Soft-optimized tests of R-410A alternative refrigerant R-32 in a

split system heat pump

By Stephen Li

Jan 16 2014

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R32 L41a R290 R410A

Flash point (oC) 240 oC(COC)

-104 oC(COC)

NA

Oil compatibility POE Mineral POE

Temperature glide (oF) 0.0 4.0 0 0.2

ASHRAE safety class A2L A2L A2 A1

GWP 675

R32 test done by others

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OD condition A B 109 H1 H2 14

test unit ref Qc (btu/hr) EER∆Tdis

(F)Qc

(btu/hr) EER EER∆Tdis

(F)Qh

(btu/hr) COP∆Tdis

(F)Qh

(btu/hr) COP COP∆Tdis

(F)

Honeywell

R410A DC inverter ductless split HP

baseline R410A 13648 12.62 17060 4.33

improvement R32 +3% +2% +28.8 -2% -1% +32.4

Daikin R22 DC inverter

baseline R22 20950 21086improvement vs. R410A R32

half cap +7% +14.4 +5% +19.8

improvement vs. R410A R32

full cap +10% +21.6 +11% +23.4 +7% +30.6 +10% +59.4

Emerson 3T HP improvement +3.3% -1.4% +2.6% -1.5% +3.9%+0.9% +3.5% -0.8%

Other literatures shows 3-6% improvement of capacity and 2-3% improvement of EER of R410A

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• Short term:– What’s the difference of R32 and R410A on system thermal performance at rating conditions

& extreme conditions?– Is R32 compatible to R410A system? Is there any additional design control needed?– Does R32 cause more compressor dynamic and piping vibration at rating conditions &

extreme conditions?– To get the same capacity and efficiency, which components (HX, comp, piston, charge, etc.)

need to be changed from R410A to R32?

• Long term:– Can R32 be applied to all existing models? Or which existing models can use R32 with

minor system modification?– Would R32 cause any reliability risk compared to R410A? Is there any degradation of R32

system?– Is it possible to get higher EER/COP by using R32 in the existing R410A system? What

parts need to be changed to get higher capacity and higher efficiency?

Test objective

What to learn in test? & What questions to answer after test?

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Test combinations & steps

• Tests performed• Test unit: SSZ140361BA (SN 1201157846) / AVPTC313714AA (SN

1110632843) • R32 Test scheduled 7/27/12 - 8/5/12 in Intertek (Plano, TX);• Baseline test - R410A w/ Emerson 5-ton TXV/0.059” @ GMC in-house, charge

186 oz;• Soft-optimzed test - R32 w/ Emerson production 3-ton TXV/0.049” @ Intertek;

• Test steps• N2 pressure check @ 300 psi+;• Vacuum system to 300 μm;• ID TXV was adjusted for SH O/E in cooling;• Charge was optimized based on SC liquid;• OD TXV was adjusted for SH in heating;• ID fan @ high speed tap D, ON-ON-ON-OFF w/ static pressure 0.23” H2O;

Test setup & instrumentation

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comp

accumulator

4-way valve

OD coil

check valve

dryer

TXV

Sight glass

ID coil

OD ROOM ID ROOM

check valveP, T#1

P, T#24

T#5 T#6 T#16

T#15

P, T#11

P, T#12

P, T#18

piston

Flow meter

cooling heating

m

P, T#23

T#7

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Test data locations

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data locations in refrigeration system P T Ref. mass flow rate

Comp discharge (#1) x1 x1

Comp suction (#24) x1 x1

OD coil common in (#5) x1

OD coil mid (#6) x1

OD coil out (#7) x1

After OD piston, liquid @ SV (#11) x1 x1

Suction vapor @ SV (#23) x1 x1

ID coil in (#15) x1

ID coil mid (#16) x1

ID coil common out @ TXV bulb (#18) x1 x1

Before ID TXV (#12) x1 x1 x1

Total x6 x11 x1

In addition to regular locations of air side DB/WB data and refrigeration system, the following data locations are required:

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REF PISTON TEST CHG Q AIR

Q REF

W EER SEER PRESSURE PSI TEMPERATURE SCFM

SH @

DIS

SH @

SUC

SH @

O/E

SC @

O/C

REF RAT

EH.B.

∆ ∆ ∆

ID OD COND oz COPHSP

F SUC O/E B/4 LIQ DIS SUC O/E B/4 LIQ DIS Q AIRQ

REF EFF

BASELINE R410A TEST WITH EMERSON PRODUCTION TXV

R410A

5T TXV 0.059

A 186 34679 35439 2811 12.33 147 151 367 374 63 55 104 105 160 1276 48.0 11.2 1.9 6.9 521 -2.2%

B 186 37706 38407 2437 15.47 144 148 144 310 62 56 97 91 141 1278 50.0 11.4 3.3 7.3 515 -1.9%

C 186 33698 35234 2468 13.65 135 139 313 319 60 51 93 94 147 1284 13.1 2.2 6.8 480 -4.6%

D 186 14.0 CLF= 0.184; CD = 0.187; PLF = 0.907

H1 186 32698 36161 2520 3.80 106 321 316 311 36 120 83 79 129 1227 29.4 1.5 1.5 19.2 410 -10.6%H1C 186 8.46 HLF=0.163; CD= 0.348

H2 186 25014 2339 3.13

H3 186 19256 19810 2308 2.44 61 262 259 255 11 102 85 80 120 1241 34.1 1.4 1.4 5.5 230 -2.9%R32 TEST WITH EMERSON PRODUCTION TXV

R32 3T TXV 0.049

A 131 35996 36339 2883 12.49 153 154 383 384 389 72 57 103 105 172 1216 59.9 19.5 3.8 6.7 345 -0.9% 3.8% 2.5% 1.3%

B 131 38452 38821 2458 15.65 150 151 319 320 325 67 56 91 92 149 1214 49.2 15.4 3.7 7.0 348 -0.9% 2.0% 1.1% 1.2%

C 131 35458 35278 2426 14.62 137 138 313 313 318 65 52 91 92 153 1226 54.5 18.8 4.9 5.8 316 0.5% 5.2% 0.1% 7.1%

D 131 14.7 CLF=0.179; CD=0.122 4.8%

115 131 31315 31315 3586 8.73 157 159 493 495 500 59 56 123 126 193 1210 61.1 4.4 1.7 7.2 364 -8.9%

H1 131 34956 3.94 338 0.2 6.9% 3.7%

H1 131 33143 32724 2309 3.86 108 325 323 322 325 47 151 87 81 149 1148 48.9 12.6 8.2 12.7 247 1.3% 1.4% -9.5% 1.5%

H1 131 33359 33173 2518 3.88 111 326 323 322 326 41 144 89 83 144 1147 44.5 5.6 1.5 9.9 258 0.6% 2.0% -8.3% 2.2%

H1C 131 9.12 HLF=0.152; CD=0.287 7.8%

H2 131 25939 2351 3.24 3.7% 3.5%

H3 131 20592 12340 2360 2.56 64 273 270 268 272 10 115 87 81 119 1163 31.7 0.0 1.3 0.4 95 67.3% 6.9%-

37.7%

4.8%

12 131 18676 9398 2329 2.35 58 265 263 261 265 6 116 85 79 123 1167 37.4 0.0 1.3 0.4 70 99.8%

R32 evaluation

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Piston size sensitivity

• Comp suction SH of R32 is sensitive to piston size, SH changes 7-12 oF with 0.001” change of piston size;

• To get low comp suction SH of R32, piston size needs to be refined with smaller steps, e.g. 0.0005”;

REF PISTON TEST CHGBTUH AIR

BTUH

REF

TOTAL ID EER PRESSURE PSI TEMPERATURE SCF

M

SH @

DIS

SH @

SUC

SH @

O/E

SC @

O/C

REF RAT

EID OD COND oz WATTSWATTS COP

SUCT O/E B/4 LIQ

DISC

SUCT O/E B/4 LIQ

DISC

R32 3T TXV 0.049 H1 131 34956 3.94 338 0.2 0.2

R32 3T TXV 0.048 H1 131 331433272

4 2309 209 3.86 108 325 323 322 325 47 151 87 81 149 1148 48.9 12.6 12.6 12.7 247

R32 3T TXV 0.049 H1 131 333593317

3 2518 213 3.88 111 326 323 322 326 41 144 89 83 144 1147 44.5 5.6 5.6 9.9 258

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Test p-h diagram

3.8%

2.0% 2.0%

1.3% 1.2%

2.2%

0.0%

0.5%

1.0%

1.5%

2.0%

2.5%

3.0%

3.5%

4.0%

A B H1

R32 improvement in % over R410A

Cap EER/COP

160

141129

172

149 144

0

20

40

60

80

100

120

140

160

180

200

A B H1

Comp discharge temp (oF)

R410A R32

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Cd & SEER/HSPF

• Cd of R32 is smaller than R410A, which helps improve SEER/HSPF further;

System Data Base. Alt. RatioCooling Degradation Coefficient –Cd 0.187 0.122 0.65

Seasonal Energy Efficiency Ratio -SEER 14.02 14.70 1.05

Heating Degradation Coefficient –Cd 0.348 0.287 0.82

Heating Seasonal Performance Factor - HSPF 8.46 9.12 1.08

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Observations of soft-optimized test

• Evap out SH of R32 is about 1-2 oF higher than R410A due to the open limitation of 3T TXV (fully opened);

• Comp suction SH of R32 is higher;• ID Emerson TXV was fully opened in R32 test to make SH close to that of R410A test;

• R32 charge is ~70% of R410A, flow rate is ~67% of R410A;• R32 cond & evap pressure are ~ 10 psi higher than R410A in both cooling and

heating;• R32 cooling performance is 4% better in capacity, 1-2% better in EER, & 5%

better in SEER (w/ improved Cd);• R32 heating performance is 2% better in capacity/COP & 8% better in HSPF (w/

improved Cd);• R32 operates at extreme conditions (115 & 10 oF);

• Discharge temp & SH of R32 is ~10oF+ higher than R410A;• Comp suction SH of R32 is sensitive to piston size & valve modulation

refined piston size & careful valve sizing and selection”;

Conclusions

• Conclusions– R32 works in existing R410A system, including extreme

conditions;– R32 improves capacity by 4% and efficiency by 1-2%;– Tdis of R32 is 7-29 oF higher than R410A;– Pcond & Pevap of R32 is 10 psi+ higher than R410A;– Charge of R32 is 30% lower than R410A;– Flow rate of R32 is 33% lower than R410A;

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