Thermodynamic Performance Comparison Using HFO-1234yf and HFO-1234ze in the High Temperature Cascade Refrigeration Systems and Ecofriendly Refrigerants in Low Temperature Applications

Abstract

The present paper relates to a cascade refrigeration system which circulates a HFO refrigerant in the high temperature circuit and HFC-134a in the low temperature (173K) circuit for cryogen applications .The thermodynamic analysis using entropy generation for finding exergy destruction ratio indicating that R1234ze (GWP=6) gives better performance than R-1234yf (GWP=4) in the high temperature circuit. The numerical computation has been carried out for 173 K evaporator temperature for ten ecofriendly refrigerants in the low temperature circuit and HFO-1234yf, HFO-1234ze, R152a and R717 in the high temperature circuit. The effect of condenser temperature from temperature (303K to 333K), cascade evaporator range (253K to 293K) and evaporator temperature range 173K to 223K and temperature overlapping (Approach) rages from zero to 10 on thermodynamic performance have been investigated. It was observed that R1234ze in high temperature circuit and R 134a in lower temperature circuit is a best alternative than R1234yf in high temperature circuit and R 134a in lower temperature circuit.