Method for controlling an electronic expansion valve based on cooler pinch and discharge superheat

摘要

An electronic expansion valve (EXV) used in a refrigeration cycle for a heat pump or chiller is controlled to maintain minimum pinch for ensuring proper flooded cooler exchange performance by monitoring the delta temperature between the cooler fluid temperature (80) and the saturated suction temperature (70). The discharge superheat (70) is monitored to protect the compressor (20) from liquid slugging. If the discharge superheat (70) is lower than the expected value, the EXV opening is adjusted. A controller (15) monitors certain system variables which are used to determine the optimal position of the EXV to optimize the system performance, the proper discharge superheat value, and the appropriate refrigerant charge. <IMAGE>