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8/12/2019 2008 SAE ARSS Visteon Eval
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R1234yf SystemEnhancements and
Comparison to R134a
R1234yf SystemEnhancements and
Comparison to R134a
June 10, 2008
John Meyer
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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
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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]
Pressure
[kPaA] R134a
R1234yf
Cross at ~30C
R1234yf has lower
saturation pressure
R1234yf has higher
saturation pressure
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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 situtorque calibration
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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
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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 43 404 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
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R134a Charge DeterminationR134a Charge Determination
1800
1850
1900
1950
2000
2050
2100
300 350 400 450 500 550 600 650
Charge [g]
Pressure[
kPaG]
0
4
8
12
16
20
24
Temperatu
re[C]
Disch P
Air out T
SH
SC
560 g chosen
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1650
1700
1750
1800
1850
1900
1950
300 350 400 450 500 550 600 650
Charge [g]
Pressure
[kPaG]
0
4
8
12
16
20
24
Temper
ature[C]
Pdisch Evap SH
SC disch air
R1234yf Charge DeterminationR1234yf Charge Determination
550 g
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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
COP
,SC,SH,Capac
ity
Evap SHSubcool
COP
Capacity
Adjusting R1234yf SHAdjusting R1234yf SH
TXVs have a set screw to adjust SH setting Each valve was evaluated at a high and low
SH setting
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SH comparison
0
2
4
6
8
10
12
14
16
18
9 8 7 6 5 4 3 2 1Point
Temperatur
e[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
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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
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R1234yf Evaporator StratificationR1234yf Evaporator Stratification
4x4 thermocouple matrix on evaporator outlet
Stratification = Tmax Tmin
With similar SH settings, R1234yf shows
slightly improved stratification
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Baseline R1234yf System Defined
Same compressor, heat exchangers, lines,
lubricant
2.0T TXV from Egelhof at low SH setting
GEN II MCV from TGK
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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
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0
1
2
3
4
5
6
7
8
9 8 7 6 5 4 3 2 1
Point
Capacity
[kw]
R134a baseline
R134a IHX
R1234yf baseline
R1234yf IHX
R134a vs 1234yf IHX; CapacityR134a vs 1234yf IHX; Capacity
MCV controls capacity
43C35C25C
250018008002500180080025001800800
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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
COP[-
]
R134a baseline
R134a IHX
R1234yf baseline
R1234yf IHX
R134a vs 1234yf IHX; EfficiencyR134a vs 1234yf IHX; Efficiency
43C35C25C
250018008002500180080025001800800
43C35C25C
250018008002500180080025001800800
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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
Pressure[kPaG]
0
1
2
3
4
5
6
7
8
9
10
11
Pressure
Ratio[-]
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
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R134a vs 1234yf IHX; Compressor
Discharge Temperature
R134a vs 1234yf IHX; Compressor
Discharge Temperature
0
10
20
30
40
50
60
70
80
90
100
110
120
9 8 7 6 5 4 3 2 1
Point
Temperature[C]
R134a Baseline
R134a IHX
R1234yf baseline
R1234yf IHX
43C35C25C
250018008002500180080025001800800
43C35C25C
250018008002500180080025001800800
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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
COP[
-]
R134a baseline
R1234yf baseline
R1234yf Oil Sep
R1234yf HE evap
R134a vs 1234yf Oil Separator & High
Efficiency Evaporator; Efficiency
R134a vs 1234yf Oil Separator & High
Efficiency Evaporator; Efficiency
43C35C25C
250018008002500180080025001800800
43C35C25C
250018008002500180080025001800800
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0.00
0.050.10
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]
Quality[-]
R134a
R1234yf
Evaporator Inlet QualityEvaporator Inlet Quality
Higher quality = less liquid = lower capacity
8% Less Liquid
Inputs10C Subcool
5C Evaporation temp
Supercritical R744 high-
side pressure = 13MPa
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0.00
0.050.10
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]
Quality[
-]
R134a
R1234yf
R744
Evaporator Inlet QualityEvaporator Inlet Quality
Higher quality = less liquid = lower capacity
8% Less Liquid
29% Less LiquidInputs10C Subcool5C Evaporation temp
Supercritical R744 high-
side pressure = 13MPa
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R1234yf Performance SummaryR1234yf Performance Summary
Baseline R1234yf system used same tonnage TXV
with modified bulb charge and adjusted MCV
R1234yf has approximately 8-10C cooler
compressor discharge temperature vs R134a As near drop-in, capacity and efficiency fall slightly
short of R134a
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R1234yf Performance Summary
(cont)
R1234yf Performance Summary
(cont)
R1234yf with IHX
~Matches/exceeds R134a baseline capacity
Has slightly higher average efficiency than baseline
R134a 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
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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
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Durability Teardown ResultsDurability Teardown Results
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AcknowledgementsAcknowledgements
Thanks to. for prototype MCVs
Egelhof for prototype TXVs
JCS for tube-fin evaporator Honeywell and DuPont for R1234yf