Exergy-Based Numerical Modelling and Performance Comparison using natural, HFO, HFC and blended refrigerants in Vapour Compression Refrigeration Systems
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This paper investigates a comprehensive thermodynamic and exergy-based performance assessment of eight most widely used refrigerants: R-1234yf, R-717 (ammonia), R-32, R-290 (propane), R-134a, R-600a (isobutane), R-410A, and R-436A in a vapour compression refrigeration system and also describes this article's exergy efficiency and an irreversible process as performance indicators, with variation in evaporation temperature. Several defined state points and other thermophysical properties of the specified refrigerants are calculated using REFPROP 9.0. The system analysis assumes compressor electrical, mechanical, and isentropic efficiencies of 0.9, 0.84, and 0.85, respectively, with isenthalpic expansion, low-pressure decreases, and no superheating or subcooling. Exergetic efficiencies, compressor work input, mass flow rate, COP, and total exergy loss are determined using an exergy-based framework over an evaporator temperature range of 238-263K at constant condenser temperature of 313K. By reducing irreversibility effects, increasing COP and exergetic efficiency, and decreasing compressor effort, raising the evaporator temperature enhances system performance for all refrigerants. Because of its high latent heat and excellent thermophysical characteristics, ammonia (R-717) performs best overall, providing the maximum COP and exergetic efficiency as well as the lowest work input, exergy losses, and mass flow rate. The blend R-436A and the hydrocarbons R-290 and R-600a also exhibit good performance with low exergy destruction, making them viable low-GWP, energy-efficient choices. Despite being ecologically friendly, R-1234yf exhibits the worst thermodynamic performance, with the highest compressor work and mass flow rate and the lowest exergetic efficiency, particularly at lower evaporator temperatures. Conventional HFCs, such as R-134a and R-410A, fall in the middle but have greater environmental impacts.
