Simulation of a simple vapour-compression refrigeration system using R134a

Abstract

A computerized simulation of a simple single-stage vapour-compression refrigeration system has been made. The steady-state simulation uses the accurate property correlations developed by Cleland for refrigerant R134a. The inputs to the program are: evaporator pressure, condenser pressure, superheating at evaporator outlet, subcooling at condenser outlet and compressor isentropic efficiency. The program outputs are: refrigerating effect, compressor work input, coefficient of performance (COP) and suction vapour flow rate per kW of refrigeration. An increase in the evaporator pressure from 150 to 250 kPa improves the COP by 40%. The COP is decreased by 35% when the condenser pressure is increased from 1000 to 1500 kPa. Increasing the superheat at the evaporator outlet from 0 to 16°C improves the COP by 2.6%. An increase in subcooling at the condenser outlet from 0 to 16°C increases the COP by 20%. The COP is improved by 150% when the compressor isentropic efficiency is increased from 0.4 to 1.