Fuel-efficient, leak-tight HFC-134a systems through design

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

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

2003-02-113

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

2003-02-114

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

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

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

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”.

2003-02-118

Basic Matrix: 5 oC Control or Equal Capacity / 900 rpm

0

1

2

3

4

5

6

7

8

9

10

10 15 20 25 30 35 40 45 50


0

1

2

3

4

5

6

7

8

9

1 0

10 15 20 25 30 35 40 45 50

Eva

pora

tor

Cap

acity

[kW

]


0

1

2

3

4

5

6

7

8

9

10

10 15 20 25 30 35 40 45 50

Evaporator Air Inlet Temperature [ oC]

R134a Baseline R134a Enhanced


0

1

2

3

4

5

6

7

8

10 15 20 25 30 35 40 45 50

CO

P [

-]


0

1

2

3

4

5

6

7

8

10 15 20 25 30 35 40 45 50




0

1

2

3

4

5

6

7

8

10 15 20 25 30 35 40 45 50

2003-02-119


0

1

2

3

4

5

6

7

8

9

10

10 15 20 25 30 35 40 45 50


0

1

2

3

4

5

6

7

8

9

10

10 15 20 25 30 35 40 45 50




0

1

2

3

4

5

6

7

8

9

10

10 15 20 25 30 35 40 45 50Eva

pora

tor

Cap

acity

[kW

]


0

1

2

3

4

5

6

7

8

10 15 20 25 30 35 40 45 50


0

1

2

3

4

5

6

7

8

10 15 20 25 30 35 40 45 50

CO

P [-

]


0

1

2

3

4

5

6

7

8

10 15 20 25 30 35 40 45 50



2003-02-1110

Evaporator Low Air Flow: 5 oC Control

0

1

2

3

4

5

6

7

8

9

10

10 15 20 25 30 35 40 45 50


Eva

pora

tor

Cap

acity

[kW

]


Same cooling capacity for900/ 1500/ 2500 rpm

Evaporator Low Air Flow: 5 oC Control / 1500 rpm

0

1

2

3

4

5

6

7

8

10 15 20 25 30 35 40 45 50

CO

P [-

]


0

1

2

3

4

5

6

7

8

10 15 20 25 30 35 40 45 50Evaporator Air Inlet Temperature [ oC]



0

1

2

3

4

5

6

7

8

10 15 20 25 30 35 40 45 50

Low evaporator airflow = 28 lit/s

Set-point = 5°C

2003-02-1111


0

1

2

3

4

5

6

7

8

9

10

10 15 20 25 30 35 40 45 50


Eva

pora

tor

Cap

acity

[kW

]


Same evaporator capacity for900/ 1500/ 2500 rpm

Low evaporator airflow = 28 l/sSet-point =10°C


0

1

2

3

4

5

6

7

8

10 15 20 25 30 35 40 45 50


0

1

2

3

4

5

6

7

8

10 15 20 25 30 35 40 45 50

CO

P [

-]


0

1

2

3

4

5

6

7

8

10 15 20 25 30 35 40 45 50



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.

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

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

2003-02-1115

SAE R134a Baseline System Charge Determination (1300g was selected)

0

2

4

6

8

10

12

14

16

18

20

1000 1100 1200 1300 1400 1500 1600

Charge [g]

CO

P [

-] /

Su

bco

ol [

K] /

Pre

ssu

re [b

ar]

0

20

40

60

80

100

120

140

160

180

200

Tem

per

atu

re [

°C]

Prcpo DTsubcool COP Trcpo

Prcpo = pressure compressor out DTsubcool = subcool condenser out Trcpo = temperature compressor out

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.

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

2003-02-1118

45

40

25

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

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

2003-02-1120

Histogramm, temperature corrected, 468 measurements

0

10

20

30

40

50

60

70

00,0

060,0

120,0

180,0

24 0,03

0,036

0,042

0,048

0,054 0,0

60,0

630,0

660,0

69

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

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

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.

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

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

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

Documents

Fuel-efficient, leak-tight HFC-134a systems through design