Thermodynamic analyses of ejector refrigeration cycle with zeotropic mixture

Abstract

In this study, a model is established for an ejector with a zeotropic refrigerant as the working medium, and the refrigeration cycle of the ejector is analysed. Depending on the boiling point, different refrigerants are combined to prepare R123/R245fa, R245fa/R141b, R141b/RC318, R245fa/R134a, R245fa/R22, R141b/R134a, R245fa/R143a, and R141b/R22. The temperature and pressure in the generator, evaporator, and condenser are calculated using these refrigerants, and the influence of the temperature glide on these conditions is investigated. The performance of the ejector refrigeration cycle is also studied. The results indicate that the outlet temperatures of both the generator and evaporator can be increased using a zeotropic mixture compared to that using a pure refrigerant. In the condenser, the average temperature difference of the heat transfer is larger than that of the pure refrigerant because of the temperature glide characteristics of the zeotropic refrigerant, which reduces the heat transfer area of the condenser. Among the studied refrigerants, using R245fa/R22 (0.3/0.7) as the working medium yields the refrigeration cycle with the best COP (0.293), which is 4% and 22% higher than those using R22 and R245fa, respectively. The results reveal the advantages of zeotropic refrigerants and provide a theoretical foundation for further research.