they allow realizing co-

generation of heat and electricity and they ideally

facilitate utilization of renewable energy carriers and

fulfil guidelines formulated in energy policy of the

European Union. Unfortunately, in Hungary, thermal

water based district heat supply operates in about ten

settlements only. In the next years, we expect changes

in this field and hope that an increasing number of

settlements will utilize thermodynamic and economic

advantages of thermal water. Geological capabilities

of Zalaegerszeg and its region provide excellent

109


2. Foreseeable design of the proposed new

geothermal heat source

In the first stage of the development, public buildings

marked red on the map (ones defined by the

municipality) are designated for geothermal heat

supply. Additional buildings identified by us during

our on-site review (marked blue) will also join the

geothermal heat supply.

The district heat supply system is radially arranged.

On the heat source side, there are 3 wells (marked T1,

T2, T3) from where thermal water is transferred to the

thermal water complex [primary side]. Here starts the

district heat supply grid, filled up with soft water of

varying mass flow, and goes to the individual

buildings. The recipient thermal centers may be

designed as direct thermal centers during the future

design process.

The cooled down thermal water comes to the injection

well, while also the heat supply of the nearby two

secondary schools can be solved by the cooled down

water using heat pumps.

3. Proposal for thermal water supply of

the swimming pool of the town

For heat supply and thermal water supply of the

swimming pool of the town we suggest boring a new

thermal well – independently of the geothermal

district heat supply of the town. Practically, this

thermal well would utilize the thermal water of the

Upper Pannon layer, just like to the well at Aqua-Park

marked ZG-3. This means that expectedly it would

yield 40 to 45°C thermal water with a bottom

deepness of about 900 to 950 m. This thermal water

may be suitable to heat the sports and leisure pools

and maintain their temperature as well as to supply the

fill–discharge system of the warm water pools

directly. Of course, this thermal water can be used

also for heating the swimming pool building and for

domestic hot water supply – possibly supported by

heat pump.

Usage of CH-dry wells

Based on the experience obtained in thermal water

utilization in Hungary, transformation of dry

hydrocarbon wells into thermal water production is

not successful and economical in all cases because

state and tubing of the well may cause

problems;

subsequent filter tubing results in strong

choking;

production is possible with compressor-

supported artificial exploitation only (e.g. in

Kiskunmajsa), diving pumps cannot be

applied.

Due to these risk factors, usage of abandoned

hydrocarbon wells is not recommended.

Locations of the new thermal wells proposed

On the map, we propose two locations for establishing

new wells:

- Békeliget and

- the area between the shopping center and

railways.

Optimum distance of these well locations and

convenient situation of the thermal water complex

justify this selection. However, the precise well

locations will be defined based on deep-going

thermal water geological, seismological and other.

4. Estimated investment costs of stage I

Decrease of expenses (cost reduction)

Heating demand of consumers varies with weather

and time within a day. These variations can be

controlled. Outdated equipment pieces are manually

controlled, but changes in heat demand can be

controlled manually with considerable inaccuracy

only, leading to wasting operation. Expenses can only

be reduced by controllability of the internal

temperature of consumers. Control of internal

temperature depending on weather and time of day

can be realized with central control valves or

thermostatic valves mounted to the heating panels. Via

control on the consumer side, the circulated thermal

water quantity can be changed, and this way, a

thermal water consumption corresponding to changes

of weather and times of day can be realized. Instead of

choke and mix control of pumps used for thermal

water transport, significant energy saving can be

attained by changing revolutions controlled by

frequency changer.

After optimizing internal temperature and thermal

water quantity circulated, control of water quantity

exploited from the thermal well is the next task. In the

case of a positive well, it can be solved by a control

valve while in the case of mechanical exploitation, it

is possible by changing number of revolutions of the

drowned pump. In this case, we propose control of

revolutions of drowned pumps.


Heating with varying volume flow instead of constant

volume flow results in reduction of thermal water and

energy consumption. For comparison, we give here

annual water quantity circulated in a 90/70°C system

controlled alone by quality (constant volume flow)

and controlled alone by quantity (varying volume

flow) for one unit of heat output demand (1,000 kW)

when thermal water temperature is 95°C. While in a

system of constant volume flow, the circulated water

quantity is annually 47,300 cubic meters, in a system

of varying volume flow, 33,800 cubic meters pro year

are sufficient, and this means almost 30% saving.

For performing control tasks, freely programmable

controllers (PLCs, DDCs) can be applied, enabling

implementation of monitoring systems.

Fig. 1.Plannedgridtrack and wellschema

5. Design of a district heating grid based on

geothermal energy

District heat supply is an important sector of

energetics industry both in Europe and in Hungary.

650 thousand flats constructed with prefabricated

technology in the past decades are heated with

district heat. Grid-based utilities play essential role in

settlements. Among utility grids, district heating

systems represent the most complex technology.

They are equipment-intensive, their investments and

operation are expensive, while their role is important

in energetics because they allow realizing co-

generation of heat and electricity and they ideally

facilitate utilization of renewable energy carriers and

fulfil guidelines formulated in energy policy of the

European Union. Unfortunately, in Hungary, thermal

water based district heat supply operates in about ten

settlements only. In the next years, we expect changes

in this field and hope that an increasing number of

settlements will utilize thermodynamic and economic

advantages of thermal water. Geological capabilities

of Zalaegerszeg and its region provide excellent

110

4


opportunities for utilizing geothermal energy as well

as for generating high-enthalpy thermal water.

Economic utilization of thermal water and expansion

of its application by a wide range of consumers may

be allowed by constructing a district heating system.

Economic optimization of establishing and operating

district heating systems may reduce costs of district

heating considerably. Optimization of construction

means definition of optimum tube diameters.

Grid planning

We propose a pipeline track system of radial topology

that can be constructed in multiple stages. We have

dimensioned the grid and pipeline diameters so that

they cover also demands of the second stage. The grid

will be designed for the reviewed number of

consumers based on the specified heat demands. We

regard temperature of the exploited thermal water to be

85 to 90 °C and, based on it, we construct an indirect

system of district heating grid of a primary temperature

drop of 80-50 °C. Usually, consumers are placed in a

separate heat center, and we reckon with convertibility

of the existing thermal centers. Basedon experience,

heat centers and secondary systems are exaggerated,

and the previous temperature drop of 90-70°C can be

replaced by a temperature drop of 70-55°C.

Fundamental formulas applied within calculations:

• Mass flow:

m = − .

Temperature values in the formula: = 80° and = 50 °.

• Volume flow:

= .

• Flow rate:

v =

.

• Reynolds number:

= ∙ .

• Coefficient of pipe friction:

Coefficient of pipe friction λ is calculated within

iteration steps by the help of Colebrook-White

relation because flow occurs in the range called

transient zone.

1√ = −2 ∙ 3,7 ∙

+ 2,51√ .

• Specific resistance:

= + 8 ∙

∙ .

• Pressure drop based on the hydraulic Ohm’s law:

Δp = ∙ .

References

[1] Garbai L., Kontra J.: Zalaegerszegváros geotermális alapú távhő

ellátása (Geothermal sourced district heat supply of town

Zalaegerszeg) (study), Budapest, 2015

[2] Kontra J., Varga J.: Távhő Cselekvési Terv Geotermális

energetikai fejezete (District Heat Action Plan, Section

Geothermal Energetics) Budapest, 2013

[3] Kontra J.: Lakitelek Népfőiskola geotermális energia hasznosítási

és épület rekonstrukciós tervezésés tanulmány (Geothermal

energy utilization and building reconstruction plan and study of

Lakitelek College) Budapest, 2012



International J. Acta Polytechnica Hungarica Vol. 13, No.

5, 2016. DOI: 10.12700/APH.13.5.2016.5.8.

[5] Kurčová M., Ehrenwald P.: Possibility Cooperation of

Space Heating System with Heat Pump, 8th International

Symposium on Exploitation of Renewable Energy

Sources, EXPRES 2016, Subotica, Serbia, Proceedings

pp. 52-56, ISBN 978-86-919769-0-3.

[6] Nyers J.: A new analytical method for defining the

pump's power optimum of a water-to-water heat pump

heating system using COP, I J Thermal Science, pp 324.

2016, online. DOI 10.2298/TSCI161110324N

[7] Zuza Straková, Ján Takács: The Mechanical Ventilation

for Large-Area Buildings of Engineering Industry, 8th

International Symposium on Exploitation of Renewable

Energy Sources, EXPRES 2016, Subotica, Serbia,

Proceedings pp. 41-45, ISBN 978-86-919769-0-3.

[8] Belo B. Füri: Experimental Measurements with Methanol

filled vertical Thermo-siphon for receiving Energy of

Environment, Symposium EXPRES 2016, Subotica,

Serbia, Proceedings pp. 20-24, ISBN 978-86-919769-0-

3.

THERMAL COMFORT TESTS USING THERMAL MANIKINS EXPRES 2017 ISBN 978-86-919769-1-0

Thermal comfort tests using thermal manikin BALÁZS CAKÓ

PhD Student

Breuer Marcell Doctorial School, University of Pécs, Faculty of Engineering and Information Technology

Department of Mechanical Engineering at University of Pécs, Faculty of Engineering and Information Technology

2 Boszorkány u.,H-7626 Pécs Hungary


Keywords:thermal manikin, comfort theory, thermal comfort, test chamber

1. Introduction People spend almost 90% of their lives indoors,

therefore it is essential that designedinteriors should

provide comfortable circumstances where one can

feel fine and is capable of achieving optimal

performance both in terms of physical and mental

work. Comfort theory as a scientific field of research

has been given priority amongst research areas only in

the past few decades. Research showsthat physical

parameters such as air temperature, humidity, air

velocity and temperature of the surface that human

thermal sensation of the enclosed interior play

significant role in the development of human thermal

sensation. Obviously, other parameters such as air

movement, noise, lighting and a variety of radiations

(ionization, solar radiation, vibration)also contributeto

the achievement of optimal well-being. In my

research, I mainly study thermal comfort, i.e.the

impacts of temperature, humidity and air movement

on human well-being. Human thermal sensation or

thermal comfort is defined by ASHRAE (1981) 55-81

standard as follows: "Pleasant thermal sensation is a

state of mind expressing satisfaction in terms of

thermal environment."

2. An Overview of Comfort Theory

One’s satisfaction in terms of thermal environment is

determined by the heat and mass transfer between the

body and the environment, which is greatly

influenced by the activity being done, the

environment and clothing. The activity has a great

impact on the heat production, heat loss and heat

control of a human body. Mass transport largely

depends on air temperature, its spatial and temporal

distribution and change, the medium radiation of the

ambient surfaces, as well as the partial pressure of

water vapour in air and air speed. In addition, is

depends on the thermal insulation of clothing and the

way affects evaporation.

Human body develops heat in four ways: convection

(32-35%), radiation (42-44%), evaporation (21-26%),

and conduction (breathing) (2-4%). Their extent

highly depends on the temperature of the human

body, the surrounding air and surfaces, which is

illustrated in the following diagram.

Fig. 1. Correlation between temperature and heat loss

If, for sake of interpretation, the temperature of the

human body is considered constant and independent

of outside temperature, it can be seen that when the

outside temperature increases, dry heat loss is

reduced, while wet heat loss increasesin order the

0

20

40

60

80

100

120

140

160

10 20 30

Heat

loss

[W]

Temperature [°C]

Total heat loss= dry+wet

Dry heat loss= radiation+convection

Heat loss by radiation Heat loss by Convection

Wet heat loss= evaporation + breathing Heat loss by evaporation

111

4


opportunities for utilizing geothermal energy as well

as for generating high-enthalpy thermal water.

Economic utilization of thermal water and expansion

of its application by a wide range of consumers may

be allowed by constructing a district heating system.

Economic optimization of establishing and operating

district heating systems may reduce costs of district

heating considerably. Optimization of construction

means definition of optimum tube diameters.

Grid planning

We propose a pipeline track system of radial topology

that can be constructed in multiple stages. We have

dimensioned the grid and pipeline diameters so that

they cover also demands of the second stage. The grid

will be designed for the reviewed number of

consumers based on the specified heat demands. We

regard temperature of the exploited thermal water to be

85 to 90 °C and, based on it, we construct an indirect

system of district heating grid of a primary temperature

drop of 80-50 °C. Usually, consumers are placed in a

separate heat center, and we reckon with convertibility

of the existing thermal centers. Basedon experience,

heat centers and secondary systems are exaggerated,

and the previous temperature drop of 90-70°C can be

replaced by a temperature drop of 70-55°C.

Fundamental formulas applied within calculations:

• Mass flow:

m = − .

Temperature values in the formula: = 80° and = 50 °.

• Volume flow:

= .

• Flow rate:

v =

.

• Reynolds number:

= ∙ .

• Coefficient of pipe friction:

Coefficient of pipe friction λ is calculated within

iteration steps by the help of Colebrook-White

relation because flow occurs in the range called

transient zone.

1√ = −2 ∙ 3,7 ∙

+ 2,51√ .

• Specific resistance:

= + 8 ∙

∙ .

• Pressure drop based on the hydraulic Ohm’s law:

Δp = ∙ .

References

[1] Garbai L., Kontra J.: Zalaegerszegváros geotermális alapú távhő

ellátása (Geothermal sourced district heat supply of town

Zalaegerszeg) (study), Budapest, 2015

[2] Kontra J., Varga J.: Távhő Cselekvési Terv Geotermális

energetikai fejezete (District Heat Action Plan, Section

Geothermal Energetics) Budapest, 2013

[3] Kontra J.: Lakitelek Népfőiskola geotermális energia hasznosítási

és épület rekonstrukciós tervezésés tanulmány (Geothermal

energy utilization and building reconstruction plan and study of

Lakitelek College) Budapest, 2012



International J. Acta Polytechnica Hungarica Vol. 13, No.

5, 2016. DOI: 10.12700/APH.13.5.2016.5.8.

[5] Kurčová M., Ehrenwald P.: Possibility Cooperation of

Space Heating System with Heat Pump, 8th International

Symposium on Exploitation of Renewable Energy

Sources, EXPRES 2016, Subotica, Serbia, Proceedings

pp. 52-56, ISBN 978-86-919769-0-3.

[6] Nyers J.: A new analytical method for defining the

pump's power optimum of a water-to-water heat pump

heating system using COP, I J Thermal Science, pp 324.

2016, online. DOI 10.2298/TSCI161110324N

[7] Zuza Straková, Ján Takács: The Mechanical Ventilation

for Large-Area Buildings of Engineering Industry, 8th

International Symposium on Exploitation of Renewable

Energy Sources, EXPRES 2016, Subotica, Serbia,

Proceedings pp. 41-45, ISBN 978-86-919769-0-3.

[8] Belo B. Füri: Experimental Measurements with Methanol

filled vertical Thermo-siphon for receiving Energy of

Environment, Symposium EXPRES 2016, Subotica,

Serbia, Proceedings pp. 20-24, ISBN 978-86-919769-0-

3.

THERMAL COMFORT TESTS USING THERMAL MANIKINS EXPRES 2017 ISBN 978-86-919769-1-0

Thermal comfort tests using thermal manikin BALÁZS CAKÓ

PhD Student

Breuer Marcell Doctorial School, University of Pécs, Faculty of Engineering and Information Technology

Department of Mechanical Engineering at University of Pécs, Faculty of Engineering and Information Technology

2 Boszorkány u.,H-7626 Pécs Hungary


Keywords:thermal manikin, comfort theory, thermal comfort, test chamber

1. Introduction People spend almost 90% of their lives indoors,

therefore it is essential that designedinteriors should

provide comfortable circumstances where one can

feel fine and is capable of achieving optimal

performance both in terms of physical and mental

work. Comfort theory as a scientific field of research

has been given priority amongst research areas only in

the past few decades. Research showsthat physical

parameters such as air temperature, humidity, air

velocity and temperature of the surface that human

thermal sensation of the enclosed interior play

significant role in the development of human thermal

sensation. Obviously, other parameters such as air

movement, noise, lighting and a variety of radiations

(ionization, solar radiation, vibration)also contributeto

the achievement of optimal well-being. In my

research, I mainly study thermal comfort, i.e.the

impacts of temperature, humidity and air movement

on human well-being. Human thermal sensation or

thermal comfort is defined by ASHRAE (1981) 55-81

standard as follows: "Pleasant thermal sensation is a

state of mind expressing satisfaction in terms of

thermal environment."

2. An Overview of Comfort Theory

One’s satisfaction in terms of thermal environment is

determined by the heat and mass transfer between the

body and the environment, which is greatly

influenced by the activity being done, the

environment and clothing. The activity has a great

impact on the heat production, heat loss and heat

control of a human body. Mass transport largely

depends on air temperature, its spatial and temporal

distribution and change, the medium radiation of the

ambient surfaces, as well as the partial pressure of

water vapour in air and air speed. In addition, is

depends on the thermal insulation of clothing and the

way affects evaporation.

Human body develops heat in four ways: convection

(32-35%), radiation (42-44%), evaporation (21-26%),

and conduction (breathing) (2-4%). Their extent

highly depends on the temperature of the human

body, the surrounding air and surfaces, which is

illustrated in the following diagram.

Fig. 1. Correlation between temperature and heat loss

If, for sake of interpretation, the temperature of the

human body is considered constant and independent

of outside temperature, it can be seen that when the

outside temperature increases, dry heat loss is

reduced, while wet heat loss increasesin order the

0

20

40

60

80

100

120

140

160

10 20 30

Heat

loss

[W]

Temperature [°C]

Total heat loss= dry+wet

Dry heat loss= radiation+convection

Heat loss by radiation Heat loss by Convection

Wet heat loss= evaporation + breathing Heat loss by evaporation

112

THERMAL COMFORT TESTS USING THERMAL MANIKINS

body could lose the heat produced during metabolic

processes. One of the tools of the in-depth assessment

of these effects is a thermal manikin.

research conducted with thermal manikins does not

usually include test done with perspiring manikins,

and the available literature do not address

sufficient detail. Therefore, my aim is

3. Background

Thermal manikins were originally developed for

US military to test protective clothing,

thermal sensation research was carried out with

Instead of subjective judgment, thermal manikin

offered a better, more accurate optionto conduct further

comfort-theory tests and applications in

medicine. The historical background of m

that at we carried out thermal comfort studies led by

Zoltán Magyar at the University of Pécs, Faculty of

Engineering and Information Technology

the following) with a thermal manikin currently owned

by the Budapest University of Technology and

Economics. Utilizing the research conducted

education, I carried outradiation asymmetry

measured the thermal capacity of various

practice classes.

Fig. 2. Segments of

thethermal manikin

The thermal manikin used for the research

assembled by Swedish professionals at the

Architecturein the 1980s. This manikin later

Department of Building Engineering at the Budapest

University of Technology, the University of Pécs was

the Department of Mechanical Engineering

University of Pécs, Faculty of Engineering and

Information Technology received it in 2010 for

research purposes, where a new, state of the art data

logger and software for processing was installed in it

The thermal manikin is a model made up of a thermal

The test chamber used in the tests is found at

THERMAL COMFORT TESTS USING THERMAL MANIKINS ISBN 978-86

produced during metabolic

depth assessment

thermal manikin. Currently,

conducted with thermal manikins does not

include test done with perspiring manikins,

the available literature do not address this topic in

, my aim is to expand

knowledge on thermal comfort, particularly due to

evaporation. The research aims to explore the

combined effects of the factors

comfort, and to complement the current evidence

earlier researches. The expected result is a

algorithm for designing thermal comfort, which

could be included in the relevant standards

originally developed for the

test protective clothing, and later

carried out with them.

hermal manikins

tionto conduct further

applications in human

The historical background of my research is

carried out thermal comfort studies led by dr.

University of Pécs, Faculty of

Engineering and Information Technology (UPFEIT in

currently owned


he research conducted there in

radiation asymmetry tests and

various during test

The thermal manikin used for the research was

professionals at the Institute of

later got to the

at the Budapest

, the University of Pécs was

the Department of Mechanical Engineering at



, where a new, state of the art data

was installed in it.

made up of a thermal

test body, a control unit, data logger and

display carrying outdata processing and display

test body was developed from a plastic dummy that has

the same dimensions as those of an average adult.The

body is a fiberglass reinforced polyester shell,

items providing mechanical support

cavities of it, as well as the pipes required for

the flat cables leading to each body part

the manikin was divided into 18 segments

wires were recessed in the surface of

(section). An aluminium layer of 0.4 mm average

thickness was applied on the

insulation layer by using metal spraying technology,

order to achieve a more uniform temperature

distribution on the whole surface.

testing is to measure the electrical power needed to

maintain the required surface temperature of the heated

body part.

Fig. 3. Thethermal manikinduring testing

The test chamber used in the tests is found at Department of Mechanical Engineering at University

EXPRES 2017 86-919769-1-0

thermal comfort, particularly due to


affecting thermal

complement the current evidence of

. The expected result is a refined

thermal comfort, which later

be included in the relevant standards.

control unit, data logger and a computer

carrying outdata processing and display.The



fiberglass reinforced polyester shell, and the

items providing mechanical support were fitted into the

pipes required for hiding

body part. The surface of

segments, and heating

wires were recessed in the surface of each body part

An aluminium layer of 0.4 mm average

e plastic electrical

etal spraying technology, in

to achieve a more uniform temperature

. The principle of



during testing

Department of Mechanical Engineering at University


of Pécs, Faculty of Engineering and Information

Technology, ant it is a chamber developed in

accordance with the requirements of the relevant

standards and literature for thermal comfort tests, as

4. Previous experiences

A number of problems resented themselves during t

research, industrial orders and the labor

including the maintenance of the existing thermal

manikin, which is quite complicated due to

structural design. In addition, during the

arecurring demand to carry out test breaking down

individual parts of the body

segmentse.g.:when gloves and other complex

clothing were tested. The given surfaces of the test

chamber werealso required to be divided

sub-surfaces of markedly different temperature

to carry out thermal sensation tests modelling ordinary

buildings (radiators located under the windows

test software developed by UPFEITfor the previous

dummy also proved to be difficult, data processing

required a lot of subsequent work and very large

amounts of data had to be used. In view of t

5. The proposedchamber and manikin

The design of the proposed test chamber

from that of the current one. Surfaces are going to be

divided to a number of surface elements that

controlled independently. My further aim

opportunity to realise all possible air

feasible in a space of that in orderto be able to test how

different air conduction systems affect thermal comfort

In addition, my goal is to create a test chamber

humidity can be controlled. The chamber and the wire

networks are going to be designed to be suitable for

medical research (operating room, occupational

tests, etc.). The development of surfaces providing

markedly different surface temperature

complicated by using traditional surface heating and

cooling fields, and the transition of surface temperature

would be not marked enough.For these reasons we

rejected the systems applying water

approach, Peltier modules might offer a solution

advantage of them is that they can heat and cool, the

change can be easily solved without using

are characterized by rapid response, so they might

be used in different shock tests. The surface of the

chamber will be divided to 250x250 mm surface

sections, the surface will be made ofsome material of

good thermal conductivity; the first idea is to apply

copper, which may change depending on

resources available.






well as for measuring the performance of heat emitters.

The chamber is 4 m long, 3.5 m wide and 2.9 m high.

Every surface of the test chamber

cooled separately, thereby it is suitable to perform

radiation asymmetry and comfort tests as well

resented themselves during the

research, industrial orders and the laboratory tests,

existing thermal

which is quite complicated due to its

during the tests, it was

o carry out test breaking down the

individual parts of the body to further

gloves and other complex items of

given surfaces of the test

divided further into

temperature in order


the windows). The

for the previous

, data processing

and very large

In view of these

experiences, may aim is to develop a

thermal manikin and testchamberthan the one used

before, and apply them for thermal comfort

Fig. 4. Software carrying out the tests

nikin

chamber differs greatly

Surfaces are going to be

elements that can be

aim is to provide

all possible air conduction

be able to test how

thermal comfort.

chamber where

. The chamber and the wire

designed to be suitable for

occupational health

opment of surfaces providing

surface temperature is too

traditional surface heating and

surface temperature

For these reasons we

applying water. As a first

modules might offer a solution. The

heat and cool, the

ing valves. They

so they might also

n different shock tests. The surface of the

250x250 mm surface

made ofsome material of

; the first idea is to apply

depending on the financial

Fig. 5. Conceptional development of surface treatment

The Peltier modules will be fixed on the

surface, then heat sinks will be mounted on them

The backside of the module will be

order to provide uniform distribution of the surface

temperature,the copper surface

wallpapered or painted. A specific software is

going to control the Peltier modules

During the development of thermal manikin

surface of the manikin will be divided to more

segments than that of the earlier one, andour

to create a manikin that is able to evaporat

perspire. While developingthe final concept

going to usemy past experiences and

colleagueswith medical background

controlling testing is going to be developed in a

way that both the collection and evaluation of data

would be carried out easier than

EXPRES 2017 86-919769-1-0



can be heated and

ly, thereby it is suitable to perform

tests as well.

, may aim is to develop a more advanced

than the one used

thermal comfort tests.

Software carrying out the tests

development of surface treatment

modules will be fixed on the copper

s will be mounted on them.

ckside of the module will be insulated. In

distribution of the surface

copper surface will be either

A specific software is

modules.

During the development of thermal manikin, the


earlier one, andour aim is

able to evaporate, and

final concept, I am

past experiences and involve

al background. The software

going to be developed in a

both the collection and evaluation of data

easier than before.

113


body could lose the heat produced during metabolic

processes. One of the tools of the in-depth assessment

of these effects is a thermal manikin.

research conducted with thermal manikins does not

usually include test done with perspiring manikins,

and the available literature do not address

sufficient detail. Therefore, my aim is

3. Background

Thermal manikins were originally developed for

US military to test protective clothing,

thermal sensation research was carried out with

Instead of subjective judgment, thermal manikin

offered a better, more accurate optionto conduct further

comfort-theory tests and applications in

medicine. The historical background of m

that at we carried out thermal comfort studies led by

Zoltán Magyar at the University of Pécs, Faculty of

Engineering and Information Technology

the following) with a thermal manikin currently owned


Economics. Utilizing the research conducted

education, I carried outradiation asymmetry

measured the thermal capacity of various

practice classes.

Fig. 2. Segments of

thethermal manikin

The thermal manikin used for the research

assembled by Swedish professionals at the

Architecturein the 1980s. This manikin later

Department of Building Engineering at the Budapest

University of Technology, the University of Pécs was

the Department of Mechanical Engineering



research purposes, where a new, state of the art data

logger and software for processing was installed in it

The thermal manikin is a model made up of a thermal

The test chamber used in the tests is found at


produced during metabolic

depth assessment

thermal manikin. Currently,

conducted with thermal manikins does not

include test done with perspiring manikins,

the available literature do not address this topic in

, my aim is to expand

knowledge on thermal comfort, particularly due to


combined effects of the factors

comfort, and to complement the current evidence

earlier researches. The expected result is a

algorithm for designing thermal comfort, which

could be included in the relevant standards

originally developed for the

test protective clothing, and later

carried out with them.

hermal manikins

tionto conduct further

applications in human

The historical background of my research is

carried out thermal comfort studies led by dr.

University of Pécs, Faculty of

Engineering and Information Technology (UPFEIT in

currently owned


he research conducted there in

radiation asymmetry tests and

various during test

The thermal manikin used for the research was

professionals at the Institute of

later got to the

at the Budapest

, the University of Pécs was

the Department of Mechanical Engineering at



, where a new, state of the art data

was installed in it.

made up of a thermal

test body, a control unit, data logger and

display carrying outdata processing and display



body is a fiberglass reinforced polyester shell,

items providing mechanical support

cavities of it, as well as the pipes required for

the flat cables leading to each body part

the manikin was divided into 18 segments

wires were recessed in the surface of

(section). An aluminium layer of 0.4 mm average

thickness was applied on the

insulation layer by using metal spraying technology,

order to achieve a more uniform temperature

distribution on the whole surface.



body part.

Fig. 3. Thethermal manikinduring testing

The test chamber used in the tests is found at Department of Mechanical Engineering at University

EXPRES 2017 86-919769-1-0

thermal comfort, particularly due to


affecting thermal

complement the current evidence of

. The expected result is a refined

thermal comfort, which later

be included in the relevant standards.

control unit, data logger and a computer

carrying outdata processing and display.The



fiberglass reinforced polyester shell, and the

items providing mechanical support were fitted into the

pipes required for hiding

body part. The surface of

segments, and heating

wires were recessed in the surface of each body part

An aluminium layer of 0.4 mm average

e plastic electrical

etal spraying technology, in

to achieve a more uniform temperature

. The principle of



during testing

Department of Mechanical Engineering at University






4. Previous experiences

A number of problems resented themselves during t

research, industrial orders and the labor

including the maintenance of the existing thermal

manikin, which is quite complicated due to

structural design. In addition, during the

arecurring demand to carry out test breaking down

individual parts of the body

segmentse.g.:when gloves and other complex

clothing were tested. The given surfaces of the test

chamber werealso required to be divided

sub-surfaces of markedly different temperature


buildings (radiators located under the windows

test software developed by UPFEITfor the previous

dummy also proved to be difficult, data processing

required a lot of subsequent work and very large

amounts of data had to be used. In view of t

5. The proposedchamber and manikin

The design of the proposed test chamber

from that of the current one. Surfaces are going to be

divided to a number of surface elements that

controlled independently. My further aim

opportunity to realise all possible air

feasible in a space of that in orderto be able to test how

different air conduction systems affect thermal comfort

In addition, my goal is to create a test chamber

humidity can be controlled. The chamber and the wire

networks are going to be designed to be suitable for

medical research (operating room, occupational

tests, etc.). The development of surfaces providing

markedly different surface temperature

complicated by using traditional surface heating and

cooling fields, and the transition of surface temperature

would be not marked enough.For these reasons we

rejected the systems applying water

approach, Peltier modules might offer a solution

advantage of them is that they can heat and cool, the

change can be easily solved without using

are characterized by rapid response, so they might

be used in different shock tests. The surface of the

chamber will be divided to 250x250 mm surface

sections, the surface will be made ofsome material of

good thermal conductivity; the first idea is to apply

copper, which may change depending on

resources available.








Every surface of the test chamber

cooled separately, thereby it is suitable to perform

radiation asymmetry and comfort tests as well

resented themselves during the

research, industrial orders and the laboratory tests,

existing thermal

which is quite complicated due to its

during the tests, it was

o carry out test breaking down the

individual parts of the body to further

gloves and other complex items of

given surfaces of the test

divided further into

temperature in order


the windows). The

for the previous

, data processing

and very large

In view of these

experiences, may aim is to develop a

thermal manikin and testchamberthan the one used

before, and apply them for thermal comfort

Fig. 4. Software carrying out the tests

nikin

chamber differs greatly

Surfaces are going to be

elements that can be

aim is to provide

all possible air conduction

be able to test how

thermal comfort.

chamber where

. The chamber and the wire

designed to be suitable for

occupational health

opment of surfaces providing

surface temperature is too

traditional surface heating and

surface temperature

For these reasons we

applying water. As a first

modules might offer a solution. The

heat and cool, the

ing valves. They

so they might also

n different shock tests. The surface of the

250x250 mm surface

made ofsome material of

; the first idea is to apply

depending on the financial

Fig. 5. Conceptional development of surface treatment

The Peltier modules will be fixed on the

surface, then heat sinks will be mounted on them

The backside of the module will be

order to provide uniform distribution of the surface

temperature,the copper surface

wallpapered or painted. A specific software is

going to control the Peltier modules

During the development of thermal manikin


segments than that of the earlier one, andour

to create a manikin that is able to evaporat

perspire. While developingthe final concept

going to usemy past experiences and

colleagueswith medical background

controlling testing is going to be developed in a

way that both the collection and evaluation of data

would be carried out easier than

EXPRES 2017 86-919769-1-0



can be heated and

ly, thereby it is suitable to perform

tests as well.

, may aim is to develop a more advanced

than the one used

thermal comfort tests.

Software carrying out the tests

development of surface treatment

modules will be fixed on the copper

s will be mounted on them.

ckside of the module will be insulated. In

distribution of the surface

copper surface will be either

A specific software is

modules.

During the development of thermal manikin, the


earlier one, andour aim is

able to evaporate, and

final concept, I am

past experiences and involve

al background. The software

going to be developed in a

both the collection and evaluation of data

easier than before.

114

THERMAL COMFORT TESTS USING THERMAL MANIKINS EXPRES 2017

ISBN 978-86-919769-1-0

6. Objectives

My primary aim is to study the boundary

conditions of thermal spaces aiming to meet the

thermal comfort needs in the space studied within

the confines of people - buildings - comfort –

energy relations, as well as to establish a design

algorithm for this, which can be applied more

easily than the existing ones. The algorithm is

expected to be made of* empirical, multifactorial

correlations, thereby it is going to be difficult to

perform the calculations manually, therefore I am

going to develop a simulation program for

dimensioning. I am going to apply the following

research methods:

• Laboratory and simulation tests are going to be

carried out in different temperature conditions

• The factors influencing thermal comfort are

going to be studied by modelling winter and

summer conditions.

• The tests are going to be performed at various

ambient temperatures, and their respective heat

losses are going to be measured by the thermal

manikin.

• I am going to study the evaporative heat loss of

the body surface by evaporation and their

effect on thermal sensation.

• The tests are going to be carried out for various

kinds of clothing.

7. Methods

1. Laboratory test with live subjects: a subjective

thermal sensation tests by live subjects, involving

students, completing comfort tests.

2. Laboratory tests with a manikin: evaporation and

heat loss tests by using a thermal manikin in the

test chamber of the heat engineering laboratory.

8. Acknowledgement

The financial background of my studies has

beenprovided by the EU tender project called

EFOP-3.6.1-16-2016-00004 Extensive

improvements at the University of Pécs in order to

implement smart specialization, Smart engineering

solutions serving health promotion - thermal

comfort. My research has been carried out under the

supervision of Mrs. Eördögh Dr. Márta Mária

project supervisor from the Faculty of Engineering

and Information Technology of University of Pécs,

and under the guidance of Dr. László Fülöp.

References

[1] Révai, T., Magyar, Z., Bánhidi, L., Lenkovics, L., Laborc, Gy.

(2011): Don kanyarban viselt katonaruhába öltöztetett műemberen

végzett hőérzeti mérések. Sereg Szemle, 2011 (3).

[2] Magyar, Z., Ambrus, Cs. (2011): Sugárzási hőmérséklet

aszimmetria vizsgálata thermal manikinrel. Magyar

Épületgépészet, 60 (6) pp.1-5.

[3] Magyar, Z. (2011): Measurements with Thermal Manikin.

Instalatorul, Romania. 2011 (8).

[4] Bánhidi, L., Kajtár L. (2000): Komfortelmélet

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