temperature glide to an acceptable range, the boiling point may not
be too far from that of R22. The following refrigerants were
selected: R143a, R32, R125, R152a, R134, R134a and R124. At this
time no manufacturer plans to produce R134.

Refrigerants R143a, R32 and R125 are "low boilers" with
boiling points below that of R22, while refrigerants R152a, R134,
R134a and R124 are "high boilers" with boiling points above those
of R22. The binary mixtures investigated here consist of one low
boiler and one high boiler. During the course of the

investigation, it became clear that mixtures containing R32 show a

consistently better performance than those with other low boilers.

Results are presented for the following mixtures:

R32/R134a,
R32/R152a,
R32/R134,
R32/R124,
R143a/R134a,
R143a/R152a,
R143a/R124,
R125/R134a,
R125/R152a,
R125/R124.

Since R32, R152a and R143a are flammable components, it was decided
to also investigate the ternary mixtures:

R32/R152a/R134a,

R32/R152a/R134 and

R32/R152a/R124.
It is expected that the ternary mixtures can substitute for
R32/R152a. The addition of a nonflammable component will reduce
the overall flammability of the mixture. However, extensive tests
are necessary to evaluate the flammability.

Puture work will include the evaluation of ternary mixtures

16



Ee

Of the pure fluids R152a ranks best with a 5.8 % improvement
over R22, followed by R134 with 2 % improvement. and R134a with a1
% decrease. These results indicate that R152a, R134 and R134a can
be used as replacement refrigerants, achieving better or about
equal performance as R22. However, the volumetric capacity of
these replacements is about 40 % smaller, which ‘requires the use of
a 40 % larger compressor.

In Appendix 2 all summary data for all binary mixture runs are
listed in English units. In Appendix 3 results for the
calculations with ternary refrigerant mixtures are presented in
English units.

The best ternary mixture contains R124 with a concentration of
0.6 indicating that the flammability could be reduced compared to
the pure constituents, R32 and R152a. For the: other ternary fluids
this effect is less pronounced. , : :

This analysis presents an idealized condition. To what extent
the savings found in this study can be implemented will depend
strongly on the actual equipment design and on. secondary effects
such as the influence of pressure drops, superheating of the
refrigerant in the compressor, and superheating and subcooling in
the evaporator and condenser. :

4.2 Seasonal Performance : : .
I oo
The calculation of the seasonal performance was conducted for the.

following fluids and mixtures: the reference fluid R22, R32/R152a,

R32/R134, R32/R134a and R32/R124. The ternary mixtures are not

37



Exhipit 9: “Cooling cop and volui metkic_capacity for Binary

Refrigerant ee

VoR(Btu/tt?)

60

i
‘
40~ : 4
20 — ;
i :
0 i y H ,
0 02 0.4 0.6 og 1.0
Concentration of R-125 |
“Me R-125/R-134a —@ R-125/R-124 +. R-125/R-152a

33



strong influence concentration shift can have on the seasonal
performance complicates the situation.
Depending on the given climate region one mixture may perform

better than others. The amount of resistance heat that is required

depends strongly on the design point of the heat pump. If the

current design practice would be changed so that the heat pump
application determines the size of the air-conditioner, the need
for resistance heat could be reduced or eliminated, influencing the
choice of the replacement mixture.

Actual energy savings achieved by employing concentration
shifts depend strongly on the climate and on actual operating and
design conditions over an entire year.

In this chapter, concentration shift is assumed to be
initiated by active means. However, concentration shift can also
be initiated by passive means and the mere fact that some parts of
a heat pump store refrigerant. This concentration shift may
influence the performance of the system and has to be considered in

the design.



approach such as that proposed by the US at the first climate
negatiations. (A tax as small as $ 0.01 per pound of carbon
dioxide would result in an increase of $ 15.00 per pound using the
100 year equivalent global warming potential.)

However, it is important to recognize that for HCFC 22 the
global warming potential is relatively small compared to the
indirect global warming effect caused by the production of carbon
dioxide to provide the power for air-conditioning or heat pumping.
Estimates indicate that up to 10% of the total global warming
caused by a typical air-conditioner is contributed by R22 /3/. Any
xeplacement must, therefore, be at least as efficient as R22 in
order to achieve a significant net reduction in the global warming
effect.

Currently no pure fluid drop-in replacements for R22 have been
identified. Refrigerant mixtures of already available or

identified constituents, however, may be able to replace R22 in

existing and future equipment and in future applications. This

report examines the replacement of R22 from two points of view:
-- The feasibility of a drop-in replacement for residential heat
pumps, air-conditioners and window air-conditioners is
investigated.
Replacement of R22 by refrigerant mixtures that would
potentially lead to energy savings by a completely new design

of the heating and cooling equipment.



70.01
70.01

0.01
70.01
0.01
0.01
70.01
70.07
70.01
70.01
0.01

70.01

70.01
-0.01

0.01
°0.01

0.01
70.01
0.01
-0.01
70.01
0.01
70.01
70.01
70.01
70.01
70.01
70.01
70.01
70.01
70.01
70.01
70.01
70.01
70.01
70.01

FO3

-0.01
70.01
70.01
0.01
0.01
-0.01
-0.01
0.01
-0.01
-0.01
0.01
0.01
70.01
70.01
-0.01
0.01
70.01
70.01
70.01
70.01
0.01
70.01
70.01
70.01
0.01
0.01
70.01
70.01
70.01
70.01
70.01
70.01
70.01
70.01
0.01
0.01
70.01
0.01
70.01
0.01
0.01
0.01
70.01
70.01
0.01
0.01
0.01
70.01
70.01
0.01
0.01
70.01
70.01
70.01
0.01
-0.01
70.01
70.07
0.01
0.01
-0.01
70.01
0.01
70.01
-0.01
0.01
0.01
70.01
70.01
-0,01

x1 X20 -X3_— COP Vol .Flow
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11996 981
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11996 986
11996 992
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11996 1036
11996 1157
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11996 939
11996 937



concentration ranges for combustible refrigerant-air mixtures are
12.7 - 33.4 vol% for R32, 4 -17 vol% for R152a and 7 - 18 vol% for
R143a. With regard to mixtures there seems to be general agreement
that mixing flammable with non-flammable refrigerants reduces the
flammability. However, we were unable to ascertain the

flammability limits of the mixtures.

5.2 Materials Compatibility

Inquiries to refrigerant manufacturers yielded reluctance on their
behalf to the release of information on refrigerant- materials
compatibility. The use of the ARI data base was recommended. The
data base contains currently eighty reports from various sources,
mostly manufacturers. Since the data base is not computerized yet,
a list of titles was obtained with the following information of
concern here: There are 13 reports concerning R134a, 2 for
R22/R142b, 2 for R124, and 1 for R125. None were available for any
other fluid investigated in this report. All reports that were
screened are listed below. The data available and reported are
very scattered. There is no complete set of information available
for a single refrigerant nor the information concerning the same
material for all refrigerants. Taking this in to consideration, it
is not possible to generate a general table or chart. This is a

clear indication that further research in this area is needed.

Allied Signal Incorporated

R.H.P. Thomas and H.T. Pham, Evaluation of Environmentally
Acceptable Refrigerant/Lubricant Mixtures for
Refrigeration and Air Conditioning (R134a)

52



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APPENDIX #1

The following pages of this appendix List the Subroutine BDESC which contains all parameters for the CSD
equation of state that were used to evaluate the properties of the pure refrigerants.

BLOCK DATA BDESC

THIS ROUTINE INITIALIZES THE COMMON BLOCKS CONTAINING INFORMATION
ABOUT THE PURE COMPONENTS. IT IS NOT REFERENCED DIRECTLY BY ANY
OTHER SUBROUTINE BUT MUST BE INCLUDED IN THE EXECUTABLE ELEMENT.
DATA ARRAYS ARE DIMENSIONED TO ACCOMODATE ADDITIONAL

PURE COMPONENTS.

EXPLANATION OF CONSTANTS:
COEFF(I,J) - FOR REFRIGERANT J, COEFFICIENTS OF A, B, CPO
CURVE FITS:
A= AO * EXPCATAT + AZ*TAT) (Ku M**3/KMOL*#2)
B = BO + BI*T + B2*T*T (H**3/KNOL)
CPO = CO + CI*T + C2*T*T (KJ/KMOL K)
(STORED IN ORDER AO,A1,A2,80,B1,82,C0,C1,C2)
CRITCI,J) - FOLLOWING INFORMATION FOR REFRIGERANT J:
1 = 1 - MOLECULAR WEIGHT
2 - REFERENCE TEMPERATURE FOR ENTHALPY AND ENTROPY (K)
3 - CRITICAL TEMPERATURE (K)
4 - CRITICAL PRESSURE (KPA)
5 - CRITICAL VOLUME (M**3/KMOL)
HREF(J) - REFRIGERANT NAME (ASHRAE DESIGNATION)
H2ERO(J) - VALUE OF SATURATED LIQUID ENTHALPY OF REFRIGERANT
J AT ITS REFERENCE TEMPERATURE (KJ/KMOL)
SZERO(J) - VALUE OF SATURATED LIQUID ENTROPY AT REFERENCE
TEMPERATURE (KJ/KMOL K)
R - GAS CONSTANT (KJ/KMOL K)
TOLR = RELATIVE CONVERGENCE TOLERANCE FOR ITERATION LOOPS
SHOULD BE AT LEAST 10 TIMES LARGER THAN MACHINE PRECISION
ITHAX - HAXIMUM ITERATION COUNT FOR ITERATIVE LOOPS
LUP - LOGICAL UNIT TO WHICH ANY WARNING MESSAGES ARE WRITTEN

A, B COEFFFICIENTS EVALUATED FROM ASHRAE (1981) SATURATION
DATA UNLESS INDICATED.

A2AN2A0 ANMAAMAANAAAAANAANAAAAAOAADAAA

IMPLICIT REAL (A-H,0-2)
DIMENSION COEFF(9,20),CRIT(5,20), HZERO(20), SZERO(20)
CHARACTER*6 HREF(20)

COMHON /ESDATA/ COEFF, CRIT

COHHON /HREF1/ HREF

COMMON /HSZERO/ HZERO, SZERO

COMMON /RDATAG/ R

COMMON /TOL/ TOLR, ITMAX,LUP

COMMON /TOLSH/ TOLH,TOLS

DATA R /8.314/

DATA TOLR /1.0E-7/

DATA TOLH,TOLS /0.01,0.001/

DATA ITHAX,LUP /20,6/

DATA FOR R11, R12, R13, 21381, R14, R22, R23, R113, R114,
R142B, R1S2A, R261A, R123, R143A, ISOBUTANE, R125, R134
R134A, R32, METHANE

R11, TRICHLOROFLUOROMETHANE

manana

DATA HREF(1) /'R11'/

DATA C(CRITCI,1),1=1,5) /137.37E0,233.15E0,471.2E0,4467.E0, .247E0/
OATA HZERO(1),SZERO(1) /0.0,0.0/

DATA (COEFF(I,1),1=1,9) /5394.655E0, -2.709516E-3,1.168022E-7,

1 .1869326E0, -2.318627E-4,4.275137E-8,

1 23.48052E0, .2510723E0, -2.28722E-4/

R12, DICHLORODI FLUOROMETHANE

c
c
c



aannaeena

oe

DATA HREF(20)_/*R-CHAR'/

DATA (CRIT(I,20),1=1,5) /100.0,50., 100.0, 1000.0,0.0/

DATA HZERO(20),SZERO(20) /0.0,0.0/

DATA (COEFF(1,20),1=1,9) /1064.,-0.01204,0.0,
0.1680, -8.066E-4,0.0,

44.40,0.5560,0.0/



suggests that for mixtures with boiling points in close proximity
of one another, as is the case here, a deviation in COP of less
than 3% can be expected /11/. This could also affect the ranking
of the mixtures in this report.

The analysis of the seasonal performance is accurate within
the accuracy of the bin method employed. Generally the bin method
is suitable for providing overview information and is used in
connection with the rating of air-conditioners and heat pumps. The
model employed here uses the same information and reasoning as will
be used later for actual testing of equipment. Therefore, it is

ensured that this method and actual tests correspond.

4.7 Global Warming Potential (GWP) and Ozone Depletion Potential
(ODP)

Exhibit 15 shows the effects of using pure and mixed refrigerants
on direct global warming, indirect global warming, total global
warming and ozone depletion. The value for the GWP of R32 is based
on a lifetime estimate from EPA /3/.. The GWP and ODP values are
calculated by linearly interpolating between the pure components of
a mixture and weighted with the specific volume of the liquid
leaving the condenser as compared to these values of R22. In this
way the GWP and ODP is evaluated based on the actual’ charge within
a system (columns entitled "Charge Based"). The underlying
assumption is made that a system charged with any fluid to the same
liquid level as a system would be charged with R22 is optimally

charged. The values for the pure substances are taken from /1/.

48



The use of a mixture as a substitute for R22 implies that the
concentration is selected so that the vapor pressure is close or
equal to R22. This entails that the capacity of the mixture is
also similar to the capacity of R22. These similarities mean the
compressor and motor size do not have to be modified. However, by
changing the mixture concentration, the vapor pressure changes and
the capacity can be modulated.

The change in concentration can be achieved by passive means,
which do not require any additional controls, or by active means
such as rectification columns, which usually require controls,
valves and possibly additional, parasitic power. The range of
composition shift by passive means is limited.

The simplest way of affecting a shift in concentration is to
use an accumulator at the evaporator outlet. This represents a

passive means. Whenever liquid floods out of the evaporator

because the outdoor temperature is dropping, it is stored in the

accumulator. Since the liquid's concentration is different from
the overall concentration circulating in the system, a
concentration shift is accomplished. A higher pressure mixture is
left circulating. The accumulator is a passive device. No
auxiliary power, valves or other controls are required. Its
capability to affect the concentration is limited.

The rectification column used in a Japanese heat pump is more
effective in shifting the concentration /11/. However, active
controls and valves are required. Other concepts suggest molecular

sieves as a separation means /8/.

20



included to shorten calculation times. It is expected that the
seasonal performance of the ternary mixtures will be quite similar
to the binary mixture of the same performance level.

Since the steady state performance under design conditions
showed clearly that mixtures containing R32 are the primary
candidates for replacing R22, the seasonal performance evaluation
is limited to these mixtures. The pure components were included to
demonstrate that the fluid with the better performance under design

conditions shows also the better seasonal performance.

Exhibit 11 shows a bar chart of the seasonal performance

factor (SPF) for both heating and cooling seasons. The first group
of bars represents the cooling seasonal performance factor, CSPF,
and the subsequent groups represent the six climate regions for
heating. A comparison of the fluids indicates, that when a fluid
performs better in the cooling case it will usually be better in
the heating case. Since the actual performance of any working
fluids depends strongly on the hardware design, the ranking may
vary with actual applications. The mixtures containing R32 show
significant improvements,’ while some of the pure fluids show a
reduction in the SPF compared to R22. As can be expected from
previous discussions, the mixture R32/R152a exhibits the best
seasonal performance, followed by R32/R134 and R32/R134a, while
pure R125 shows the poorest. The last four lines in this table are

explained in the section ‘Concentration Shift'.



APPENDIX #3,

This appendix contains a Listing of the short output files for all computer runs conducted for ternary mixtures.
The refrigerants are specified by code numbers according to the following table.
f

R22 6

R142b 10

R152a " .
R143a 4 :
R124 15

R125 . 16

R136 17

R134a 18

R32 19



Table of Contents
List of Exhibits ©... 1... eee ee ee ee

Abstract 2. 6 6 6 ee ee ee we ee ee

ao ® Ww

Findings 2... 6 6 ee ee ee we

1.0 Background and Objective... ....... 80028 2 ee 7

2.0 Simulation Approach ...........602808048 11
2.1 Computer Model ..... 2... 5.5.22 ee wee 11
2.2 Refrigerant Properties es 15
2.3 Refrigerant Mixtures ...... 2.6.22 -020. 15
2.4 Operating Conditions .. ee ee 17
2.5 Capacity Modulation with Mixtures es 19
3.0 Seasonal Performance Evaluation .........4.. 21
\
4.0 Results and Discussions ... er 29
4.1 Performance Under Design conditions ee ee ew 29
4.2 Seasonal Performance ........05. 2.02806 37
4.3 Concentration Shift... .... 2. ee ee ee 40
4.4 Drop-in Application vs. New Systems ........ 44
4.5 Implications of Counter-flow Design and the Use of
Mixtures .. rs oe eee 45
4.6 Sensitivity Considerations and Accuracy . . 46
4.7 Glcbal Warming Potential (GWP) and Ozone Depletion
Potential (ODP) ..........0422282228 48
5.0 Flammability and Materials Compatibility ...... 51
5.1 Flammability .. es rs 51
5.2 Materials Compatibility ee 52
6.0 Further Work... 6 eee ee ee ee we ee we ee 54

References . . 1. 1. 1 6 ee ee ee ee ee wee ee 55

Appendices i



oO 0 3.33 40.2 3.7 53.5 199 11996 1056 78.8
0.1 0 3.47 32.9 3.6 64.3 230 11996 1012 78.8
0.1 0.1 3.52 33.3 3.6 62.2 222 11996 997 78.8
0.1 0.2 3.56 33.7 3.6 60.6 216 11996 987 78.8
0.1 0.3 3.59 34.1 3.6 59.3 212 11996 979 78.8
0.1 0.4 3.61 34.4 3.6 58.3 208 11996 973 78.8
0.1 0.5 3.63 34.7 3.6 57.4 205 11996 969 78.8
0.1 0.6 3.64 34.9 3.6 56.7 202 11996 965 78.8
0.1 0.7 3.65 35.0 3.6 56.1 200 11996 962 78.8
0.1 0.8 3.66 35.2 3.6 55.7 198 11996 959 78.8
0.1 0.9 3.67 35.3 3.6 55.3 196 11996 957 78.8
0.2 0.8 3.74 31.0 3.5 63.0 218 11996 940 78.8
0.2 0.7 3.73 30.7 3.5 63.8 221 11996 942 78.8
0.2 0.6 3.72 30.5 3.5 64.7 224 11996 944 78.8
0.2 0.5 3.71 30.1 3.5 65.7 227 11996 948 78.8
0.2 0.4 3.69 29.8 3.5 67.0 232 11996 952 78.8
0.2 0.3 3.67 29.4 3.5 68.5 237 11996 958 78.8
0.2 0.2 3.64 29.0 3.5 70.3 243 11996 965 78.8
0.2 0.1 0.7 3.60 28.5 3.5 72.4 250 11996 976 78.8
0.2 0 0.8 3.55 28.0 3.5 75.1 260 11996 990 78.8
0.3 0 0.7 3.58 24.7 3.4 85.5 289 11996 983 78.8
0.3 0.1 0.6 3.63 25.2 3.4 82.3 278 11996 968 78.8
0.3 0.2 0.5 3.68 25.6 3.4 79.6 269 11996 956 78.8
0.3 0.3 0.4 3.71 26.1 3.4 77.4 261 11996 948 78.8
0.3 0.4 0.3 3.73 26.5 3.4 75.5 255 11996 942 78.8
0.3 0.5 0.2 3.75 26.9 3.4 73.8 250 11996 938 78.8
0.3 0.6 0.1 3.76 27.2 3.4 72.4 245 11996 934 78.8
0.3 0.7 0 3.77 27.5 3.4 71.2 241 11996 932 78.8
0.4 0.6 0 3.78 24.7 3.3 80.0 266 11996 931 78.8
0.4 0.5 1 3.76 24.4 81.7 272 11996 935 78.8
0.4 0.4 74 24.0 3.3 83.6 278 11996 940 78.8
0.4 0.3 3.71 23.6 3.3 85.9 286 11996 946 78.8
0.4 0.2 0.4 3.68 23.1 3.3 88.6 294 11996 956 78.8
0.4 0.1 0.5 3.63 22.7 3.3 91.8 305 11996 968 78.8
0.4 0 0.6 3.57 22.2 3.3 95.6 318 11996 985 78.8
0.5 0 0.5 3.54 20.3 3.3 105.1 347 11996 994 78.8
0.5 0.1 0.4 3.61 20.8 3.3 100.8 332 11996 974 78.8
0.5 0.2 0.3 3.66 21.2 3.3 97.2 320 11996 960 78.8
0.5 0.3 0.2 3.70 21.6 3.3 94.2 309 11996 950 78.8
0.5 0.4 0.1 3.73 22.1 3.3 91.5 301 11996 942 78.8
0.5 0.5 0 3.75 22.4 3.3 89.2 293 11996 937 78.8
0.6 0.4 QO 3.70 20.5 3.3 99.0 323 11996 949 78.8
0.6 0.3 0.1 3.67 20.1 3.3 102.0 333 11996 957 78.8
0.6 0.2 0.2 3.63 19.7 3.3 105.4 344 11996 969 78.8
0.6 0.1 0.3 3.57 19.3 3.3.109.5 358 11996 985 78.8
0.6 0 3.49 18.9 3.3.114.2 375 11996 1007 78.8
0.7 Oo 3.43 17.7 3.3 122.8 404 11996 1024 78.8
0.7 0.1 3.52 18.1 3.3 117.7 385 11996 78.8
0.7 0.2 3.58 18.4 3.3 113.3 369 11996 981 78.8
0.7 0.3 3.63 18.8 3.2 109.5 356 11996 968 78.8
0.8 0.2 3.53 17.4 3.3 120.8 393 11996 996 78.8
0.8 0.1 3.46 17.0 3.3 125.5 411 11996 1016 78.8
0.8 Q 3.37 16.7 3.3 131.0 432 11996 1044 78.8
0.9 o 3.30 15.8 3.3 138.7 460 11996 1066 78.8
0.9 0.1 3.40 16.2 3.3 132.8 437 11996 1035 78.8

1 0 3.23 15.1 3.3 145.8 488 11996 1090 78.8

#U.S. Government Printing office : 1992 - 312-014/40059



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nqngegee 449999 ae eR MMENAN ANS 2444444 AMARANANANARRAAARANAIMAMAAAEE NS NNN
Waco eco ao oo oo oto ook dh hhh dd hd whi ohh ob on bo MD HT od ac aed doa eed ed ed aed edad aad asad aad ae aad HA MA

3.6

RMMNVOOCAR NAD CNOVMOKAMNTENAQQAM TNH QHMAOKN +4 COM MENMNAK QEKTOONAgQaK qaqa Tagn
Noeeees Beccreerce Renny cers SON ussecccsses
Ssesss SERBS SS SABRE REE RMG HANNAN SNA NAN AA NS SANNA RR SS SS SSEE SH OHSS SS SSSSSS

RAMRSIIS SS SSSSSSSEKLLLLLKRERTRTK KE RKKTLERAEKKRKKK SSS HSSSRASRSNRRARASSL IF

Bee eS ee ee Sak acek ok aici ck ad ck acohed ad ated eked ode et etatec nt atatreic ated lel wfadet acid whet

WNORQAK-Q|KONyMAK CoOMAMYNONAKYHYMANK OOK ANN

S00S600 SocacedGcS Sececcdcsdssces ocdd5

IMR COM AM EMA KH CORK NK COOK AME NON ae
sooo scaccacd sos socccccc5

QHEMAK OOM AMT NEN AAOAh AEM COM AMYNYN ONYMATK CONANT AYMATK COM AMAT COT Or aan enema
eccocd Sdddcdddcdacccccedca Scocccsddccocs Ssoccccocd ecoco 3 Sodcccococe

CODDOOVO KR He KR EE KN AAA ANAM MM MMM MMS PESTS INNINHNOQOOORRNN AEQAA-GOCDDOOOOS

SSdSddSdSddddSSSSdSSESSSSSSSSSOSSSSSSSSSSCSSSSSSSSSSSSGSSS

B555555555555555 555555555

SESS S SESS SSIES ESET STII SS

SSSSSSSSSSSS SSSR SSS RSRRRRSSRRRHRRSS ESSE SS RRS SSS
BESS SS SS SSS SSS SSS SSS SS SISSSSSS SSS SSP PSS TIT T SETI TITS
Segggssesesesaeaeesseeaae

SSSSSSSSSSESSSSSSSIFIFID

EEREREEEEREREREEEEREEEEE

geegerococooaoocooesseee





ibit 7: OL i: COP id um c Capacity for Binary
ige t Mixture

3.5 1.

2.5

ver(stu/tt?)
180

160 wd

140 «

120

1o0"TMy"

80...

60

407%

0) 0.2 0.4 0.6 ‘0.8 1.0

Concentration of R-32 i

“M@ = R-32/R-134 -@ &-32/R-134a “@ R-32/R-124 = R-32/R-152a
31 |



which contain small amounts of R22 increasing the likelihood that
existing lubricants can be used.

2.4 Operating Conditions |
Typical numbers for operating conditions are derived from
performance data of existing residential air-conditioners as
described in the ASHRAE testing and rating procedure /6/.
Air-conditioning: Outdoor air inlet temperature 95 F
Outdoor air outlet temperature floating
Indoor air inlet temperature 80 F
Indoor air outlet temperature 52 F
(based on the specified air flow rate of 400
cfm per ton of cooling)
These temperatures represent ‘the design point of the air-
conditioner. At the above specified values, the air-conditioner
meets the building load at steady state operation. For less severe
cooling cases the thermostat cycles the equipment on and off. A
second case is evaluated with 82 F outdoor temperature and all
other conditions are unchanged. This value ‘is usually measured
under part load operation when the equipment is cycling on and off.
The part load performance can be reduced by up to 25 % compared to
steady state operation. However, when the air-conditioner has an
automatic expansion valve this’ degradation, caused by fluid
migration during the off-cycle, can be almost entirely eliminated

/7/. It is assumed that the part-load performance is identical to

the steady-state performance at that condition for the following

17



Exhibit 4:
Fractional Temperature Bin Hours for
Six six Heating | Climates of the Continental (US

| Region rv
| 2750

092
086
076
078
.087
-102
094
074
055
047
038
029
018
-010
005
002
001

* In Pacific Coast Region

|
Exhibit 4a: !
Fractional Temperature Bin Hours for

a Generalized Cooling Climate of the Continental US

1



(based on an air flow rate of 800 cfm)
The second operating condition is heat pump operation at 17 F
outdoor air inlet temperature. Typically, even the continuously
operating heat pump does not reach the full capacity required by
the building and resistance heat has to be used to supplement the

heat pump.

2.5 Capacity Modulation with Mixtures. i

It has been repeatedly reported and implemented in at least one
commercial product that the capacity of a heat pump can be
controlled, within certain limits by changing the concentration of
the circulating mixture /8-11/. With this effect the capacity of
the heat pump does not drop off as rapidly as it would with a pure
refrigerant. In turn, the need for resistance heat (COP=1.0) is
reduced. Since a heat pump has a COP larger ‘than 1.0 even at
severe operating conditions, energy savings can be accomplished by

this maneuver.

Since the pressure controls the specific vapor volume, the
mixture concentration determines the mass flow rate of a compressor
with constant speed and displacement volume is able to establish.
The range of pressure that can be covered depends on the device
that accomplishes the concentration shift, the difference in
boiling points of the constituents of the binary mixture, and the
initial concentration. For ternary mixtures the situation is more
complex and the range of pressures depends on the boiling point of

the intermediate component as ‘well.

19



A Cool (exe) Volumetric Cai t or Bina:

cop

3.5 Moone

22 5.

2.5

VCR(Btu/tr)
180

160

140

120

VCR
400 . oe re ee deena B28 a

80

60 : + we i sense

40—~

20

0 0.2 0.4 06 en ae 1.0
Concentration of R-143a

“HF R-143a/R-134a “Oe =R-143a/R-124 “@ = R-143a/R-152a

32



displacement. Other output values are not of concern here. Energy

Exhibit 3: Sample Printout of Computer Run with HAC1.

NEWTON-RAPHSON METHOD IS USED TO. SOLVE A SET OF NONLINEAR EQUATIONS.
HTFs USED.IN COND. AND EVAP. ARE BOTH AIR.

A VOLUME FLOW RATE OF HTF IN EVAP.(CFM): 400.00

A VOLUME FLOW RATE OF HTF IN COND.(CFM): 800.00

COOLING LOAD IS FIXED BY SPECIFYING HTF TEMPS. IN EVAP.

IN COND. SIDE, TEMP. OF HTF ENTERING COND. IS FIXED.

TEMP. OF HTF LEAVING COND. VARIES.

CONSTANT UAs ARE USED IN CON. AND EVAP.

CONSTANT COMPRESSOR EFF.

Yoteiietinticiniiee GIVEN PARAMETERS *#tebnonnninanece
REFRIGERANTS R22 AND R22 ; F = .0000; X = 1.000 MASS FRAC.R22
AMBIENT TEMP: 35.0 C
HX STREAM TEMPS: SOURCE (IN, OUT): 26.0, 10.6 €
SINK = CIN)= 35.0 C
COMPRESSOR EFFICIENCY : .7000
IMPOSED PRESSURE DROPS: COND = «0 KPA; EVAP = .0 KPA
IMPOSED E SUPERHEAT, C SUBCOOLING, ASHC (C): 0 0 0
UA CEVAP, COND): 400.0, 500.0 W/C
HEAT CAPACITY OF HTF (EVAP,COND): 227.8, 417.6 W/C
COOLING LOAD: 3514.9 WATTS
AREA EVAP, COND, FACTOR E, C, NSEGM :4.00000,5.00000, 1.00000, 1.00000 1

detinbieineieiee® STATE PARAMETERS eddnndranenee
STATE T ¢C) P a v $ Xt XV xa
HX STR REF (KPA) (KJ/KG) (M“3/KG) (KJ/KG _K) (MASS FRAC)
1 EVAP CUT 26.0 6.6 613.6 253.4 3.86E-2 .000 1.000 1.000 .000
2 COMP IN 0 6.6 253.4 3.866-2 +000 .000 .000 .006
3 COHP DIS 45.9 296.3 1.32E-2 «000 =.000 1.000 .000
4 COND VST 44.0 263.4 1.138-2 000 =.000 © .000 .000
5 COND LST 35.0 109.1 9316-4 000 =.000 .000 .000
6 COND CUT 35.0 109.1 9.31E-4 000 «=.000 §=.000 = .000
7 EVAP IN 10.6 109.1 0.00E+0 000 1.000 1.000  .282
B EVAP VST 26.0 253.4 3.866-2 000 =©.000 ©=.000 §=.000
9 LSHX OUT 0 109.1 9.31E-4 000 =.000 ©=.000 -.000

‘eeemeeenRH CALCULATED PARAMETERS *teeninnnias
WORK = 1043.5 QEVAP = 3514.8 QCOND = 4558.3 HX21 = +0 HX67 = -0 WATT
Cop = 3.368 REF. MDOT= .0243529 KG/S VCR= 3735. KJ/M*3 PR = 3.28
VOLUHE FLOW RATE (CC/SEC) : 941.12
LHTD IN EVAP (GIVEN, CAL), LMTD IN COND 8.787 8.787 11.641
AIR TEMP DROP, REF TEHP GLIDE IN EVAP 15.430 ~000
AIR TEMP GLIDE, REF TEMP DROP IN COND 10.915 +000
COMPRESSOR DISPLACEMENT VOLUME =20.4592 CC/REV
ENERGY BALANCE:E SUP,C SUB,SUP(FRAC HEAT): .00 .04 800.52
ENERGY BALANCESE SUP,C SUB,SUP(UALMTD ): .00 04 800.54
EVAP SUPERHEAT, COND SUBCOOLING & SUPERHEAT: (C)  .00 00 35.55
FRACTIONS HEAT IN EVAP TP,SUP,COND SUB, TP, SUI 000 .000 .000 .824 .176
7 FRACTIONS AREA IH EVAP TP,SUP,COND SUB, TP, SUI 000 .000 .000 .728 .272

balances are used to verify thermodynamic consistency. Other data
are available for detailed design of air-conditioners. The
particular heat pump design modelled here implies that the four-
way-valve, that switches from heating to cooling, maintains the

counter-flow characteristic of the: heat exchangers. This is not

14





aaa

aa0

e200

ana

ona

aan

eA

c
c
c

DATA HREF(10) /'R142B'/

DATA CCRITCI,10),121,5) /100.49,233.15,410.3,4120. ,0.231/
DATA HZERO(10),SZERO(10) /0.0,0.0/

DATA (COEFF(1,10),1=1,9) /4512.576E0, -3.229507E-3,2.608976E-7,
1 0.1730507E0, -2.648172E-4, 1.032608E-7,

1 16.39145E0, .2717191E0, -1.589334E-4/

R1S2A, 1, 1-DIFLUOROETHANE.

DATA HREF(11) /'R1S2A'/

DATA (CRIT(I,11),1=1,5) /66.05,233.15,386.7,4492.,0.181/

DATA HZERO(11),SZERO(11) /0.0,0.0/

DATA (COEFF(I,11),1=1,9) /3106.312E0, -2.776653E-3, -6.258540E-7,
1 .1283451E0, -.1726218E-3,2.790653E-8,

1 22.2831680, .1539874E0, -3.015434E-6/

R115, PENTAFLUOROMONOCHLOROETHANE, C2CLF5

DATA HREF(12)_/*R1154/

DATA (CRITCI, 12), 1=1,5) /154.465,233.15,353.05,3153. ,0.252/
DATA HZERO(12),SZERO12) /0.0,0.0/

DATA (COEFFCI, 12),1=1,9) /6177.259E0, -5.5402296-3,2.635930E-6,
1 .2674781E0,-6.346145E-4,5.512517E-7,

1 20.0246E0, .3765849E0, -2.703487E-4/

R123, 1, 1-DICHLORO-2,2,2-TRIFLUOROETHANE

DATA HREF(13) /'R123*/

DATA CCRITCI,13),1=1,5) /152.930,233.15,456.94,3674. ,0.278/

DATA HZERO(13),SZERO(13) /0.0,0.0/

DATA (COEFF(I,13),1=1,9) /5885.629E0, -2.2446861E-3, -1.0342735E-6,
1 .1957662E0, -1.6784282E-4,-9.9567402E-8,

1 29.2604E0, .302994E0,-1.92907E-4/

RIG3A, 1,1, 1-TRIFLUOROETHANE

DATA HREF(14) /'R143A'/

DATA (CRITCI,14),1=1,5) /84.04,233.15,346.3,3758. ,0.194/
DATA HZERO(14),SZERO(14) /0.0,0.0/

DATA (COEFF(I,14),1=1,9) /3092.03,-3.42907E-3,1.49460E-7,
1 0,137902,-1.96301E-4,1.78383E-8,

1 14,0656,0.254765,-1.29865E-4/

R124: 1-CHLORO-1,2,2,2-TETRAFLUOROETHANE (R124)

DATA HREF(15) /'R124'/

DATA CCRITCI,15),1=1,5) /136.475,233. 15,395.65, 3660. ,0.244/
DATA HZERO(15),SZERO(15) /0.0,0.0/

DATA (COEFF(I,15),1=1,9) /4718.786E0, -2.847854E-3,-1.0857E-6,
1 .1818017E0, -2.256066E-4, -3.890926E-8,

1 30.97765E0, .2542056E0, -9.364136E-5/

R125: PENTAFLUOROETHANE

DATA HREF(16) /'R125'/

DATA CCRITCI,16),1=1,5) /120.03,233.15,339.45,3630.6,0.210/
DATA HZERO(16),SZERO(16) /0.0,0.0/

DATA (COEFF(1,16),1=1,9) /2971.488E0, -2.111917E-3, -3.734385E-6,
1 .1443116E0, -1.410596E-4,-1.969504E-7,

1 22.65024E0, .2956679E0, -1.694896E-4/

R134: 1,1,2,2-TETRAFLUOROETHANE

DATA HREF(17)_ /#R1364/
DATA (CRIT(I, 17),1=1,5) /102.034,233.15,392.1,4562. ,0.189/
DATA HZERO(17),SZERO(17) /0.0,0.0/

DATA (COEFF(I, 17), 1=1,9) /3689.1E0,-2.83434E-3,-1.22280E-6,
1 16461880, -1.84369E-4, -.253676E-7,

1 32.5208E0, .22281960,-1.06829E-4/

RI3Z4A 1,1,2,2-TETRAFLUOROETHANE



-- For some superior mixtures all constituents are presently
available or have been commercially produced; for other
alternatives they will be available in the near future; for
some alternatives they are not yet scheduled for commercial
production.

-- The mixtures with the most significant improvement in COP are
flammable (R32/R152a) or contain flammable components so that
they may be flammable (R32/R152a/R124, R32/R152a/R134).
However, it is expected that the addition of a third
nonflammable component will reduce the fire hazard.

-- The binary mixture of 30% R32 and 70% R134a shows a six
percent performance improvement over R22 and may be
nonflammable. .

-- Further work in the following areas is required in order to
facilitate the use of the proposed mixtures:

Materials compatibility,

Flammability,

Oil compatibility,

Compressor life,

Chemical stability,

Thermodynamic properties,

Transport properties,

Performance in actual cycles,

Design of means for concentration shift, and
Redesign of air-conditioning and heat pump systems.

-- The possibility still exists that pure fluids can be found or
developed that may be acceptable substitutes for R22.

Acknowledgement

fhe authors thank the numerous reviewers and EPA personnel for
constructive criticism and their contributions to the report. The
support of this project by the US Environmental Protection Agency
through ICP Inc. and the University of Maryland is greatfully
acknowledged. .



table, with the term 'cooling' replaced by 'heating'. The tenth
and eleventh columns show the power requirement and consumption of
\ .

electric energy due to the resistance heat. Zeros in the eleventh

column indicate that no resistance heat is needed because the heat
“pump capacity is sufficient (for high bin temperatures) or no

heating is required at all (below a bin temperature of 22 F in this

case). :

All seasonal performance calculations were performed according
to this method for the fluids listed in the chapter 4.2.
4.0 Results and Discussions |
4.1 Performance Under Design Conditions '
A total of 500 runs were conducted with HAC], to determine the
performance of the pure components and their mixtures listed in
Chapter 2.3. An additional 190 runs were conductea with the
ternary version, HACT1, for the three ternary mixtures. The
results for all runs are available in data files that contain
complete printouts as shown in Exhibit 3. Each run also generates
a short output file that contains the most. crucial results. The
short output files for all runs are listed in Appendix 2 with a
list of code numbers for the refrigerants. The following
parameters are listed in the short output ‘files: fluid code
numbers, R1, R2; mixing coefficient, FO; concentration, .x (mass
fraction); COP; volumetric capacity, VCR; pressure ratio, PR;

suction pressure, Ps; discharge pressure, Pd; cooling. load, CLOAD;

compressor work, WORK; the compressor discharge temperature, Tsup;

29


16 «18 -0.01 0.1 33 65.8 3.67 57.0 209 11996
16 18 -0.01 0.2. 3.32 69.0 3.61 60.9 220 11996
16 18 -0.01 0.3 30 72.4 3.56 65.2 232 11996
16 18 -0.01 0.4 26 75.8 3.51 70.1 246 11996
16 18 -0.01 0.5. 3.21 79.3 3.46 75.6 262. 11996
16 18 -0.01 0.6 4 82.8 3.42 81.8 280 11996
16 18 -0.01 0.7 3.04 85.9 3.38 89.0 301 11996
16 18 -0.01 0.8 91 88.5 3.34 97.4 326 11996
16 18 .-0.01 0.9 2.72 89.8 3.32 107.3 356 11996.
16 18 -0.01 12.45 88.6 3.31 119.2 394 11996
16. 11 -0.04 0 3.56 61.9 3.67 48.2 177 11996
16 11: .-0.01 0.1 3.57 64.5 3.61 50.9 184 11996
16 14 -0.01 0.2 iB 67.3 3.56 53.9 192 11996
16,11 -0.01 0.3 7 70.4 3.51 57.5 202 11996
16 11 -0.01 0.4 3.55 73.9 3.46 61.7 213 11996
16 11 -0.01 (0.5 3.51 77.6 3.41 66.6. 227 11996
16 11 -0,01 0.6 3.45 81.5 3.37 72.6 245 11996
160011: --0.01 0.7 3.35 85.6 3.33 79.9 266 11996
16 11 -0.01 0.8 3.19 89.5 3.3 89.3 295 11996
16 11 -0.01 0.9 2.92 91.8 3.29 101.7 335 11996
16 11 -0.01 1 2.45 88.6 3.31 119.2 394 11996
16 15 -0.01 0 3.04 37.1 3.94 30.1 119 11996
16 15 -0.01. 0.1 3.17 42.8 3.82 34.7 132 11996
16 15 -0.01 0.2 3.28 48.9 3.71 39.9 148 11996
16 15 -0.01 0.3 3.37 55.3 3.62 45.8 166 11996
16 15 -0.01 0.46 3.45 61.8 3.53 52.5 185 11996
16 15 -0.01 0.5 3.49 68.46 3.46 59.9. 207 11996
16 15 -0.01 0.6 3.42 74.9 3.39 68.4 232 11996
16 15 -0,01 0.7 3.30 81.1 3.34 78.1 261 11996
16 15 -0.01 0.8 3.12 86.5 ~3 89.4 295 11996
16 15 -0.01 0.9 2.85 89.8 3.29 102.9 338 11996
16 15 -0.01 12.44 88.6 3.31 119.2 394 11996
19 18 -0.01 0 2.60 42.7 5.146 36.7 189 11989 99
19 18 -0.01 0.1 2.74 52.6 4.88 44.0 214 11989 99
19° 18 -0.01 0.2 2.82 62.0 4.69 51.4 241 11989 9
19° 18 --0.01 0.3 2.84 70.9 4.55 58.7 267 11989 99
19.18 -0.01 0.4 2.84 79.2 4.47 65.9 - 294 11989 99
19° 18 -0.01. 0.5 2.81 87.1 4.42 72.8 322 11989 99
19 18 -0.01 0.6 2.78 94.5. 4.39 79.6 350 11989 99
19 18 -0.01 0.7 2.73 101.5 4.39 86.1 378 - 11989 99
19° 18 -0.01. 0.8 2.68 108.2 4 92.4 407 , 11989 46.99
19 18 -0.01 0.9 2.62  114.5.4.42 98.4 435 11989 46.99
19 18 -0.01 1 2.56 120.4 4.46 104.0 464 11989 46.99
19.11 -0.01 0 2.83 42.8 5.01 33.1 166 11989 46.99
19° 11 -0.01 0.1 2.93 49,5 4.81 37.9 182 11989 1199 187 46.99
19 11 -0.01 0.2 2.99 56.5 4.65 43.1 200 11989 1174 192 46.99
19 11 -0.01 . 0.3 3.02 63.7 4.53 48.7 221 11989 1162 198 46.99
19 11 -0.01 0.4 3.03 71.0 4.44 54.7 243 11989 1161 204 46.99
19. 11 -0.01 0.5 3.01 78.6 4.38. 61.2 268 11989 1169 211 46.99
19° 11 --0.01 0.6 2.96 86.4 4.34 68.2. 296 11989 1185 217 46.99
19 11 -0.01 0.7 2.90 94.5 4.33 75.9 329 11989 1212 225 46.99
19 11 -0.01 0.8 2.81 102.9 4.34 84.4 366 11989 125) 232 46.99
19 11 -0.01. 0.9 2.70 111.6 4.38 93.7 411 11989 1301 240 46.99
19 11 -0.04 1 2.56 120.4 4.46 104.0 464 11989 1370 249 46.99
14 18 -0.01 0 2.60 42.7 5.14 36.7. 189 11989 1350 155 46.99
14 18 -0.01 0.1 2.60 45.1 5.01 39.6 198 11989 1352 155 46.99
14 18 -0.01 0.2 2.59 47.5 4.88 42.6 208 11989 1353 156 46.99
14 18 -0.01 0.3 2.57 50.0 4.76 46.0 219 11989 1365 156 46.99
14 18 -0.01 0.4 2.55 52.5 4.65 49.5 230 11989 1379 156 46.99
14-18 -0.01 0.5 2.52 54.9 4.55 53.3 243 11989 1395 156 46.99
14 18 0.01 0.6 2.48 57.3 4.46. 57.5 256 11989 1419 156 46.99
14 18 -0.01 0.7 2.43 59.6 4.38 61.9 271 11989 1448 156 46.99
14 18 -0.01. 0.8 2.36 61.7 ~3 66.8 287 11989 1487 156 46.99
14 18 -0.01 0.9 2.29 63.5 4.23 72.1 305 11989 1535 156 46.99
14 18 -0.01 1 2.19 65.0 4.17 78.0 325 11989 1601 155 46.99
14 11 -0.01 0 2.83 42.8 5.01 33.1 166 11989 1241 181 46.99



19 0.1 2.89 45.1 4.99 35.2
19 0.2 2.98 55.0 4.74 42.6
19 0.3 3.01 64.3 4.58 50.0
19 0.4 3.00 73.2 4.47 57.6
19 0.5 2.97 81.8 4 65.2
19 0.6 2.91 90.1 4.36 72.9
19 0.7 2.86 98.1 4.35 80.6
19 0.8 2.76 105.9 4.37 88.5
19 0.9 2.66 113.4 4.4 96.3
19 12.56 © 120.4 4.46 104.0
19 0 1.45 19.0 11.72' 18.8
19 0.1. 1.56 24.0 10.94. 22.5
19 0.2 1.62 29.0 10.34 26.5
19 0.3 1.64 33.9 69 30.6 303 11989 2138 224 17.01
19 0.4 1.65 38.6 9.59 34.7 333 11989 2130 238 17.01
19 0.5 1.64 43.0 9.38 38.8
19 0.6 1.62 47.3 9.24 42.8
19 0.7 1.60 51.4 9.17 46.7
19 0.8 1.57 55.3 9.14 50.5
19 0.9 1.54 58.9 9.14 54.1
19 1 1.51 62.4 9.18 57.5
19 0 1.70 20.7 10.96 17.1
19 0.1 1.75 24.0 10.48: 19.5
19 0.2 1.79 27.6 10.06 22.2
19: 0.3 1.81 31.4 9.72. 25.3
19 0.4 1.81 35.4 9.45 28.6
19 0.5 1.79 39.5 9.24 - 32.3
19 0.6 1.76 43.8 9.11 36.3
19 0.7 1.72 48.2 9.03 40.7
19 0.8 1.67 52.9 9.02 45.7
9 0.9 1.60 57.6 9.06 51.2
19 1 1.51 62.4 9.18 * 57.5
14 0 1.45 19.0 11.72 18.8
14 0.1 1.44 20.1 11.36 20.4
14 0.2 1.42 21.2 11.03 22.1
4 0.3 1.39 22.3 10.72. 23.9
4 0.4 1.36 23.3 10.42 26.0
4 0.5 1.33 24,310.15 28.3
ita 0.6 1.28 25.3 9.91 30.8
14 0.7 1.23 26.1 9.7 33.5
14 0.8 1.16. 26.5 9.53- 36.6
14 0.9 1.06 26.4 9.45 40.2
19 O 1.54 15.6 12.3 14.2
19 0.1 1.67 20.5 11.36 17.6
19 0.2 1.74 25.6 10.58 21.5
19 0.3 1.77 30.6 10.01. 25.6
19 0.4 1.77 35.6 9.63 29.8
19 0.5 1.75 40.4 9.37 34.2
19 0.6 1.72 45.0 9.21 38.7
9 0.7 1.67 49.6 9.12 43.3
19 0.8 1.63 54.1 9.1 48.0
19 0.9 1.57 58.3 9.12 52.8
19 11.51 62.4 9.18 57.5
19 0 1.40 10.6 13.04 10.1
19 0.1 1.73 17.1 11.29 14.3
19 0.2 1.81 23.3 10.23 19.2
19 0.3 1.83 29.3 9.58 24.3
19 0.4 1.81 34.8 9.21 29.3
19 0.5 1.77 40.1 9 34.4
19 0.6 1.72 45.2 8.9 39.4
19 0.7 1.67 50.1 8.89 44.5
9 0.8 1.61 54.7 8.92 49.3
19 0.9 1.56 58.9 9.02 53.8
19 1 1.51 62.4 9.18 57.5
4 11 0 1.70 20.7 10.96 17.1
4 11 0.1 1.68 21.6 10.69 18.3



%@ 11 -0.01 0.2 22.5 10.44 204 11989 2110 214 17.01
%& 11 -0.01 0.3 23.5 10.19 215 11989 2140 210 17.01
% 11. -0.01 0.4 24.6 9.95 227 11989 2181 1
%@ 11 +001 0.5 25.7 9.72 242 11989 2236 = 203 17.01
1% 11 -0.01 0.6 26.8 9.51 259 11989 2314 200 17.01
1% 11 -0.01 (0.7 27.7 9.32 281 11989 2427 196 17.01
14 11 -0.01 0.8 28.4 9.17 309 11989 2601 193 17.01
14 11 0.01 0.9 28.4 9.12 349 11989 2914 191 17.01
14° 15 -0.01 O 10.6 13.04 132 11989 2517 170 17.01
14 (15 -0.01 0.7 12.8 12.05 145 11989 2303 168 17.01
1% «#15 -0.01 0.2 15.0 11.41 162 11989 2275 172 17.01
4% «15 -0.01 0.3 17.1 10.87 181 11989 2278 175 17.01
16 15 -0.01 0.4 19.3 10.4 201° 11989 2308 178 17.01
%6 15 -0.01 0.5 21.4 10.02 224 11989 2365 180 17.01
14 15 -0.01 0.6 23.3 9.71 2469 11989 2453 1

1% «15 -0.01 278 11989 2581

% 15 -0.01 313° 11989 2775 e

1
38.5 357° 11989 3096 189 17.01

% (15 -0.01



Exhibit 5a:

Map of the US Displaying Lines of Constant Cooling Load Hours



THEORETICAL ANALYSIS OF REPLACEMENT REFRIGERANTS FOR R22

FOR RESIDENTIAL USES

Abstract

Future risks of stratospheric ozone depletion and the relatively
high global warming potential of R22 might eventually lead to
further limitations on the use of R22 in heat pump and air-
conditioning systems. This report investigates the feasibility of
replacement refrigerants that would cause the least disruption to
current technology. It is desirable that any substitute is at
least as energy efficient as R22 so that the indirect effect on
global warming does not outweigh the direct effect. To date, no
acceptable pure component has been identified as a drop-in
substitute for R22. However, binary and ternary mixtures appear to
be candidates that warrant further investigation.

The coefficient of performance (COP) and the seasonal
performance factor (SPF) were calculated in a model for binary and
ternary substitutes. The ternary mixture of R32/R152a/R124 showed
the best performance with an increase in COP of 13.7 % over R12.
The best chlorine-free ternary mixture is R32/R152a/R134 with a
12.6 % increase. The best chlorine-free binary mixture is
R32/R152a with a.12.1 % improvement in COP over R22. The binary
mixture of R32/R134a shows a performance improvement of six percent
ever R22. Since it contains 70 % R134a it may not be flammable.

Significant design changes to the system will be necessary to
realize all these gains with mixtures, likely requiring a
considerable research and development effort. Some of the design
changes could reduce the energy savings. On the other hand,
modelling predicts that the SPF can be improved by modulating the
capacity by changing mixture concentration.

The greenhouse warming potential of the R32/R152a/R124 mixture
and its ozone depletion potential are reduced by a factor of 5

compared to R22. The greenhouse warming potential of
R32/R152a/R134 is reduced by a factor of 3 compared to R22 and the
ozone depletion potential is zero. The greenhouse warming

potential of R32/R152a is reduced by a factor of 6 compared to R22
and the ozone depletion potential is zero. :

In practice, the ranking of the substitutes presented ‘in this
report may change due to the influence of transport properties and
other variables which have been ignored in the model.



List of Exhibits

Exhibit 1: Total Clx Concentrations (1985-2000). . . .
Exhibit 2: Greenhouse Warming Potential of R22 and other
HCFC's and Carbon Dioxide. . . . oe
Exhibit 3: Sample Printout of Computer “Run with’ HAC1. .
Exhibit 4: Fractional Temperature Bin Hours for Six Heating
Climates of the Continental US. . oe
Exhibit 5: Map of the US Displaying Lines of constant
Cooling Load Hours. . .- se
Exhibit 5a: Map of the US Displaying Lines of constant
Cooling Load Hours. . - - re ee ry

Exhibit 6: Sample Seasonal Performance Calculation. .

Exhibit 7: Cooling and Heating COP and Volumetric capacity
for Binary Refrigerant Mixtures. .

Exhibit 8: Cooling and Heating COP and Volumetric Capacity”
for Binary Refrigerant Mixtures. . .

Exhibit 9: Cooling and Heating COP and Volumetric Capacity

for Binary Refrigerant Mixtures. . .
Exhibit 10: COP of Mixtures in Sequence According to Their
Performance. . « ee
Exhibit 10a: Best Substitutes ‘for R22. 2. + « oe
Exhibit 11: Seasonal Performance of R22 and the Five Best
Replacements for One Cooling and Six Heating Climates. . .
Exhibit 12: Seasonal Performance Factors (SPF) for One
Cooling and Six Heating Climates. . - © «© +© © see
Exhibit 13: Ratio of Heating Capacities. . .
Exhibit 14: Seasonal Performance of Ra2/Ri52a and R32/R124
With and Without a Rectifier. . .
Exhibit 15: Greenhouse Warming (100 yr. Horizon) “and ozone
Depletion Potential. . oe
Exhibit 16: Direct and Indirect’ contributions “to “global
Warming. «©. - 6+ © © © © © © © © © © ‘# #8 8

8

9
14

23
25

26
28

31

32



true for conventional systems. The air flow rates are 400 cfm for
the indoor heat exchanger (the evaporator during the air-
conditioning mode) and 800 cfm for the outdoor heat exchanger.
These values are specified in the ASHRAE Standard for the
respective heat exchangers for a cooling load of one refrigeration

ton.
2.2 Refrigerant Properties

The refrigerant properties are obtained based on the CSD equation
of state that was developed at NIST /5/. The subroutine BDESC is
listed in Appendix #1 which shows all coefficients of the pure
refrigerants as they are used for this report. . This facilitates
reruns which may become necessary as coefficients are updated. For
mixtures the CSD equation of state requires a mixing coefficient.
For the work conducted here, the mixing coefficient is assumed to
be -0.01 for all mixtures. This value is an average of the known

values and was used because no mixing coefficients were available

for the fluids under investigation.

2.3 Refrigerant Mixtures

The choice of substitutes was limited to fluids that are as similar
to R22 as possible to minimize changes to current. equipment. In
selecting the pure refrigerants that can serve as constituents for
mixtures, priority was given to those fluids that do not contain
chlorine, with R124 as an exception because of its very low ozone

depletion potential. Further, in order to limit the effect of the

15



THEORETICAL ANALYSIS OF REPLACEMENT REFRIGERANTS FOR R22

FOR RESIDENTIAL USES

Findings

Evaluation of R22 substitutes has to occur because of concerns
about ozone depletion and greenhouse warming effect.

There is currently no pure fluid that is considered to be a
suitable drop-in substitute for R22.

Any substitute should seek to have at least the same energy

efficiency as R22. Otherwise, the indirect global warming
effect may offset any gains in the reduced global warming
potential of the substitute. Selection of the final

substitute should consider a balanced trade-off between direct
and indirect global warming effect, ozone depletion and other
health and safety concerns.

There are several binary and ternary mixtures of refrigerants
that warrant further investigation as substitutes for R22.

Models predict that a mixture containing R32 and R152a and R32
and R124 show potential for significant performance
improvements of up to 13:7 % in COP over R22 in residential
air-conditioners, heat pumps and window air-conditioners.

Hardware changes (counter-flow heat exchangers) will be
necessary to achieve this improvement and requirements like
increased fan power may offset the predicted energy savings.

The most energy efficient replacement mixture, R32/R152a/R124,
as predicted by modelling, has a global warming potential and
ozone depletion potential that is five times lower than the
values for R22 (based on a 100 year time horizon).

The replacement mixture with the least direct impact on the
environment is R32/R152a with a global warming potential that
is six times lower than for R22 and an ozone depletion
potential of zero. Its predicted COP is 12.1% above that of
R22. :

The ranking of the substitutes may change due to the influence
of transport properties and other variables not considered in
this report.

The use of mixtures offers the potential advantage that the
concentration can be shifted to meet capacity requirements.
This can lead to a reduction in resistance heat and increased
seasonal performance.



The use of a variable speed drive will accomplish the same
goal of obtaining a variable capacity. By combining variable speed
and shifting concentration the’ available range of capacity
modulation is considerably increased.

The effect of the rectifier is modeled here by repeating the
calculation for the low temperature heat pump case using the same
mixture with a different concentration. It is assumed that a
concentration change of 20 % is achievable with'a rectifier. This
is an arbitrary number, but rectification processes far exceed such
a composition shift and a twenty percent change lis achievable with
rather simple equipment. : I

Concentration shift requires that part of the charge is stored
somewhere in the heat pump. “ The system has to be designed to
operate independent of the amount of charge, and the charge
required is expected to be larger than for a ‘conventional heat
pump.

In an experimental project it was determined that a heat pump
operating on a mixture of R13B1/R152a that utilizes composition
shift using just an accumulator, yielded an ‘an % performance
increase over a heating season /10/. |

|
3.0 Seasonal Performance Evaluation .
The seasonal performance expressed by the seasonal performance
factor (SPF) is defined as the ratio of the total amount of cooling
provided during a season divided by the total amount of electrical

energy consumed during that season for the purpose of cooling.

21



SEPA

United States Air And
Environmental Protection Radiation
Agency (ANR-445)

Theoretical Analysis of
Replacement Refrigerants ©
for R22 for Residential Uses. :

EPA/400/1-91/041
January 1992



4.4 Drop-in Application vs. New systems

Although the modelling results presented in this report demonstrate’
the potential for significant energy savings, only the application
of the substitutes in actual machinery can demonstrate the real
potential. The closer the machinery approaches the model
assumptions the closer the predicted ‘energy savings are achieved.
Variables such as transport properties and oil compatibility which
were not considered in the model because they are not known for
most of the proposed substitute mixtures may significantly
influence the actually achievable energy savings.

However, the mixtures discussed here may be near drop-in
substitutes requiring only changes in the expansion device to
adequately accommodate the substitute. Without changing heat
exchangers, the performance | of some of the better fluids most
likely would be similar to that of R22. How closely the R22

efficiency is met depends on the selection of a suitable

concentration, which primarily determines the capacity of the

substitute and on the degree to what the existing heat exchangers
approach counter-flow characteristics. It is expected that the
performance of drop-in fluids for conventional designs is not very
sensitive to the concentration selected. Therefore, the
concentration would be chosen to match the capacity requirements,
at least for initial tests.

Based’ on the simulation results, no reliable assessment can be
made of the performance of drop-in substitutes. The actual

performance can only be determined by tests in existing air-

44



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THEORETICAL ANALYSIS OF REPLACEMENT REFRIGERANTS FOR R22

FOR RESIDENTIAL USES

jackgro' d_ Objecti

R22 is widely used as a refrigerant in commercial’ refrigeration and
\
commercial and residential air-conditioning and heat pumping. R22

has favorable thermodynamic and transport properties and well known
i

However, questions have been raised about the long term

material compatibility characteristics.

viability of R22. Its ozone depletion potential is 0.05, much less
than Ril or R12. But because the level of stratospheric chlorine
is expected to rise during the next decade, Exhibit 1, extensive
use of R22 could contribute to surplus chlorine and thus ozone
depletion for a long time. In Exhibit 1, the area enclosed between
the two curves is a measure for the increased long term risk if
there is an additional amount of Cl, available in the stratosphere.
Currently, scientists are concerned that additional chlorine will
cause significant ozone depletion /1/. If it does, there will be
inevitably calls for more stringent reductions in R22 than those
recorded during the London revisions of the Montreal Protocol where
a resolution was passed to phase out use in new machinery by 2015
or those proposed in the Clean Air Act revisions /2/.
Furthermore, the greenhouse warming potential of R22 is quite
high compared to carbon dioxide, the most important green house

gas. The United Nations Intergovernmental Panel jon Climate Change
|

(IPCC) has published a '



DATA HREF(2) /*R12'/

DATA (CRITCI,2),1=1,5) /120.91E0, 233. 15E0,384.95E0,4180.E0, .217E0/
DATA HZERO(2), ‘SZEROC2) /0.0,0.0/

DATA (COEFF(I,2),1=1,9) fais. 876E0, -3.319879E-3,2.419441E-7, |

1 es }38782E-8,

1 18.4874£0, .2617816E0, -2.. OusB6oEe 47 '

R13, CHLOROTRIFLUOROMETHANE

eae

DATA HREF(3) /'R13'/ ‘
DATA (CRIT(1,3),1=1,5) /104.46,233.15,302.0,3921.,0.181/ i
DATA HZEROC3), SZEROC3) /0.0, 0.0/

DATA (COEFF(I,3),1=1,9) /2518.9960, -4.206832E-3,1.854713E-7,

1 .1414323E0,-2. 982745E-4, 1. 339647E- 7, H
1 13.86910E0, .2323698E0, -1.830952E-4/

R13B1, BROMOTRI FLUOROMETHANE

aao

DATA HREF(4)/'R13B1'/

DATA CCRITCI,4),1=1,5) /148.91,233.15,340.2,4017. ,0.200/
DATA HZERO(4), SZEROC4) /0.0,0.: 0/

DATA (COEFF(1,4),1=1,9) /4095.393E0,-5.743494E-3,3.740058E-6,
1 0. 181346160, -4. 813153e- 4,4.548773E-7,

1 20.68068E0,0.2112316E0, -1.61476E-4/

R14, TETRAFLUOROMETHANE

eae

DATA HREF(S) /'R14'/

DATA (CRITCI,5),121,5) /88.00,200.00,227.5,3795.,0.141/

DATA HZERO(S), S2EROC5) /0.0, 0.0/

DATA (COEFF(I,5),1=1,9) 27. 40560, -3.429461E-3, -6.475736E-6,
1 0.09966432E0, -1.57113E-4,-2.950201E-7,

1 46.42957E0, . 1845298E0,-9.518905E-5/

R22, CHLOROODI FLUOROMETHANE

ano

DATA HREF(6) /'R22'/

DATA (CRITCI,6),1=1,5) /86.47,233.15,369.3,5054. ;0.169/

DATA HZERO(6), SZERO(6) 10.0, '0.0/

DATA (COEFF(1,6),1=1,9) 12730. 846E0, -2.979927E-3,-7.651239E-7,
1 .1203449€0, -1. 6275926- -4,-1.132347E-8, :
1 21 -98390E0, 127743960, ~4..788723E- Sf :

R23, TRIFLUOROMETHANE

ean

DATA HREF(7) /*R23'/ |
DATA CCRIT(I,7),1=1,5) /70.01,233.15,299.1,4900. ,0.133/ |
DATA HZEROC7), SZEROC7) /0.0,0.0/

DATA (COEFF(1,7),1=1,9) i778. 200E0, -3.676280E-3, -8.794795E- 7, |
1 0. 0932186360, ae 513167E-4, 1.773370E-9, H
1 23.60294£0, .08228732E0,3. 82653E-5/ i

R113, 1,1,2-TRICHLOROTRI FLUOROE THANE

anna

DATA HREF(8) /*R113'/

DATA (CRITCI,8),1=1,5) /187.38, 233.15, 487.5 3456. ,0.329/
DATA HZEROCA) $ZERO(B) /0,0,0. 07

DATA (COEFF(I,8),1=1,9) 77608. 63E0, -2.41486£-3,-4.38971E-7,
1 0.2365185E0, -2.: 228472E-4, -5.601952E-8,

1 76.2637E0,0.119641E0, 7. 18786E-5/

R114, 1,2-DICHLOROTETRAFLUOROETHANE

aan

DATA HREF(9) /'R114°/ i
DATA (CRIT(I,9),121,5) /170.92,233.15,418.8,3248. ,0.307/ H
DATA HZEROC9}, SZERO(9) /0.0,0. ay :
DATA (COEFF(I,9),1=1,9) /5929.736E0, -2.860181E-3, -4.815203E- 7,
1 0.2218744E0, -2.: 883043E- 4,1.81892E-8, :
1 37.2482E0, -537339E0, -2.39995E-4/

c
© R142B, 1-CHLORO-1,1-DIFLUOROETHANE
c



al Perfo: actors (S fo foolin

The last four lines pertain to the influence of composition shift,
when a rectifier is used.

FLUID CSPF HSPF I HSPF IT HSPF ITT HSPF IV HSPF VV HSPF VI

R22
R32/R126
R32/R134
R32/R152a
R1438/R124
R32/R134a
R125/R152a
R143a/R152a

BRNNIQISRWR

R152a
R125/R124
R134a

PREP RRPRES
RFGSUNVSAIRE

Sonus uonnt
whinbiniy
Hie sand

R32/R1528
R32/R152a

R32/R126
R32/R124

ROPE
SR RY

4.3 Concentration shift

In order to determine the suitability of the mixtures for capacity
control by concentration shift, the ratios of the maximum to
minimum capacity are compared. The numeric values are listed in
Exhibit 13. The maximum and minimum values are for the pure fluids
which constitute a given mixture. Although in reality only a
fraction of this ratio can be accomplished without very
sophisticated controls, it indicates the suitability of a given

mixture. It can be seen from Exhibit 13 that R32/R124 has the

widest range of composition shift, a capacity ratio of 5.2,

followed by the second best mixture, R32/R134, with a ratio of
3.60. The best performing chlorine-free binary mixture ranks

fourth with a ratio of 2.95.



ibi le Seasonal formance Calculation.
FLUID R22/R22 .
SEASONAL COOLING PERFORMANCE
CLK 3825 DESIGN T: 9% . a
COP (95) 3.37 . .
COP (82) 4.34
\ DESIGN CAPACITY 95 F (kW): 3.5
BIN TEMP CLH FRAC. CLOAD CLOAD COP «=— POWER
Bin # F K kW kW kuh/h
1 67 292.6 0.2146 «= (0.233 5.46 0.043 0.009
2 72 295.4 0.231 0.817 5.09 0.161 0.037
3 77 «298.2 0.216 = 1.400 4.71 0.297 0.064
4 82 300.9 0.161 1.983 4.34 0.457 0.074
5 87 = 303.7 0.104 2.567 3.97 0.647 0.067
rs 92 306.5 0.052 3.150 3.59 0.876 0.046 kwhel csPF
7 97 309.3 0.018 «= «3.733 3.22 1.159 4.25
8 102 312.0 0.004 «4.317 2:85 1.516
TOTAL ENERGY
SEASONAL HEATING PERFORMANCE
HLH 750 DESIGN T: 37 kwhel HSPF
cop (47) «3.67 47 284. 3.55
cop (17) 2.57 kwh
DESIGN CAPACITY 35 F (kW): 3.5. , 1006.
BIN TEMP HLH FRAC. HLOAD © HLOAD =—COP. RESISTANCE
BIN # F K kW kwh7h kW kwh/h
1 62 289.8 0.291 0.350 0.102 4.22 0 f)
2 57 287.0 0.239 «0.933 0.223 4.04 0 0
3 52 284.3 0.19% «= 1.517 0.294 3.85 0 0
4 47 281.5 0.129 «2.100 0.271 0 0
5 42 278.7 0.081 2.683 0.217 3.49 0 r)
6 37 275.9 0.041 3.267 «0.134. 3.30 0 0
7 32 273.2 0.019 «3.850 0.073. 3.12 0.35 0,006
8 27 270.4 «0.005 4.433 0.022 2.9% 0.93 0.005
9 22 © 267.6 «0.001 5.017 0.005 2.75 1,52 0.002
10 17 264.8 © 5.600 0.000 © 2.57 2.10 0
1" 12 262.0 0 6.183 0.000» «2.39 «2.591 0.000 2.68 0
2 7 259.3 0 6.767 0.000 2.203.071 3.27 0
3 2 256.5 0 7.350 0.000 2.02 3.639 3.85 ry
% “3 253.7 0 7.933 0.000 1.84 = 4.319 4.43 0
5 -8 250.9 0 8.517 0.000 1.65 5.151 5.02 0
6 “13 208.2 0 9.100 0.000 4.47 6.190 5.60 0
7 “18 265.6 0 9.683 0.000 «1.297.526 6.18 c)
8 +23 202.6 0 10.267 0.000 1.10 9.305 6.77 0
TOTAL ENERGY 1.342 0.013

column as total electric energy consumed for the season in kWhel
and total amount of cooling provided in kWhc. The ratio of these
two numbers yields the CSPF of 4.25. 7

fhe lower section of Exhibit 6 refers to the same calculation
for the first heating case. In this case the lowest temperature
bin for which heating is required is 22 F. The meaning of the

first nine columns is the same as for the upper section of the

28



conditioners.

4.5 Implications of Counter-flow Design and the Use of Mixtures
A system designer developing a new.system for operation with R22
substitutes should employ counter-flow heat exchangers, or at least
those which resemble counter-flow as closely as possible, to take
advantage of the gliding temperatures. Conventional design
practice relies on cross-flow heat exchangers. | This is the best
choice considering the refrigerant saturation temperature is
essentially constant and the pressure drop on the air side very
small. The fan power requirement is also small.

In this study, it was assumed that counter-flow heat
exchangers are available, and that the temperature-enthalpy curve
in the two-phase range of a refrigerant mixture: is linear (linear
temperature profile). This is not always true. Any deviation from
a linear temperature profile reduces the performance to some
degree. To investigate the penalty that cross-flow heat exchangers
inflict on refrigerant mixtures, the model was updated to include
cross-flow heat exchangers. The NTU method was implemented for
counter- and cross-flow heat exchangers. For R22 the result is the
same for both heat exchangers as expected. The mixture R32/R124
was chosen as an example since this fluid mixture has the largest
temperature glide. With counter-flow heat exchangers the
improvement over R22 for R32/R124 is 13.4 % as shown in Exhibit 10.
With cross-flow heat exchangers the improvement over R22 is reduced

to 8 %. This result indicates, in order to take full advantage of

45 |



In the evaluation of the HSPF, resistance heat is included.
The resistance heat is treated as an additional power input to the
heat pump with a coefficient of performance (COP) of 1.0 whenever
the heating capacity of the heat pump drops below the building
requirement. For the results presented here no concentration shift
is considered which is discussed later in detail. Exhibit 6 shows
a sample calculation. The upper section pertains to cooling, the
lower to the first of the six heating cases. In the upper left
hand corner, the name of the refrigerant is listed (here R22/R22,
since this is the case of pure R22). In addition, the CLH of 3825
hours and the cooling design temperature of 95 P are given. Next,
‘the COP's are listed for two conditions, 95 F ana 82 F outdoor
temperatures respectively, and the design cooling capacity of 3.5
kW is given. The first column lists the bin number, the second
lists ‘the characteristic bin temperature in F,-and the third the
temperature in K. The fourth column gives the fraction of time
during which a temperature is found in the respective bin, the
fifth lists the cooling capacity, the sixth column shows the amount
of cooling provided for one hour and the seventh column the COP of
the air-conditioner for the respective temperature bin. The cop is
linearly interpolated based on the two values ‘Listed above. The
eighth column gives the power requirement for the compressor. The
ninth column lists the amount of electric energy consumed for one

hour of cooling while the temperature is in -the’ respective

temperature bin. The over all results are listea inthe tenth



19 0.1 4.72 72.7 2.94 52.8 155 11996 746 140 78.8
19 0.2 4.85 88.0 2.83 64.1 181 11996 724 148 78.8
19 0.3 4.90 102.0 2.76 75.2 207 11996 718 155 78.8
19 0.4 4.89 115.1 2.71 86.0 233 11996 720 162 78.8
19 0.5 4.84 127.3 2.68 96.5 258 11996 727 167 78.8
19 0.6 4.76 138.9 2.66 106.8 285 11996 738 173 78.8
19 0.7 4.66 149.9 2.66 117.0 312 11996 755 178 78.8
19: 0.8 4.53 160.3 2.68 126.9 340 11996 777 184 78.8
19 0.9 4.37 170.2 2.71 136.5 370 11996 804 190 78.8
19 1 4.20 179.3 2.76 145.8 402 11996 837 197 78.8
19 0 4.32 68.7 3.03 53.5 162 11996 813 134 76.8
19 0.1 4.53 84.2 9 64.7 187 11996 775 142 78.8
19 0.2 4.64 98.5 2.81 75.8 213 11996 757 149 78.8
19 0.3 4.68 111.5 2.75 86.3 237 11996 752 155 78.8
9 0.4 4.67 123.5 2.71 96.3 261 11996 753 161 78.8
19 0.5 4.63 134.5 2.69 105.8 285 11996 760 167 78.8
19 0.6 4.57 144.7 2.69 114.8 309 11996 770 173 78.8
19 0.7 4.49 154.3 2.69 123.3 332 11996 783 178 78.8
19 0.8 4.40 163.2 2.71 131.3 355 11996 799 184 78.8
19 0.9 4.30 171.5 2.73 138.8 379 11996 817 190 78.8
19 1 4.20 179.3 2.76 145.8 402 11996 837 197 78.8
19 0 4.56 66.0 2.99 48.2 144 11996 775 152 78.8
19 0.1 4.70 76.6 2.89 55.6 161 11996 747 156 78.8
19 0.2 4.81 87.4 2.81 63.5 179 11996 731 161 78.8
19 0.3 4.87 98.4 2.75 71.9 198 11996 722 165 78.8
19 0.4 4.88 109.4 2.71 80.7 219 11996 720 170 78.8
19 0.5 4.86 120.5 2.68 89.9 241 11996 724 174 78.8
19 0.6 4.80 131.9 2.67 99.7 266 11996 732 178 78.8
19 0.7 4.72 143.5 2.66 110.1 293 11996 745 182 78.8
19 0.8 4.59 155.4 2.67 121.2 324 11996 765 187 78.8
19 0.9 4.42 167.4 2.7 133.1 359 11996 794 191 78.8
19 1 4.20 179.3 2.76 145.8 402 11996 837 197 78.8
4 0 4.32 68.7 3.03 53.5 162 11996 813 134 78.8
14 0.1 4.34 72.7 2.96 57.6 170 11996 810 134 78.8
14 0.2 4.35 76.7 «9 62.0 180 11996 808 134 78.8
1% 0.3 4.35 80.7 2.84 66.6 189 11996 809 134 78.8
14 0.4 4.33 84.7 2.79 71.5 199 11996 811 134 78.8
4% 0.5 4.30 88.7 2.74 76.7 210 11996 817 134 78.8
4 0.6 4.26 92.5 «7 82.1 222 11996 825 134 78.8
4 0.7 4.20 96.1 2.67 87.9 234 11996 836 134 78.8
4 0.8 4.13 99.5 2.63 94.0 248 11996 852 134 78.8
4 0.9 4.03 102.5 2.61 100.5 262 11996 873 133 78.8
4 13.91 105.1 2.59 107.4 278 11996 900 132 78.8
4 0 4.54 66.0 2.99 48.2 144 11996 775 152 78.8
4 0.1 4.56 69.3 2.94 51.4 151 11996 770 150 78.8
4 0.2 4.58 72.8 2.88 54.9 158 11996 767 148 78.8
4 0.3 4.59 76.6 2.83 58.8 166 11996 766 147 78.8
4 0.4 4.58 80.5 2.78 63.2 176 11996 767 145 78.8
4 0.5 4.55 84.6 2.76 68.2 187 11996 772 143 78.8
4% 0.6 4.51 88.9 2.69 73.8 199 11996 780 142 78.8
14 0.7 4.43 93.4 2.66 80.3 213 11996 793 140 78.8
14 0.8 4.32 97.8 2.63 87.8 231 11996 815 137 78.8
14 0.9 4.15 101.9 6 96.7 252 11996 848 135 78.8
14 1 3.91 105.1 2.59 107.4 278 11996 900 132 78.8
mw 0 3.97 40.4 3.17 30.1 96 11996 885 130 78.8
uw 15 0.1 4.34 48.7 3.01 36.4 109 11996 810 130 78.8
4% 15 0.2 4.64 56.8 2.89 43.0 124 11996 757 130 78.8
4 15 0.3 4.70 64.5 8 50.0 140 11996 747 132 78.8
4 15 0.4 4.70 71.9 2.73 57.1 156 11996 748 134 78.8
4% 15 0.5 4.66 78.9 2.68 64.6 173 11996 754 135 78.8
4 15 0.6 4.59 85.4 2.63 72.3 191 11996 766 135 78.8
4 15 0.7 4.49 91.5 6 80.5 209 11996 784 135 78.8
4 15 0.8 4.34 97.0 2.58 89.0 230 11996 810 134 78.8
4 15 0.9 4.15 101.6 2.58 97.9 252 11996 847 134 78.8
4 15 1° 3.91. 105.1 2.59 107.4 278 11996 900 132 78.8
16 (18 0 3.33 62.8 3.72 53.5 199 11996 1056 152 78.8





reasons. Cyclic losses have two major sources, the heat capacity
of the heat exchangers and of the working fluid, and the migration
of the refrigerant during the off periods. Experimental results
show that by eliminating the refrigerant migration, the cyclic
losses are eliminated almost entirely, up to 90% /7/. These losses
will not effect the ranking of the fluids investigated here
assuming migration can be eliminated. Usually, thermostatic
expansion valves, which represent state-of-the-art technology,
prevent refrigerant migration. The performance of the air
conditioner is linearly interpolated between the two rating points
allowing for the entire cooling temperature range to be covered.
For heat pumping it is generally accepted design practice that

the air-conditioner designed for. the cooling application has to
serve as a heat pump as well, although the unit's capacity is not
optimized for this application. The simulation accounts for this
fact. For heating applications the function of the outdoor heat
exchanger and the indoor heat exchanger are reversed. Thus in the
model, the heat pump. condenser. is now described with the evaporator
air flow rate and UA value and vice versa. Calculations are
performed at two cases. For both cases the indoor air conditions
are:
Heat Pumping: Indoor air inlet temperature: 70 F

Indoor air outlet temperature: floating
and the first outdoor air case is:

Outdoor air inlet temperature: 47 F

Outdoor air outlet temperature: 33 F

18



10.

11.

12.

13.

14.

References

Draft report of the United States Intergovernmental Panel on
cFc emissions. (This reference will be updated as soon as
more detailed information is available.) |

|

Draft of the Revision to the Clean Air Act,

William Kopko, Private Communication, U.S. Environmental
Protection Agency, Global Change Division, Washington D.C.,
March 1991. |

McLinden, Mark 0. and R. Radermacher, Methods of Comparing the
Performance of Pure and Mixed Refrigerants in Vapor
Compression Cycles, International Journal of Refrigeration,
10, 6, 318- 325, (1987). !

Application of a Hard Sphere Equation of State to Refrigerants
and Refrigerant Mixtures, G. Morrison, M.O. McLinden, NBS
Technical Note 1226 (1988). '

ANSI/ASHRAE Standard 116 (1983).

Laboratory Investigation of Refrigerant Migration in a Split
Unit Air-conditioner, W. Mulroy, D.A. Didion, NBSIR 83-2756,
(1983).

Bedeutung der nicht azeotropen Zwei-Stoff~Kaeltemittel beim
Einsatz Waermepumpen und Kalteanlagen, H., Kruse, R. Jakobs,
Ki Klima und Kaelte Ingenieur, 8, 564-571,| (1977).

The Use of NARMs and Their Display in Ln(p)-h Diagrams, H.
Schwind, Kaeltetechnik, 14, 98-103, (1962).

Performance of a Conventional Residential Heat Pump Operating
With Nonazeotropic Refrigerant Mixtures, W. Mulroy, D.A.
Didion, NBSIR 86-3422, (1986). |

Development of Rectifying Circuit With Mixed Refrigerants, Y.
Yoshida, S. Suzuki, ¥. Mukai, K. Nakatani and K. Fujiwara,
International Journal of Refrigeration, 12, 182-187, (1989).

Thermal Environmental Engineering, J.L. ‘Threlkeld, Second
Edition, Prentice-Hall Inc. Englewood Cliffs, NJ, (1970).

Cynthia Gage, Private Communication, U.S. EPA, Research
Triangle Park, NC, June 1990. |

Oak Ridge National Laboratory, Private Communication.

55



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xhibit O: COP. of ixtures in S$ ce. According to Their
Performance. :

R22 is listed first as reference. For ternaries.the amount of

R152a was traded for amounts of the ‘third component.
(concentration in mass fraction) !
IRt IR2 1R3_-X1__-X2_—«X3._—« COP Change ~VCR PR PSUC DIS Tsup
%- kd/m kPa kPa K
R22 R22 1 3.37 0 3735 3.3 614 2015 360
R32 RISZaR1ZG 0.2 0.2 0.6 3.83 13.7 2878 3.4 412 1409 352
R32 R124 0.3 0.7 3.82 13.46 3377 3.3 495 1650 355
R32 R1S2a.R1Z46 0.3 0.4 0.3 3.79 12.6 3439 3.4 493 1672 363°
R32 R152a 0.4 0.6 3.78 12.1 3809 551 1833 363
R32 R134 0.3 0.7 3.77 11.8 3512 512 1740 354
R32 RISZa RIZ4a_ 0.4 0.5 0.1 3.76 11.7 3865 3.3 563 1872 358
R125 R152a 0.2 0.8 3.58 6.2 2511 3.6 372 1326 348
R32 RI34a 0.3 0.7 3.58 6.2 3820 3.4 589 1993 354
R143a R124 0.3 0.7 3.57 5.9 2170 3.5 339 1175 338
R143a R152a 0.1 0.9 3.57 5.9 2413 3.6 353° 1271 350
R152a R152a 1 3.56 5.8 2308 3.7 332 1219 351
R136 R134 1 3.44 2.0, 1940 3.84 287 1104 338
R13ha R134a 1 3.33 -1.2 2342 3.72 369 1373 340
R32 R32 1 3.23 -4.2 6227 3.35 1005 3363 382
R124 R124 1 3.04 -9.8 1382 3.94 208 817 337
R143a R143a 1 2.89 -14.3 3441 3.11 740 2301 339
R125 R125 1 2.45 -27.4 3305 3.31. 821 2718 336
IR1 IR2  IR3 Xt -X2_-X3_—- COP Change VCR PR PSUC PDIS Tsup
%  BTUsft3 psia psia Fi
R22 R22 1 3.37 0 100 3.3 89 292 189
R32 R1ISZa R124 0.2 0.2 0.6 3.83 13:7 77 3.4 60 206 176
R32 R124 0.3 0.7 3.82 13.46 91 3.3 72 260 180
R32 R1ISZaARIZG 0.3 0.46 0.3 3.79. 12.6 92 3.4 72 263 1%
R32 -R152a 0.4 0.6 3.78 12.1 102 3.3 80 266 19%
R32 R134 0.3 0.7 3.77 11.8 94 «3.4 7% 252177,
R32 -R1IS2a RIB4a 0.4 0.5 0.1 3.76 11.7 103 3.3 82 272 - 185)
R125 R152a 0.2 0.8 3.58 6.2 67 3.6 56 192 167
R32 -R134a 0.3 0.7 3.58 6.2 102 3.4 86 289 «177
R143a R126 0.3 0.7 3.57 5.9 58 3.5 49 171149,
R143 R152a 0.1 0.9 3.57 5.9 65 3.6 51 184 171"
R152a R152a 1 3.56 5.8 62 3.7 48 177 173
R134 R136 1 3.44 2.0 52 3.8 42 «160 148
R134a R134a 1 3.33 -1.2 63 3.7 53 199 152
R32 R32 1 3.23 -4.2 167 3.4 146 488227
R124 R126 1 3.06 -9.8 37 3.9 30 119 147
R143a R143a 1 2.89 -146.3 92 3.1 107 334 151
R125 R125 1 2.45 -27.4 -89 3.3 119 396 146

35





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Of the pure fluids considered here, R125: and R143a show a
higher GWP than R22, Exhibit 15. The only refrigerant with some
ODP is R124 with a value of 40 % of that of R22. -However, when
these components are used as part of a mixture their contribution
is diminished. The mixture with the lowest GWP 237 is R32/R152a
with an ODP of 0.0, followed by R32/R124 with a GWP of 443 and an
ODP of 0.007. Among the ternary mixtures, it is expected that
those with the smaller additive of R124, R134 or R134a show the
smaller environmental impact. It is concluded that the binary
mixture of R32/R152a is the most favorable fluid from an
environmental point of view with regard to all aspects, GWP, ODP
and potential for energy savings. While the addition of a third,
nonflammable component reduces the risk of | flammability, it
increases the GWP and ODP. Again there seems |to be a trade-off
between global risks as described by GWP and ODP and local risks
caused by the flammability of the fluids. i

; |
5.0 Flammability and Materials Compatibility |
5.1 Flammability
Out of the seven refrigerants used in this investigation, three are
flammable: R32, R143a and R152a. Phone calls to refrigerant
manufacturers produced no further conclusive and referable
information.

It is expected that R32 has the lowest heat of combustion and

the lowest flammability of the three components. It presents thé

least danger. R152a shows the highest flammability. The

51 i



US. Exhibit 5 shows a map indicating the heating climates.

In Exhibit 4 the total number of cooling load hours (CLH) and
heating load hours (HLH) are specified (that is the number of hours
in a season during which cooling or heating are required) and
fractions of total load hours for each temperature bin. The air-
conditioning performance is evaluated for one standardized climate
where the total number of hours that require cooling capacity (CLH)
is 3825 hours.

For climates where heating is required, there are six typical
climate regions distinguished by their total heating load hours
(HLH) and the heating load design temperature. The first region
has a total of 750 heating load hours. It represents a very
moderate climate found in Florida or southern Texas, Exhibit 5.
The lowest temperature bin encountered is usually in the range of
22 F for about one hour during a typical season. The most severe
climate region (Region V) is found. in a belt through the northern
states in the US and the total heating load hours are given as 2750
hours. The lowest temperature bin is at -23 F. A sixth region is
introduced to account for the Pacific North West. The number of
cooling load hours is very high, 2750 hours, even though the
temperatures are very moderate, the lowest temperature bin is at 22
F just as in Region I, i.e. Florida. With the help of the map in
Exhibit 5, it is possible to select for any location in the US the

appropriate region and determine the seasonal heating performance

for a heat pump.

24



t Work

To implement a fluid mixture proposed in this report, a number of
parameters have to be considered and investigated. They include
material compatibility, flammability and toxicity as well as
thermodynamic and transport properties, oil compatibility,
compressor life, and cost. In addition, the actual performance of
the fluids and mixtures in air-conditioning and heat pump units has
to be verified by experiment. This includes the complete redesign
of systems. Lastly, concentration shift using rectifiers (or other
means) has to be investigated. Parallel to this effort computer
simulation programs have to be extended to account for the non

linearity of the temperature glide.

54



14 0.1 3.57 64.7 3.6 51.3 184 11996 985 171 78.8
14 0.2 3.57 67.7 3.53 54.7 193 11996 98 169 78.8
4 0.3 3.56 70.8 3.46 58.5 203 11996 989 167 78.8
14 0.4 3.53 74.2 +4 62.9 214 11996 995 165 78.8
4 0.5 3.50 77.6 3.34 67.8 226 11996 1006 163 78.8
4 0.6 3.44 81.1 3.28 73.4 241 11996 1022 161 78.8
4 0.7 3.36 84.6 3.23 79.8 258 11996 1045 159 78.8
14 0.8 3.25 88.0 3.18 87.4 278 11996 1080 156 78.8
14 0.9 3.10 90.7 3.14 96.4 303 11996 1133 154 78.8
14 1 2.89 92.3 3.11 107.4 334 11996 1218 151 78.8
14 0 3.04 37.1 3.94 30.1 119 11996 1157 147 78.8
4 0.1 3.30 44.2 3.74 36.0 135 11996 1065 147 78.8
14 0.2 3.53 51.4 3.58 42.4 152 11996 997 147 78.8
14 0.3 3.57 58.2 3.47 49.2 171 11996 985 149 78.8
14 0.4 3.55 64.7 3.37 56.3 190 11996 990 151 78.8
4 0.5 3.51 70.8 3.29 63.7 210 11996 1001 152 78.8
14 0.6 3.45 76.6 3.22 71.5 231 11996 1020 152 78.8
4 0.7 3.36 81.8 3.17 79.7 253 11996 1048 153 78.8
14 0.8 3.23 86.3 3.14 88.4 277 11996 10&7 152 78.8
4 0.9 3.08 89.9 3.11 97.6 304 11996 1142 152 78.8
14 _ 1 2.89 92.3 3.11 107.4 334 11996 1218 151 78.8
16 0 3.33 62.8 3.72 53.5 199 11996 1056 152 78.8
16 0.1 3.33 65.8 3.67 57.0 209 11996 1057 151 78.8
16 0.2 3.32 69.0 3.61 60.9 220 11996 1060 150 78.8
16 0.3 3.30 72.4 3.56 65.2 232 11996 1067 150 78.8
16 0.4 3.26 75.8 3.51 70.1 246 11996 1078 149 78.8
16 0.5 3.21 79.3 3.46 75.6 262 11996 1095 148 78.8
16 0.6 3.14 82.8 3.42 81.8 280 11996 1119 148 78.8
16 0.7 3.04 85.9 3.38 89.0 301 11996 1155 147 78.8
16 0.8 2.91 88.5 3.34 97.4 326 11996 1209 147 78.8
6 0.9 2.72 89.8 3.32 107.3 356 11996 1294 146 78.8
16 1 2.45 88.6 3.31 119.2 394 11996 1438 146 78.8
16 0 3.56 61.9 3.67 48.2 177 11996 987 173 78.8
16 0.1 3.57 64.5 3.61 50.9 18 11996 984 170 78.8
16 0.2 3.58 67.3 3.56 53.9 192 11996 983 167 78.8
16 0.3 3.57 70.4 3.51 57.5 202 11996 984 165 78.8
16 0.4 3.55 73.9 3.46 61.7 213 11996 990 162 78.8
16 0.5 3.51 77.6 3.41 66.6 227 11996 1000 159 78.8
16 0.6 3.45 81.5 3.37 72.6 245 11996 1019 156 78.8
16 0.7 3.35 85.6 3.33 79.9 266 11996 1050 153 78.8
16 0.8 3.19 89.5 +3 89.3 295 11996 1103 151 78.8
16 0.9 2.92 91.8 3.29 101.7 335 11996 1204 148 78.8
16 1 2.45 88.6 3.31 119.2 394 11996 1438 146 78.8
16 0 3.04 37.1 3.94 30.1 119 11996 1157 147 78.8
16 0.1 3.17 42.8 3.82 34.7 132 11996 1109 148 78.8
16 0.2 3.28 48.9 3.71 39.9 148 11996 1073 148 78.8
16 0.3 3.37 55.3 3.62 45.8 166 11996 1043 148 78.8
16 0.4 3.45 61.8 3.53 52.5 185 11996 1018 148 78.8
16 0.5 3.49 68.4 3.46 59.9 207 11996 1006 147 78.8
16 0.6 3.42 74.9 3.39 68.4 232 11996 1029 148 78.8
16 0.7 3.30 81.1 3.36 78.1 261 11996 1065 147 78.8
16 0.8 3.12 86.5 3 89.4 295 11996 1126 147 78.8
16 0.9 2.85 89.8 3.29 102.9 338 11996 1233 146 78.8
16 1 2.44 88.6 3.31 119.2 394 11996 1438 146 78.8
19 0 3.97 40.4 3.17 30.1 96 11996 885 130 78.8
19 0.1 4.85 62.9 2.91 45.0 131 11996 724 140 78.8
19 0.2 4.95 81.9 2.79 59.5 166 11996 710 151 78.8
19 0.3 4.95 98.3 2.71 72.9 198 11996 710 159 78.8
19 0.4 4.92 113.0 2.66 85.6 227 11996 714 165 78.8
19 0.5 4.87 126.6 2.62 97.6 256 11996 722 170 78.8
9 0.6 4.78 139.2 2.61 109.0 284 11996 735 174 78.8
19 0.7 4.66 150.8 2.62 119.6 313 11996 754 179 78.8
19 0.8 4.52 161.4 2.65 129.4 343 11996 778 184 78.8
19 0.9 4.36 171.0 7 138.2 373 11996 807 190 78.8
19 1 4.20 179.3 2.76 145.8 402 11996 837 197 78.8
19 0 4.42 56.4 3.11 41.7 130 11996 795. 131 78.8





YIUS/M $2 b-Y/2E-4 KAY VCL-H/ZE-Y = YIUS/M BZSL-U/ZE-U eest-u/2e-u V7)
1A 4dSH AddSH Al 4dSH iit ddSH ll 4ddSH 1l4dSH ddSo
e = =: aN 0
= Eg =
— | = = |b
RE = ZmN=_ = \ a
aS . = Ze
N = wy
= a 4 -&
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JayNOIY & INOUPIAA pue IIA

bZL-u/ZE-Y pue EZG1-Y/Ze-Y Jo BUeUIO}aAg jeuoseag
“ph NquUg

43



t 13: atio o eating | ies.

The R22 value is given for reference purposes. Ternary mixtures
are not listed since fluid separation is less efficient. The
capacities are listed in kJ/m.

Mixture Capacity . : Capacity . Ratio
ist comp. 2nd _com.
R22 3050 3050 : 1.00
R32/R152a 5179 . 1755 | " 2.95
R32/R134 5179 1444 3.60
R32/R124 5179 999 | 5.20
R32/R134a 5179 1811 2.87
R143a/R152a 3035 1755 ! 1.73
R125/R152a 3007 1755 | 1.71
R125/R124 3007 999 : 3.01
R143a/R134a 3035 1811 ' 1.68
R125/R134a 3007 1811 J 1.66

Assuming that a realistic concentration shift of 0.2 can be
accomplished with rather simple means (short distillation column),
the SPF was evaluated for two mixtures, R32/R152a and R32/R124.
The first represents an example for a medium range capacity ratios,
and the second exhibits the largest capacity ratio. The results
are listed in the last four lines of both sections of Exhibit 12.
Exhibit 14 shows a bar graph that reflects the influence of a
concentration shift. For cooling there is no change in
concentration and performance, assuming the original concentration
is used. For heating the HSPF is consistently higher with a
concentration shift. The increase in HSPF is as high as ten
percent for R32/R124 and as high as six percent for R32/R152a. For
severe conditions, climate regions II through v the mixture with
the lower CoP but larger capacity shift, R32/R124 has the better
performance by up to 6 %. This is because none or little

resistance heat is required with the higher capacity fluid. The

41 |



14 11 -0.01 0.1 2.83 44.8 4.9 35.3 173 11989 1241

14° 11 -0.01 0.2 2.83 46.9 4.79 37.7 181 11989 1264

1% «11 -0.01 0.3 2.81 49.1 4.69 40.5 190 11989 1250

4 11 -0.01 0.4 2.79 51.5 4.6 43.6 200 11989 1260

1% «11 -0.01 0.5 2.75 54.0 4.5 47.1 212 11989 1277

14 11 -0.01 0.6 2.70 56.6 4.42 51.3 227 11989 1301

14 11 -0.09 0.7 2.63 59.2 4.34 56.1 244 11989 1336

% 11 -0.01 0.8 2.53 61.7 4.27 61.9 265 11989 1389

14 «14 -0.01 0.9 2.39 63.9 4.21 69.1 291 11989 1469

%@ 11 --0.01 1 2.19 65.0 4.17 78.0 325 11989 1601

4 «15 -0.01 0 2.41 26.6 5.55 20.4 113 11989 1460

1% 15 -0.01 0.1 2.66 29.5 5.19 24.2 126 11989 1331

4% «15 -0.01 0.2 2.79 34.4 4.92 28.5 1460 11989 1258

1% «15. -0.01 0.3 2.80 39.1 4.76 33.1 157 11989 1253

% 15 -0.01 0.4 2.79 43.7 4.59 38.1 175 11989 1260

% 15 -0.01 0.5 2.75 48.1 4.46 43.4 19% 11989 1279

%@ 15 -0.01 0.6 2.69 52.4 4.36 49.1 214 11989 1308

14 15 -0.01 0.7 2.60 56.3 4.28 55.3 237 11989 1350

% 15 -0.01 0.8 2.49 59.9 4.23 62.1 263 11989 1408

4 15 -0,01 0.9 2.36 62.9 4.19 69.7 292 11989 1488

% 15 -0.01 1 2.19 65.0 4.17 78.0 325 11989 1601

16 18 -0.01 0 2.60 42.7 5.14 36.7 189 11989 1350

6 1 2.60 44.7 5.05 39.1 198 11989 1353

16 2 2.58 46. 4 208 11989 1359

16 2.56 a 219 11989 1371

16 4 2.53 eS 48. 233 11989 1389

16 5 2.48 53.9 4.74 52. 248 11989 1416

16 6 2.41 56.3 4.68 5 266 «11989 1455

16 7 2.32 58.4 4.63 288 11989 1513

16 8 2.19 60.0 4.6 315 11989 1604

16 9 2.00 60.3 4.6 350 11989 1753 149 46.'
16 101.71 57.6 4.66 400 11989 2059 151 46.99
16 0 2.83 42.8 5.01 33.1 166 11989 1241 181 46.99
16 0.1 2.84 44.6 4.92 35.0 172 11989 1238 177 46.99
16 0.2 2.84 46.5 4.84 37.1 180 11989 1238 174 46.99
16 0.3 2.83 48.6 4.76 39.6 188 11989 1242 170 46.99
16 0.4 2.81 50.9 4.69 42.5 199 11989 1251 167 46.99
16 0.5 2.77 53.5 4.62 45.9 212 11989 1268 163 46.99
16 0.6 2.71 56.2 4.56 50.2 229 11989 1296 159 46.99
16 0.7 2.61 59.0 4.51 5 250 11989 1344 156 46.99
16 0.8 2.46 61.5 4.48 62.5 280 11989 1427 152 46.99
16 0.9 2.21 62.7 4.5. 71.9 323 11989 1591 150 46.99
16 11.71 57.6 4.66 85.8 400 11989 2059 151 46.99
16 0 2.41 24.6 5.55 20.4 113 11989 1460 149 46.99
16 0.1 2.52 28.4 5.33 23.3 124 11989 1392 148 46.99
16 0.2 2.62 32.5 5.14 26.7 137 11989 1343 148 46.99
16 0.3 2.69 36.8 4.97 30.6 152 11989 1307 147 46.99
16 0.4 + 2.76 41.2 4.83 35.1 169 11989 1282 146 46.99
16 0.5 2.75 45.7 4.71 40.2 189 11989 1279 146 46.99
16 0.6 2.67 50.2 4.63 46.1 213 11989 1315 146 46.99
16 0.7 2.56 54.5 4.56 53.1 262 11989 1375 147 46.99
16 0.8 2.38 58.2 4.52 61.6 279 11989 1473 147 46.99
16 0.9 2.13 60.4 4.54 72.2 328 11989 1651 148 46.99
16 11.717 57.6 4.66 85.8 400 11989 2059 151 46.99
19 0 2.41 24.6 5.55 20.4 113 11989 1460 149 46.99
19 0.1 3.00 38.2 4.92 29.2 144 11989 1172 157 46.99
19 0.2 3.09 50.3 4.62 38.4 177 11989 1136 171 46.99
19 0.3 3.09 61.0 4.45 47.4 211 11989 1137 182 46.99
9 0.4 3.05 71.0 4.34 56.2 244 11989 1152 192 46.99
19: 0.5 2.99 80.6 4.28 65.0 278 11989 1174 202 46.99
19 0.6 2.92 89.8 4.25 73.8 314 11989 1204 211 46.99
19 0.7 2.83 98.6 4.26 82.3 351 11989 1239 220 46.99
19 0.8 2.74 106.7 4.31 90.4 389 11989 1280 229 46.99
19 0.9 2.65 114.1 4.37 97.8 427 11989 1324 238 46.99
19° 15 -0.01 1 2.56 120.4 4.46 104.0 464 11989 1370 249 46.99
19° 17 «0.01 0 2.70 35.0 5.34 28.3 151 11989 1303 151 46.99



2.0 Simulation Approach
It is the goal of the theoretical analysis presented here to study

only the effect of the thermodynamic properties of the working
fluids. The cycle model used resembles the ideal vapor compression
cycle as closely as possible. The only exceptions are a compressor
efficiency of 0.7 and the use of air-to-refrigerant heat
exchangers. The latter is necessary to ensure that the gliding
temperature effect of mixtures is accounted for!

2.1 Computer Model

A computer model HAC1 was developed. It isa UA-model in which the
product of the overall heat transfer coefficient and heat exchange
area (UA) are given. Prior studies have shown ‘that a comparison
between pure and mixed working fluids provides meaningful results
only when the fluids perform identical task. This implies that the
air streams being heated or cooled undergo the same temperature
changes at the same flow rates independent of whether or not a
mixture or pure component is used /4/.. This can be obtained ina
consistent way with a UA-model . It is assumed that the temperature
glide of the mixtures is linear, though this-is not always true.
The implications of this assumption are discussed under Results and
Discussion. HAC1 uses the Newton-Raphson method to solve a set of
eight non-linear equations simultaneously. To have the design of
the heat pump affect the results of the calculations to the least

possible degree, almost all operating parameters were set to ideal

11



|
Refrigerant Breakdown Voltage for Isotron 22/142b Blends for
Refrigeration: Material Compatibility

Pennwalt Corporation

Isotron 22/142b Blends for Refrigeration: | Material
Compatibility ; \

Carrier Corporation . i

Solubility of R-123 and R1i34a in Oils
Motor Materials in R-123 and R-134a

UL 984 Tests with R-134a and Oils

Polymer and Elastomer Performance in R-123 and R-134a
Sealed-Tube Texts of R-123 and R-134a with Mineral Oils
Sealed-Tube Tests of R-12 and R-134a with PAGS

Copeland Corporation

Evaluation of Polyalkylene Glycol Candidates with HFC-134a in
Refrigeration Compressors

-I. Dupon: e Nemour: >mpan' Incor orated

Compatibility of Elastomers with HFC-134a at About 25°
Solubility of Refrigerants in Lubricants; HFC-134a

Compatibility of HFC-134a with Refrigeration system
Materials

Compatibility of Alternative Refrigerants with
Elastomers (R124) ;

Mutual Solubilities of Water with Fluorocarbons and
Fluorocarbon-hydrate Formation (R124, R15,'R134a)

Disassembly and Inspection of Compressor in
Laboratory Refrigerator Charged with R-134a

ICI Chemicals and Polymers Limited

Compatibility of Nonmetallic Materials with
Refrigerants and Lubricants
|
Tecum: roducts n

Materials Compatibility of R-134a in Refrigerant
Systems I.

53



ana

00

mann aAAANAANAAAMANANAAAAANAAAANAAAAAAAAAAANAAAADD

DATA HREF(18) /'RI34A'/

DATA (CRIT(I,18),1=1,5) /102.030,233.15,374.3,4067. ,0.199/
DATA HZEROC 18), SZERO(18) /0.0,0.! 07

DATA (COEFF(I,18),1=1,9) 73611 .BEO, -2.89497E-3,-1.2B106E-6,
1 .144618E0,- “4. 84368E-4, - .253676E-7,

1 19.6704E0, .258433E0,-1.178714E-4/".

R32: DIFLUOROMETHANE

DATA HREF(19) /'R32'/

DATA (CRITCI,19),1=1,5) /52.024,233.15,351.55,5814.23, .1211/
DATA HZERO(19),SZERO(19) /0.0,0.0/

DATA (COEFF(I,19),1=1,9) /1463.431,-1.212964E-3, -3.811882E-6,
1 0.07560431, -5.783178E-5, -8.592812E-8,

1 26.53804,0.05489753,1.574905E-5/

R161B

DATA HREF(20) /'R141B'/

DATA (CRIT(I,20),1=1,5) /116.95,233. 15,477.85, 4400. ,0.25205/
DATA HZERO(20), ‘SZERO(20) /9.0, 0.0/

DATA (COEFF(I,; 20), 151,9) 14778. 65, -°1.54402E-3, -1.53332E-6,

1 0.169895, -1. O03E-4, -0.144243E-6,

1 21.0244 ,0.277793,-1.73962E-4/

R216A, 1,3-DICHLOROHEXAFLUOROPROPANE

DATA HREF(12) /*R216A'/

DATA (CRIT(I, 12), 1=1,5) /220.93,233. 15,453. 14,2754.1,0.3847/
DATA HZERO(12), SZERO(12) /0.0,0.0/

DATA (COEFF(1,12),1=1,9) /8431.44,-2.45916E-3,-9.91754E-7,

1 0.265720, -2.204186-4,-1.68111E-7,

1 B.79769,0.654246,-5.39923E-4/

R216B, 1,2-DICHLOROHEXAFLUOROPROPANE

DATA HREF(13) /'R216B'/

DATA (CRITCI,13),1=1,5) /220.93,233.15,453.14,2754.1,0.3867/
DATA HZEROC13), SZERO(13) 10.0,0.0/

DATA (COEFF(I, 43), 1=1,9) 78390. 00, -2.45916E-3,-9.91754E-7,

1 0.265720, -2. 20418e- ie 1.68111E-7,

1 8.79769,0.654246, -5.39923E-4/

ISOPENTANE

DATA HREF(14) /'1-PENT'/

DATA (CRITCI, 14), 1=1,5) /72.151,233.15,460.4,3384.255 ,0.305/
DATA HZERO(14), SZERO(14) /0.0,0.0/

DATA (COEFF(1,14),1=1,9) /4763.80, -6.8115E-4,-2.94776-6,

1 0.2131, -1.65196-4,-1.3550E-7,

1 0,0,0.0,0.0/

ISOBUTANE

DATA HREF(15) /'1-BUT'/

DATA CCRIT(I,15),1=1,5) /58.124,233.15,408.1,, 3647.7,0.263/
DATA HZEROC15),, SZERO(15) /0.0,0.0/

DATA (COEFF(I,15),1=1,9) 73009. 71,-1.4706E-4,-4,: 3998E-6,

1 0.1803,-1. BiGte~ 4, 9. 9068E-8,

1 27.6833,0.199384, 1.06305E-4/

METHANE
COEFFICIENTS ARE BASED ON SATURATION DATA FROM IUPAC TABLES

DATA HREF(20) /'CH4'/

DATA (CRIT(I,20),1=1,5) /16.043, 111.631, 190.555, 4595. 0,0.09892/
DATA HZERO(20) , SZERO(20) 70.0, 0.0/

DATA (COEFF(I,20),1=1,9) /623.: 650, -4.42548E-3, -2.66667E-6,

1 0. 0725603, -2. 15762E-4,7. 38690E-8,

1 35.8200, -0.0340480, 1. 12485-4/

CHARACTERISTIC REFRIGERANT



desuperheating region is assumed to be the same as. for the two-
phase region. _ The heat transfer process is’ governed by the
difference between the dew point temperature. and the air
temperature. Each run of HAC1 produces an output file as shown in
Exhibit 3 for pure R22. The first section of the output describes
the program features in short and lists the air flow rates.

The second section of the output file states all input values,
the specified refrigerant mixing coefficient, concentration (mass
fraction), the ambient temperature and temperatures of the air
streams into and out of the evaporator and into the condenser.
Further compressor efficiency, pressure drops, super heat,
subcooling, additional superheat, and overall heat transfer
coefficients are listed followed by the heat capacity (calculated
by multiplying mass flow rate with specific heat) and the cooling
capacity. The end of this section of the output shows heat
exchanger areas, adjustment factors (1.0 all the time) and the
number of segments into which each heat exchanger is divided in
order to account for the non-linearity of the temperature glide.
For this investigation the number of segments was set to 1.0 to
speed up the calculation procedure. |

In the third section of the sample printout the calculated
thermodynamic properties at each state point throughout the cycle
are. listed. ;

The fourth section states all other calculated results:
compressor work, the amounts of heat exchanged | cop, refrigerant
mass flow rate, volumetric capacity, pressure ratio, and compressor
|

13



THEORETICAL ANALYSIS OF REPLACEMENT REFRIGERANTS FOR R22

FOR RESIDENTIAL USES

Prepared for

US Environmental Protection Agency
Global Change Division
Office of Atmospheric and Indoor Air Programs
Office of Air and Radiation

by

Reinhard Radermacher and Dongsoo Jung
Department of Mechanical Engineering
The University of Maryland

College Park, MD 20742-3035 |

December 1991



same concentration can be used for both cases. without any
significant penalties in COP.

As a comparison of the Exhibits 7-9 shows, the cooling COP
spans a rather wide range from 2.45 for R125 to a maximum of 3.83
for the mixture of R32/R152a/R124 with a concentration of
0.2/0.2/0.6.

The results obtained for binary and ternary mixtures are summarized
in Exhibits 10 and 10a. R22 is listed first as reference.
Mixtures are listed in sequence according to their performance.

The best mixture was found to be a ternary of R32/R152a/R124.
The COP is 13.7 % larger and the volumetric capacity 23 % smaller
than the respective values for R22.

The mixture R32/R124 is the best binary fluid pair. The COP
is 13.4 % larger and the volumetric capacity 9.6 % smaller than for
R22. The ternary mixture of R32/R152a/R134 ranks third and is the
best chlorine-free fluid, followed by the binary mixture R32/R152a
with 12.1 % improvement in COP and with a volumetric capacity that
is 2 % larger as that of R22. R32/R152a provides essentially the
same capacity than R22 and could be used as a drop-in replacement.
The fifth ranked mixture is the binary R32/R134. The sixth mixture
which is the last showing an improvement in excess of 11 % in COP
over R22 is R32/R152a/R134a. The best heating performance is found
for the same (or only marginally different) concentrations that
show maximum cooling performance. Since the operating conditions
in heating are more severe, i.e. the temperature lift is larger,

the increase in COP is less pronounced than for cooling.

34



fg,
~
Ne
Ray
3 ae



This factor is very similar to the coefficient of performance
(CoP). The only difference is that the cop is an instantaneous
value of a continuously operating air-conditioner while the SPF
xepresents an average over the entire season. The heating seasonal
performance factor (HSPF) is defined in an analogous way: the total
amount of heating supplied to a building divided by the total
amount of electrical energy consumed for heating purposes. Total
electrical energy consumption refers to compressor power and
additional electrical heaters required to meet the building load.
Fans and controls are not included. In this report the
abbreviation CSPF refers to the cooling SPF, and HSPF refers to the
heating SPF.

In order to determine the SPF the ASHRAE Temperature Bin
Method is employed as outlined in the testing and rating standards
for heat pumps /6/. For the purpose of the bin method the outdoor
temperature scale is divided into temperature intervals or 'bins'
each of a span of 5 F, for example from 70 F to 75 F. Each bin is
characterized by an average temperature. For example the bin from
70 F to 75 F has an average temperature of 72 F. It is assumed
that whenever an outdoor temperature is found in the range from 70
F to 75 F that the equipment performs as if the ‘temperature were 72
F for that time period. It is necessary to know how many hours a
temperature is found in the respective bin during an entire season.
The number of hours varies with the climate. Exhibit 4 lists the
bin temperatures for one generalized cooling climate and six

typical heating climates spanning the various climate zones in the

22





the performance increase mixtures offer, counter-flow heat
exchangers should be used. This finding has to be verified by
experiments with refrigerant-to-air heat exchangers.

When more than four tube banks are necessary in order to
approximate counter-flow, the pressure drop on the air side will
increase, leading to higher fan power requirements. The energy
savings mixtures offer may therefore be offset by additional
parasitic losses.

On the other hand, in order to take advantage of the
refrigerant temperature glide, the heat exchanger area could be
increased and the air flow rate could be reduced, Thus the net fan
power may not change as a result. This would lead to higher air
temperatures leaving the condenser, a feature that should be
advantageous for heat pump applications.

The use of mixtures would complicate the maintenance of heat
pump systems. One component may escape preferentially when a
leakage occurs. The development of devices that allow the simple
determination of the concentration of the remaining refrigerant
charge and of the amount of the components that have to be added
can eliminate this difficulty. Another solution could be to
replace the entire charge, which is practical only when the

original charge can be reclaimed and recycled.

4.6 Sensitivity Considerations and Accuracy
fhe accuracy of the results depends to a large degree on the model

itself. The model describes a heat pump or air-conditioner almost

46



and the evaporator air inlet temperature in C, Tairin. The first
set lists all mixture runs at design conditions. The second set
lists those runs that were used for seasonal performance
calculations. It contains R22 values for comparison.

In this chapter the results are discussed that were obtained
for the design conditions at 95 F outdoor air temperature for air
conditioning and 47 F outdoor air temperature for heating.

Exhibits 7 through 9 show the COP and volumetric capacity for
the cooling cases of the binary mixtures listed in Chapter 2.3.
R22 has a cooling COP 3.37 and a volumetric capacity of 3735 kJ/m.
In this simulation, the heating COP is calculated for a cooling
case under heating conditions. Therefore, in order to obtain the
true heating COP the values shown in the Appendix have to be
increased by 1.0. This was considered in the evaluation of the
seasonal performance. Based on the peak performance for cooling,
the mixture concentration is selected that will be used for the
investigation of the seasonal performance. A comparison of the
concentrations at which optimum performance is achieved for cooling

and those at which the heating performance is optimum yields that

there are only minor differences of less than 0.1. Therefore, the



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Exhibit 5
Map of the US Displaying Lines of Constant Heating Load Hours



Exhibit 2: '
Greenhouse Warming Potential of R-22 and Other HCFC's and Carbon Dioxide

Fluid

— Dioxide

| Methane-inc indirect
Nitrous Oxide
CFC-11

CFC-12

HCFC-22
HFC-32*
CFC-113
CFC-114

|} CFC-115
HCFC-123

HCFC-124
HFC-125
HFC-134a
HCFC-141b
HCFC-142b
HEC-143a
HFC-152a
cet,

“ Reference /3/

report in which the higher greenhouse warming potential (GWP) of
R22 is compared for different time periods to other HCFCs, HFCs and
to carbon dioxide, Exhibit 2. As concern about the global warming
heightens, the availability of R22 could be threatened. Its price

could rise if "greenhouse gas taxes" are passed or if green house

gases are limited in an allowance system under a comprehensive



APPENDIX #2

This appendix contains a listing of the short output files for all computer runs conducted for binary mixtures.
The refrigerants specified by code numbers according to the following table.

i
R22 6 !
R142b 10 '
R152a cn) Hl
R143a 4 |
R124 15 '
R125 16 |
R134 17
R134a 18

R32 19 1



as an ideal refrigeration cycle. The only deviations from an ideal

cycle are the compressor efficiency of 0.70 and the use of fixed
air temperatures instead of fixed saturation temperatures of the
refrigerant. The latter choice was necessary to account for the
gliding temperature range of mixtures. As has been shown, another
choice may either favor the pure component or’ the mixture /4/.
Whether or not an actual design achieves the predicted performance
depends largely on the system designer and to what degree the
idealized assumption can be met. The closure on the energy balance
in this model is better than 0.1 %. The model applied here assumes
that the temperature glide is linear in the two-phase range. For
most mixtures this is not true. Taking into consideration any non
linearities will increase the calculation effort considerably but
could potentially change the ranking of the mixtures of Exhibit 10.
This is true especially when comparing binary and ternary mixtures.

However, there are other factors to consider. The accuracy of
the refrigerant data is one. The work presented here is based on
the CSD equation of state as published and provided by NIST /3/.
The version used here is current, but the data for some of the
replacement refrigerants could be updated in the future. Any
update on refrigerant properties will effect the results reported
here to an undetermined degree which depends on the magnitude of
the changes. |

Another uncertainty results from the use of a mixing
coefficient of -0.01. The mixing coefficient effects the results

to some extent. An as yet unpublished study conducted at EPA

47



The GWP is based on the integrated time horizon pased on 100 years.

The direct and indirect contribution to global warming were
calculated based on the seasonal performance factor for the
substitute mixtures based on a refrigerant charge that is
equivalent to seven pounds of R22 for the life time of ten years
for a heat pump. It is assumed that 1.61lb of carbon dioxide is
generated per kWh of electricity. The results for the direct and
the indirect contributions are shown in the remaining columns of
Exhibit 15. Exhibit 16 shows a bar chart displaying the direct and
indirect contributions. The results show clearly that the proposed
substitutes show less .impact on the global warming than R22.
R32/R152a and R32/R124 have the lowest GWP. The first because the
contribution of the fluids is low, the second because of the
calculated COP is high. Only tests in actual machinery can

demonstate which of the fluids will have the least: global warming

impact. !
/
it 15: Warmi : i .and_ Ozone
:
FLUID conc. VOL. ‘GwWP ODP = «GWP oP GWP ‘SPF Indir. Total
m3/kg CHARGE BASED TOT.CHAR cooling GiIP GuP
R22 1 0.000907 1500 0.05 1500 0.050 4755 4.25 72000 76755
R32 4 0.00115 560 0 442 0.000 1400 !
R152A 4 0.00119 140 Oo 107 0.000 338 \
RIB 1 0.000834 1200 0 1305 0.000 4137 :
RI3GA 1 0.000887 1200 0 1227 0.000 33890 1
R1IG3A 1 0.0012 2900 @ 2192 0.000 6948 ,
R125 1 0.000693 2500 0 3272 0.000 10372 |
R126, 1 0.000771 430 0.02 506 0.024 1604 .
R32/R152A 0.4 0.00118 308 0.000 237 ~«40.000 750 4.77 66151 64901
R32/R126 0.6 0.00104 508 0.008 443 0.007 1404 4.84 63223 64628
R32/R134A 0.7 0.00109 752 0.000 626 0.000 1984 4.57 66958 68942
RIGSA/R124 0.3 0.000882 1171 0.014 1204 0.014 3817 4.59 66667 70484
“RI25/R126 0.3 0.000795 1051 0.014 1199 0.016 3801 4.45 68764 72565

49 '



conditions. Input values are the evaporator air inlet and outlet
temperatures and the air flow rate, the condenser air inlet
temperature and flow rate, heat exchange areas and heat transfer
coefficients (estimated based on actual’ equipment). Other
variables such as pressure drops, superheat and subcooling at
evaporator and condenser outlet, and superheating of the suction
gas in the compressor are set to zero. It is assumed that the
compressor displacement is always sufficiently large to pump
whatever volume flow rate the evaporator provides. The isentropic
efficiency is set to 0.7. For both, the evaporator and condenser,
the overall heat transfer coefficients are 0.1 kJ/mK, and’ the
areas are 4.0 and 5.0 m* respectively. The cooling load is assumed
to be a sensible load only.

According to today's design criteria, the outdoor heat
exchanger which is the condenser during air-conditioning opération
was chosen to be the larger heat exchanger since the ‘amount of heat
rejected is larger than the cooling capacity. The evaporator has
to be small to provide a cooling surface on a temperature low
enough for dehtimidification. Area and heat transfer coefficients
are calculated based on actual designs. For most of the results
presented here, it is assumed that all heat exchangers are counter-
flow heat exchangers. The impact of cross-flow heat exchangers is
investigated in Chapter 4.5. It is further assumed that during
desuperheating of the vapor in the condenser, the inside tube
surface temperature is below the saturation temperature of the

vapor. Therefore, the heat transfer coefficient in the

12