An auto-refrigerating cascade cycle has some unique advantages for small refrigeration units

for which it has a wide range of operation temperatures from 77 K for nitrogen liquefaction to 230 K for conventional refrigeration. For the three-level auto-refrigenerating cascade system

effect of the components ratios of non-azeotropic mixture as a medium on the performances was investigated. Through the experimental comparisons of the performance of compressor and the cooling performance of evaporator

refrigerant mixtures of R600a

R23 and R14 with four ratios of 35/35/30

35/30/35

30/35/35 and 35/25/40 were designed

of which all the conditions of evaporator were approximate. The evaporation temperature for the ratio of 35/30/35 was lower than others. For this auto-refrigerating cascade system

its evaporator temperature can be as stable as down to 175 K under conditions of 60 W cooling load and 180 K of designed evaporation temperature. Based on the experimental study on the performances of the two compositions under different cooling loads

the highest COP values of 8.47% and 14.4% for the ratios of 35/30/35 and 35/35/30 were achieved

respectively.