A computerized analytical model for evaluating hydrocarbon fluids as natural alternative refrigerants

This paper describes a computer-based analytical model for evaluating the performance of natural hydrocarbonfluids as alternative refrigerants in vapour-compression refrigeration systems. To model the com- pression process that takes place in the superheated region, the model determines the compressor's discharge temperature from the entropy-temperature relationship. In this respect, the model departs from the common practice of representing this process by the polytropic relationship which introduces significant errors par- ticularly in the proximity of the saturated-vapour line. The paper demonstrates the improved accuracy of the present compression model compared to the polytropic model and verifies the self-supported, computer- based analytical model of the closed cycle by comparing its estimates for the key cycle parameters with those obtained from the published literature for R134a, R290, R600, and R600a.