Fuel-efficient, leak-tight HFC-134a systems through design ...
Transcript of Fuel-efficient, leak-tight HFC-134a systems through design ...
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2003-02-111
Fuel-efficient, leak-tight HFC-134asystems through design and qualitycomponents
Brussels, February 10-11, 2003
Hans Fernqvist
Volvo Car CorporationGothenburg, Sweden
prepared & presentedby
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2003-02-112
Acknowledgement
William Hill, General Motors
Stephen Lepper, Ford Motor Comp.
Xinzhong Li, University of Illinois
Mahmoud Ghodbane, Delphi Harrison Thermal Systems
Conrad Norris, Sanden Technical Centre (Europe) GmbH
Christophe Petitjean, Valeo Climate Control
Anders Sinijärv, Zexel-Valeo Sweden AB
Anders Lindborg, Ammonia Partnership AB
Johan Olsson, Denso Sales Sweden AB
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Content- Efficiency of HFC-134a systems = fueleconomy for use of mobile air conditioning
- Reduction of controlled losses / emissionsof HFC-134a
- Reduction of uncontrolled losses / emissions
- Emissions in production / assembly plant
- Conclusion
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DefinitionsDefinitions
COP = Coefficient Of Performance
System Cooling Power Input
Evaporator CapacityCOP = =
Higher COP Lower fuel consumption
for the same cooling capacity (evaporator heat load)
Compressor Power
-------------------------------------
HFC-134a = R 134a
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2003-02-115
0,0
0,5
1,0
1994 1998 2002 2006
AC-System energy / fuel consumption
Year
12
34
5 6
1. New condenser, “sub cool” type2. Externally controlled, variable displacement compressor
3. Adjustable set point -> prevent unnecessary “cool down & reheat”4. New evaporator & next generation externally controlled, variabledisplacement compressor5. Next generation (sub cool) condenser ( 11% system COP improvement)
6. Integrated and optimized climate - and engine control6. Integrated and optimized climate - and engine control
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2003-02-116
SAE - ARCRP
• Baseline R 134a
• Transcritical CO2 (R 744)
• Enhanced R 134a
• Hydrocarbon (Propane R 290) secondary loop (indirect system)
vs.• Baseline R 134a
• Enhanced R 134a
SAE-ARCRP = Society of Automotive Engineers -Alternate Refrigerant Cooperative Research Project
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2003-02-117
COP and cooling performance- steady state, +15 - +45 °C- soak and cool-down- dynamic behaviour- effect of disturbed condenser/gas cooler
air-flow
- steady state, +15 - +45 °C
Graphs on the next two slides, showing evaporatorcapacity at 15, 25, 35 and 45°C for 900, 1500 and2500 (compressor) rpm are with evaporator airflow =109-130 l/s = max blower. This is NOT typicalcooling load/ capacity at normal use (steady state) butmore what appears first minutes of a cool-downsequence.
Typical cooling load levels for normal use are shownon the two slides for “Low evaporator airflow”.
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Basic Matrix: 5 oC Control or Equal Capacity / 900 rpm
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Basic Matrix: 5 oC Control or Equal Capacity / 1500 rpm
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Eva
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Cap
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[kW
]
Basic Matrix: 5 oC Control or Equal Capacity / 2500 rpm
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Evaporator Air Inlet Temperature [ oC]
R134a Baseline R134a Enhanced
Basic Matrix: 5 oC Control or Equal Capacity / 1500 rpm
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10 15 20 25 30 35 40 45 50
CO
P [
-]
Basic Matrix: 5 oC Control or Equal Capacity / 2500 rpm
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10 15 20 25 30 35 40 45 50
Evaporator Air Inlet Temperature [ oC]
R134a Baseline R134a Enhanced
Basic Matrix: 5 oC Control or Equal Capacity / 900 rpm
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Basic Matrix: 10 oC Control or Equal Capacity / 900 rpm
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Basic Matrix: 10 oC Control or Equal Capacity / 2500 rpm
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Evaporator Air Inlet Temperature [ oC]
R134a Baseline R134a Enhanced
Basic Matrix: 10 oC Control or Equal Capacity / 1500 rpm
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10 15 20 25 30 35 40 45 50Eva
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Basic Matrix: 10 oC Control or Equal Capacity / 900 rpm
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Basic Matrix: 10 oC Control or Equal Capacity / 1500 rpm
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CO
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Basic Matrix: 10 oC Control or Equal Capacity / 2500 rpm
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Evaporator Air Inlet Temperature [ oC]
R134a Baseline R134a Enhanced
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Evaporator Low Air Flow: 5 oC Control
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Evaporator Air Inlet Temperature [ oC]
Eva
pora
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Cap
acity
[kW
]
R134a Baseline R134a Enhanced
Same cooling capacity for900/ 1500/ 2500 rpm
Evaporator Low Air Flow: 5 oC Control / 1500 rpm
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CO
P [-
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Evaporator Low Air Flow: 5 oC Control / 2500 rpm
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10 15 20 25 30 35 40 45 50Evaporator Air Inlet Temperature [ oC]
R134a Baseline R134a Enhanced
Evaporator Low Air Flow: 5 oC Control / 900 rpm
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Low evaporator airflow = 28 lit/s
Set-point = 5°C
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2003-02-1111
Evaporator Low Air Flow: 10 oC Control / 900 rpm
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Evaporator Air Inlet Temperature [ oC]
Eva
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Cap
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[kW
]
R134a Baseline R134a Enhanced
Same evaporator capacity for900/ 1500/ 2500 rpm
Low evaporator airflow = 28 l/sSet-point =10°C
Evaporator Low Air Flow: 10 oC Control / 900 rpm
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Evaporator Low Air Flow: 10 oC Control / 1500 rpm
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10 15 20 25 30 35 40 45 50
CO
P [
-]
Evaporator Low Air Flow: 10 oC Control / 2500 rpm
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10 15 20 25 30 35 40 45 50
Evaporator Air Inlet Temperature [ oC]
R134a Baseline R134a Enhanced
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2003-02-1112
Summery of SAE-ARCRP results
Baseline R 134a COP
5°C s.p. 1.8 - 4.4
10°C s.p. 1.8 - 5.9
Low evaporator airflow 1.2 - 3.6
Enhanced R 134a COP
5°C s.p. 2.4 - 5.7 = 14-38% up
10°C s.p. 2.4 - 7.3 = 0.4-38% up
Low evaporator airflow 1.7 - 4.6 = 10-47% up
Average, over a total of 36 conditions, COP for EnhancedR 134a is up 24.7% compared to COP for Baseline R 134a.
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2003-02-1113
0,0
0,5
1,0
1994 1998 2002 2006
AC-System energy / fuel consumption
Year
12
34
5 6
Baseline
Enhanced
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2003-02-1114
Conclusions & comments on COP
- wide span of COP depending on operating conditions- no significant influence on COP due to loss of refrigerant(see next slide)- no direct connection between size of charge (g R 134a)and COP
COP is determined by:- technology used for components (evaporator, condenser,compressor,...)
- design of tubes and hoses (pressure drop)- operating conditions (PD level = condenser cooling,...)- ...
a 600 g system can have same, lower or higherCOP compared to a 1000 g system
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2003-02-1115
SAE R134a Baseline System Charge Determination (1300g was selected)
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-] /
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ar]
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Prcpo DTsubcool COP Trcpo
Prcpo = pressure compressor out DTsubcool = subcool condenser out Trcpo = temperature compressor out
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2003-02-1116
Fuel consumptionPreliminary calculations based on results from SAE-ARCRPfor the “Baseline R 134a” system, using Euro combineddrive cycle and US climatic profile
average, annual (compressor) power = 1.16 kW
For the above conditions, the estimated additional fuel(gasoline) consumption is approx. 0.055 lit./ kW / 10 km.
With an annual, average mileage of 15 000 km, this givesan annual fuel use for use of the AC-system
1.16 × 0.055 × 15 000/10 = 96 lit. / year(add 6.5 % to annual fuel consumption)
Similar calculations remains to be done for Enhanced R 134aand the other two systems in SAE-ARCRP.
Note: European climatic profile is cooler / lower than US→ annual, average fuel consumption for Europe < 96 lit./y.
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2003-02-1117
Controlled losses (emissions)
- hose permeation- seal/o-ring permeation
• connections• components (compressor body, R/D, etc.)
- compressor shaft-seal (normal) leak flow
- component leaks (braze/weld porositiesetc. / component supplier leak check)
- connection leaks / assembly line leakcheck
Material,design andspecificationrelated
Processmethod andequipmentrelated
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2003-02-1118
45
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15
g / y
Year
2002 2003
1
1. Nylon lined hoses (lower permeation)
2. New compressor shaft-seal, mechanical → lip type
3. Increased component requirements vs. suppliers
4. Shorter hoses, double o-ring crimp-fits and connections
1989 - 1991
2
3
4
New line equipment forconnection (and compo-nent) leak check.From tracer gas/ manualsniffing to pressure decay.
15-20 g/y
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2003-02-1119
PERMEATION COMPARISON - 15 DAYS AT 90 °CPERMEATION COMPARISON - 15 DAYS AT 90 °C
0,306
0,123
0,0880,0689
0,03650,0095
0
0,05
0,1
0,15
0,2
0,25
0,3
0,35
Per
mea
tion
kg/
m/y
r
4860 4870 X864-028 4890 X880-065 X870-184
Hose Constructions
Courtesy of Good Year Automotive Hoses
Laboratory comparative test
R-12 ‘rubber/rubber’ hoses ≈ 3 times higher
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2003-02-1120
Histogramm, temperature corrected, 468 measurements
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Class
Nu
mb
er o
f car
s
,00%
20,00%
40,00%
60,00%
80,00%
100,00%
120,00%
30 g/y 40 g/y
Pressure decay testmethod, (dry) air20 bar, 16 minutes.
Result from linetest October 2001.
All 468 cars wereOK at the regularHe-sniffing leakcheck.
Total of 4 cars> 40 g/y
Result above and method concept implies that averageloss rate for OK systems after this test ≤ 20 g/y≤ 20 g/y
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2003-02-1121
Summery of controlled losses- achievable total, controlled losses (permeation + component/connection leaks) for European conditions ≤ 15 + 20 ≤ 35 g/y.
- the (controlled) loss rate is totally independent of size of charge.→ a poorly designed and checked 600g system can have a lossrate of 70-100 g/y where a well designed (“state of the art”) 1000gsystem can be well below 35 g/y.
- therefore, the unit for loss rate should be [ g/y] and NOT [%].
- if % of nominal charge is being used for any volunteer agree-ment or regulation, regarding max allowable loss-/emission rate,this will stop, or even reverse, the general and ongoing trend toreduce system charges.
≤ 35 g/y
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2003-02-1122
Uncontrolled losses (emissions)= leaks that occur on the system during usage due to:
• corrosion (external)• wear• fatigue (cracks)
• mechanical damage (e.g. stone shot on condenser)
All of the above reasons for leaks can be avoided orminimised by proper choice of materials used in com-ponents, by proper designs and careful work regardingpackaging and assembly line instructions and work.
That the above can be achieved, and to a veryreasonable cost, have already been demonstrated.
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2003-02-1123
Production adapter / filling gunProduction adapter / filling gun
Refrigerantvalve
Vacuumvalve
Openingpin
Dead space≤ 2cm³
Emissions / car ≤ 0.1 g HFC-134a
Emissions in production / assembly plant
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2003-02-1124
Final Summery- Preliminary calculations on fuel consumptionconfirm previous estimations (ECCP) of + 5-6%
- Substantial improvements already demonstra-ted with “Enhanced R 134a” system
- Further improvements of system efficiency /reduced fuel consumption are envisioned
- Technologies and designs for fully acceptablerefrigerant containment are already available
- Cost to implement fuel efficient, low emissiveHFC-134a systems is moderate, or none, if donein a proper and wise way.
75-80 l/y
60 l/y
≤ 35-40 g/y
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2003-02-1125
ConclusionHFC-134a systems offers well proven, wellfunctioning and safe mobile air conditioning
Next generation HFC-134a systems are highlyviable environmental alternatives, both regar-ding direct as well as indirect emissions
Can be achieved with already availabletechnologies to very competitive cost
Thank you for your attentionThank you for your attention