Performance analysis of the natural mixture R744/R600a refrigeration cycle

Environmental conservation issue advances the refrigerant substitute for the Freons. Natural working fluid must be a perfect choice. Therefore, natural friendly refrigerants R744 and R600a are selected in this research to be a binary mixture. Such a mixture can weaken their shortcomings by decreasing high heat rejection pressure as that of pure R744, and reducing flammability as that of pure R600a. Meanwhile the heating coefficient of performance (COP_h) increases. Theoretical thermal calculation of a refrigeration cycle using natural mixture R744/R600a has been conducted in this research. The results show that within the R744 mass fraction of 100/0~94/6, the R744/R600a mixture can be charged directly. Under the same conditions, the optimum high pressure of R744/R600a system is reduced by 1.2MPa while the heating COPh is increased by 8.5%. Up to now, none of the potential substitutes can play a satisfying role in air conditioning and refrigeration fields. Research on R744/R600a refrigeration cycle is expected to offer useful guidelines for refrigerant substitute.