&EPA
United States Air and
Environmental Protection Radiation
Agency (ANR-445)
EPA/430/R-92/007
September 1992
Experimental Investigation of R-22
Replacement Refrigerants in a Split-
System Residential Air Conditioner
EPA
430
R
92
007
c.2
HFC-152a
Printed on Recycled Paper
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-------
Obi
Q,9s
v)
Experimental Investigation of R-22 Replacement
Refrigerants in a Split-System Residential Air Conditioner
Prepared for
US. Environmental Protection Agency
Technology & Substitutes Branch Global Change Division
Office of Atmospheric and Indoor Air Programs
Office of Air and Radiation
Washington D.C. 20460
by
Sekhar N. Kondepudi
September 1992
22
CO
HEADQUARTERS LIBRARY
ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
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CONTENTS
Acknowledgements 3
Major Findings 4
Refrigerants and the Environment 6
Choosing the Best Alternatives 7
Project Objectives 8
Previous Work 9
Testing Details 10
Results and Discussions 13
Performance Results 13
Normalized Results 16
Retrofit and New Equipment Applications 16
Refrigerant Charge and Mass How 19
Comparisons with Simulations and Breadboard Testing 20
Conclusions and Further Work 23
References 23
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MAJOR FINDINGS
• Experimental testing of five blends of R-32/R-134a and
R-32/R-152a, potential R-22 replacements, was performed
in a 2-ton split-system residential air conditioning system.
The only change made to the original R-22 system was a
non-production hand-operated expansion device and a
different lubricant
* The R-32 mixtures provided similar efficiency and capaci-
ties to R-22 with minimal hardware changes.
• The 40/60% mass fraction blend of R-32/R-134a had
capacity and steady-state efficiency 1% greater than R-22,
• The 30/70% blend of R-32/R-134a had a 5% lower capaci-
ty and a steady-state efficiency within 1% of R-22 perfor-
mance. The seasonal energy efficiency levels were within
2% of the R-22 values.
• Since capacity is a driving force for retrofit applications,
the 40/60% of R-32/R-134a may be a good retrofit refriger-
ant for existing R-22 systems.
• All the blends of R-32/R-134a and R-32/R-152a had
steady-state efficiency levels within 2% of R-22 perfor-
mance levels but lower capacity levels.
• The R-32/R-152a blends (30/70% and 40/60%) had
steady-state efficiency levels within 1.5% of R-22 but had a
capacity reduction between 8 and 12%. Simulations have
shown these blends to have the most promising energy
performance potential, and with appropriate hardware
modifications and optimization, it may be possible to
improve efficiency and capacity levels considerably.
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table 1: Overview of Steady-State Results
(2 ton, 10.25 SEER Split System Air Conditioner)
(ARI Rating Condition 80-67/95)
Refrigerant
R-22
R-32/R-134a
(20/80 Mix)
R-32/R-134a
(30/70 Mix)
R-32/R-134a
(40/60 Mix)
R-32/R-152a
(30/70 Mix)
R-32/R-152a
(40/60 Mix)
Capacity ("A" Test)
Base
-10%
-5%
+1%
-12%
-8%
% CHANGE
EER("A"Test)
Base
-1%
0% ,
+1%
+1%
-1.5%
SEER
Base
-3%
-2%
-1%
-5%
-2%
• Assumptions made in computer simulation, such as sys-
tem optimization and counterflow heat exchangers,
resulted in differences between the modeling and experi-
mental results. The thermodynamic properties used in the
simulations may have also contributed to the variation in
the results.
• With appropriate hardware modifications and optimiza-.
tion, it is expected that systems using the R-32/R-134a and
R-32/R-152a blends could achieve performance levels sim-
ilar to that predicted by simulations.
• Independent tests conducted by Lennox Industries on sim-
ilar equipment using the same refrigerant blends con-
firmed trends and results reported above.
• The present set of tests were for a cooling only, split-sys-
tem air conditioner. The next immediate step should be a
study of refrigerant blends in heat pumps operating in
both heating and cooling modes.
• The results from these tests form the basis of preliminary
"drop-in" tests of R-22 substitutes in operating residential
air conditioning equipment. While the results are encour-
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aging, a considerable amount of further work needs to be
done prior to commercialization. Future work should
include evaluation of:
* Counterflow Heat Exchangers for Air Systems
• Charge, Superheat, and Subcooling Optimization
• Expansion Devices
• Heat Pumps—Cooling and Heating Modes
• Composition Shifts of the Refrigerant Blends
* Accumulators and Reversing Valve Dynamics
• Compressor life
• Materials Compatibility (long term)
• Flammability
• Servicing Issues
REFRIGERANTS AND THE ENVIRONMENT
• The environmental problems of ozone-depleting chloroflu-
orocarbons (CFCs) have been identified and are restricted
worldwide by the Montreal Protocol. Fully haiogenated
CFCs, including the widely used refrigerants R-ll, R-12,
R-114 and R-502, are being phased out by the end of 1995
in the United States.
• A similar CFC phaseout, including restrictions on HCFC-22,
will be negotiated under the Montreal Protocol in
November 1992.
• R-22 is presently used in a wide variety of applications
(Figure 1). The concern that continued use of HCFC-22
will lead to increased levels of stratospheric chlorine and
to more significant ozone depletion, has lead to calls for an
R-22 phaseout between the years 2000 and 2010.
• The Rio convention framework indicates that global wann-
ing is the next dominant environmental issue and that CFC
and HCFC alternatives will be included in efforts to mini-
mize global warming effects.
* Industry, government, and academia are concentrating
efforts to develop alternatives for R-22.
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Figure 1: Multiple Uses of HCFC-22
Other
(refrigerated transport,
industrial,
household ice making)
Retail food 1%
11% s^S& ^^». Reciprocating chillers
18%
Unitary-heat
pumps/central air
32%
Residential-
window units
16%
Other
(centrifugal chillers,
packaged terminal)
67% Air Conditioning
33% Refrigeration
CHOOSING THE BEST ALTERNATIVES
Several refrigerants and replacements are being evaluated
as R-22 replacements.
To achieve a significant net reduction in global wanning
effects when substituting R-22 with alternatives, it is
important that the alternatives have both a low direct
global warming potential and are at least as energy-effi-
cient as R-22.
Energy efficiency is especially significant domestically/
since unitary air conditioners and heat pumps must meet
the 1992 Department of Energy (DOE) minimum energy
efficiency standard [1] of 10.00 Seasonal Energy Efficiency
Ratio (SEER).
Flammability, toxicity, and human health risks, as well as
system performance, materials compatibility, and costs,
must be carefully evaluated before the best alternatives
can be determined.
-------
• Computer simulations and breadboard tests have indicat-
ed that chlorine-free refrigerant blends of R-32/R-134a
and R-32/R-152a can deliver capacities and energy effi-
ciency levels greater than that of R-22.
• These simulations and breadboard type tests have only a
limited value beyond which actual, "drop-in" tests must
be performed to test actual viability.
PROJECT OBJECTIVES
• Evaluate the "drop-in" performance of potential R-22
alternatives blends in an actual full scale 2-ton residential
split-system .air conditioner.
• Measure the Capacity, Steady-State, and Seasonal Efficiency
of the air conditioner.
* Demonstrate that comparable capacity and efficiency can
be achieved with minimal hardware changes.
• Provide direction for evaluating engineering design changes
in R-22 systems to achieve optimized energy performance.
• Test refrigerant blends of R-32/R-134a and R-32/R-152a
based on results obtained by Radermacher and Jung [2]
and Pannock and Didion [3] fTable 2).
* Measure differences in performance between different
refrigerant compositions.
Table 2: List of Refrigerant Blends Tested
Refrigerant Blend
R-32/R-134a
R-32/R-134a
R-32/R-134a
R-32/R-152a
R-32/R-152a
Composition Ratio
20/80%
3070%
40/60%
30/70%
40/60%
(Mass)
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PREVIOUS WORK
* Vineyard, Sands, and Start [4] found that refrigerant mix-
tures with high potential for improved performance over
R-22 included R-32/R-124, R-32/R-142b, R-143a/R-124,
R-143a/R-142b, and R-143a/G-318.
• Radermacher and Jung [2] conducted a simulation study
of potential R-22 replacements in residential equipment.
They found that the most promising mixtures were R-32/
R-152a mixture in a 40/60% blend by mass and
R-32/R-134a in a 30/70% blend by mass.
• Sands, Vineyard, and Nowak [5] compared R-22, R-12, and
R-114 with 11 single component non-CFC refrigerants to
estimate heat pump performance potential. The study con-
cluded that R-152a, R-143a, R-134a, and R-134 had the best
performance of the 11 refrigerants evaluated.
• Other studies [6,7,8,9] suggest that when heat transfer fluids
exchange heat with a refrigerant mixture in a counterflow
mode, the thermodynamic irreversibilities could be reduced
by matching the temperature glide on the refrigerant side
against the drop in the air side. This will result in an
improved efficiency or COP for heat pumps and air condi-
tioners. Other advantages of NARMs include capacity con-
trol and increased capacity at lower ambient temperatures.
• Pannock and Didion [3] performed a set of simulations
followed by tests using chlorine-free refrigerant mixtures
on a mini-breadboard heat pump system. They found that
two refrigerant mixtures, R-32/R-134a and R-32/R-152a,
performed better than R-22 for certain composition ranges
using counterflow heat exchangers. ,
• Shiflett, Yokozeki, and Bivens [10] conducted "drop-in"
tests of a 32/68% mass ratio blend of R-32/R-134a in a
room air conditioner. The test results showed comparable
capacity and efficiency to R-22. They also concluded that
R-32/R-134a mixtures with less than 25% R-32 by mass are
non-flammable for almost all conditions.
• Treadwell [11] performed laboratory tests using Propane
(R-290) and found that by increasing compressor displace-
ment it was possible to attain capacities and efficiencies
similar to that of R-22.
• The Air Conditioning and Refrigeration Institute (ARI)
[12], in consultation with various equipment and refriger-
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ant manufacturers, has identified a set of 10 refrigerants
that the member companies will screen as potential R-22
replacements (Table 3).
Table 3: ARI Recommended List of Potential R-22 Replacements
Refrigerant
R-32/R-125
R-32/R-134a
R-32/R-125/R-134a
R-290 (Propane)
R-134a
R-717 (Ammonia)
R-32/R-125/R-134a/R-290
R-32/R-125/R-134a
R-125/R-143a
R-125/R-143a/R-134a
% Composition By Weight
60/40
30/70
10/70/20
20/55/20/5
30/10/60
45/55
40/45/15
TESTING DETAILS
• Tests were conducted for the U.S. EPA, at the facilities of
ETL Testing Laboratories in Cortland, NY. To verify the
tests conducted at ETL, similar tests were conducted at
Lennox Industries in Dallas, TX.
• All tests were conducted in accordance with the ARI
Standard 210/240 and ASHRAE Standards 37-1988 and
116-1989 for testing unitary equipment [13,14,15].
• A 2-ton split-system air conditioner manufactured by
Lennox Industries with a rated Seasonal Energy Efficiency
Ratio (SEER) of 10.25 was tested. Details of the condenser
and evaporator section are given in Tables 4 and 5.
10
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Table 4: Geometrical Specifications of Condenser Unit
Manufacturer
Face Area
Tube Diameter
No. of Tube Rows
Tube Material
Pins Per Inch
Fin Type
Fan Specs
Air Flow
Fan RPM
Fan Power
Fan Motor
Compressor
Lennox Industries
12.60ft2
0.375 inches
1
Copper
20
Enhanced, rippled aluminum
20 inch diameter, 3 Blades
2500 dm
850
200 watts
1/6 HP
Copeland CR22K6-PFV
Table 5: Geometric Specifications of Evaporator Coil
Manufacturer
Coil Type
Face Area
Tube Diameter
No. of Tube Rows
Tube Material
Fins Per Inch
Rn Type
Lennox Industries
A Coil (or V Coil) with 2 slabs
3.44 ft2 (1.72 ft2 per slab)
0.375 inches
2
Copper
15
Enhanced, rippled aluminum
11
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No hardware changes were made except for the use of a
non-production hand-operated expansion device. This
allowed for a "drop-in" comparison of the refrigerant
blends.
The following parameters were measured:
1. System Capacity—as measured on the evaporator coil
2. Power Consumption—Compressor and Fan
3. System Efficiency—EER and SEER
4. Refrigerant Pressures and Temperatures
5. Refrigerant Mass Flow Rate
6. Airside and Refrigerant Side Energy Balances
Figure 2 is a test schematic showing the test setup and
locations of thermocouple and pressure tap locations,
along with other instrumentation such as mass flow meter
and hand-operated expansion device.
A hand-operated needle valve was used as the expansion
device to allow for a continuous control over the level of
refrigerant expansion.
Figure 2: Schematic of Test Configuration
Evaporate* Coil
Temperature & Pressure
Twnp«*tur« Only
12
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• Thermodynamic properties for the refrigerant blends used
were based on a modified version of REFPROP 3.0, which
includes data on R-32 and R-32 mixtures.
• The original mineral oil lubricant used with R-22 is not
compatible with R-134a. Therefore, a polyol ester-based
lubricant developed for use with R-134a was used with the
R-32/R-134a blends. Flushing of the system was per-
formed to ensure that minimal traces of the original lubri-
cant were present. The same polyester lubricant was used
with the R-32/R-134a blends was used with the R-32/R-
152a blends.
• The amount of refrigerant charge was based on a 15°F
superheat setting at the compressor suction. The charge
was adjusted to attain the best HER at the "80/67-95" test
condition. In order to maintain consistency, the same
superheat setting was used for all the blends.
• The same test facilities, instrumentation, and test person-
nel were used for all the tests. This minimized any uncer-
tainty and inaccuracy in the measurements.
RESULTS AND DISCUSSIONS
PERFORMANCE RESULTS
• Capacity, power, HER, and SEER for each refrigerant tested
are summarized in Tables 6 and 7.
• The results show that only the 40/60% R-32/R-134a
blend had better performance than the R-22 baseline. In
all other cases, the EER values were all within 2% of the
R-22 baseline.
• • The capacities of the other blends were less than the R-22
baseline and it is expected that with appropriate hardware
changes and optimization, performance can be improved.
• The energy balance between the refrigerant side and the
airside were typically within 5% of one another. All refer-
ences to capacity are based on air side measurements.
• The results obtained from the ETL and Lennox tests are
within 3 to 5% of each other. This range is well within
expected range of experimental error considering that the
tests were conducted on different test units in different
test facilities.
13
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Table 6: Summary of ETL Results
(AN Percentage Compositions Are by Mass)
DOE "A" Test (80/67-95)
Airside Capacity (Btuh)
Total Power (W)
EER (Btuh/W)
Comp Disch Pressure (psig)
Comp Suet Pressure (psig)
Comp Disch Temperature (F)
Comp Suet Temperature (F)
R-22
(Baseline)
23690
2489
9.52
260.5
81
185.5
63
R-32/R-134a Mixture
20/80%
20610
2179
9.46
221
62.5
169
65
30/70%
22390
2345
9.55
250
71
175
64
40/60%
23870
2498
9.56
276
79.5
181
63
R-32/R-152a Mixture
30/70%
20630
2152
9.59
209
60
186
68.5
40/60%
21550
2297
9.38
231.5
66
190
66.5
DOE "B" Test (80/67-82)
Net Capacity (Btuh)
Total Power (W)
EER (Btuh/W)
Comp Disch Pressure (psig)
Comp Suet Pressure (psig)
Comp Disch Temperature (F)
Comp Suet Temperature (F)
R-22
(Baseline)
25320
2319
10.92
225
77
170.5
59.5
R-32/R-134a Mixture
20/80%
22390
2059
10.87
190.5
60
156.5
62.5
30/70%
24210
2195
. 11.03
215
68
162
62.5
40/60%
25610
2349
10.90
238
75.5
167
60.5
R-32/R-152a Mixture
30/70%
21250
2009
10.58
178.5
57.5
171
66
40/60%
23060
2135
10.80
197
63.5
174
64
SEER
10.10
9.80
9.90
10.00
9.58
9.89
14
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Table 7: Summary of Lennox Results
(All Percentage Compositions Are by Mass)
DOE "A" Test (80/67-95)
Net Capacity (Btuh)
Total Power (W)
EER (Btuh/W)
Comp Disch Pressure (psig)
Comp Suet Pressure {psig)
Comp Disch Temperature (F)
Comp Suet Temperature (F)
R-22
(Baseline)
24134
2468
9.78
257
76.6
183.6
60.5
R-32/R-134a Mixture
20/80%,
21181
2186
9.69
221.7
60.8
167.3
; 62
30/70%
21996
v-.
2342
9.39
249
70.3
174.5
63.5
40/60%
23933
2538
9.43
281
79.6
181.8
62.8
R-32/R-152a Mixture
30/70%
20522
2174
9.44
205.4
58.9
182.5
66.8
40/60%
22136
2337.49
9.47
232
66.3
189
66.8
DOE "B" Test (80/67-82)
Net Capacity (Btuh)
Total Power (W)
EER (Btuh/W)
Comp Disch Pressure (psig)
Comp Suet Pressure (psig)
Comp Disch Temperature (F)
Comp Suet Temperature (F)
R-22
(Baseline)
25543
. 2319
11.01
223
74.4
155.1
59.5
R-32/R-134a Mixture
20/80%
22756
2076
10.96
190
59.6
160.7
62.7
30/70%
23795
2230
,10.67
214
676
160.7
61 .6 '
40/60%
26313
2396
10.98
241.7
76.3
168.6
61.1
R-32/R-152a Mixture
30/70%
22231
2049
10.85
175.9
56.9
169.1
65.7
40/60%
23919
2217
10.79
200.8
64.8
174;4
66
SEER
10.16
10.08
9.68
10.24
10.00
9.94
15
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NORMALIZED RESULTS
• ••" "~
• Tables 8 and 9 present the data from ETL and Lennox nor-
malized against the R-22 baseline. This allows for a more
direct comparison of the results obtained in the different
laboratories.
• The data shows that the capacities and power consump-
tion decreased by the same percentage (except for the
40/60% R-32/R-134a blend). Hence, efficiencies remain
effectively constant. This indicates that if a capacity boost
could be achieved with an appropriate increase in power
consumption, then results closer to the R-22 baseline could
be achieved.
RETROFIT & NEW EQUIPMENT APPLICATIONS
• For the R-32/R-134a blends, 30/70 and 40/60% composi-
tions appear to have good potential. Both capacities and
efficiencies are within 5% of the R-22 system for both
these blends. Since the seasonal efficiencies measured in
the ETL tests are within 2% of one another (ETL results),
it can be assumed that the use of these blends will have a
minimal impact on SEER. This can be achieved with mini-
mum hardware changes and forms the.basis of a good
retrofit refrigerant.
• Simulations indicate that the R-152a blends have a high
performance potential and it is expected that with appro-
priate hardware changes in the compressor, heat exchang-
er, and expansion devices, and other system optimization,
it may be possible to achieve higher capacity and efficien-
cy levels than were measured in these tests.
16
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V
Table 8: Performance Relative to R-22: ETL Results
(All Percentage Compositions Are by Mass)
DOE "A" Test (80/67-95)
Net Capacity (Btuh)
Total Power (W)
EER (Btuh/W)
R-22
(Baseline)
1.000
1.000
1.000
R-32/R-134a Mixture
20/80%
0.870
0.875
0.994
30/70%
0.945
0.942
1.003
40/60%
1.008
1.004
1.004
R-32/R-152a Mixture
30/70%
0.871
0.865
1.007
40/60%
0.910
0.923
0.986
DOE "B" Test (80/67-82)
Net Capacity (Btuh)
Total Power (W)
EER {Btuh/W)
R-22
(Baseline)
1.000
1.000
1.000
R-32/R-134a Mixture
20/80%
0.884
0.888
0.996
30/70%
0.956
0.947
1.010
40/60%
1.011
1.013
0.999
R-32/R-152a Mixture
30/70%
0.839
0.866
0.969
40/60%
0.911
0.921
0.989
SEER
1.000
0.970
0.980
0.990
0.949
0.979
17
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Table 9: Performance Relative to R-22: Lennox Tests
(Alt Percentage Compositions Are by Mass)
DOE "A" Test (80/67-95)
Net Capacity (Btuh)
Total Power (W)
EER (Btuh/W)
R-22
(Baseline)
1.000
1.000
1.000
R-32/R-134a Mixture
20/80%
0.878
0.886
0.991
30/70%
0.911
0.949
0.960
40/60%
0.992
1.028
0.964
R-32/R-1528 Mixture
30/70%
0.850
0.881
0.965
40/60%
0.917
0.947
0.968
DOE "B" Test (80/67-82)
Net Capacity (Btuh)
Total Power (W)
EER (Btuh/W)
R-22
(Baseline)
1.000
1.000
1.000
R-32/R-134a Mixture
20/80%
0.891
0.895
0.995
30/70%
0.932
0.962
0.969
40/60%
1.030
1.033
0.997
R-32/R-152a Mixture
30/70%
0.870
0.884
0.985
40/60%
0.936
0.956
0.980
SEER
1.000
0.992
0.953
1.008
0.984
0.978
18
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REFRIGERANT CHARGE
• Tables 10 and 11 show the amount of refrigerant charge
and mass flow rates measured in the tests.
Table 10: Amount of Refrigerant Charged/Reclaimed (ETL Tests)
Refrigerant
R-22
R-32/R-1348
R-32/R-134a
R-32/R-134a
R-32/R-152a
R-32/R-152a
Ratio
(% Mass)
—
20/80
30/70
40/60
30/70
40/60
Charge Ami
(Ibs-oz)
4-05
4-12
4-05
4-05
3-05
3-12
Reclaim Amt
(Ibs-oz)
4-05
4-08
4-02
4-04
3-03
not measured
Table 11: Refrigerant Mass Flow Rates ("80/67-95 Condition")
Refrigerant Blend
R-22
R-32/R-134a
R-32/R-134a
R-32/R-134a
R-32/R-152a
R-32/R-152a
Mass Ratio
—
20/80%
30/70%
40/60%
30/70%
40/60%
Mass Flow Rate (Lb/Hr)
ETL
375
291
302
305
196
212
Lennox
352
295
300
305
206
219
19
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COMPARISONS WITH SIMULATIONS
AND BREADBOARD TESTS
• Table 12 and Figures 3 and 4 compare the simulation and
breadboard testing conducted at the University of Maryland
and the MIST to the "drop-in" results. Hie simulations pre-
dict that the refrigerant blends tested differently. There are
several reasons for the difference in results.
• Counterflow heat exchangers were used in simulations
and NIST test rig to better utilize temperature glide of the
refrigerant mixture. The system tested at ETL was a stan-
dard production unit and had crossflow heat exchangers
which could have impacted the performance.
• The breadboard test used water to refrigerant heat exchang-
ers to obtain a constant capacity and the associated impact
on the energy efficiency. In an actual operating system, the
heat exchangers are air-to-refrigerant type and capacity is
not easily controlled.
* Simulations assumed minimal subcooling and superheat
since thermodynamically, these would be desirable.
Practically, this could lead to incomplete condensation and
evaporation. The EPA tests had 15°F superheat and 5-10°F
subcooling, which could impact performance.
• Coefficients used for thermodynamic properties used in
the University of Maryland simulations differed from the
EPA tests.
• Better performance from the refrigerant blends tested is
expected with further optimization such as optimum super-
heat settings, counterflow heat exchangers, and better trans-
port and thermophysical properties of refrigerant blends.
20
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Table 12: Comparison of Experimental and Simulation Results
(Simulation Data from Radermacher & Jung [4], Experimental Data from ETL)
ARI "A" Test Conditions
Refrigerant
R-22
R-32/R-134a
(20/80 Mix)
R-32/R-l34a
(30/70 Mix)
R-32/R-134a
(40/60 Mix)
R-32/R-152a
(30/70 Mix)
R-32/R-152a
(40/60 Mix)
% Change in Capacity
Test
Base
i13
-5
+1
-12
-9
Simulation
Base
-10
+2
+13
-9
+2
% Change in COP
Test
Base
-0.5
+0.5
+0.5
+1
-1.5
Simulation
Base
+5
+6
+6
+12
+12
21
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Figure 3: Comparison of Capacity
(ARI "A" Test Condition)
Base
1.2-1
ETL Tests
R-32/H-152a
30/70% 40/60%
R-32/R-134a
20/80% 30/70% 40/60%
Simulation
I INIST Simulation
Refrigerant Blends
Figure 4: Comparison of COP
(ARI "A" Test Condition)
Base
1.2-]
1.0-
0.8
R-32/R-134a
20/80% 30/70% 40/60%
R-32/R-152a
30/70% 40/60%
I ETL Tests
I Lennox Tests
I UMd Simulation
I I NIST Simulation
E73 NIST Tests
Refrigerant Blends
22
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CONCLUSIONS AMP FURTHER WORK
* R-32 based refrigerant mixtures have been shown to be
promising potential R-22 replacements in a split-system
air conditioner. These tests were conducted in accordance
with the ARI Rating Conditions and parameters measured
included capacity, efficiency, and seasonal efficiency.
• The tests demonstrate that these refrigerants can achieve
comparable performance levels to that of existing R-22
systems. With additional work and optimization/ it should
be possible to improve the performance levels beyond that
of R-22.
• While the results of this test program are encouraging;
considerable work is needed to better evaluate these alter-
natives. The following further Work is. recommended:
a. Use of Counter Flow Heat Exchangers to optimize
performance of blends with temperature glide.
b. Optimize Charge, Superheat, and Sub Cooling levels
c. Use larger capacity compressors to make up capacity
shortfall—experimental verification needs to be done.
d. Investigate the use of chemical additives to R-22
based lubricants for compatibility .with new blends
e. Conduct Heating Tests on heat pumps
f. Conduct Composition Shifts Study for optimization
in heating and cooling
g. Investigate Accumulators and Reversing Valve Dynamics
h. Study Compressor Life and Materials Compatibility
i. Study Flammability Aspects including Risk Analysis
j. Investigate Serviceability Issues
REFERENCES
1. National Appliance Energy Conservation Act (NAECA), Public Law 100-12,
January 1987.
2. Radermacher R. and Jung D, 1991, "Theoretical Analysis for Replacement
Refrigerants for R-22 For Residential Uses/' U.S. Environmental Protection
Agency Report, U.S. EPA/400/1-91/041.
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3. Pannock J. and Didion D., 1991, "The Performance of Chlorine-Free Binary
Zeotropic Refrigerant Mixtures in a Heat Pump," National Institute for
Standards and Technology Report, NISTIR 4748. (NTIS #PB92-149814/AS)
4. Vineyard E.A., J.R. Sands and XG. Statt, 1989, "Selection of Ozone-Safe Non-
Azeotropic Refrigerant Mixtures for Capacity Modulation in Residential
Heat Pumps," ASHRAE Transactions, Paper #3199, Vol 95, Part 1.
5. Sands J.R., E.A. Vineyard and R.J. Nowak, 1990, "Experimental Performance
of Ozone-Safe Alternative Refrigerants," ASHRAE Transactions, Paper #3399
Vol. 96, Part 2.
6. Hogberg M. and X Berntsson, 1991, "A Residential Heat Pump Working with
the Non-Azeotropic Mixture HCFC-22/HCFC142 b—Experimental Results
and Evaluation," Paper #492, XVIII International Congress of Refrigeration,
Montreal, Canada.
7. Goto M., N. Inque and J. Nakamura, 1991, "Performance of Vapor Compression
Heat Pump System Using a Non-Azeotropic Refrigerant Mixture," Paper #62,
XVIII International Congress, of Refrigeration, Montreal, Canada.
8. Takamatsu H., Sh. Koyama, Y. Ikegami and X Yara, 1991, "An Experiment on
a Vapor Compression Heat Pump System Using Non-Azeotropic Refrigerant
Mixtures," Paper #105, XVIII International Congress of Refrigeration,
Montreal, Canada.
9. Galloway J.E. and V.W. Goldschmidt, 1991, "Air to Air Heat Pump
Performance with Three Different Non-Azeotropic Refrigerant Mixtures,"
ASHRAE Transactions, Paper #3473, Vol. 97, Part 1.
10. Shiflett M.B., Yokozeki A, and Bivens D.B., 1992, "Refrigerants as HCFC-22
Alternatives," Proceedings of the 1992 International Refrigeration
Conference—Energy Efficiency and New Refrigerants, July 1992. pp. 35-44.
11. Treadwell D.W. "Application of Propane (R-290) to a Single Packaged
Unitary Air Conditioning Product," Proceedings of the International CFC
and Halon Alternatives Conference, pp. 348-351. December 1991.
12. Air Conditioning and Refrigeration Institute, 1992: R-22 Alternative
Refrigerants Evaluation Program (AREP)—Participants Handbook, ARI,
Arlington, VA.
13. ASHRAE Standard 116,1989: Methods of Testing for Seasonal Efficiency of
Unitary Air-Conditioners and Heat Pumps (1989).
14. ASHRAE Standard 37, 1988: Methods of Testing for Rating Unitary Air-
Conditioners and Heat Pump Equipment (1988).
15. ARI Standard 210/240 Unitary Air-Conditioning and Air-Source Heat Pump
Equipment (1989).
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