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Improvement of Energy Efficiency by Cascade System with Co2 Refrigerant


MOJ Civil Engineering
Yukio Yamaguchi* and Kenji Amagai
SANDEN Environmental Products Corporation
Kenji Amagai, SANDEN Environmental Products Corporation

Abstract

Global warming is commonly issue in worldwide. From point of global warming point of view, alternate HFC refrigerant to natural refrigerant is one of the means to reduce global warming gas which is used to refrigeration system in food store such as supermarket and convenience store. Carbon dioxide (hereinafter CO2) is one of the dominant candidates as low Global Warming Potential (hereinafter GWP) refrigerant. However CO2 refrigerant has lower efficiency for refrigeration because of low critical temperature. Also CO2 refrigerant has higher system pressure than HFC refrigerant. Therefore typical cascade refrigeration system is equipped HFC refrigerant in higher temperature cycle. This report indicate the potential of CO2-CO2 cascade system even CO2 refrigerant itself has lower efficiency than HFC refrigerant. And this report shows optimization of discharge pressure, suction pressure and internal heat exchanger are important to get better performance. 

Keywords

CO2, Carbon dioxide, Coefficient of performance, Cascade, Pressure, Suction, Exchanger, Refrigerant, Temperature, Optimization, Discharge, Compressor, Gas cooler, Expansion valve, Evaporator

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