With the rapid development of refrigeration industry

more attention is being given to the auto-cascade refrigeration system because of its simple structure

reliable operation and higher system efficiency. The performance of auto-cascade refrigeration system is influenced by the ratio of mixed refrigerants

which is not conductive for its application in large and medium scale systems. In the paper

based on the theoretical analysis about the relationship between the auto-cascade system performance and working fluid ratio

the traditional single-stage auto-cascade system is improved. In order to adjust the mass flow of mixed refrigerant the parts including electronic expansion valve

liquid storage tank and rectifier are installed in high and low temperature circulating loop. Programming by Matlab software and invoking Refprop 9.0 are adopted to carry out the simulation. Experimental results are compared with those of theoretical simulation under three compression ratio. The results show that the improved auto-cascade system has the higher COP when R23 mass concentration is between 0.32 and 0.40

and the simulation results agree well with the experiment results. The experimental results show that the system exergy efficiency is almost not affected by the R23 mass concentration. It is further proved that the performance of the auto-cascade system is not affected by the ratio of the working fluids

which provides a basis for the popularization and application of the auto-cascade system in the large and medium-sized refrigeration systems.