Exergy analysis of mobile air conditioning system and dual evaporator refrigeration system using ecofriendly alternatives of R134a
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Date
2021-02
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
In the present study, exergy analysis of mobile air conditioning system with expansion work recovery and dual evaporator refrigeration system has been carried out using ecofriendly alternatives of R134a. The alternatives have low global warming potential as compared to R134a. Present model developed in EES has been duly validated with previous research work. The effect of evaporator temperature, expander isentropic efficiency, compressor isentropic efficiency, degree of subcooling and degree of superheating on system performance has been studied for both the systems. Mobile air conditioning system with expansion work recovery has been used to decrease throttling losses in the system. Exergetic efficiency was highest in case of R1234ze(E) whereas R1234yf has lowest exergetic efficiency among all the refrigerants studied. R450A and R513A have exergetic efficiency inferior to R134a but superior to R1234yf. Relative irreversibility of compressor was highest at lower evaporator temperature and at higher evaporator temperature; highest relative irreversibility was found in condenser. Total exergy destruction in the system was found to be highest for R513A and lowest for R134a. In dual evaporator refrigeration system, performance of the system is largely influenced by the evaporator with lower evaporating temperature. With increase in evaporator 2 (low temperature evaporator) temperature, average percentage decrease in COPs for R1234yf, R1234ze(E), R450A and R513A were found to be 5.32%, 0.61%, 2.86% and 3.27%, respectively when compared with R134a. Exergetic efficiencies for R134a, R1234yf, R1234ze (E), R450A and R513A are found to be 29.95%, 28.48%, 29.84%, 29.14 and 29.06%, respectively. Highest irreversible losses occurred in compressor and lowest in mixing chamber. Poorest performance is shown by R1234yf among all the refrigerants. R450A and R513A have been found to perform better than R1234yf.