PERFORMANCE EVALUATION OF MULTI EVAPORATOR VAPOUR COMPRESSION REFRIGERATION SYSTEM WITH LIQUID-VAPOUR HEAT EXCHANGER AND FLASH CHAMBER USING ALTERNATIVE PURE REFRIGERANTS

Abstract

Parametric investigation of energy and exergy analysis of multi-evaporators at different temperatures with individual expansion valve and individual compressor using flash chamber and liquid vapour heat exchanger is carried out for R134A, R142B, R152A, R600 and R1234YF as alternative refrigerants. In engineering equation solver, a computational model is developed for these systems, simple multi-evaporator system and improved one system. The present investigation has been done for evaporator-I in the range -120C to -200C, evaporator-II in the range 10C to 40C and condenser in the range 350C to 550C. Performance parameters like exergetic efficiency, the coefficient of performance and exergy destruction ratio are calculated over these ranges and compared for these refrigerants. The performance comparison of the simple multi-evaporator system and improved system for dairy plant application, COP improves by 16.99%, 15.97%, 15.88%, 16.24% and 18.41% for refrigerants R134A, R142B, R152A, R600 and R1234YF respectively in multi-evaporator system with flash chamber and LVHE. Exergy efficiency improves by 16.98%, 15.97%, 15.87%, 16.22% and 18.36% for refrigerants R134A, R142B, R152A, R600 and R1234YF respectively in multi-evaporator system with flash chamber and LVHE. Due to additional components in basic system, flash chamber and LVHE, exergy destruction in multi-evaporator system increases. EDR % increases by 20.37%, 16.84%, 14.74%, 18.66% and 24.92% for refrigerants R134A, R142B, R152A, R600 and R1234YF respectively in multi-evaporator system with flash chamber and LVHE. The corresponding values of input energy consumed for expansion valve, evaporator and compressor are varied between 7% to 18%, 11% to 22% and 18 % to 24 % respectively. From the point of enery-exergy analysis, R142B is best among all five selected refrigerants as total exergy destruction of all components is always less for R142B than that of all others and R142B refrigerant has higher COP and Exergetic efficiency in this modified system. Also, R142B has least EDR in this analysis. Though R142B have highest COP and exergetic efficiency among all refrigerants, it is not recommended due to its GWP 2400, which is highest among all. Second best refrigerant R600 has only GWP 3. Hence it is recommended over R142B in dairy plant application.