Development of CO2 Scroll Compressor for Automotive Air-Condit
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Development of CO 2 Scroll Compressor for Automotive Air-conditioning Systems Mitsubishi Heavy Industries. LTD Nagoya R & D Center Compressor Laboratory Makoto Takeuchi Introduction • Problems of R134a Refrigerant • Properties of CO2 Refrigerant • Advantage of Scroll Compressor • Loss Analysis of CO2 Scroll Compressor ( Changing Displacement Only ) • Technologies for High Efficiency • Loss Analysis of Prototype CO2 Scroll Compressor • Efficiency of Prototype CO2 Scroll Compressor • Conclusions
Transcript of Development of CO2 Scroll Compressor for Automotive Air-Condit
Development of CO2 ScrollCompressor for Automotive Air-conditioning Systems
Mitsubishi Heavy Industries. LTDNagoya R & D Center
Compressor Laboratory
Makoto Takeuchi
Introduction• Problems of R134a Refrigerant• Properties of CO2 Refrigerant• Advantage of Scroll Compressor• Loss Analysis of CO2 Scroll Compressor ( Changing Displacement Only )• Technologies for High Efficiency• Loss Analysis of Prototype CO2 Scroll
Compressor• Efficiency of Prototype CO2 Scroll Compressor• Conclusions
ASHRAENumber ODP GWP Safety
HFC R134a 0 1300 Safe
HC R290 0 <3 flammable
NH3 R717 0 <1 Toxic
CO2 R744 0 1 Safe
Problems of R134a Refrigerant
CO2 is the most promising natural refrigerantbecause of its low GWP and safety.
Properties of CO2 [ System ]
CO2 cycle involves super critical pressure.CO2 system is high pressure cooling cycle.CO2 system has intercooler to improve the capacity and the coefficient of performance (COP).
Evaporator
High Pressure Receiver
Compressor
ValveCondenser
Intercooler Gas Cooler
Orifice Critical Point
IntercoolerEvaporator
Compressor
Pres
sure
(M
Pa)
Orifice
Critical Point
Evaporator
Compressor
Pres
sure
(MPa
)
EnthalpyEnthalpy
3.5
7.410
0.2
1.44.1
CO2 System R134a System
Gas Cooler
Intercooler
Valve
EvaporatorLow Pressure Receiver Compressor
Latent HeatAAAAAAAAAAAAAAAAAA
( kJ/kg )
Density ofSaturated Vapor
( kg/m3 )
Capacity VolumeRatio
( kJ/m3 )
CO2 232 97.6 22600
R134a 198 14.4 42860
Properties of CO2 [ Thermophysical ]at 0?
Capacity Volume Ratio=Latent Heat × Density of Saturated Vapor
Because the capacity volume ratio of CO2 is 8 times larger than that of R134a , displacement of CO2 compressor is 1/8 of current R134a compressor.
1950
198019701960 1990 2000
Wobble-type
Swash-type
Scroll-type
Advantage of Scroll Compressor (1)
Advantage of Scroll Compressor (2)1:High Volumetric Efficiency2:Low Pressure Loss3:Low Mechanical Loss4:Low Noise and Vibration
Scroll Compressor for CO2 Refrigerant
Loss of Scroll Compressor
Drive Bearing
Thrust Bearing
Orbit Scroll Fixed Scroll
Pressure Loss
Mechanical Loss
Indicative LossOver Compression Loss
Leakage and Heat Loss
Thrust Bearing Loss
Drive Bearing LossMain Bearing Loss
Sub Bearing LossOldham Ring Loss
Sub Bearing
Main BearingOldham Ring
R134aCO20
50
100
150
200Pressure Loss
Indicative Loss(Leakage,Heat)Mechanical Loss
Theoretical Adiabatic Compression PowerPo
wer
Con
sum
ptio
n (%
)
Loss Analysis of CO2 Scroll Compressor
Changing DisplacementOnly
Technologies for High Efficiency• Improvement of Indicative Loss
• Improvement of Mechanical Loss
Tip contact mechanism is applied toprototype CO2 scroll compressor
Thrust rolling bearing is applied toprototype CO2 scroll compressor
0
50
100
150
200
Pressure LossIndicative Loss(Leakage,Heat)Mechanical Loss
Theoretical Adiabatic Compression Power
CO2Prototype
(%)
Pow
er C
onsu
mpt
ion
Loss Analysis [ Prototype ]
CO2Changing Displacement
Only
R134a
Prototype CO2 Scroll Compressor
CO2 Prototype
f 135 f 125
23 6
13 105
Diameter (mm)
Weight (kg)
Displacement (cm3)
Current(R134a)
Adia
batic
Effi
cienc
y (%
)
Rotating Speed ( min -1 )
50
60
70
80
90
100
0 500 1000 1500 2000 2500 3000 3500 4000
Scroll Analysis
Wobble Analysis Scroll Measurement
Scroll has higher efficiency especially in high speed because ofno suction valve and less pressure drop.
Efficiency of Prototype CO2 Scroll
Conclusions•Tip contact mechanism and thrust
rolling bearing are applied to prototypeCO2 scroll compressor for improvementof efficiency.
•Prototype CO2 scroll compressorachieved high efficiency.( Adiabatic Efficiency = 76% )
