Performance analysis of a vapour compression-absorption cascaded refrigeration system with undersized evaporator and condenser

Abstract

In a present study, the performance of a vapour compression-absorption cascaded refrigeration system (CRS) under fouled conditions was analysed. The main effect of fouling is to decrease the effectiveness of the heat exchanger. Thus, the overall conductance (UA) of the heat exchanger is decreased. Hence, another interpretation of fouling is to reduce the effective size of the heat exchanger. In the present work, the percentage decrease in the overall conductance value (UA) of evaporator and condenser due to their fouling is varied from 0 to 50% and its consequences on various aspects of CRS are generated to ascertain any possible patterns. The detailed first law analysis reveals that for a clean evaporator and condenser, the electricity consumption is 67.5% less than vapour compression system (VCS) for the same cooling capacity. CRS is able to save only 61.3% of electrical energy when evaporator and condenser conductance is reduced by 50% due to fouling. Evaporator and condenser fouling decreased the COP and rational efficiency of the system by 4.7% and 10.5% respectively. It is also important to note that irreversibility in the evaporator and condenser is increased by 42.4% and 62.1% respectively, when their individual performance is degraded by 50% due to fouling.