Influence of Leakage of Natural Non-azeotropic Mixture Refrigerants on System Performance in an Auto-cascade Refrigeration Cycle

摘要

This paper presents a methodology for analyzing the leakage of non-azeotropic mixture refrigerants in an auto-cascade refrigeration cycle. The influence of leakage in different parts of the refrigeration systems on composition changing of refrigerant was analyzed seriously based on the isothermal leakage of the non-azeotropic refrigerant in the two-phase region. And this paper utilizes the auto-cascade cryogenic refrigerator using natural 'refrigerant R600a/CO2 as the target to investigate the leakage characteristics at outlets of condenser and evaporator respective. The results demonstrated that the influence of leakage at vapor-liquid separator, exits of condenser and evaporator on the refrigerant composition is greater than those of others. When the composition of refrigerant changes obviously due to the leakage of refrigerant, the influence of leakage at outlet of evaporator on system performance is the largest, that leads to a relatively large change on pressure ratio of compression, refrigerating capacity per unit volume, refrigerating capacity per unit mass and coefficient of performance (COP).