16ME320 – RENEWABLE ENERGY UTILIZATION - SNS ...

[16ME320-REU K.PRAKASH,ASP/MECH,SNSCT

16ME320 – RENEWABLE ENERGY UTILIZATION

Two mark Important questions & Answers

Unit 1

1. Discuss world energy use

world energy consumption for electricity generation by source was coal at 41%,

natural gas at 22%, nuclear at 11%, hydro at 16%, other sources (solar, wind, geothermal,

biomass, etc.) at 6% and oil at 4%. Coal and natural gas were the most used energy fuels

for generating electricity.

2.Define Reserves

"Reserves" represent that portion of demonstrated resources that can be recovered

economically with the application of extraction technology available currently or in the

foreseeable future. Reserves include only recoverable energy

3. Contrast the environmental aspects

All energy sources have some impact on our environment. Fossil fuels—coal, oil, and

natural gas—do substantially more harm than renewable energy sources by most measures,

including air and water pollution, damage to public health, wildlife and habitat loss, water

use, land use, and global warming emissions

4.what is the energy scenario of tamilnadu

Tamilnadu has highest installed renewable energy capacity (7,979 MW by Sep 12, TEDA)

in India. Renewable energy contributes 52% of the total installed capacity of the state. ...

Tamilnadu has the highest growth rate for the wind installation with CAGR of 15% over the

period of five years from FY 2007 to FY 2012

5.Infer the economics of renewable energy

The economics of renewables is about profitability, and profitability depends on three

drivers: (1) the market price or value of renewable electricity; (2) the costs of renewables

SNS COLLEGE OF TECHNOLOGY

COIMBATORE-35

DEPARTMENT OF MECHANICAL ENGINEERING


relative to those of other energy resources; and (3), importantly, policies to promote

renewables and environmental goals

6.List the energy conservation methods

Lighting. ...

Turn off and run equipment only when required. ...

Clean and maintain equipment. ...

Shade windows and walls. ...

Replace existing lights with LED. ...

Use natural airflow. ...

Check air conditioning lines. ...

Optimise appliances.

7. List three non – conventional energy sources of electric energy in India

Currently, some of the important and widely used non conventional sources of energy are

tides, wind, solar geothermal heat, and biomass comprising animal waste, agricultural waste,

and human body waste

8. Mention the present contribution of different types of plants in India

More than 65% of India's electricity generation capacity comes from thermal power plants,

with 85% of the country's thermal power generation being coal-based. The ten biggest

thermal power stations operating in India are all coal-fired, with five of them owned and

operated by state-run National Thermal Power Corporation (NTPC). Power-technology.com

profiles India's ten biggest thermal power plants by installed capacity.

9.What is the approximate amount of total power generation in India

The country's installed power generating capacity of 334.4 gigawatt (GW, or 1,000

megawatts) as of January 2018 is the world's fifth-largest. Over the last five years, India put

up 99.21 GW of additional capacity. Of this, 91.73 GW came from thermal sources, 5.48 GW

from hydro, and 2 GW from nuclear sources

10.Explain about renewable resources

These are capable of being regenerated by ecological processes within reasonable period.

Theyhave potential torenew themselves.Examples: solar, water,wildlife, natural

vegetation.These are furthersub classified into two types such as

i)Continuousresources:continuouslyrenewedresources.(Solarenergy,wind, tidal

energy)ii)Extrinsicresources:resourcesarepronetobreakdownordegradation,yet are

continuously if wellmanaged. (Human skills, institutions, management abilities)

11.What arefive basiccauses of environmental problems?

Unsustainable resource, Rapid population growth, Poverty, Neglecting environmental costs in

production, Lack ofawareness in ecosystems.


12.Define pollution?

Pollutionisdefinedasexcessivedischargeofundesirablesubstancestothe

environment,adverselyalteringthenaturalqualityoftheenvironmentandcausing damage to

biomass, plants and animals.

13. Describeair pollution and statethe classifications of airpollutants

Theairpollutionwhichoccursinthetropospherelevelismainlyduetothe

industriesandvehicles,suchapollutedairaffectsvegetation,promotescorrosion, blocks out

sunlightand

deteriorationofrubber,paints,etc.,.Therearetwotypesprimarypollutantsreleasedintotheairinitsori

ginalform (CO,NO,SO2,etc.,)andwhilesecondarypollutantsbecomesubsequenttoreactions

intheairtoformnewpollutants(Ozone,SO2,Aldehydes,Ketones,Peroxyacyl nitrate, etc.,).

14. What are the sources ofairpollution

?Thenaturalsources(volcaniceruptions,forestfires,biologicaldecay,sources

ofradioactivityinatmosphere)andmanmadesources(Anthropogenic)suchasfossil fuel burning,

vehicular emissions, power plants,agricultural activities, etc.

15. What are organic pollutants?

They are polychlorinatedbiphenylandDDT(DichloroDiphenylTrichloroethane, a pesticide).

16.What meant by carbon monoxide?

It is colorless, odorless flammable gas which is a product of incomplete combustion.6. What

are the sources of Sulphur dioxide?The sourcesofSO2are fromthe industries and manmade

activities.

Unit 2

1. Enumerate Reflection losses.

Some of the incident radiation is lost through the reflection from the surface of the cell and

the material used to protect them from weather. The loss due to reflection in an antireflective-

coated cell is between 5 and 10%

2. What is incomplete absorption?

Photons with less energy than the energy gap Eg will simply generate heat in the cell. The

higher the energy gap, the greater the wastage.

3. What i s Partial utilization of photon energy explain?.

Many of the photons which generate electron hole pairs have more energy than is needed for

this operation. The excess energy is dissipated as heat . Thus the higher the energy gap, the


smaller the wastage. Taking into account for second and third loss factors, it follows that a

semiconductor with an energy gap of 0.9 eV would be best adopted for the AMO spectrum

4. State Collection losses

Only those carriers reach the junction before recombining are collected and contribute to the

output current while others simply generate heat. This collection efficiency is the ratio of the

actual short circuit current density and the short circuit current density which would be

obtaining in the case of no recombination.

5. List Factors affecting collecting efficiency

1. The absorption characteristics of the semiconductor determines the geometrical

distribution of the generated electron-hole pairs in the crystal

2. The junction depth

3. The width of the depletion layer

4. The rate at which electron and holes combine at surface

5. The average distance an electron will travel in the p-region and the hole in the n-

region before recombining

6. The existence and strength of any inbuilt electric fields resulting from impurity

concentration gradients in the surface and base regions which help to accelerate

carriers towards the junction.

7. What are Voltage factors, explain?

The open-circuit voltage is always less than energy gap for the following reasons:

An open circuit voltage equal to the potential of the electric field at the junction can be

obtained only at extremely high inputs which can be attained by unconcentrated sunlight

Due to doping ,the barrier height is always less than the energy band gap

8. State Absorption length.

The average distance that travels into a material before about 63% of it is absorbed is called

the absorption length of that material

9. Define Diffusion.

The average distance that light generated minority carriers can move towards the built-in-

field before they drop back into fixed state is called the diffusion length

10. Write importance of Photovoltaic materials?

The choice between higher efficiency and lower fabrication cost often boils down to a choice

between crystalline and thin film materials. Crystalline devices are more efficient but thin

film devices cost less. Many materials are being investigated with emphasis on crystalline

Silicon, amorphous silicon, Polycrystalline thin films and III-V single crystal materials


11. Write few PV applications?

Photovoltaic devices have been around doing exotic things like generating electricity for

satellite in space. But the real value of PV lies in its potential to produce electricity on earth

and to do so cheaply enough to complete with conventional sources of electricity like nuclear,

coal, oil and natural gas.

12. How PV is Communicated

PV is also used for powering systems that provide communication in remote locations. Many

such applications are for transmitters on hill tops or mountains, where PV with battery

storage has clear advantages over systems that require fuelling or maintenance

13. Explain Warning signals

Systems to provide warning signals in isolated areas are another natural use of PV and one of

the largest existing PV markets

14. Remote monitoring means what?

Small PV systems, most under 200W are being used in remote locations for maintaining

various phenomena. In all the cases, there is battery backup and details of uses are as follows

Pollution data

Seismic record

Weather and climatic information

Highway conditions

15. State Physics of the sun

The sun has an effective black body temperature of 5762 K. The temperature in the central

interior regions is estimated at 8 x 106 to 40 x 106 K and the density at about 100 times that of

water.

16. Define Solar constant

The eccentricity of the earth’s orbit is such that the distance between the sun and the earth

varies by 1.7%. At a distance of one astronomical unit 1.495 x1011 m, the mean earth-sun

distance , the sun subtends an angle of 32’.

17. State Beam radiation

The solar radiation received from the sun without having been scattered by the atmosphere.

Beam radiation is often referred to as direct solar radiation.

18. Define Diffuse radiation


The solar radiation received from the sun after its direction has been changed by scattering by

atmosphere. Diffuse radiation is referred to some meteorological literature as sky radiation or

solar sky radiation.

19. Define Global radiation

The total solar radiation (sum of beam and diffuse radiation) on horizontal surface is often

referred to as global radiation

20. Irradiance means what ?

W/m2. The rate at which radiant energy is incident in per unit area of surface

Irradiation J/m2.

The incident energy per unit area on a surface found by integration of irradiance over a

specified time, usually an hour or day. H is used for isolation for a day and I is used for

isolation for an hour.

Solar time

It is the time based on the apparent angular motion of the sun across the sky, with solar noon

the time the sun crosses the meridian of the observer. Solar times does not coincide with the

local tome clock. It is necessary to convert standard time to solar time by applying the

following corrections

Solar time = standard time + 4(Lst – Lloc) + E

21. What do you mean byAir mass (m)

Air mass is the ratio of the optical thickness of the atmosphere through which the beam

radiation passes to the optical thickness if the sun were at zenith angle subtended by a vertical

line to the zenith.

22. Enumerate Measurements of solar radiation.

Short wave radiation

Radiation originating from the sun, in the wavelength range of 0.3 to 3.0 µm

Long wave radiation

Radiation originating from sources at temperature near ordinary ambient temperatures

and thus all at wavelengths greater than 3 µm

23. What is Pyrheliometer?

An instrument for measuring solar radiation from the sun and from a small portion of the sky

around the sun at normal incidence.


24. What is Pyranometer

An instrument for measuring total hemispherical solar radiation, usually on a horizontal

surface.

25. Sunshine recorder used for.

Sunshine recorder is used to measure hours of bright sunshine.

26. Solar radiation data used for.

1. Instantaneous measurements or values integrated over some period of time

2. The time or time period of measurements

3. The measurements of beam, diffuse or total radiation and the instruments used

4. The period over which they are averaged

5. The receiving surface orientation

6. 26.What is Solar drying

Solar drying is a traditional method for preserving food. The drying process removes the

moisture and helps in the preservation of the product.

27. Enumerate solar desalination

Solar energy can be used for providing drinking water. By using an equipment known as

“Solar Still” the saline or impure water can be desalinated using solar water.

28. How Solar cooker works

Solar cooker does not require any type of fuel like dung,wood, coal , kerosene etc., It works

only on solar energy.

29.Why Black coatings are needed?

In order to convert solar radiation falling on the absorber system into heat the absorber has to

be coated with black coloured paints or other similar materials

30.What is Collector glazing

A transparent cover over the absorber of the collector has the function of allowing the solar

radiation to pass through it and act as an opaque certain to the radiation emitted by the hot

absorber

31. Transmission through glass cover means

A clean sheet of ordinary window glass transmits about 84% of the energy incident on glass

surface.

32. Transmission through plastic covers mweans


Some of the plastics such as clear acrylic, PVC and GRP are capable of transmitting as much

or even more energy than glass.

33.Define Double glazing.

Two layers of glass are sometimes used in order to reduce the heat losses from the absorber.

34.Factors considered for Collector designs

a) Built in channels

b) Tubes bonded on the blackened surface of the absorber sheet

c) Tubes bonded on the exposed surface of the absorber sheet

d) Tubes fitted in grooves

e) Corrugated sheet fixed on flat sheet

f) Both sides corrugated sheets

g) Hexagonal channels etc.,

35.What are Collector energy losses

Solar radiation in the collector is uniform and steady

Collector performance is in steady state condition

Absorber plate and transparent covers are at uniform temperatures.

Energy loss upward through the transparent covers is one dimensional

Energy loss downward through the bottom insulation is two dimensional

Energy loss sideways through the edge insulation is one dimensional around the perimeter of

the collector

36..Explain Performance of Solar Cell

Reflection of some power at the cell surface

Absorption resulting in the generation of electron-hole pairs and parasitic absorption

resulting in production of heat. A part of sunlight is not absorbed and is transmitted

through the cell.

Separation and collection of photo generated carriers

Flow of carriers towards the external contacts.

Dissipation of the photo generated power in an external load


UNIT 3

1. Define Wind energy:

Wind energy is an indirect energy from of solar. About 1 percent of total solar

radiation that reaches the earth is converted in the atmosphere into the energy of the wind.

2. Write Wind energy technology Equation

The kinetic energy, u, of a sample volume, A(δx), and densityῤ, moving with

velosityὐ, where A is a unit area perpendicular to the wind stream and δx is parallel to the

wind stream, is:

3. State the influence of Aerodynamics

Modern wind turbines extract energy from the wind stream by transforming the winds

linear kinetic energy to the rotational motion needed to turn an electrical generator. This

change is accomplished by a rotor which has one , two or three blades or airfoils attached to a

hub, wind flowing over the surfaces of these airfoils generates the forces that cause the rotor

to run.

4. Principle of wind energy conversion:

When wind is blowing it exerts two types of forces , lift and drag on the object in its

path. Drag force acts in the same direction as the wind while lift force is perpendicular to the

direction of the wind.

5. Rotor design means

In order to understand the effect of difference in rotor design it is useful to describe

how the blades of a rotor react to the wind, and to define some of the standard design

parameters.

6. What is Pitch

The lift force created cause the rotor to rotate. In order to generate the max amount of

lift, the blades must be set at an appropriate angle to the wind.

7. Solidify means what

This is usually defined as the percentage of the circumference of the rotor which is

filled by the rotor blades.

8. What is Tip-speed ratio?

This is the ratio of the speed of the blades tips to the speed of the wind

9. State Performance coefficient:

The performance coefficient of a rotor is the friction of wind energy passing through

the rotor disc which is converted into shaft power. This is measure of the efficiency of

the rotor and it varies with the tip-speed ratio.


10. What is Torque:

Torque is the turning force produced by the rotor. It depends on thesolidify and tip-

speed ratio of the rotor.

11. What is various designs of rotors

Two or three –bladed horizontal axis wind mills are used for electricity generation

they are not suitable for water pumping because

1. They can not produce enough torque to start the piston pump working

2. They rotate too quickly to directly drive a reciprocating pump. This too

difficult manufacturing

3.

12. List the parameters to chose Site elevation:

The following parameter should be measured

1. Avg annual wind speed

2. Avg monthly wind speed for each month

3. Typical diurnal wind speed pattern for each month

4. Length and annual distribution of lull periods

13. How Wind measurement made

Various option available for taking wind measurement depending on the time

available, budget available and accuracy required.

14. How Quality of wind data is measured:

Until quite recently there was little standardisation of wind data collection except at

major airports where data has had to be collected in an internationally agreed manner.

15. State wind turbines in WE

there are two fundamentally different types of wind turbines. The first is the

horizontal axis wind turbine, which has the axis of rotation to the parallel to the wind

stream

16. What is wind stream system:

a modern HAWT is composed of several sub system

1. The rotor, which consist of one two three blades mounted on a hub and may

include aerodynamic braking system 2.The yaw system which potions the

rotor perpendicular to the wind stream ,3.the tower , 4.Balance of station

system including roads ground support equipment and interconnection

equipment.

17. What is rotor in WE?

The rotor, which converts the winds kinetic energy into the kinetic energy rotation.

18. Explain Drive trains:


The major component of drive train are the low and high speed shafts, the mechanical

braking system, bearing, coupling, gearbox or transmission, and nacelle.

19. State Yaw-control system:

Horizontal axis wind turbines fall into two categories: upwind machines or down

wind machines. Yaw systems are used to orient the plane of the rotor perpendicular to

the wind stream

20. Explain Wind energy utilization:

Small windmills with direct mechanical drive matched to a pump and storage tank,

are now in extensive use in many parts of the world including India. Wind energy is

high quality form of mechanical energy that can be converted into electrical energy

with minimum loss

21. Explain Origin of tides:

Tide are created by the gravitational attraction of the moon and sun acting on the

ocean of the rotating earth

22. State Tidal barrage design:

A modern tidal energy scheme consists of a barrage or a dam that is constructed

across an estuary and is equipped with a series of gated sluices to permit entry of

water to basin

23. In tide barrage what are the Modes of operation:

A tidal barrage can be operated one of three different modes:

Ebb generation Flood generation Two way generation

24. State Wave energy:

Ocean wave are created by the interaction of the winds with the surface of the sea

25. What are Terminators?

We get max energy when several devices are mounted on a linear spine oriented at 90

degree to the wave direction known as terminator mode.

26. What are Attenuators?

In attenuators mode, the device is parallel to the wave direction.

27. What tare the factors determine the o/p from a wind energy converter

1. The wind speed 2. The cross section of wind swept by rotor

3. The overall conversion efficiency of the rotor transmission system and generator or

pump.

28. Define isodynes

They are contours of constant wind popwer again it is important to know the averaging

period

29. Explain wind survey?

a.Instrumentation b.Data recording system c.Types of data d.Data reporting

30. What is aero turbine?

Aero turbines convert energy in moving air to rotary mechanical energy..In general they

require pitch control and yaw control.


UNIT 4

1.Explain The Process Of Photosynthesis?

In the process of Photosynthesis, sunlight is absorbed by chlorophyll in the

chloroplasts of green plant cells and utilized by the plant to produce carbohydrates from

water (H2O) and carbon dioxide(CO2) taken from the atmosphere.

6CO2+6H2O sunlight C6H12O6+6O2

2. What Is Bio Mass Production Efficiency?

It is the efficiency of converting incident solar energy in to the chemical energy

stored in carbohydrates in plants.

3. Write Any One Implication Of Rising CO2 Levels On Bio Mass Production.

The concentration of CO2 would increase relative to CO2 Photorespiration would be reduced

in favor of Photosynthesis.

4. Mention The Three Aspects Of Bio Mass Resources Development.

Detailed characterization of the soil properties. Growth

measurements and

Energy values of the test species

5. Write The Application Of Bio Mass Conversion.

Direct combustion ,Gasification, Cogeneration

6. Explain the types of Gasifier.

Fixed bed updraft gasifier.Fixed bed down draft

gasifier.Cross draft gasifier.Fluidized bed gasifier.

7. Advantage OfGasifier Design.

It is suitable for many biomass fuels. It can gasify wet fuel

and does not require any specific fuel size. Lower value of water decomposition

and thermal efficiency is higher.

8. Explain the Fixed Bed Down Draft Gasifier.

The fixed bed down draft gasifieris similar to the updraft design except that the

process air is introduced at or above the combustion zone, exiting near the bottom of the

chamber.

9. Explain the Cross Draft Gasifier.

It is very compact gasifier and is highly suitable for small power outputs. This Gasifier is also

good for changing loads.

10. Explain The Fluidised Bed Gasifier.


The Fluidised Bed Gasifier have been developed which promise greater capacity and gas

production rates than fixed bed type.

11. Benefits of bio gas technology.

It generates many social benefits such as reduction in the cutting in the cutting trees for

fuelwood, reduction in the drudgery of women and children, improvement in sanitation and

environment, reduction in the incidence of eye and lung diseases, and greater availability of

time for productive employment.

12. What is the family based plants.

There are two well tested and field-worthy designs of biogas plants. They are (i) floating gas

holder type)(KVIC type gobar gas plant). (ii) Fixed dome type (Janata biogas plant).

13. Technical Problems and constraints of biogas.

Problems caused due to modification brought in the design specification at the local level.

Seasonal variation in gas production due to lack of temperature control and poor

insulation of the plant.Inefficient designing of gas applications.

14. Socio-economic problems and constraints of biogas.

Socio-economic problems which can slow down the progress of the program are as under:

Installation of over-size plants simply due to a symbol of social prestige.Lack of

awareness due to illiteracy.Lack of financial resources or capacity to borrow loans

from financing institutions

15. What are the problems raised due to biogas for the different stages of lifecycle.

The following problems crop up from time to time:

i. Defective construction by untrained or improperly trained

masons

ii. Lack of strict supervision in training courses

iii. Delayed supply of raw materials and plant components

iv. Lack of coordination among various agencies

16. List the methods of converting biomass into useful forms of energy.

Bio chemical and, Thermochemical

17. Write the Advantages of gasifiers.

It is very easy to operate the gasifier.Its maintenance is easy.It is sturdy in construction and,

It is reliable in operation.

18. Write the direct thermal applications.

Cement manufacture, Glassmaking, Brickmaking, Ceramics and pottery, Rubbermanufacture,

Fertilizer production.


19. Write the classification of biogas plant.

Bio gas plants mainly classified as following types

Continuous and batch types.The dome and the drum types.Different variations in the drum

type.

20. Factors affecting the bio digestion or generation of gas.

The following factors that affect the generation of gas

PH or the hydrogen-ion concentration.Temperature.Total solid content of the feed material

loading rat

Unit V

1) What is fuel cell?

Fuel cell comprises two electrochemical conducting electrode separated by an electrolyte.

the fuel is fed outside of one electrode and air or oxygen is supplied from outside of other

terminal.

2) What is Chemical polarization?

It is a surface phenomena and the magnitude of which depends in part upon how ions

are discharged at the electrodes and in part upon the rate at which they are discharged.

3) What is Concentration polarization?

In a electrochemical cell, there is a loss of potential due to the inability of the surrounding

material to maintain the initial concentration of the bulb fluid after currents begins to flow.

4) What are the methods involved in Production of hydrogen?

The following methods are generally considered for the production of hydrogen

1. Electrolysis of water

2. Thermal decomposition of water

3. Thermo chemical methods

5) Enumerate Hydrogen as alternative fuels

Hydrogen is a secondary energy carrier just as electricity. Thus the primary energy

(nuclear, solar, hydro or even fossil) is needed for its production. The introduction of

Hydrogen as an energy source on a sizeable scale involves 5 basic issues.

1. Production

2. Storage and transport

3. Usage of Hydrogen as energy source

4. Safety


5. Economics and management.

6) Advantage in Hydrogen storage?

1. Its spectrum of applications must be of high importance for the energy market and its

usage must be as clean as possible;

2. Its transport or transmission should be feasible at low coats;

3. Its storage should be technically and economically feasible

7) Classifications of Hydrogen storage and systems?

1. Stationary large storage system

2. Stationary small storage system

3. Mobile storage systems for transport and distribution

4. Automobile fuel reservoirs

8) What is stationary large storage system?

These storage systems are typically located at the production sites, and at the terminals

of pipelines and other transportation paths. They typically include, besides the storage

capacity related components like the reservoir, also a power consuming system component i.e

machinery or plant such as compressors and liquefiers. Accordingly the corresponding costs

may include significant power dependent capital costs and energy cost components.

9) What is stationary small storage system?

They are most used for intermediate storage, for ex, at industrial sites. Here, normally

only capacity related costs are relevant.

10) What are mobile storage systems for transport and distribution?

These include bulk carriers like liquid hydrogen tankers, or similar smaller systems like

as LH2 and gas truck trailers. Cost components here include capacity dependent investment

costs and operational costs.

11) What is an Automobile fuel reservoir?

These are the tanks used for the onboard storage of hydrogen used as fuel for road

vehicles. For hydrogen powered vehicles the tank weight needed by some hydrogen storage

methods may give rise to the excessive fuel consumption. The operating costs also on the on

broad storage method and vehicle range.


12) Explain about underground hydrogen storage?

Future hydrogen supply systems will have a structure similar to those of today’s natural

gas supply systems, where underground hydrogen storage has been shown to be feasible. Spl

technical problems for the case of pure hydrogen are manageable. So far a gas cavern has

been used since 1971 in kiel to store town gas with a content of upto 65% hydrogen at

pressure of about 180 bar. Underground hydrogen storage is of special importance for

stationary large scale storage systems

13) List Types of polarization?

1. Chemical polarization

2. Concentration polarization

3. Resistance polarization

15) List various types of fuel cells?

1. Hydrogen oxygen fuel cell

2. Bio chemical cells

3. Regenerative cells

16) What is Regenerative cell

1. Thermally regenerative cells are medium efficiency devices (5 to 20 %) with

proven cell life times of up to 12000 hours.

2. In air cooled systems, the regenerative size will depend primarily on the

condenser to air heat transfer co efficient.

17) What are Bio chemical cells?

In bio chemical cell one or both electrode reaction are promoted or catalyzed by

biological process. Biochemical cells can be divided into two types.

18) Types of bio chemical cells?

1. Indirect cell 2. Direct cell

19) List the Elements of fuel cell?

a) electrolyte

b) Load

c) Oxidizer

d) Fuel


20) Write the Fundamentals of electrochemistry?

Fuel cells operate on the principles of electrochemistry and so we consider Daniel

cell which consists of load variation and container divided into two parts by a partition that

permits the diffusion of ions b/w them.in the left hand compartment which contains zinc

sulphate, we complete the circuit by connecting the two electrodes by a wire that can deliver

current to an external load.

21) What are the Type of fuel cells.

1) Hydrogen fuel cell

2) Hydrazine fuel cell

3) Hydrocarbon fuel cell

4) Alcohol fuel cell

22) What are the main components of the fuel cells.

A fuel electrode (anode)

An oxidant or air electrode(cathode)

An electrolyte.

23) Explain two types of hydrogen cells

Low temperature cells: The electrolyte temp is 90 c. it is sometimes pressurized but not

by great amount usually say up to 4 atmospheres. High pressure cells: pressure is up to about

45 atmosphere and temperature up to 300◦C

24) Classification of fuel cells according to the temperature range.

Fuel cells may be classified a according to the temperature range:

Low temperature : 25-100◦C

Medium temperature : 100 500◦C

High temperature : 500-1000◦C

Very High temperature : above 1000◦C

25) Classify the fuel cell according to to the physical state of the fuel.

Gas-hydrogen, lower hydro carbon

Liquid-alcohol, hydrazine, higher hydro carbon.

Solid-metal etc.

26) Desired properties of an ideal ion exchange membrane electrolyte are:

High ionic conductivity

Zero electronic conductivity


Low degree of electro –osmosis.

Mechanical stability.

27) Advantage and Dis advantage of fuel cells.

The fuels take little time to go into operation.

As fuel cells do not make noise, they can be readily accepted in residential

areas.

28) Define conversion Efficiency of fuel cells.

The electrical energy generated by fuel cells depends on what is called the free energy

rather than on the heat energy of overall cell reaction.

29) What is polarization?

In a practical fuel cell the theoretical output voltage is not attained for several reason as

outline below and the difference b/w the theoretical voltage and the actual voltage.

30) what are the main type of polarization.

Active polarization

Resistance or ohmic polarization

Concentration polarization.

31) What are Types of electrode and explain.

Porous electrode & Non Porous electrode.

Porous electrode: the design of these electrodes has been based on the assumption

that is necessary to maintain a three phase boundary b/w gas, electrode and electrolyte.

Non Porous electrode: the concept of Non Porous electrode diffusion membrane

electrode and the problems of interface control and of direct chemical reaction with the

electrolyte.

32) List the Application of fuel cell.

Domestic use

Central power station

Automotive vehicle &

Special application.

33) Explain the hydrogen in the near future .

Direct use of hydrogen as an aircraft fuel in air transport.

Use of hydrogen in the processing of heavy oil.


34) What is electrolysis?

The process of splitting water into hydrogen and oxygen by means of direct electric

current .

35) What is electrolyte?

An electrolysis cell consists of two electrodes commonly flat metal or carbon plate

immersed in an aqueous conducting solution.

36) Advantage and Dis advantage of electrolyze.

Advantage: two-fold relatively few parts are required and those needed are relatively

inexpensive and individual cell may be isolated for repair or re placement simply by short

circuiting the two abject cells with temporary bus bar connection.

Dis advantage: inability to handle high current densities because of cheaper component parts.

37) Principle of hydrogen storage.

Compressed gas storage

Liquid storage

Line pack system

Under ground storage

38) Types of transport.

Hydrogen transport

Liquid Hydrogen transport

Metal Hydride transport

39) Advantage of claimed hydrogen fuel engine

They are higher efficiencies.

The amount carbon monoxide and hydrocarbon in the exhaust should be very

small.

40) What is the future scope of hydrogen?

It is unlikely that hydrogen would serve as a major fuel for electric power generation

by utility. Hydrogen could also be used for storing and distributing electrical energy.

16ME320 – RENEWABLE ENERGY UTILIZATION - SNS ...

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