Post on 31-Mar-2015
R744 MAC Systems from conventional driven vehicles to EVs
October 2009
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Content
Natural Refrigerant R744 (CO2) for MAC
System Experience
Phase 1: Functionality R744 AC & Heating System
Phase 2: Performance AC & Heating Systems
Phase 3: Controllability AC
Phase 4: Driveability & Cost for Small Vehicles AC
Phase 5: COP System Optimisation AC
Phase 6: Durability Tests AC Systems
E-Vehicles, Hybrid electrical Vehicles and PHEV
Confidential
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No ozone depletion; ODP = 0
Lowest possible GWP of 1
Classified under the American Standard Heating and Refrigeration (ASHRAE) as A1
Non toxic and non flammable
R744 is one of the best known and understood substances in term of scientific research and applications.
Humans inhale and exhale it
Mankind puts it in soda and drinks it
It is a natural substance of the atmosphere
Highest efficiency, lowest indirect emissions and best LCCP vs. all others
Lowest total cost of ownership
Why Natural Refrigerant R744 (CO2)
Confidential
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Single AC & HP
AC only
Dual AC & HP
System Experience
OE has build up more than 50 prototype vehicles with R744 – Systems
Future development trends towards Electrical Vehicles with A/C and HP HEV and PHEV with A/C and HP Battery cooling Thermal management
Confidential
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OE System Experience
1997 2000 2004 2009
R744 Function
System Control
Small Vehicle
COP
System Durability Testing
AC & Heating Systems
AC Systems Only
Performance
Confidential
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Phase 1: Functionality R744 AC & HS (1997-1999)
First development steps with R744: Demonstrate that R744 operates as refrigerant under all climate conditions Show the functionality of
- Single AC-System- Coolantside Heat Pump System- Air Side Heat Pump System- Hot Gas Cycle System
Therefore several cars were equipped with R744- Systems …
… Audi … Daimler … BMW
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HVAC
Eva
po
rato
r
Gas
coo
ler
Compressor
Accu
Air Air
IHX
HPValve
LPValve
P/T
EXV
Heating Mode:
System Description: Air Heat Pump System
Phase 1: Functionality R744 AC & HS (1997-1999)
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Phase 2: Performance AC & HS (2000-2004)
Optimisation of the Cooling- and Heating Performance in R744 Systems
Vehicle model build up
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AC Pull Down Results R744 vs. R134a (Full Size Truck)
Pull Down Head Temperature R744 vs R134a Tamb=38°C; RH=40%; SL=1000W/m2;
10
20
30
40
50
60
70
80
0 10 20 30 40 50 60 70 80 90 100 110 120 130
Time [min]
Ave
rage
Hea
d Te
mp
[°C]
T_Breath_aver_R744 [°C] T_Breath_aver_R134a [°C]
Comfort Temperature 22°C
50 kph REC
80 kph REC
50 kph OSA
80 kph OSA
IDLE REC
110 kph OSA
18 min
10 K
Phase 2: Performance AC & HS (2000-2004)
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Heat Up Result Hot Gas System
R744 Hot Gas Cycle Coolant & Fuel Fired Heater Coolant
-20
-10
0
10
20
30
40
50
0 5 10 15 20 25 30 35 40 45Time [min]
Hea
d T
emp
[°C
]
Comfort Temp. 22°C14 min 21 min
28 min
- R744 HG Cycle- Coolant & FFH- Coolant
Cabin Head TemperatureAmbient temperature = -10°C
Phase 2: Performance AC & HS (2000-2004)
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Time [ min ]
Pressure
80
60
40
20
Tunnel In
Tunnel Out
Speed variation
Blower variation
Pre
ss
ure
[ b
ar
]
Phase 3: Controllability AC (2002-2008)
Targets:- Same or better controllability as R134a systems- Safe handling of the high system dynamic- Noise and torque optimised controlling
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Time [ min ]
9 °C
12 °C
6 °C
3 °C
9 °C
6 °C
3 °C
System conditions:
Cycle: Forced Idle
n_engine: 2000 rpm
Blower: 7
T_Evap: Variable
Compr.: Variable
- Stable outlet temperature within the control range of 3°C – 12 °C
Evaporator Temperature Setpoint Variation
Phase 3: Controllability AC (2002-2008)
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Phase 4: Driveability & Cost for Small Cars (2004-2006)
Vehicle Build Up for Different OEMs
Small compressors, optimized heat exchangers and control strategy have been applied to show the AC functionality in small cars with low torque engines
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Md [%]
t [-]
MEng
35/120 bar
1000 2000 3000 4000 5000 6000
Engine torque
MCom
Pcomp [%]
t [-]
Pmax
35/120 bar
1000 2000 3000 4000 5000 6000
PIdle
Compressor torque
Max. Cooling power point
Compressor torque
Controlling Strategy
Phase 4: Driveability & Cost Small Cars (2004-2006)
~~MCom
Md [%]
Adjustable max torque timing
Available engine torque
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Solution: Small Car Low Cost AC-Systems Small size fixed or variable displacement compressor Application adapted and optimized control strategy Coaxial IHX as part of lineset MCP Evaporator and Gascooler Full Flexible Tubing System PXV-System
Result: Perfect drivability for small cars with R744 AC-Systems
Phase 4: Driveability & Cost Small Cars (2004-2006)
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Phase 5: COP System Optimisation AC (2007-2009)
Phase 5 was motivated to further improve COP and reduce fuel consumption of R744 AC systems
The development phases 1 to 4 were focused on functionality and performance of R744 Systems
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Vehicle Test Results – Fuel Consumption
NEDC Fuel Consumption Test R134a vs. R744VW Touran TDI 1,9l; Tambient =20/28/35degC
Additional Fuel Consumption R134a Additional Fuel Cons. R744
T ambient
Ad
dit
ion
al
Fu
el
Co
ns
um
pti
on
l/1
00
km
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Phase 6: Durability Tests AC Systems (1999-2009)
OE has built up several vehicles with different R744 systems for durability testing at Obrist and Costumers
Obrist Engineering Vehicles (AC and Heating Systems)
Audi A4 1.6lSingle AC-SystemBuild up: 1999Mileage: ~113.000 kmMore then 10 years of city cycle operation !!
Ford Galaxy 1,9TDIAC & HG System and MCPBuild up: 2003Mileage: ~115.000 kmR&D vehicle
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Kia Sportage 1,9 TDISingle AC-SystemBuild up: 2007100.000 km Durability Test in Dubai
VW Lupo 1,0Single AC-SystemBuild up: 2004Accelerated Lifetime test 40.000 km
OE has built up several vehicles with different R744 systems for durability testing at Obrist and Costumers
Costumer Vehicles (AC Systems)
Phase 6: Durability Tests AC Systems (1999-2009)
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EVs, HEVs and PHEVs
EVs, HEVs and PHEVs have additional needs for cooling and heating compared to conventional vehiclesCabin heating and coolingBattery cooling
Efficiency in cooling and heating becomes key, since
any energy required for heating and/or cooling needs
has to be drawn from the batteryHigh battery cost Range reduction issue
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EV Heating System Consequences
Electrical Heating R744 HP
NEDC wheel average 3kW 3kW
Heating requirement 6kW 1,5kW
NEDC theo. range 90km 90km
20degC real range 60km 60km
-20degC real range 20km 45km
Vehicle becomes useless
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Example: Air Side Heat Pump for EV
High Efficient E-Compressor
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CartridgeAC - System
Battery Box
Li-Ion Battery Cooling System Development
Coolant to Refrigerant to Air
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R744 Development for conventional driven vehicles completed R744 Development for Evs, HEVs and PHEV under way
R744 is the future refrigerant since it is the only refrigerant fullfilling all the requirements for MACs and battery cooling systems
ODP and GWP
COP and Efficiency
Cost
HP capability
Summary