1 2000 Torahide Takahashi CalsonicKansei Corporation Development of Carbon Dioxide (CODevelopment of Carbon Dioxide (CO 2 2 ) Applied) Applied Refrigeration SystemRefrigeration System 2 2000 Contents of PresentationContents of Presentation 1. Introduction 2. System Components & Specifications 3. Control Method 4. Results of Vehicle Tests 5. Summary 6. Future Activities 3 2000 In the development of CO2 refrigeration systems, the challenge to be met is to assure the cycle safety and the required coolingassure the cycle safety and the required cooling performance at the same timeperformance at the same time, due to the higher refrigerant gas pressure & temperature at the compressor outlet. (Compared with HFC134a systems) In order to meet this challenge, the CO2 refrigeration system we have developed uses an electrically controlled expansion valve. 1. Introduction1. Introduction With the introduction of this electrically controlled valve, our system has successfully achieved the required cooling performance and safety levels. 4 2000 CO2 Refrigeration System Gas cooler Compressor Internal heat exchanger A BC D E 2-1 Components Accumulator Relief valve Pressure SW Pressure sensor Temperature sensor 2. System Components & Specifications2. System Components & Specifications Evaporator Electrically controlled expansion valve Pressure (MPa) A BC DE Enthalpy (J/kg) 3.5 10 0C31C Mollier chart 5 2000 2-2 Specifications of components2-2 Specifications of components Compressor HFC134a systemCO2 system variable displacement type, swash plate Displacement : 184 cc/rev Gas cooler Multi-flow type Core size (mm): 690W x 372H x 19D Frontal area: 0.257 m2 Evaporator Laminate type Core size (mm): 235W x 265H x 64D Frontal area: 0.0628 m2 Internal heat exchanger Double tube serpentine type Size: 19(dia) x 4 connections Expansion valve Thermal expansion valve Electrically controlled expansion valve fixed displacement type, swash plate Displacement : 30 cc/rev Multi-flow type Core size (mm): 702W x 374H x 27D Frontal area: 0.262 m2 Multi-flow type Core size (mm): 265W x 213H x 88D Frontal area: 0.0553 m2 6 2000 2-3 Electrically controlled expansion valve2-3 Electrically controlled expansion valve P (PinPout) Compressor outlet pressure & temperature Duty Up Time Solenoid applied voltage Down b a LargerSmaller IN OUT Inlet pressure: Pin Outlet pressure: Pout Main valve Solenoid Pilot valve Piston Plunger 7 2000 Compressor Gas cooler Internal heat exchanger Electrically controlled expansion valve 2-4 Vehicle installed condition2-4 Vehicle installed condition Evaporator (Passenger room) 8 2000 3. Control3. Control 3-1 System control 3-1 System control Compressor off value on electric pressure sensor Mechanical pressure switch operation value Relief valve operation value Compressor outlet pressure (Mpa) Compressor outlet temperature (C) Compressor off value on temparature sensor T2 Expansion valve control zone Expansion valve control zone Pressure limit Thermal limit P4 P3 P2 P1 T1 Pmax Tmax Protection control zone Cooling performance control zone P0 T0 Low pressure protection zone 9 2000 3-2 Cooling performance control3-2 Cooling performance control Control amplifier PTC set value Intake air temperature sensor Pex Proper duty value Electrically controlled expansion valve Pd / TdPs / Ts Tex Pe / Te Evaporator back temperature sensor Engine revolution Passenger room temperature Ambient sensor Gas cooler Compressor Evaporator Internal heat exchanger Accumulator Clutch Clutch 10 2000 3-3 System protection control 3-3 System protection control (at gradual pressure & temperature rise)(at gradual pressure & temperature rise) Compressor outlet pressure (Mpa) Compressor outlet temperature (C) T2 P4 P3 P2 P1 T1 Pmax Tmax Protection control zone Gradual rise Gradual rise P0 T0 Cooling performance control zone 11 2000 3-3-1 Protection control at gradual pressure rise3-3-1 Protection control at gradual pressure rise Time Compressor OFF Pressure (Mpa) P2 Expansion valve opening ratio (%) 100 0 Opening ratio will increase until the pressure becomes lower than the control returning value. P1 Amplifier spec. value Protection control zone Cooling performance control zone P0 Rising ratio determining Returning point 12 2000 3-3-2 Protection control at gradual temperature rise3-3-2 Protection control at gradual temperature rise Time Temperature (C) Compressor OFF T2 Expansion valve opening ratio (%) 100 0 Opening ratio will increase until the temperature becomes lower than the control returning value. T1 Amplifier spec. value Protection control zone T0 Rising ratio determining Returning point Cooling performance control zone 13 2000 3-4 System protection control3-4 System protection control (at rapid pressure & temperature rise) (at rapid pressure & temperature rise) T2 P4 P3 P2 P1 T1 Pmax Tmax P0 T0 Compressor outlet pressure (Mpa) Protection control zone Rapid rise Rapid rise Compressor outlet temperature (