Optimization analysis on R290/CO2 cascade refrigeration system.

In this paper, a new type cascade refrigeration system that uses carbon dioxide and propane which are environment friendly as refrigerants is established. To ensure the safe operation of the system ,to maximize the COP and minimize the exergy destruction of the system, It is analyzed that the design parameters including the evaporating temperature t1, the condensing temperature tk, the temperature difference in the cascade-condenser △t, the compressor efficiency of high-temperature cycle ɳh, the compressor efficiency of low-temperature cycle ɳ1, the degree of superheat ,the degree of subcooling and others for maximum system COP and optimum mass flow ratio of relationship. The results obtain maximum COP of system operation and optimum mass flow ratio in different operation conditions.