ENERGY AND EXERGY ANALYSIS OF VAPOUR COMPRESSION REFRIGERATION SYSTEM WITH R-502 AND ITS ALTERNATE REFRIGERANTS

Abstract

The chlorofluorocarbon (CFC) and hydro chlorofluorocarbon (HCFC) refrigerants are being replaced by hydro fluorocarbon (HFC) and HFC mixtures due to environmental concerns about depletion of the ozone layer and global warming. Various researchers have suggested different alternative to R-502 such as R-404A, R-402A, R-402B, R-403B, R-408A, R-407B etc. R-502 has ozone depletion potential 0.230, which have harmful effect on ozone layer; hence R-502 is required to be phased out by year 2030 in developed countries and by year 2040 in developing countries. A refrigeration system with R-502 using alternative refrigerants needs to be modified or alternatively redesigned due to variation in the physical properties of these new refrigerants. R-507A and R-404A being long term ozone friendly refrigerants is the common choice for R502 as alternate refrigerants. In the present work energy and exergy analysis of vapour compression refrigeration cycle for R502 and its alternate refrigerants (R-404A & R507A) has been carried out by varying evaporator temperature between -50°C to 0°C and condenser temperature between 30°C to 60°C, with the help of Engineering Equation Solver (EES). The parametric investigation such as coefficient of performance, volumetric cooling capacity, pressure ratio, exergy destruction ratio, exergetic efficiency, and efficiency defect in individual components for R-502, R-507A and R-404A have been carried out theoretically and have been compared with the experimental available data. The results indicate that evaporating and condensing temperatures have pronounced effect on exergy destruction in the components such as compressor, condenser, and throttle valve where as in the evaporator it is negligible. The exergetic efficiency and COP of the cycle change to large extent with the variation in evaporator and condenser temperatures. The computational analysis has allowed the determination of the best energetic and exergetic performances of R-502 and its substitute refrigerant R-507A and R-404A.