Abstract: The heat transfer performance of condenser-evaporator has a significant impact on the performance of auto-cascade refrigeration cycle. Effects of openings of throttle valves on condenser-evaporator heat transfer performance of auto-cascade refrigeration cycle are studied experimentally. The results show that the exergy loss of condenser-evaporator is the biggest one in heat exchangers of auto-cascade refrigeration cycle, which can be reduced by adjusting the openings of main and tributary throttle valves. There is a pinch point at either cold end or hot end of condenser-evaporator. Effect of the opening of main throttle valve on the exergy loss of condenser-evaporator is more significant than that of tributary throttle valve. There are a set of openings of main and tributary throttle valves that minimize the exergy loss of condenser-evaporator under steady operation condition.

Key words: Auto-cascade refrigeration, Condenser-evaporator, Exergy analysis, Heat transfer performance, Opening of throttle valve