r1234yf system enhancements and comparison to … system enhancements and comparison to r134a...
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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