中文摘要：

对R744／R290、R744／R600a混合自然工质的热力性质进行分析比较，并将它们用于自复叠制冷循环，对系统的循环特性进行分析。经过计算，得出了两种混合工质制冷性质的不同点及环境温度、制冷温度、混合工质中R744浓度对系统性能的影响。为今后R744／R290、R744／R600a的实验研究和实际应用提供了理论依据，减少了实验的工作量。

英文摘要：

The thermodynamic properties of the natural mixture working substances R744/R290 and R744/R600a were compared for an auto-cascade refrigeration system. The cycle performance was analyzed. The effect on the system performance of the ambient temperature, the refrigeration temperature and the mole fraction of R744 in the mixtures were calculated. The result may provide theoretic reference for the study and application of R744/R290 and 744/R600a mixture.