R1234yf SystemEnhancements and

Comparison to R134a

R1234yf SystemEnhancements and

Comparison to R134a

June 10, 2008

John Meyer

R1234yf AgendaR1234yf Agenda

► System Performance Evaluation

– TXV (Egelhof) and MCV (TGK) tuning

– Baseline and enhanced system test results» IHX

» Oil Separator

» High Effectiveness Evaporator

► Compressor Durability

P-T for R134a and R1234yfP-T for R134a and R1234yf

0

500

1000

1500

2000

2500

3000

3500

-10 0 10 20 30 40 50 60 70 80 90

Temperature [C]

Pre

ssu

re[k

PaA

] R134a

R1234yf

Cross at ~30C

R1234yf has lowersaturation pressure

R1234yf has highersaturation pressure

R134a Stand EvaluationR134a Stand Evaluation

► Production system used for analysis

► 160cc variable displacement compressor

► 16mm IRD condenser

► 2.0T cross-charged TXV

► 58mm plate-fin evaporator

► Slightly modified discharge and liquid line

– Modified for installation on stand

► Slightly modified SL

– To allow for in situ torque calibration

R1234yf – Stand EvaluationR1234yf – Stand Evaluation

► Changes to R134a system hardware– Same 16mm IRD condenser

– Same 58mm plate-fin evaporator

– Same VS16 compressor, new MCV set points

– Same 200 cc PAG

– 2.0T, 2.5T, 1.75T TXVs at high & low SH settingsevaluated

– Same slightly modified discharge and liquid line

– Same slightly modified SL to allow for torquecalibration

Evaluation MatrixEvaluation Matrix

Compressor

Temp Flow Temp RH

RPM l/s °C l/s °C %

1 2500 700 45 140 43 40

2 1800 650 45 140 43 40

3 800 600 45 140 43 40

4 2500 700 37 140 35 40

5 1800 650 37 140 35 40

6 800 600 37 140 35 40

7 2500 700 27 100 25 40

8 1800 650 27 100 25 40

9 800 600 27 100 25 40

Condenser Airflow Evaporator Airflow

R134a Charge DeterminationR134a Charge Determination

1800

1850

1900

1950

2000

2050

2100

300 350 400 450 500 550 600 650

Charge [g]

Pre

ssu

re[k

PaG

]

0

4

8

12

16

20

24

Tem

pera

ture

[C]

Disch P

Air out T

SH

SC

560 g chosen

1650

1700

1750

1800

1850

1900

1950

300 350 400 450 500 550 600 650

Charge [g]

Pre

ssu

re[k

PaG

]

0

4

8

12

16

20

24

Tem

pera

ture

[C]

Pdisch Evap SH

SC disch air

R1234yf Charge DeterminationR1234yf Charge Determination

550 g

35C, 1800RPM (pt 5)

0

2

4

6

8

10

12

14

0 1 2 3 4 5

# of 60 degree CCW turns of the TXV

CO

P,S

C,S

H,C

ap

ac

ity

Evap SH

Subcool

COP

Capacity

Adjusting R1234yf SHAdjusting R1234yf SH

► TXVs have a “set screw” to adjust SH setting

► Each valve was evaluated at a high and lowSH setting

SH comparison

0

2

4

6

8

10

12

14

16

18

9 8 7 6 5 4 3 2 1Point

Tem

pera

ture

[C]

R134a baseline

R1234yf 2T high SH

R1234yf 2T low SH

R1234yf 2.5T high SH

R1234yf 2.5T low SH

R1234yf 1.75T high SH

R1234yf 1.75T low SH

R1234yf vs R134a; Evaporator SH

1.75T TXV (blue) seems to loseControl of SH at high loads

43C35C25C

250018008002500180080025001800800

R1234yf TXV and MCV EvaluationR1234yf TXV and MCV Evaluation

► Cross charge TXVs from Egelhof

► 2.0, 2.5, and 1.75T valves tested

► 1.75T TXV is undersized

► TXV at low SH

– Although no strong indication that low SH leads toimproved performance:» Low SH facilitates IHX integration

» Improved evaporator discharge air stratification

► MCVs from TGK

► Initial MCV calibration slightly off

► Gen II MCVs better tuned for this system

R1234yf Evaporator StratificationR1234yf Evaporator Stratification

► 4x4 thermocouple matrix on evaporator outlet

– Stratification = Tmax – Tmin

► With similar SH settings, R1234yf showsslightly improved stratification

Baseline R1234yf System Defined

► Same compressor, heat exchangers, lines,lubricant

► 2.0T TXV from Egelhof at “low” SH setting

► “GEN II” MCV from TGK

R1234yf EnhancementsR1234yf Enhancements

► Internal Heat Exchanger (IHX)

– Production Intent (SOP ‘09)

– Fully validated with R134a

► Oil Separator

► High efficiency evaporator

– Tube-fin

– Same package

– Lower air-side pressure drop

0

1

2

3

4

5

6

7

8

9 8 7 6 5 4 3 2 1

Point

Ca

pa

cit

y[k

w]

R134a baseline

R134a IHX

R1234yf baseline

R1234yf IHX

R134a vs 1234yf – IHX; CapacityR134a vs 1234yf – IHX; Capacity

MCV controls capacity

43C35C25C

250018008002500180080025001800800

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

9 8 7 6 5 4 3 2 1

Point Number

CO

P[

-]

R134a baseline

R134a IHX

R1234yf baseline

R1234yf IHX

R134a vs 1234yf – IHX; EfficiencyR134a vs 1234yf – IHX; Efficiency

43C35C25C

250018008002500180080025001800800

43C35C25C

250018008002500180080025001800800

Discharge and Pressure RatioDischarge and Pressure Ratio

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

9 8 7 6 5 4 3 2 1Point

Pre

ss

ure

[kP

aG

]

0

1

2

3

4

5

6

7

8

9

10

11

Pre

ss

ure

Ra

tio

[-

]

R134a

R1234yf

R134a

R1234yf

P [kPaG] R134a [C] 1234yf [C]

1700 62.9 65.0

1800 65.2 67.5

1900 67.5 69.9

2000 69.6 72.2

P-T relationship predicts~100kPa lower discharge

pressure for R1234yf

43C35C25C

250018008002500180080025001800800

R134a vs 1234yf – IHX; CompressorDischarge Temperature

R134a vs 1234yf – IHX; CompressorDischarge Temperature

0

10

20

30

40

50

60

70

80

90

100

110

120

9 8 7 6 5 4 3 2 1

Point

Te

mp

era

ture

[C]

R134a Baseline

R134a IHX

R1234yf baseline

R1234yf IHX

43C35C25C

250018008002500180080025001800800

43C35C25C

250018008002500180080025001800800

0

1

2

3

4

5

6

7

8

9 8 7 6 5 4 3 2 1

Point

Ca

pa

cit

y[k

w]

R134a baseline

R1234yf baseline

R1234yf Oil Sep

R1234yf HE evap

R134a vs 1234yf – Oil Separator & HighEfficiency Evaporator; Capacity

R134a vs 1234yf – Oil Separator & HighEfficiency Evaporator; Capacity

43C35C25C

250018008002500180080025001800800

43C35C25C

250018008002500180080025001800800

MCV controls capacity

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

9 8 7 6 5 4 3 2 1

Point Number

CO

P[

-]

R134a baseline

R1234yf baseline

R1234yf Oil Sep

R1234yf HE evap

R134a vs 1234yf – Oil Separator & HighEfficiency Evaporator; Efficiency

R134a vs 1234yf – Oil Separator & HighEfficiency Evaporator; Efficiency

43C35C25C

250018008002500180080025001800800

43C35C25C

250018008002500180080025001800800

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75

20 30 40 50 60 70 80

Condensing Temperature [C]

Qu

ali

ty[

-]

R134a

R1234yf

Evaporator Inlet QualityEvaporator Inlet Quality

► Higher quality = less liquid = lower capacity

8% Less Liquid

Inputs10°C Subcool5°C Evaporation tempSupercritical R744 high-side pressure = 13MPa

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75

20 30 40 50 60 70 80

Condensing Temperature [C]

Qu

ali

ty[

-]

R134a

R1234yf

R744

Evaporator Inlet QualityEvaporator Inlet Quality

► Higher quality = less liquid = lower capacity

8% Less Liquid

29% Less LiquidInputs10°C Subcool5°C Evaporation tempSupercritical R744 high-side pressure = 13MPa

R1234yf Performance SummaryR1234yf Performance Summary

► Baseline R1234yf system used same tonnage TXVwith modified bulb charge and adjusted MCV

► R1234yf has approximately 8-10°C coolercompressor discharge temperature vs R134a

► As near drop-in, capacity and efficiency fall slightlyshort of R134a

R1234yf Performance Summary(cont)

R1234yf Performance Summary(cont)

► R1234yf with IHX

– ~Matches/exceeds R134a baseline capacity

– Has slightly higher average efficiency than baselineR134a across all points

– ~Matches R134a compressor discharge temperature

► R1234yf with Oil Separator

– Small increase in capacity and efficiency

– Falls short of baseline R134a at high ambient

► R1234yf with High Efficiency Evaporator

– Small increase in capacity and efficiency

– Falls short of baseline R134a at high ambient

R1234yf Compressor TestingR1234yf Compressor Testing

► Initial Compressor Durability

– High Pressure Low Charge – high load and temperature test

» Completed initial testing - No issues

– High Speed – high friction and high temperature test

» Completed initial testing – No issues

Durability Teardown ResultsDurability Teardown Results

AcknowledgementsAcknowledgements

► Thanks to….

– for prototype MCVs

– Egelhof for prototype TXVs

– JCS for tube-fin evaporator

– Honeywell and DuPont for R1234yf