IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 1 of 21

Appendix A: System Setup Tests

A. Inlet air velocity and temperature distribution

These tests were performed prior to starting the refrigeration system performance test 

to verify uniformity of air velocity and temperature at the inlet to the heat exchangers. 

Each test was performed for both heat exchangers (condenser and evaporator) and 

over a relevant range of air velocities and inlet air temperatures. 

For each of the system tested, the adjustment of air velocity distribution was not 

straightforward. After several iterations, condenser velocity profiles were achieved 

within ±8% for each of the predefined three airflow conditions and the evaporator 

velocity profiles were measured within ±6% for each of predefined two airflow

conditions. The results at selected airflow conditions are presented below. 

5 159 313 467 621

33

113

193

273

353

mm

mm

Deviation from average velocity [%]

5%-10%

0%-5%

-5%-0%

-10%--5%

-15%--10%
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 2 of 21

34 100 166 232

31

94

157

220

mm

mm

Deviation from average velocity [%]

3%-5%

1%-3%

-1%-1%

-3%--1%

-5%--3%

SAE IMAC R134a condenser inlet temperature profile

20.0

25.0

30.0

35.0

40.0

45.0

50.0

T11 T12 T13 T14 T15 T21 T22 T23 T24 T25 T31 T32 T33 T34 T35 T41 T42 T43 T44 T45 T51 T52 T53 T54 T55

TC number

Temperature [oC]
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 3 of 21

SAE IMAC R134a evaporator inlet temperature profile

20.0

25.0

30.0

35.0

40.0

45.0

50.0

T11 T12 T13 T14 T15 T21 T22 T23 T24 T25 T31 T32 T33 T34 T35 T41 T42 T43 T44 T45 T51 T52 T53 T54 T55

TC number

Temperature [oC]

SAE IMAC R134a Evap#2 Temp Profile

20.0

25.0

30.0

35.0

40.0

45.0

50.0

T11 T12 T13 T14 T15 T21 T22 T23 T24 T25 T31 T32 T33 T34 T35 T41 T42 T43 T44 T45 T51 T52 T53 T54 T55

TC Number

Temperature Deg C

25 Deg C

30 Deg C

35 Deg C

40 Deg C

45 Deg C
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 4 of 21

SAE IMAC R134a Comp#4 Evap#3 Temp Profile April 27, 2006

20

25

30

35

40

45

50

T11 T12 T13 T14 T15 T21 T22 T23 T24 T25 T31 T32 T33 T34 T35 T41 T42 T43 T44 T45 T51 T52 T53 T54 T55

TC Number

Temperature Deg C

25 Deg C

30 Deg C

35 Deg C

40 Deg C

45 Deg C

B. Air side pressure drop

Each time there was a heat exchanger change, the dry air pressure drop was measured 

at room conditions to verify the specification. The airside pressure drop of both the 

evaporator and the condensers are shown below. 
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 5 of 21

SAE IMAC R134a evaporator airside pressure drop

0

20

40

60

80

100

120

140

160

180

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00

Face Velocity [m/s]

Airside pressure drop DPea [Pa]

Phase II R152a/R134a Evap

IMAC Evap#1

IMAC Evap#2

IMAC Evap#3

SAE IMAC R134a condenser airside pressure drop vs. face velocity

0

20

40

60

80

100

120

140

160

180

200

0 1 2 3 4 5 6 7

Face velocity [m/s]

Airside pressure drop DPca [Pa]

Phase II R152a/R134a

IMAC R134a cond#3

IMAC R134a cond#6

IMAC R134a cond#7
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 6 of 21

C. Refrigerant charge determination

Charge determination was conducted at three different conditions (I35, L35 and I25) 

from the test matrix presented later in this chapter. Evaluation at three conditions 

allowed evaluation of optimum charge at low and high ambient conditions. In some 

cases only one condition was run to check charge where it was expected that there 

would be no impact on charge. Optimum charge was picked based on standard 

industry practices.

SAE IMAC charge determination test matrix

Test 

Name

Ambient 

temp. 

[

oC/o

F]

Compr 

speed 

[rpm]

Condenser Evaporator

Inlet air 

temp. 

[

oC/ o

F]

Flow rate 

[l/s/CFM]

Inlet air 

temp. 

[

oC/ o

F]

Flow rate 

[l/s/CFM]

Simulated 

air 

selection

RH 

[%]

Dew 

point 

[

oC]

I35a 35/95 900 35/95 342/725 35/95 109/230 OSA 40 19.4

L35a 35/95 1500 35/95 689/1460 35/95 130/275 OSA 40 19.4

I25a 25/77 900 25/77 342/725 25/77 90/190 OSA 80 21.3

The charging procedure was as follows: after evacuation, the system was charged with 

the lowest reasonably expected quantity of refrigerant 500~600g. The system was 

maintained at constant air temperature, humidity, and airflow rates through condenser 

and evaporator, and compressor speed, as prescribed by the charging condition. When 

steady state conditions were achieved data were taken and refrigerant was added in 

increments of 50g (or 25g). 
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 7 of 21

SAE IMAC R134a charge determination test (condenser #1 without sbcoler section)

condition I35a: compressor 900rpm, condenser 35degC, 725 scfm, 

evaporator 35degC@40%RH (dew point Tdpei = 19.4degC), 

230scfm, exit DTsuperheat kept = 6~8 K 

0

5

10

15

20

25

1200 1300 1400 1500

Charge [g]

C

O

P [-] / Qe [kW] / D

T [K] / T

[C]

0

500

1000

1500

2000

Prcpo [kPa] / Prcpi [kPa]

COP_avg Q_avg DTsub_cro Teao_at_nozzle DTsup_ero Prcpo Prcpi
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 8 of 21

SAE IMAC R134a charge determination test (condenser #1 without sbcoler section)

condition L35a: compressor 1500rpm, condenser 35degC, 1460 scfm, 

evaporator 35degC@40%RH (dew point Tdpei = 19.4degC), 

275scfm, exit DTsuperheat kept = 6~8 K 

0

10

20

30

40

50

60

70

80

90

500 600 700 800 900 1000 1100 1200 1300 1400 1500

Charge [g]

C

O

P [-] / Qe [kW] / D

T [K] / T

[C]

0

500

1000

1500

2000

Prcpo [kPa] / Prcpi [kPa]

COP_avg Q_avg DTsub_cro Teao_at_nozzle DTsup_ero

Tcro Tcri Prcpo Prcpi
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 9 of 21

SAE IMAC R134a charge determination test (condenser #1 without sbcoler section)

condition I25a: compressor 900rpm, condenser 25degC, 725 scfm, 

evaporator 25degC@80%RH (dew point Tdpei = 21.3degC), 

190scfm, exit DTsuperheat kept = 6~8 K 

0

5

10

15

20

25

500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600

Charge [g]

C

O

P [-] / Qe [kW] / D

T [K] / T

[C]

0

500

1000

1500

Prcpo [kPa] / Prcpi [kPa]

COP_avg Q_avg DTsub_cro Teao_at_nozzle DTsup_ero Prcpo Prcpi
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 10 of 21

SAE IMAC R134a charge determination test (condenser#5 -- with biggest sbcooler section)

condition I35a: compressor 900rpm, condenser 35degC, 725 scfm,

evaporator 35degC@40%RH (dew point Tdpei=19.4degC), 230 scfm, exit DTsuperheat kept=6~8k

0

10

20

30

40

50

60

700 800 900 1000 1100 1200 1300 1400 1500 1600

charge [g]

COP [-]/Qe [K

W]/DT [K]/T [C]

0

200

400

600

800

1000

1200

1400

1600

1800

2000

COP_avg Q_avg Teao_at_nozzle DTsup_ero DTsub_cro Tcro Prcpo Prcpi
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 11 of 21

SAE IMAC R134a charge determination test (condenser#5 -- with biggest sbcooler section)

condition L35a: compressor 1500rpm, condenser 35degC, 1460 scfm,

evaporator 35degC@40%RH (dew point Tdpei=19.4degC), 275 scfm, exit DTsuperheat kept=6~8k

0

5

10

15

20

25

30

35

40

45

50

700 800 900 1000 1100 1200 1300 1400 1500 1600

charge [g]

COP [-]/Qe [K

W]/DT [K]/T [C]

0

200

400

600

800

1000

1200

1400

1600

1800

2000

COP_avg Q_avg Teao_at_nozzle DTsup_ero DTsub_cro Tcro Prcpo Prcpi
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 12 of 21

SAE IMAC R134a charge determination test (condenser#5 -- with biggest sbcooler section)

condition I25a: compressor 900rpm, condenser 25degC, 725 scfm,

evaporator 25degC@80%RH (dew point Tdpei=21.3degC), 190 scfm, exit DTsuperheat kept=6~8k

0

5

10

15

20

25

30

35

40

700 800 900 1000 1100 1200 1300 1400 1500 1600

charge [g]

COP [-]/Qe [K

W]/DT [K]/T [C]

0

200

400

600

800

1000

1200

1400

1600

COP_avg Q_avg Teao_at_nozzle DTsup_ero DTsub_cro Tcro Prcpo Prcpi
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 13 of 21

SAE IMAC R134a charge determination test (condenser#5 -- with biggest sbcooler section)

condition L45a: compressor 1500rpm, condenser 45degC, 1460 scfm,

evaporator 35degC@25%RH (dew point Tdpei=12.0degC), 275 scfm, exit DTsuperheat kept=6~8k

0

5

10

15

20

25

700 800 900 1000 1100 1200 1300 1400 1500

charge [g]

C

OP [-]/Qe [K

W]/DT [K]/T [C]

0

500

1000

1500

2000

2500

COP_avg Q_avg Teao_at_nozzle DTsup_ero DTsub_cro Prcpo Prcpi
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 14 of 21

SAE IMAC IHX1 I35a charge test

0

2

4

6

8

10

12

14

16

18

900 1000 1100 1200 1300 1400 1500

Charge [g]

Temp [C] / DT [C] / Q [kW] / C

OP [-]

0

200

400

600

800

1000

1200

1400

1600

1800

P [kPa]

COP_indoor_av

g

DTsub_cro

Qindoor_avg

Ten

Selected charge

= 1300 [g]

Prcpi

Prcpo
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 15 of 21

SAE IMAC IHX2 I35a charge test

0

2

4

6

8

10

12

14

16

18

900 1000 1100 1200 1300 1400 1500

Charge [g]

Temp [C] / DT [C] / Q [kW] / C

OP [-]

0

200

400

600

800

1000

1200

1400

1600

P [kPa]

COP_indoor_av

g

DTsub_cro

Qindoor_avg

Ten

Selected charge

= 1325 [g]

Prcpi

Prcpo
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 16 of 21

SAE IMAC R134a Cond#6 Charge Test at I35a 06/01/2006

-2

0

2

4

6

8

10

12

14

16

800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450

Charge g

COP [-] /Q [kW] / DT [degC]

0

200

400

600

800

1000

1200

1400

1600

1800

P kPa]

Dtsub_cro

COPinavg

Dtsup_ero

Qindooravg

Prcpo

Prcpi
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 17 of 21

SAE IMAC R134a Cond#7 Charge Test at I35a 06/06/2006

0

5

10

15

20

25

900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450

Charge g

COP [-] /Q [kW] / DT [degC]

0

200

400

600

800

1000

1200

1400

1600

1800

P kPa]

Dtsub_cro

COPinavg

Dtsup_ero

Qindooravg

Prcpo

Prcpi
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 18 of 21

SAE IMAC R134a Comp#4 Evap#2 Charge Test at I35a 04/19/2006

-5

0

5

10

15

20

25

30

800 850 900 950 1000 1050 1100 1150 1200

Charge g

P [Kpa]

0

200

400

600

800

1000

1200

1400

1600

1800

2000

P [Kpa]

Dtsub_cro

COPinavg

Dtsup_ero

Qindooravg

Prcpo

Prcpi
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 19 of 21

SAE IMAC R134a Evap#3 Charge Test at I35a 04/29/2006

Note: 1050[g] was selected for evap#3 as system charge

0

5

10

15

20

25

750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300

Charge g

COP [-] /Q [kW] / DT [degC]

0

200

400

600

800

1000

1200

1400

1600

1800

2000

P kPa]

Dtsub_cro

COPinavg

Dtsup_ero

Qindooravg

Prcpo

Prcpi
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 20 of 21

SAE IMAC R134a Evap#4 Charge Test at I35a 05/11/2006

0

5

10

15

20

25

30

700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300

Charge g

COP [-] /Q [kW] / DT [degC]

0

200

400

600

800

1000

1200

1400

1600

1800

2000

P kPa]

Dtsub_cro

COPinavg

Dtsup_ero

Qindooravg

Prcpo

Prcpi

D. Oil circulation rate measurement

Before the final performance test, oil circulation rate was measured with two different 

compressor speeds and conditions. The oil type, the initial oil charge, and the target oil 

circulation values were recommended by the compressor manufacturer. Oil circulation 

was measured by taking refrigerant/oil samples from the liquid line and measuring the 

mass ratio of refrigerant to oil. 

The measurement results for oil circulation rate and system charge amounts for each 

system are given in the following table. 
IMAC Team 2 - Improved Efficiency Final Report December 2006

Appendix A: System Setup Test Page 21 of 21

Refrigerant charge and oil [lubricant] charge 

Description of Technology Charge 

Amount [gm] Oil Circulation (%) Comments

900 rpm 4000rpm

Improved Condensers

Baseline (Cond #3) 1050 1.46 5.95 Oil charge 137 cc, comp#4

Condenser #6 1200 - -

No oil circulation rate were measured for 

cond #6 and #7 but with same oil charge 

137 cc as the baseline

Condenser #7 1200 - - Oil charge 137 cc

Improved Evaporators

Baseline (Evap #1) 1050 1.46 5.95 Oil charge 137 cc

Evaporator #2 950 - - Oil charge 137 cc

Evaporator #3 1050 - - Oil charge 137 cc. 

Evaporator #4 1025 - - Oil charge 137 cc

Internal Heat Exchangers

Baseline 1100 0.33% 0.87% comp#2

Commercial 1 HX #1 1150 0.82% -

Commercial 2 HX in Parallel #2 1250 1.05% 

(1500rpm) -

Baseline 1200 1.46 5.95 Oil charge 137 cc, comp#4

Automotive Tube Type #4 1300 1.84 3.85 

(2500rpm) Oil charge 137 cc, comp#4

Automotive Core Type #4 1325 - - Oil charge 137 cc, comp#4

Cycling Fixed Compressors:

Baseline (BoB Variable) 1150 1.46 5.95 Oil charge 137 cc, with TXV

Fixed Piston comp#8 1150 0.93 1.25 

(2500rpm)

Fixed Scroll comp#7 1150 8.2

(1485 rpm) -

Insulated Suction Lines

Tested in BoB System with IHX 

Type #4 1325 - - Oil charge 137 cc, comp#4

Improved variable compressors

Baseline comp#1 1350 0.73 1.22

Compressor #2 1350 0.23 0.87 Integrated oil separator

Compressor #3 1350 0.41 1.42

Compressor #4 1150 1.46 5.95

Compressor #6 1150 1.52 2.92

Condenser Subcooling Pass 

Designs:

Design #1 1350 0.73 1.22 External receiver

Design #3 1250 ‘- ‘- Integrated receiver

Design #5 1300 ‘- ‘- Integrated receiver

Best of Best System

ARCRPII Baseline 1125 0.66 1.16

IMAC BoB 1150 1.46 5.95