In light of the low-temperature cycle in the cascade refrigeration system using blends of CO2/R170

the mathematical models of solid-liquid equilibrium and vapor-liquid equilibrium were developed.The models were used to determine the range of mixing ratio in which crystallization of the mixture at a low temperature could be prevented.The cycle performance and flammability of mixed refrigerants with different mixing ratios were analyzed.The impact of mixing ratio on cycle performance and flammability was investigated.The effects of medium temperature on the whole COP of the cascade refrigeration system using R290 as high-temperature circuit refrigerant and blends of CO2/R170 as low-temperature circuit refrigerant were analyzed.A better refrigerant for the low-temperature circuit of cascade refrigeration system was found.