Cost efficient R744 AC System for compact vehiclesFebruary 23th, 2005 – VDA Wintermeeting 2005Copyright 2005, Visteon Corporation.

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Cost efficient Cost efficient R744 AC System R744 AC System

for Compact Vehiclesfor Compact Vehicles

Dr. Roman HecktVisteon Deutschland GmbH

VDA Wintermeeting 2005

Cost efficient R744 AC System for compact vehiclesFebruary 23th, 2005 – VDA Wintermeeting 2005Copyright 2005, Visteon Corporation.

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AgendaAgendaAgenda• Motivation

• cost efficient R744 AC System• Targets

• Test vehicle• Vehicle• R744 Components• R744 Compressor

• Results• AC Performance• Driveability (AC-Stumble)

• Conclusions

Cost efficient R744 AC System for compact vehiclesFebruary 23th, 2005 – VDA Wintermeeting 2005Copyright 2005, Visteon Corporation.

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MotivationMotivationMotivation• Today's R134a AC-Systems could be classified in three types

410 – 380fixed displacement & internal controlled Compr.

Compact class

480 – 430external & internal controlled Compressor

Middle class

550 – 500external controlled Compressor

Upper class

Sys. Cost(no currency)Compressor Type

R134a

Cost efficient R744 AC System for compact vehiclesFebruary 23th, 2005 – VDA Wintermeeting 2005Copyright 2005, Visteon Corporation.

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MotivationMotivationMotivation• majority of realized R744 Vehicle cooling

systems use external controlled compressor

410-380fixed & int. controlled C.

Compact class

480-430ext. & int. controlled C.

Middle class

550-500external controlled C.

Upper class

Sys. Cost

Compressor Type

R134a

″

″

external controlled C.

Compressor Type

175%726-660

152%726-660

132%726-660

Cost increase

Sys. Cost

R744

⇒ the cost increase of more than 50% is not acceptable at least for compact class vehicles

Cost efficient R744 AC System for compact vehiclesFebruary 23th, 2005 – VDA Wintermeeting 2005Copyright 2005, Visteon Corporation.

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MotivationMotivationMotivation• internal controlled R744 Compressor is not feasible

(high pressure difference, needed high pressure control)

410-380fixed & int. controlled C.

Compact class

480-430ext. & int. controlled C.

Middle class

550-500external controlled C.

Upper class

Sys. Cost

Compressor Type

R134a

152%726-660Ext. contr. C.

Fixed displace. C.

Fixed C.

external controlled C.

Compressor Type

134%550-490

115%550-490

132%726-660

Cost increase

Sys. Cost

R744

⇒ cost efficient R744 AC System with fixed displacement Compressor is needed at least for compact vehicles.

Cost efficient R744 AC System for compact vehiclesFebruary 23th, 2005 – VDA Wintermeeting 2005Copyright 2005, Visteon Corporation.

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cost efficient R744 AC Systemcost efficient R744 AC Systemcost efficient R744 AC System

Targets:• Cooling performance equal to

R134a cost efficient AC systems(similar to R134a internal controlled and fixed Systems)

• driven by fixed displacement compressor • system control by clutch cycling

- EVAP icing avoided by EVAP air outlet temperature sensor- pressure switch at Comp. outlet (System protection)- temperature sensor at Comp. outlet (System & Oil protection)

• minimized AC stumble• NVH equal with R134a Systems

Cost efficient R744 AC System for compact vehiclesFebruary 23th, 2005 – VDA Wintermeeting 2005Copyright 2005, Visteon Corporation.

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cost efficient R744 AC Systemcost efficient R744 AC Systemcost efficient R744 AC Systemrealized by Visteon exemplarily in test vehicle:

• Citroen C3

• 1,4 liter petrol engine

• manual gear shift

• climate control by EATC

Cost efficient R744 AC System for compact vehiclesFebruary 23th, 2005 – VDA Wintermeeting 2005Copyright 2005, Visteon Corporation.

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Test vehicleTest vehicleTest vehicle

Visteon combined R744 Accu/IHX

high Pressure Orifice

240 * 200 * 45 mm

15cc fixed displacement

460 * 380 * 12 mm

_(TXV System)

Accu / IHX

Expansion-Device

240 * 200 * 60 mmEvaporator

120cc internal controlled

Compressor

460 * 380 * 17 mmCondenser / Gascooler

Cost efficient R744 AC System in Citroen C3

Current R134a Citroen C3

Cost efficient R744 AC System for compact vehiclesFebruary 23th, 2005 – VDA Wintermeeting 2005Copyright 2005, Visteon Corporation.

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R744 fixed displacement CompressorR744 fixed displacement CompressorR744 fixed displacement Compressor

• Fixed displacement (15cc)

• lug distance 121/55mm (small VDA)

• Internal oil separator• Low rotational inertia

⇒ low engagement torque• Low weight: < 5,0 kg (incl. clutch)

Cost efficient R744 AC System for compact vehiclesFebruary 23th, 2005 – VDA Wintermeeting 2005Copyright 2005, Visteon Corporation.

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Test vehicle – AC PerformanceTest vehicle Test vehicle –– AC PerformanceAC Performanceclimate Wind chamber test:• 40°C / 40% rh

no sun load

• 15 Minutes 50 km/h3. gear (2000rpm)

• EATC setting “Lo”

• full blower

• recirc mode0

20

40

60

80

100

120

140

160

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Time [Minutes]

Pres

sure

[bar

]

PR_Comp_Out

PR_Comp_In

Cost efficient R744 AC System for compact vehiclesFebruary 23th, 2005 – VDA Wintermeeting 2005Copyright 2005, Visteon Corporation.

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Test vehicle – AC PerformanceTest vehicle Test vehicle –– AC PerformanceAC Performance

Conclusions:• any compressor clutch off during pull down phase has deep

impact on cooling performance • in first phase of pull down with low pressure differences the

expansion device needs to be wide open to avoid clutch cycling because of high pressure or high temperature

• for later phase the refrigerant mass flow has to be limited to avoid clutch of signals because of potential EVAP icing

⇒ variable mechanical Orifice is needed either difference pressure or high pressure driven

Cost efficient R744 AC System for compact vehiclesFebruary 23th, 2005 – VDA Wintermeeting 2005Copyright 2005, Visteon Corporation.

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Test vehicle – AC PerformanceTest vehicle Test vehicle –– AC PerformanceAC Performance

0°C

10°C

20°C

30°C

40°C

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Time [Minutes]

Air

Tem

pera

ture

[°C

]TA_Panel_R134a

TA_Panel_R744

climate Wind chamber test:

• baseline test with R134a current AC system before rebuild⇒ R744 AC Performance with 15cc fixed compressor is

similar to current R134a System (120cc) inside Citroen C3.

Cost efficient R744 AC System for compact vehiclesFebruary 23th, 2005 – VDA Wintermeeting 2005Copyright 2005, Visteon Corporation.

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Test vehicle – DriveabilityTest vehicle Test vehicle –– DriveabilityDriveabilityAC Stumble Test at mild ambient:• beside the performance is the driveability the main comfort

criteria for fixed displacement compressor Systems• AC-Stumble

is compared with R134a fixed displacement AC system by subjective ratings 0,0

1,0

2,0

3,0

4,0

5,0

6,0

7,0

8,0

9,0

10,0

ratin

g

1st gear crawl 2nd gear 40km/h 3rd gear 60km/h 5th gear 120km/h

Ford Fiesta, 1,4L Petrol Engine; R134a fixed scroll compressor

Citroen C3; 1,4L Petrol Engine; R744 fixed displacement compressor☺

⇒ AC Stumble of R744 cost efficient AC System competitive.

Cost efficient R744 AC System for compact vehiclesFebruary 23th, 2005 – VDA Wintermeeting 2005Copyright 2005, Visteon Corporation.

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ConclusionConclusionConclusion

•• For a 100% penetration of the mobile AC Systems with For a 100% penetration of the mobile AC Systems with R744 cost efficient fixed displacement Compressor R744 cost efficient fixed displacement Compressor Systems are strictly required Systems are strictly required

•• The shown AC performance is similar with the replaced The shown AC performance is similar with the replaced R134a internal controlled compressor systemR134a internal controlled compressor system

•• The negative impact of AC Stumble is completive to The negative impact of AC Stumble is completive to current R134a Systemscurrent R134a Systems

•• R744 System is fully integrated in current AC controlR744 System is fully integrated in current AC control

Cost efficient R744 AC System for compact vehiclesFebruary 23th, 2005 – VDA Wintermeeting 2005Copyright 2005, Visteon Corporation.

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Cost efficient R744 AC System for compact vehiclesFebruary 23th, 2005 – VDA Wintermeeting 2005Copyright 2005, Visteon Corporation.

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Thanks for your attention.

Questions ?