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838 Goodw in Defibaugh and W eber
systematic changes become important at lower vapor pressures. Thus, we
measured low vapor pressures using a method that depends on boiling
known as ebulliometry [1 3]) and that continuously degases the sample.
In comparative ebulliometry the condensing temperature of the sub-
stance under study and a reference fluid are measured when the liquids are
boiling at the same pressure [4]. These boilers are connected via liquid
nitrogen cold traps to avoid cross-contamination of the substance being
investigated and the reference fluid. The advantage of this technique,
particularly at low pressure, is that it avoids the necessity of measuring
pressure directly; instead, the pressure is calculated from the condensing
temperature of the reference fluid and its known pressure-temperature
behavior. In addition, provided that the temperature measuring equipment
is sufficiently sensitive, irregularities of the condensation temperature may
reveal further inadequacies in the sample or reference fluid) purity [2]. Of
course, an azeotrope may not be detected with this approach. The sym-
metry of the apparatus implies that certain errors tend to be self-canceling.
In our work allowance is always made for the hydrostatic heads of
vapor [2, 4].
In comparative ebulliometry, a buffer gas subjects the sample and the
reference fluid to identical pressures. The influence of the buffer gas used in
the ebulliometric experiment was investigated by Ambrose et al. [5] with
their measurements of the vapor pressure of benzene. They found no
difference between values of the vapor pressure obtained when helium
was used as the buffer gas and those obtained when nitrogen was used.
The methods of determining vapor pressure, including comparative
ebulliometry, have been discussed extensively in the literature [2, 3].
For our work at low reduced temperatures corresponding to pressures
below 220 kPa, we have used comparative ebulliometry to supplement the
data from our static apparatus for vapor-pressure measurements. Here
we report our ebulliometric vapor-pressure measurements on 1,1,1,2-
tetrafluoroethane R134a) and chlorodifluoromethane R22), both of
which are expected to play important roles in the design of future refrigera-
tion systems. The ebulliometer used here is a refined version of an earlier
design reported by one of us [6] and is adapted from designs described in
the literature [1-4, 7-9]. To our knowledge, neither has this technique
been applied to these refrigerants previously nor has it been used at such
low temperatures.
In addition, we report static measurements made with our Burnett
apparatus [10-12] of the vapor pressure for 1,1,1,2-tetrafluoroethane
R134a) at pressures between our earlier static results [13] and the present
ebulliometric results. All these results have been combined to provide a
correlation for the vapor pressure of 1,1,1,2-tetrafluoroethane R134a) on
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Vapor Pressure of R134a and R22 839
the International Temperature Scale of 1990 (ITS-90) [14, 15] at tem-
peratures from 215 K to the critical temperature, which corresponds to
vapor pressures from 17.3 to 4055.1 kPa. For chlorodifluoromethane (R22)
we have combined our results with those already published [-16-18] to
provide a correlation (on ITS-90) from 217.1 K to the critical temperature.
Because of the importance of these two fluids, their vapor pressures
have been reported in the literature numerous times [16-25]. Important
references for 1,1,1,2-tetrafluoroethane (R 134a) include Magee and Howley
[19], Zhu and Wu [20], Baehr and Tillner-Roth [21], Piao et al. [22],
Maezawa et al. [23], Basu and Wilson [24], and Kubota et al. [25] as
well as our earlier work [13]. We argue that certain published vapor
pressure data for R134a are in error by as much as 0.024p. We suspect that
the errors resulted from inadequate degassing of the samples used in
previous work. For the sake of brevity, these compounds are referred to
with the numbering scheme used by the refrigeration industry [26] and
shown in parentheses above.
2. EXPERIMENTAL
2 1 E b u l l i o m e t e r
The ebulliometers are similar to those described by Ambrose et al.
[2, 3, 7, 8]. The apparatus used in the present work has been described in
detail elsewhere [-6]. Only the important differences, required to operate at
lower temperatures and higher pressures, are given here. The sample
ebulliometer, shown in Fig. 1, was constructed from borosilicate glass and
fitted with four bubble-caps with a total internal volume of about 50 cm 3
(the reference boiler was identical). A brass passive radiation shield was
placed around the upper outer portion of the boiler. The entire
ebulliometer and radiation shield were housed inside a second cylindrical
shield, whose temperature was controlled to 0.01 K by circulating chilled
methanol through a coil wrapped around the shields outer surface. We
found, after carefully insulating feed and return pipes, that we could reach
195 K. The thermostat shield was capped with 0.05-m-thick polystyrene
foam disks. Fiber-glass insulation was wrapped around the outside of
the shield to complete the isothermal environment. Although the vapor-
pressure measurements were insensitive to the exact shield temperature, we
always maintained it about 10 K below the fluids condensing temperature.
The sample ebulliometer was connected, via a condenser cooled with a
mixture of carbon dioxide and propanone and two traps cooled with liquid
nitrogen, to the reference boiler and a ballast volume using helium as the
transfer gas. The connections were made with 10-mm-external diameter
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840 Goodw in Def ibaugh and W eber
P R T
wel l
Me t h a n o l
Co ld wa l l
sh ie ld
~ bHea~ r
F i g . 1 . C r o s s s e c t i o n t h r o u g h t h e s a m p l e
e b u l l i o m e t e r .
g l as s t u b i n g j o i n e d w i t h g l a s s b a l l j o i n t s w h i c h w e r e s e al e d w i t h s i l ic o n e
r u b b e r o - ri n g s. T h e b a l l a s t v o l u m e w a s a b o u t 0 .0 1 5 m 3 a n d i t w a s w r a p p e d
i n fi b e r- g la s s i n s u l a ti o n . T h e p r e s s u r e o f t h e s y s t e m w a s m o n i t o r e d , b u t n o t
m e a s u r e d , w i t h a q u a r t z p r e s s u r e t r a n s d u c e r . T h e h i g h e s t v a p o r p r e s s u r e
t h a t w a s m e a s u r e d i n t h e gl as s e b u l l i o m e t e r w a s 2 15 k P a . T h e l i m i t w a s a n
o b v i o u s s a f e t y p r e c a u t i o n .
C o n d e n s a t i o n t e m p e r a t u r e s o f t h e s am p l e a n d r e f e re n c e , w a t e r , w e r e
d e t e r m i n e d w i t h t w o Y e l l o w S p r i n g C o . 2 l o n g - s t e m p l a t i n u m r e s is t a n ce
t h e r m o m e t e r s [ M o d e l 8 1 63 Q B , se ri al n u m b e r s L 9 S 4 6 09 ( H 2 0 ) a n d
F 9 1 3 5 5 ( s a m p l e ) ] c a l i b r a t e d b e t w e e n 8 3.8 a n d 6 9 2.7 K o n I T S - 9 0 . T h e
r e si s ta n c e m e a s u r e m e n t s w e r e m a d e w i th a d i g it al D C m u l t i m e t e r ( H e w l e t t
P a c k a r d C o ., M o d e l 3 4 5 7 A ) o p e r a t i n g a t a c u r r e n t o f 1 m A , w i t h a r e s o l u -
t i o n o f 0 .0 1 m l 2 , f o r r e s i s t a n c e s u p t o 3 0 .3 s F o r r e s i s ta n c e s g r e a t e r t h a n
3 0.3 s b u t le ss t h a n 3 0 3 ~ , t h e r e s o l u t i o n w a s 0.1 m s T h e m a n u f a c t u r e r s
2 I n o r d e r t o d e s c r i b e m a t e r i a ls a n d e x p e r i m e n t a l p r o c e d u r e s a d e q u a t e l y , i t i s o c c as i o n a ll y
n e c e s s a r y t o i d e n ti f y c o m m e r c i a l p r o d u c t s b y m a n u f a c t u r e r s n a m e o r l a b el . I n n o i n s t a n c e
d o e s s u c h i d e n t if i c a ti o n im p l y e n d o r s e m e n t b y t h e N a t i o n a l I n s t i t u t e o f S t a n d a r d s a n d
T e c h n o l o g y , n o r d o e s i t i m p l y t h a t t h e p a r t i c u l a r p r o d u c t o r e q u i p m e n t i s n e c e s s ar i ly t h e
b e s t a v a i l a b le f o r t h e p u r p o s e .
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Vapor Pressure of R134a and R22 841
s t a t e d a f r a c t i o n a l a c c u r a c y o f 6 .5 x 1 0 - 5 f o r t h e r a n g e w i t h a n u p p e r
b o u n d o f 3 0 .3 12 a n d a f r a c t i o n a l a c c u r a c y o f 4 .5 x 1 0 5 f o r r e s i s t a n c e s
b e t w e e n 3 0.3 a n d 3 0 3 12. W h e n t h e c u r r e n t w a s r e v e r s e d , n o d i f fe r e n c es
w e r e o b s e r v e d i n t h e m u l t i m e t e r r e a d i n g . A l t h o u g h t h e t e c h n i q u e f o r
v a p o r - p r e s s u r e m e a s u r e m e n t i s c o m p a r a t i v e , a n d o n l y s h o r t - te r m p r e c is i o n
a n d s t a b il i ty a r e r e q u i r e d o f t h e m u l t i m e t e r , w e c o m p a r e d t h e
m e a s u r e m e n t s o f t h is d e v i c e i n t w o w a y s . F ir s t, t h e m u l t i m e t e r w a s c h e c k e d
f r e q u e n t l y a g a i n s t t w o c a l i b r a t e d R o s a s t a n d a r d r e s is t o rs w i th n o m i n a l
r e s i s t a n c e s o f 10 a n d 2 5 12 t h a t w e r e h o u s e d i n a t h e r m o s t a t e d e n c l o s u r e ,
t h e t e m p e r a t u r e o f w h i c h w a s m e a s u r e d w i t h a m e r c u r y - i n -g l a s s th e r -
m o m e t e r . T h e m u l t i m e t e r w a s c h e c k e d a f te r co m p l e ti n g t h e v a p o r - p r e s s u re
m e a s u r e m e n t s a n d , a t b o t h s t a n d a r d r e si s ta n c e s, f o u n d t o b e 0 .6 6 m 1 2 h i g h ;
w h e n t h e m u l t i m e t e r w a s s h o r t e d t h i s d i s c r e p a n c y w a s n o t o b s e r v e d . A l l
t h e m e a s u r e m e n t s w e r e c o r r e c t e d f o r t h is s m a l l s y s t e m a t i c e rr o r . S e c o n d ,
t h e c o m b i n e d s t a b il it ie s o f t h e t h e r m o m e t e r s w i t h t hi s m u l t i m e t e r w e r e
c h e c k e d f r e q u e n t l y i n a t r i p l e - p o i n t - o f - w a t e r c e l l . T h e t r i p l e - p o i n t r e s i s t a n -
c es d i ff e re d f r o m t h e o r i g in a l c a l i b r a t i o n b y l es s t h a n 1 i n K . T o i m p r o v e
t h e r m a l c o n t a c t b e t w e e n t h e t h e r m o m e t e r a n d t h e c o n d e n s i n g f l u i d s , t h e
g l a s s - t h e r m o m e t e r w e l l s w e r e f i l l e d w i t h e i t h e r n - o c t a n e , s i l i c o n e o i l , o r
1 , 2 - d i h y d r o x y e t h a n e .
T h e e b u l l i o m e t e r s a n d b a l l a s t v o l u m e w e r e e v a c u a t e d a t a t e m p e r a t u r e
o f 3 0 0 K w i t h a r o t a r y v a c u u m p u m p u n t i l th e p r e s s u r e w a s b e l o w 1 P a ,
w h i l e t h e s e a l e d s a m p l e c y l i n d e r w a s a t t a c h e d t o a s i de a r m . A f t er 1 2 h t h e
5 0 - c m 3 l i q u i d s a m p l e w a s d i s t il l ed i n t o t h e b o i l e r . S u f f ic i e n t t i m e w a s
a l l o w e d f o r t h e a p p a r a t u s t o r e a c h s t e a d y s t a t e , a s i n d i c a t e d b y t e m -
p e r a t u r e d i f f er e nc e s b e t w e e n e a c h r e a d i n g o f a b o u t l m K , b e f o r e a s e ri es o f
c o n d e n s a t i o n t e m p e r a t u r e s w a s m e a s u r e d , u s u a l l y a t 6 0 - s i n t e r v a l s d u r i n g
0 . 3 h .
2 2 B u r n e t t A p p a r a t u s
T h e s t a t i c m e a s u r e m e n t s w e r e p e r f o r m e d w i t h a n a u t o m a t e d B u r n e t t
a p p a r a t u s d e v e l o p e d a t t h e N a t i o n a l I n s ti t u te o f S t a n d a r d s a n d T e c h n o l -
o g y N I S T ) , w h i c h h a s b e e n d e s c r ib e d in d et a i l s e v er a l t im e s [ 1 0 - 1 3 ] . A ll
r e s u l t s w e r e a c q u i r e d i n a n a u t o m a t e d f a s h i o n . T e m p e r a t u r e s w e r e
m e a s u r e d w i t h a n i m p r e c is i o n a n d i n a c c u r a c y o f 1 m K u s in g a p l a t i n u m
r e s i s t a n c e t h e r m o m e t e r , a n d p r e s s u r e s w e r e m e a s u r e d u s i n g a q u a r t z s p i r a l
b o u r d o n g a u g e f i t t e d w i t h a n o p t i c a l n u l l d e t e c t o r t o a n i n a c c u r a c y o f
a b o u t 0 .1 k P a . I n a d d i t i o n t o t h e p r o c e d u r e s l is t e d i n S e c t i o n 2 .3 , b e f o r e
c o m m e n c i n g m e a s u r e m e n t s , t h e s a m p l e c el l w a s fi ll ed t o a b o u t t h e c r i ti c al
d e n s i ty , c o o l e d b e l o w 2 7 3 K , a n d t h e g a s e x p a n d e d a n d e v a c u a t e d
r e p e a t e d l y u n t il a d d i t i o n a l e x p a n s i o n s h a d a n e g l ig i b le e ff ec t o n t h e
m e a s u r e d p r e s s u r e .
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842 Goodw in Def ibaugh and W eber
2 .3 . S a m p l e P u r i t y
D i s t i l l e d w a t e r f r o m t h e l a b o r a t o r y s u p p l y w a s u s e d a s t h e r e f e r e n c e
m a t e r i a l . T h e 1 , 1 , 1 , 2 - t e t r a f l u o r o e t h a n e ( R 1 3 4 a ) w a s s u p p l i e d b y E . I . D u
P o n t d e N e m o u r s a n d C o . w i t h a s ta t e d a n a l y si s f o r t h r e e i m p u r i ti e s :
x ( C 2 H F s ) = 1 .5 6 x 10 - 4 , x ( C F 3 C H 3 ) -- 1 .5 9 x 1 0 - 4 , a n d x ( C C I H 2 C F 2 H )
= 1 .5 x 1 0 - 4 . G a s - c h r o m a t o g r a p h i c a n a l y si s o f t h is s a m p l e d e t e c t e d a m o l e
f r a c t i o n o f 2 .1 5 • 1 0 - 4 f o r w a t e r [ 2 7 ] . T h e s a m p l e w a s d i s t il l ed f r o m t h e
s u p p l i e r s c y l i n d e r in t o a p r e v i o u s l y e v a c u a t e d s te e l am p o u l e . A n a l y s is o f
t hi s s a m p l e w i t h a g as c h r o m a t o g r a p h r e t u r n e d x ( H 2 0 ) = 1 .0 5 • 10 - 4
[ 2 7 ] . N o a t t e m p t w a s m a d e t o p u r i fy t h e R 1 3 4 a f u r t h er . A l iq u o t s o f t h is
s a m p l e w e r e u s e d f o r t h e v a p o r - p r e s s u r e m e a s u r e m e n t s r e p o r t e d h e r e a n d
i n R e f . 1 3 , a s w e l l a s t o d e t e r m i n e t h e c r i t i c a l t e m p e r a t u r e [ - 2 8 ] , t h e
g a s e o u s ( p , V m , T ) b e h a v i o r [ 1 3 ] , a n d g a s e o u s s p e e d - o f - s o u n d m e a s u r e -
m e n t s [ 2 9 ] . T h e c h l o r o d i f l u o r o m e t h a n e ( R 2 2 ) w a s o b t a i n e d f ro m A l li ed
S i g n al C o r p ., f r o m b a t c h B R l l 9 1 A , w i t h a s t a t ed m o l e f r a c t io n p u r i t y o f
g r e a t e r t h a n 0 . 9 9 9 5 . T h e a n a l y s i s c e r t i f i c a t e p r o v i d e d b y t h e m a n u f a c t u r e r
r e p o r t e d a m o l e f r a c t i o n p u r i t y o f 0 .9 9 9 68 a n d t h e p r e s e n c e o f f iv e
i m p u r i t i e s , o f w h i c h f o u r w e r e i d e n t i f ie d : x ( C C 1 2 F 2 ) = 0 . 0 0 0 1 8 , x ( C H F 3) =
0 .0 0 01 3 , x ( C H C 1 2 F ) = 0 .0 0 0 01 , a n d x ( H 2 0 ) = 3 x 10 - 6 . O t h e r u n s p e c if ie d
h y d r o c a r b o n s m a d e u p t h e r e m a i n d e r . G a s - c h r o m a t o g r a p h i c a n a l y s i s o f
t h e s t o c k m a t e r i a l u s i n g a n o n p o l a r s t a t i o n a r y p h a s e a n d a t h e r m a l c o n -
d u c t i v i t y d e t e c t o r i n d i c a t e d t h e p r e s e n c e o f t w o i m p u r i t i e s w i t h f r a c t i o n a l
a r e a s o f 1 9 x 10 - 6 a n d 4 .9 x 1 0 - 4 , r e s p e c t i v e l y ; b o t h e l u t e d p r i o r t o t h e
m a j o r p e a k . N o f u r t h e r a n al y s is o r p u r i f i c a ti o n w a s a t t e m p t e d .
3. R E S U L T S A N D A N A L Y S I S
T h e v a p o r p r e s s u r e o f w a t e r , w h i c h w a s u s e d a s t h e r e f e r e n c e f lu i d f o r
o u r e b u l l i o m e t r y , w a s c a l c u l a t e d f r o m b o i l i n g t e m p e r a t u r e s o n I T S - 9 0 [ 1 4 ,
1 5 ] , w i t h t h e e q u a t i o n d i s c u s s e d i n S e c t i o n 3 . 1 . N o i r r e g u l a r i t i e s w e r e
d e t e c t e d i n t h e t e m p e r a t u r e o f t h e w a t e r e b u l l i o m e t e r , th i s s u g g e st s t h e
s a m p l e h a d n o s i g n i f i c a n t c o n t a m i n a n t s .
A s a c h e c k o n t h e i n t e r n a l c o n s i s t e n c y o f t h e e b u l l i o m e t r i c re s u l ts , a n d
t o p r o v i d e a n o r m a l b o i l i n g t e m p e r a t u r e a t a p r e s s u r e o f 1 0 1 . 3 2 5 k P a , w e
f it o u r e x p e r i m e n t a l v a l u e s t o a n A n t o i n e e q u a t i o n ( a p p l ic a b l e in t h e r a n g e
1 0 t o 2 0 0 k P a )
I n ( p )
= A + B/ T+ C)
1 )
w h e r e p i s i n k P a a n d T is i n K . T o p r o v i d e a n e q u a t i o n f o r th e fl u id ra n g e
f r o m a p r e s s u r e o f a b o u t 1 0 k P a t o t h e c r it ic a l p r e s su r e , w e c o m b i n e d o u r
e b u l l i o m e t r i c r e s u lt s w i th o u r s t a t ic m e a s u r e m e n t s f o r R 1 3 4 a. F o r R 2 2 o u r
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e b u l l i o m e t r i c v a l u e s w e r e c o m b i n e d w i t h h i g h e r - p r e s s u r e d a t a f r o m t h e
l i t e ra t u r e t h a t j o i n e d s m o o t h l y w i t h o u r r e s ul ts . F o r e a c h f l ui d, t h e
c o m b i n e d s e t w a s u s e d t o d e t e r m i n e t h e c o e f fi c ie n ts i n th e e q u a t i o n
r e c o m m e n d e d b y W a g n e r [ 3 ( ~ 3 3 ] :
i n p i p e )
= (n 1z + n2 z l s
+ n~3 + n~) T c /T
( 2 )
where z = (1 - T / T c ) , T c i s t h e c r i t ic a l t e m p e r a t u r e , a n d c , d a n d t h e n s a r e
a d j u s t a b l e p a r a m e t e r s . I n o u r a n a l y s i s , w e a s s u m e d t h a t t h e v a p o r p r e s s u r e
c o u l d b e r e p r e s e n t e d b y t e r m s w i t h p o s i t i v e p o w e r s c a n d d , a n d u s i n g a n
a d a p t i v e r e g r e s si o n a l g o r i t h m [ 3 4 ] , w e s e le c te d t h e m o s t s i g ni fi c an t te r m s
f r o m the ba nk ~2, r2 .s , ~3.o .... ~9. W e we igh te d e a c h e bu l l i om e t r i c ob se r v a -
t i o n b y 6 T x d l n p / d T , w h e r e 6 T = 1 .4 x 10 3, w h i c h w e c o m b i n e d i n q u a d -
r a t u r e w i t h t h e u n c e r t a i n t y in t h e v a p o r p r e s s u r e o f w a t e r. W e w e i g h t e d
o u r s t a ti c m e a s u r e m e n t s b y 0 .1 5 ( k P a / p ) , w h e r e 0 .1 5 k P a is o u r e s t im a t e o f
t h e u n c e r t a i n t y i n p . T h i s s c h e m e e n s u r e d t h a t t h e e b u l l i o m e t r i c re s u lt s
r e c e i v e d a w e i g h t a b o u t a f a c t o r o f l 0 g r e a t e r t h a n t h e s t a t ic r es u l t s a t a
s i m i l a r p r e s s u r e . F o r R 2 2 t h e l i t e r a t u r e r e s u l t s w e r e w e i g h t e d b y a n
e s t i m a t e o f t h e u n c e r t a i n t y p r o v i d e d b y t h e s o u r ce s . In E q . ( 2 ), e a c h t e r m
e n t e r e d w i t h a h i g h d e g r e e o f s i g n i fi c a n c e a n d n o o t h e r s i g n i f ic a n t t e r m s
w e r e f o u n d . T h e p r o c e d u r e s r e q u i r e d t o p e r f o r m t h e s e c a l c u l a t i o n s h a v e
b e e n d e s c r i b e d i n d e t a i l e l s e w h e r e [ 3 5 ] .
T a b l e I g i v e s t h e v a p o r p r e s s u r e , t o g e t h e r w i t h d e v i a t i o n s f r o m t h e
A n t o i n e a n d W a g n e r e q u a t i o n s , d e t e r m i n e d a t e a c h t e m p e r a t u r e o n I T S - 90 .
S m a l l c o r r e c t i o n s h a v e b e e n a p p l i e d t o a c c o u n t f o r t h e f l u i d h e a d i n e a c h
e b u l l i o m e t e r ; f o r R 1 3 4 a w e u s e d a s t a t i c - h e a d c o r r e c t i o n f a c t o r o f 1 . 0 0 0 1 3 9 ,
wh i l e f o r R 22 we use d 1 .000124 .
3 .1 . V a p o r P r e s s u re o f W a t e r o n I T S 9 0
A l t h o u g h t h e r e a r e n u m e r o u s e q u a t i o n s f o r t h e v a p o r p r e s s u r e o f
w a t e r o n I T P S - 6 8 [ 3 6 3 8 ] , w e w e r e n o t a w a r e o f a n y c o r r e la t in g e q u a t i o n
w i t h t e m p e r a t u r e s o n I T S - 9 0 . T h e r e f o r e , w e u s e d t h e b e s t e x p e r i m e n t a l
r e s u lt s ( f ro m t h e N a t i o n a l B u r e a u o f S t a n d a r d s , t h e p r e d e c e s s o r to N I S T )
r e p o r t e d b y O s b o r n e e t al. [ 3 9 ] , S t i m s o n [ 4 0 ] , a n d G u i l d n e r et a l. [ 4 1 ]
a n d c o n v e r t e d t h e t e m p e r a t u r e s t o I T S - 9 0 u si n g t h e r e c o m m e n d a t i o n s o f
S a t o e t a l. [ 4 2 ] . T h e c o n v e r s i o n fo r m u l a [ 4 3 1 i s a c c u r a t e t o 1 m K a b o v e
2 7 3 .1 5 K a n d t o 1.5 m K b e lo w . W i t h t h e r e g r e s si o n p r o c e d u r e d e s c r i b e d
a b o v e , w e s e le c te d te r m s t o d e t e r m i n e a W a g n e r e q u a t i o n f o r w a t e r . E a c h
o b s e r v a t i o n w a s g i v e n a w e i g h t o f u n i t y i n t h e r e g r e s si o n a n a l ys i s, e x c e p t
f o r t h e m e a s u r e m e n t s o f S t i m s o n [ 4 0 ] a n d G u i l d n e r et a l. [ 4 1 ] , w h i c h
w e r e g i v e n a w e i g h t o f 10. W e u s e d t h e c r i t i c a l t e m p e r a t u r e o f 6 47 .1 K ( o n
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844 Goodw in Def ibaugh and W eber
Table I. Vapor Pressures p and Deviations
A p l = p - p c a l c . )
from Eq. 1) and A p 2 = p - p c a l c . ) from Eq. 2)
at Tempera ture s T for 1,1,1,2-Tetrafluoroethane R134a)
and Chlorodifluoroethane R22)
T p ZJpl z~p2
K) kPa) Pa) Pa)
Chlorodifluoromethane R22) ebulliometer
217.086 46.651 - 1 1 - 2 6
217.118 46.738 - 5 -2 1
218.307 49.888 8 - 6
220.217 55.272 4 - 9
221.873 60.315 5 - 5
223.409 65.309 2 - 7
224.861 70.331 1 - 5
226.227 75.331 2 - 4
227.529 80.358 5 - 1
228.828 85.632 4 0
229.978 90.529 5 4
231.225 96.095 17 16
232.206 100.664 28 30
232.151 100.319 - 5 5 - 5 5
234.240 110.609 - 1 7 - 1 1
235.712 118.364 35 - 7
236.188 120.899 - 8 1
238.205 132.295 - 31 - 2 1
238.461 133.848 17 25
239.615 140.779 - 1 8 - 7
242.718 160.936 6 20
242.742 161.070 - 2 2 - 1 0
244.060 170.274 - 21 - 1 2
245.584 181.443 - 4 9
245.464 180.565 20 29
248.502 204.388 33 36
1,1,1,2-Tetrafluoroethane R134a) ebulliometer
214.435 17.301 3 1
216.869 20.179 4 1
218.289 22.033 4 2
223.588 30.219 - 6 - 4
226.340 35.365 - 6 - 4
228.866 40.691 - 1 0 - 8
228.824 40.596 - 10 - 9
231.025 45.749 - 6 - 4
230.996 45.676 - 7 - 6
232.785 50.230 - 9 - 8
232.798 50.269 - 5 - 4
233.849 53.121 3 4
233.881 53.208 1 2
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Vapor Pressure of R134a and R22
Table I. Continued)
T p dpl Ap2
K) kPa) Pa) Pa)
234.625 55.291
234.668 55.432
235.317 57.317
236.287 60.203
236.293 60.226
236.582 61.133
238.084 65.932
239.610 71.106
239.635 71.196
241.675 78.628
242.972 83.669
242.951 83.579
244.861 91.450
244.879 91.534
247.149 101.649
249.243 111.742
251.123 121.471
252.951 131.554
254.558 140.955
256.289 151.655
258.660 167.348
261.048 184.401
262.599 196.175
264.727 213.242
Static
265.609 220.860
266.152 225.480
267.134 234.160
268.151 243.390
269.167 252.880
270.132 262.140
271.153 272.270
272.182 282.590
273.135 29Z710
273.167 293.030
276.166 326.250
281.151 387.700
285.171 443.310
289.181 504.720
293.146 571.560
297.130 645.190
301.150 726.680
305.162 815.530
309.162 912.080
313.204 1017.710
--10 --9
7 9
10 11
--16 --13
--10 --9
6 8
9 11
8 9
9 11
14 14
16 12
9 19
9 9
13 16
10 13
4 5
2 5
2 --1
1 2
--9 --12
--3 --12
I
--18
--5 --29
--40 --76
118
69
112
129
137
129
170
22
172
153
197
208
135
130
96
- 1 7
0
41
157
- 117
845
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V a p o r P r e ss u re o f R 1 3 4 a a n d R 2 2 8 4 7
~ 0
-5
I
2 2 0
9 0 0 9 0 0 0 0
F i g . 3 . F r a c t i o n a l d e v i a t i o n s
I
9 9 O -
9
e 9
I
250
T , K
zlp/p= [p-p calc.)]/p
o f t h e
e x p e r i m e n t a l v a p o r p r e s s u r e s f r o m E q . 1 ) f o r c h l o r o d i f l u o r o -
m e t h a n e R 2 2 ). O , T h i s w o r k .
tions from Eq. 1) with the coefficients given in Table II. The normal boil-
ing temperature, at a pressure of 101.325 kPa, calculated from Eq. 1) with
the coefficients of Table II is 232.351 + 0.005) K on ITS-90. The standard
deviation of the fit was 21 Pa, or 4 mK in temperature. Only at 232.2 K did
the result deviate from Eq. I) by more than 10 mK. Removal of this point
from the regression did not alter the normal boiling temperature.
There are several measurements of the vapor pressure of R22 in the
literature [16-18, 46-51] and most have quoted imprecisions of about
0.001p. All values were compared on ITS-90 [43, 52]. At temperatures
that overlap our range, most agree within the uncertainty of those
measurements. For example, the static measurements of Zander [ 16] are in
excellent agreement with Eq. 1) in the overlapping range. At 222.905 K his
T a b l e I I. C o e f f ic i e n t s a n d S t a n d a r d D e v i a t i o n s s f o r E q s . 1 ) a n d 2 ) O b t a i n e d b y
A n a l y s i s o f t h e N V a p o r P r e s s u r e s o f C h l o r o d i f l u o r o m e t h a n e R 2 2 ) a n d
1 , 1 , 1 , 2 - T e t r a f l u o r o e t h a n e R 1 3 4 a ) a
Eq . 1 ) A B C N s P a )
R 2 2 1 4.0 37 98 - 1 8 9 0 . 6 4 1 - 3 1 . 6 4 0 2 6 2 1
R 1 3 4 a 1 4 .2 14 7 5 - 2 0 1 3 . 9 5 1 - 3 7 . 2 1 7 3 7 11
Eq . 2 ) P c kP a ) n a n 2 n 3 n 4 N s P a )
R 2 2 4 9 8 7 . 1 + 1 .2 - 7 . 0 3 5 5 1 1 . 4 5 97 6 - 1 . 8 1 20 - 2 . 9 6 4 4 1 0 6 8 7 7
R 1 3 4 a 4 0 55 .1 + 0 . 3 - 7 . 6 1 7 0 2 1 .6 9 46 4 - 2 . 5 0 8 1 - 3 . 4 9 1 5 7 9 16 7
U n c e r t a i n t i e s a r e o n e s t a n d a r d d e v i a t i o n .
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848 Goodwin, Def ibaugh, and W eber
3
I I I L
AT= 25 mK v 9
- 9 " " - - - - - - - ~ ~ 9
~ 0 ,
9
v v v
' , r - " I " l - v 9 v v V "
_ 2 F I I I I I
200 250 300 350
T , K
Fig. 4. Fractional deviations
Ap/p= Ep-p calc.)]/p
of the experimental
vapo r pressures from Eq. 2) for chlorod ifluorom ethane R2 2). Tb is the
boiling temperature at a pressure of 101.325 kPa. 0 , Th is wo rk; , , Ref. 17;
A, Ref. 16; V, R ef. 18; , the error arising at ea ch temp erature from a
chang e of 0.025 K.
r e s u l t d e v i a t e s b y l es s t h a n 4 P a , a t 2 3 2 . 3 9 0 K b y 1 .2 P a , a n d a t 2 3 4 .2 2 5 K
b y - 7 P a . T h e e x c el le n t a g r e e m e n t b e t w e e n o u r v a p o r - p r e s s u r e
m e a s u r e m e n t s a n d t h o s e r e p o r t e d b y Z a n d e r [ 1 6 ] s u g g es ts t h a t b o t h s et s
o f m e a s u r e m e n t s a r e f r ee f r o m s y s t e m a t ic e r ro r s .
W e c o m b i n e d o u r v a l u e s w i t h t h o s e r e p o r t e d i n R e f s . 1 6 - 1 8 a f t e r
c o n v e r t i n g t h e t e m p e r a t u r e s t o I T S - 9 0 [ 4 3 ] . T h e s e d a t a s e t s , a s s h o w n i n
F i g. 4 , j o i n e d s m o o t h l y w i t h o u r r e su l ts a n d w e r e o b t a i n e d w i t h s a m p l e s
o f s i m i l a r p u r i t y . W e f ix e d T c a t 3 6 9 .2 7 5 K , a s r e c o m m e n d e d b y A m b r o s e
[ 5 3 ] c o n v e r t e d to I T S - 9 0 [ 4 3 ] ) , a n d f it E q . 2 ) t o t h e c o m b i n e d d a t a
w e i g h t i n g t h e l i t e r a t u r e v a l u e s b y 0 .0 0 1. T h e r e g r e s s i o n r e t u r n e d c = 2.5 a n d
d = 5 . T a b l e I I l is ts t h e co e f f ic i e n ts o f E q s . 1 ) a n d 2 ) d e t e r m i n e d f o r R 2 2 ,
t o g e t h e r w i t h t h e s t a n d a r d d e v i a t io n s a n d n u m b e r o f v a p o r p r e ss u r es in
e a c h r e g r e s s i o n .
3 .3 . 1 , 1 , 1 , 2 - T e t r a f l u o r o e t h a n e R 1 3 4 a
F o r R 1 3 4 a t h e 37 e b u l l io m e t r i c m e a s u r e m e n t s o f t h e v a p o r p r e s su r e
w e r e u s e d t o a d j u s t t h e c o e f fi ci e nt s o f E q . 1 ). T h e s t a n d a r d d e v i a t i o n
o f th e f it w a s 11 P a , o r 2 .9 m K i n t e m p e r a t u r e . T h e n o r m a l b o i l in g
t e m p e r a t u r e , a t a p r e s s u r e o f 1 0 1 . 3 2 5 k P a , c a l c u l a t e d f r o m E q . 1 ) is
247 .082 _+ 0 .00 5) K .
W e w e r e u n a b l e t o e x t e n d t h e s t a t i c e x p e r i m e n t t o a t e m p e r a t u r e
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V a p o r P r e s su r e o f R 3 4 a a n d R 2 2
8 4 9
lower than 265.6 K, about 0.9 K above the highest ebulliometric tem-
perature. Consequently, the pressure ranges did not overlap. The static
measurements reported here extend to a temperature 48 K below the
lowest temperature reported by us previously 1-13]. These pressures
deviated from the smoothing equation, discussed below and shown in
Fig. 5, within a factor of 0.9 of the estimated accuracy of the pressure
gauge.
We combined our ebulliometric measurements and static results,
including those from Ref . 13, with the critical temperature observed by
Morrison and Ward [28] of 374.179 K. A small correction was applied to
convert the temperature reported in Ref. 28 to ITS-90 [-43]. We obtained
c= 2.5 and d = 5 from a weighted regression analysis with Eq. 2) and a
standard deviation of 167 Pa, or of 1.39
x 1 0 - 4
in in p. Figure 5 shows the
experimental results as deviations from this smoothing equation. It is clear
that there are inconsistencies in the results from static and ebulliometric
experiments which, although small, far exceed the imprecision of any one
value. We suspect that the presence of air in the sample is responsible.
However, the deviations show a systematic, albeit small, undulation from
Eq. 2), which implies that the functional form is not entirely suitable.
While the difference between the ebulliometric and the static results at
265 K suggests that our static measurements were affected by the presence
of a volatile impurity, no additional significant terms remained unselected
i @ [ ] i i
[]
~-
I l l I - ' ~ [ ] , o . , ' _ ~ i - - _ _ _
0 9 ~ "
I ' I , .
-5 Tb r c
I i i i i
2 0 0 2 5 0 3 0 0 3 5 0 4 0 0
T , K
F i g . 5 . F r a c t i o n a l d e v i a t i o n s Ap/p=Ep--p calc.)]/p o f t h e
e x p e r i m e n t a l v a p o r p r e s s u r e s f r o m E q . ( 2 ) f o r 1 , 1 , 1 ,2 - t e tr a f lu o r o -
e t h a n e ( R 1 3 4 a ) . T u i s t h e b o i l i n g t e m p e r a t u r e a t a p r e s s u r e o f
1 0 1 .3 2 5 k P a . 0 , T h i s w o r k , e b u l l i o m e t r i c ; [ 3 , t h i s w o r k , s t a ti c ;
i , R e f. 1 3, s a m e s a m p l e ; - - , t h e e r r o r a r i s i n g a t e a c h t e m p e r a t u r e
f r o m a c h a n g e o f 0. 0 05 K .
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850 Goodw in Def ibaugh and W eber
a t t h e c o n c l u s i o n o f t h e r e g r e s s io n . T h e d i s c o n t i n u i t y , s h o w n i n F i g . 5,
c o u l d r e s u l t f r o m a m o l e f r a c t i o n o f a i r o f 1 0 - 5 . N e v e r t h e l e s s , t h e a g r e e -
m e n t b e t w e e n t h e r e s u lt s o f t w o s u c h d i f fe r en t te c h n i q u e s i s e x c e p t i o n a l a n d
i n d i c a te s t h a t t h e v a p o r p r e s s u re s c a n b e o b t a i n e d t o b e t t e r t h a n 3 x 1 0 - 4 p .
T a b l e I I g i v es t h e c o e ff i ci e n ts o f E q s . 1 ) a n d 2 ) f o r R 1 3 4 a , t o g e t h e r
w i t h t h e s t a n d a r d d e v i a ti o n s a n d t h e n u m b e r o f v a p o r p r es s u re s in e a c h
r e g r e s s ion .
4 . D I S C U S S I O N
F o r b o t h R 1 3 4 a a n d R 2 2 o u r a n a l y s i s p r o c e d u r e h a s s e l e c t e d t h e f o r m
o f E q . 2 ) r e c o m m e n d e d b y A m b r o s e [ 3 5 ] a n d r e t u r n e d c o e ff ic ie n ts w h i c h
a r e ty p i c a l i n m a g n i t u d e o f s u c h a n e q u a t i o n [ 3 5 ] .
4.1. Chlorodif luoromethane R22
T h e r e a r e s e v e ra l o t h e r p r e v i o u s m e a s u r e m e n t s o f t il e v a p o r p r e s s u re
f o r c h l o r o d i f l u o r o m e t h a n e [ 4 6 - 5 1 ] , m o s t t h a t ar e a v a il a b le [ 47 , 4 9 - 5 1 ]
d e v i a t e f r o m E q . 2 ) b y m o r e t h a n 0 . 00 5 p. O n l y th e m e a s u r e m e n t s o f
O g u c h i e t al . [ 4 6 ] a n d T a k a i s j i e t a l. [ 4 8 ] d i f fe r b y le ss t h a n 0 . 0 0 1 p f r o m
o u r c o r r e l a t i o n .
A s s u m i n g t h e c ri ti ca l t e m p e r a t u r e r e c o m m e n d e d b y A m b r o s e [ 5 3 ]
a n d a l s o b y H i r a t a e t a l. [ 5 4 ] a n d K o h l e n e t a l. [ 1 8 ] ) , w e c a lc u l a te f r o m
E q . 2 ) a c r i t ic a l p r e s s u r e o f 4 9 8 7 .1 _ 1 .2 ) k P a , 1 6 . 1 k P a a b o v e t h e v a l u e
g i v e n in R e f. 5 3. T h e m e a s u r e m e n t o f K l e t s k i i [ 1 7 ] l ie s 1.1 k P a b e l o w , w e l l
w i t h i n o u r e s t i m a t e d u n c e r t a i n t y , w h i le th e v a l u e o f Z a n d e r [ 1 6 ] is 2 .9 k P a
a b o v e , t h e c r i ti c a l p r e s s u r e c a l c u l a t e d f r o m E q . 2 ) .
4 .2 . 1 , 1 ,1 , 2 - Tet ra f luo ro e t ha ne R 1 3 4 a )
T h e v a p o r p r e s s u r e s r e p o r t e d b y o t h e r w o r k e r s a r e s h o w n i n F i g . 6 , a s
d e v i a t i o n s f r o m E q . 2 ) , w h e r e t h e o r d i n a t e s c al e h a s b e e n c o m p r e s s e d b y
a f a c t o r o f 1 0 0 c o m p a r e d w i t h F i g . 5 ; a l l v a l u e s w e r e c o m p a r e d o n I T S - 9 0 .
T h e r e a r e l a rg e d i f fe r en c e s b e t w e e n t h e v a l u e s o f p a t t e m p e r a t u r e s b e l o w
3 0 0 K w i t h d i f fe r e n c e s u p t o 0 .0 2 4 p . S u c h e r r o r s i n t h e v a p o r p r e s s u r e
c o u l d a r i s e f r o m i n c o n s i s t e n c i e s b e t w e e n t h e t w o t h e r m o m e t e r s u s e d f o r
o u r e b u l l i o m e t r y . F o r e x a m p l e , a n u n c e r t a i n t y o f 0 .0 5 K a t 2 6 5 K o r 0 .3 8 K
a t 2 1 5 K w o u l d b e l a r g e e n o u g h t o c a u s e s u c h d i ff er en c e s; h o w e v e r , b a s e d
o n o u r m e a s u r e m e n t s , d i s c u s s e d i n S e c t i o n 2 . 1 , o u r t h e r m o m e t r y w a s
s h o w n t o b e a c c u r a t e t o a f e w m i l l i k e l v i n a n d w e a r e a b l e t o r u l e o u t t h i s
a s t h e s o u r c e o f t h e d i f fe re n c es . A t t e m p e r a t u r e s b e l o w 2 5 0 K w e a r e a w a r e
o f t w o o t h e r i n d e p e n d e n t s et s o f v a p o r p r e s s u r e m e a s u r e m e n t s i n th e
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V a p o r P r e s su r e o f R 3 4 a a n d R 2 2 8 5
3
2 1 9 9
-1 L . ~ A T = o . ] K 9
200 300 400
T , K
Fig. 6. Fra cti on al deviations
Ap/p=[p--p calc.)]/p
of the
experimental vapor pressures fr o m Eq. 2) for 1,1,1,2-tetra-
fluoroeth ane R13 4a). O, Ref. 19; L Ref. 20; O, Ref. 21; D,
Ref. 22; A, Ref. 23; V, Ref. 24; A , Ref. 25; -- , the error arising
at each temp erature from a change of 0.1 K.
l i t e r a t u r e 1 -1 9, 2 4 ] b o t h , a r e s h o w n i n F i g . 6 , a n d w e r e o b t a i n e d w i t h a
s t a t i c t e c h n i q u e . S y s t e m a t i c e r r o r s i n s t a t i c v a p o r p r e s s u r e m e a s u r e m e n t s
c o u l d a r i s e f r o m e r r o r s i n t h e p r e s s u r e m e a s u r e m e n t o r f r o m t h e p r e s e n c e
o f v o l a t il e i m p u r i ti e s. T h e d i s c r ep a n c i e s b e t w e e n e q u a t i o n 2 ) a n d t h e s t a ti c
m e a s u r e m e n t s o f B a s u a n d W i l s o n [ 2 4 ] a r e le ss t h a n t h e e s t i m a t e d e r r o r s
i n t h e p r e s su r e m e a s u r e m e n t s o f t h e l a tt e r. B a s u a n d W i l s o n [- 24 ] d e g a s s e d
t h e i r s a m p l e b y a r e p e a t e d f r e e z i n g , p u m p i n g , a n d t h a w i n g p r o c e s s u n t i l
t h e p r e s s u r e w a s b e l o w 7 P a . W e e s t i m a t e t h a t t h e d i s c r e p a n c y o f 0 .0 2 4 p a t
2 1 0 K , b e t w e e n e q u a t i o n 2 ) a n d t h e r e su l ts r e p o r t e d i n R e f. [ 2 4 ] , c o u l d b e
a c c o u n t e d f o r w i t h a m o l e f r a c t i o n o f a i r o f 3 x 1 0 5. M o s t o f t h e s t a t i c
m e a s u r e m e n t s r e p o r t e d b y M a g e e a n d H o w l e y [ 1 9 ] d if fe r f r o m o u r v a p o r
p r e s s u r e e q u a t i o n w e ll w i t h i n t h e i r e r r o r e s ti m a t e s. M a g e e a n d H o w l e y
[ 1 9 ] u s e d a s a m p l e o f R 1 3 4 a t h a t c o n t a i n e d a m o l e f r a c t io n o f a i r o f a b o u t
1 x 1 0 6. A t t e m p e r a t u r e s b e t w e e n 2 4 0 a n d 2 5 0 K t h e r e a p p e a r s t o b e a
s te p d i s co n t i n u i t y i n th e m e a s u r e m e n t s o f M a g e e a n d H o w l e y [ 1 9 ] , t h a t
a r o s e f r o m c h a n g i n g p r e s s u r e g a u g e s . S e v e r a l o t h e r s e t s o f r e s u l t s a g r e e
w i t h E q . 2 ) t o w i t h i n 0.1 K a t t h e n o r m a l b o i l in g t e m p e r a t u r e . A t h i g h e r
t e m p e r a t u r e s t h e m a j o r i t y o f t h e r es u l ts d e v i a t e f r o m E q . 2 ) b y le ss t h a n
0 . 0 0 2 p , o r l e s s t h a n 0 . 1 K . F o r e x a m p l e , t h e r e s u l t s r e p o r t e d b y B a e h r a n d
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8 5
G o o d w i n , D e f i b a u g h ,
a n d W e b e r
Tillner-Roth 1-21] differ by less than 0.0001p from Eq. 2) at temperatures
up to the critical. Such agreement between independent vapor-pressure
measurements is truly remarkable. In contrast, the measurements of
Kubota et al. [25] appear to have a systematic error with differences
between 0.004p and -0.005p. The recent measurements of Zhu and Wu
[20] between 279 and 363 K show a similar trend to those of Kubota et
al. [25]. The vapor-pressure equations given by the Japanese Association
of Refrigeration JAR) 1-55] and by Baehr and Tillner-Roth [21] were
both derived from information independent of ours and Ref . 19. These
equations predict vapor pressures below 300 K that are much too high but
tend toward agreement with our data at higher temperatures. The JAR
[55] correlation was derived with data reported by Basu and Wilson [24],
while that attributed to Baehr and Tillner-Roth 1-21] used data of Bier et
al. [56] at lower temperatures. In view of the excellent agreement between
our measurements of the vapor pressure of R22 with those reported by
Zander [16] and for R134a with the precise static measurement of Magee
and HoMey [19] at temperatures below 250 K despite the slight discon-
tinuity in their results), we conclude that the measurement of Basu and
Wilson [24] and the correlations of JAR [55] and Baehr and Tillner-Roth
[21] are in error by as much as 0.02@ at 220 K.
Assuming the critical temperature to be that observed by Morrison
and Ward [28] and adopted by McLinden et al. [57]) we calculate from
Eq. 2) a critical pressure of 4055.1 _+ 0.3)kPa, 12.9 kPa below the value
given in Ref. 28, but only 0.9 +_ 10)kPa below Ref. 57 and well within
twice the combined uncertainty; Weber reported po = 4055.9 kPa [13]. The
critical pressure reported by Kubota et al. [25], from an extrapolation of
their vapor-pressure equation a Chebyshev polynomial), and that adopted
by Tang et al. [58], for use in a simplified crossover model for the critical
region, is 9.9 kPa above our value.
ACKNOWLEDGMENTS
One of us A. R. H. G.) would like to thank Drs. Douglas Ambrose
and Michael Ewing for stimulating his interest in ebulliometric measure-
ment of vapor pressure that began at University College, London, with
Ref. 9.
R E F E R E N E S
1 . C . B . Wi l l i ngham, W. J . Tayl or , J . M . P i gnocco , and F . D. Ross i n i , J .
Res. Natl. Bur.
Stand.
35:219 1945).
2 . D . A m b r o s e , i n
Specialist Periodical Reports Chemical Thermodynamics Vol. I M . L.
M cG l ash an , ed . Ch em i ca l Soc ie ty , Lo ndo n~ 1973) , pp . 240-246 .
3 . D . A m b r o s e ,
Exp erim ental Thermodynamics VoL II. Experimental Thermodynamics of
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Vapor Pressure of R 34a and R22 853
Non -Rea c t i ng F l ui ds , B . L e N e i n d r e a n d B . V o d a r , e d s . ( I U P A C B u t t e r w o r t h s , L o n d o n ,
1975) , 626-634.
4 . D . A m b r o s e , M . B . E w i n g , N . B . G h i a s s e e , a n d J . C . S a n c h e z O c h o a , J. Chem. Thermodyn.
22:589 (1990).
5 . D . Ambrose , C . H. S . Sprake , and R . Townsend , J . Chem. Thermodyn. 1:499 (1969).
6 . L . A . Webe r , submi t t ed for publ i ca t i on .
7 . D . Ambrose , J . Phys . E 1:41 (1968).
8 . D . Ambrose , C . H. S . Sprake , and R . Townsend , J. Chem. Thermodyn. 4:247 (1972).
9 . M . B . Ewi ng and A. R . H. Goodwi n , J. Chem. Thermodyn. 23:1000 (1991).
1 0 . M . W a x m a n a n d J . R . H a s t i n g s , J. Res. Natl . Bur. Stand. 75C:165 (1971) .
1 1 . M . W a x m a n , H . A . D a v i s , M . H o r o w i t z , a n d B . E v e r h a r t , Rev. Sc i . Ins t rum. 55:1467
(1984).
12 . D . L i nsky , J . M . H. Leve l t Senge rs , and H. A. Davi s , Rev. Sc i . Ins t rum. 58:817 (1987).
13. L . A. Weber , Int . J . Thermophys . 10:617 (1989).
1 4. B . W . M a n g u m a n d G . T . F u r u k a w a , Guidel ines for Real i z ing the Internat ional
T e m p e r a t u re S c a l e o f 1 9 90 I T S - 1 9 9 0 ) , N I S T T e c h n i ca l N o t e 1 26 5 (U .S . G o v e r n m e n t
Pr int ing Off ice , W ash ing ton , D.C. , 1990) , p . 5 .
1 5 . H . P r e s t o n - T h o m a s , M e t r o l o g i a 27:3 (1990).
16 . M . Zande r , i n Proc . Fo urth Symp. Thermophys . Prop., J . R . M oszynsk i , ed . (ASM E,
New York, 1968) , p . 114.
17. A. V. K letsk i i , Tepl o f i z i ehesk i e Sovoi s t va Freona-22 ( K o m i t e t S t a n d a r t o v , M e r i
I z m e r i t e l n y k h P r i b o r o v p r i S o v e t e M i n i s t r o v S S SR , M o s k v a , 1 9 70 ); Thermophys i ca l
Proper t i e s o f Freon-22 ( I s rae l P rogram for Sc i en t i f i c T rans l a t i on , J e rusa l em, 1971) .
18 . R . Kohl en , H . Kra t zke , and S . M ul l e r , J . Chem. Thermodyn. 17:1141 (1985).
19 . J . W. M agee and J . B . Howl ey , submi t t ed for publ i ca t i on .
2 0 . M . Z h u a n d J . W u , s u b m i t t e d f o r p u b l i c a t i o n .
2 1 . H . D . B a e h r a n d R . T i ll n e r - R o t h ,
J . Chem. Thermodyn.
23:1063 (1991).
22 . C . -C . P i ao , H . Sa t o , and K. Wa t anabe , A S H R A E . T r a n s . 96:132 (1990) .
2 3 . Y . M a e z a w a , H . S a t o , a n d K . W a t a n a b e ,
J . Chem. Eng. Data
35:228 (1990).
24 . R . S . Basu and D. P . Wi l son , In t . J . Thermophys . 10:591 (1989).
2 5 . H . K u b o t a , T . Y a m a s h i t a , Y . T a n a k a , a n d T . M a k i t a , Int . J . Thermophys. 10:629 (1989).
26 . R . C . Downi ng , Fl uorocarbon Re f r i ge rant Handb ook (Pren t i ce -Ha l l , Engl ewood C l i f f s ,
N.J. , 1988), pp. 5-8.
2 7 . T . J . B r u n o , p r i v a t e c o m m u n i c a t i o n ( T h e r m o p h y s i c s D i v i s i o n , N I S T ) .
2 8 . G . M o r r i s o n a n d D . K . W a r d , Fluid Pha se Equi l ib. 62:65 (1991).
2 9 . A . R . H . G o o d w i n a n d M . R . M o l d o v e r , J . Chem. Phys . 93:2741 (1990).
30 . W. Wagne r , Cryogeni c s 13:470 (1973).
31 . W. Wagne r , Bul l. Ins t . Int . Fro id An ne xe 4:65 (1973).
3 2 . W . W a g n e r , H a b i t a t i o n s s c h r i f t , T U B r a u n s c h w e i g 1 9 7 3 , Forschr . -Ber VDI-Z. Reihe 3,
nr. 39 (1974).
3 3 . W . W a g n e r , A N e w C o r r e la t io n M e t h o d f o r T h e r m o d y n a m i c D a t a A p p l i e d to t h e V a p o ur -
P r e s su r e C u r v e f o r A r g o n , N i tr o g e n , a n d W a t e r ( I U P A C T h e r m o d y n a m i c T a bl es P r o j e ct
Cent re , PC / T 15 , London , 1977) .
3 4 . M . B . E w i n g , p r i v a t e c o m m u n i c a t i o n ( U n i v e r s i t y C o lle ge , L o n d o n ) .
3 5 . D . A m b r o s e , J . Chem. Thermodyn. 18:45 (1986).
3 6 . A . S a u l a n d W . W a g n e r , J . Phys . Chem. Re f Dat a 16:893 (1987).
3 7 . D . A m b r o s e a n d I . J . L a w r e n s o n , J . Chem. Thermodyn. 4:755 (1972).
3 8 . D . A m b r o s e a n d C . H . S . S p r a k e , J. Chem. Thermodyn. 4:603 (1972).
39 . N . S . Osborne , H . F . S t i mson , E . F . F i ock , and D. C . Gi nni ngs , J . Res . Nat l . Bur . Stand.
10:155 (1933).
8/9/2019 Vapor Pressure R134a R22
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854 Goodw in Def ibaugh and W eber
40. H. F . St imson, J . Res. Natl. Bur. Stand. 73A:493 1969).
41. L . A. Guildner , D. P . Johnson, and F. E . Jones, J . Res. Natl. Bur. Stand. 80A:505 1976).
42. H. Sato , K. W atanab e, J . M. H. Le velt Sengers , J . S . Ga llagher , P . G. Hil l , J . S traub, a nd
W. Wagner , J . Phys. Chem. Ref Data 20:1023 1991).
43. B IP M Supplementary Information fo r ITS-90 1990), p. 17.
44. J . M. H. L evelt Sengers , J . S traub, K. Wa tanab e, and P. G. Hil l , J . Phys . Chem. Re f Data
14:193 1985).
45. D. R. Douslin , J . Chem. Thermodyn. 3:187 1971).
46. K. Oguchi , H. Sagara , I . Matsushita , K. Watanabe, and I . Tanishita , Tra ns. Jap. Soc.
Mech. Eng. 45:1522 1979).
47 . A. Kumaga i and H. Iwasak i , J . Chem. Eng. Data 23:193 1973).
48 . Y. Taka ish i , M. Uematsu , and K. Watanabe , p V T and Vapor Pressure Data for R22
XV Int. Conf. Refrig., Venice, 1979).
49. L . M. Lagutina, Cholod. Techn. 43:25 1966).
50. A. F . Benning and R. C. McHarness , Ind. Eng. Chem. 31:912 1939); 23:479 1940); 32:698
1940); 32:814 1940).
51. H. S. Booth and C. F. Swinehart, J. Am. Chem. Soc. 57:1337 1935).
52 . J . L . Ridd le , G. T . Furukawa , and H. H. P lumb, Platinium Resistance Thermometry N B S
M ono grap h 126 U.S. Govern m ent P r in t ing Off ice, W ash ing ton , D.C. , 1973).
53. D. Am brose, Vapour-Liquid Critical Properties Nat iona l Phys ica l Labora to ry , Repor t 107
HM S O, L o n d o n , 1 9 8 0 ) .
54 . M. Hira ta , K. Nagahama, J . Sa i to , and N. Wakamatsu , Eigth Autumn Meet . Soc. Chem.
Eng. Ja pa n 1974), p. 44.
55. Thermophysical Properties o f Environmentally Acceptable Fluorocarbons HC FC -134 a and
H C F C - 1 2 3 Japanese Associat ion of Refr igerat ion, 1990).
56. K. Bier, L . Oellr ich , M . Tiirk , an d J . Zh ai , Bericht iib er die Ki~lte-Klima-Tagung
Klimatechnisher Verein , Stut tgart , 1990).
57. M. O . McL inden , J . S. Ga l laher , L . A. Weber , G. M orr i son , D. W ard , A . R. H. Goodw in ,
M. R. Moldover , J . W. Schmidt , H. B. Chae, T . Bruno, J . F . Ely , and M. L. Huber ,
A S H R A E T r a n s . 95:263 1989).
58. S. Tang, G. X. Jin, and J. V. Sengers, Int. J. Thermophys. 12:515 1991).