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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 ?