DYNAMIC CHARACTERISTICS OF AN AIR-TO-WATER HEAT-PUMP SYSTEM

This paper investigates the dynamic characteristics of a residential heat-pump system during start-up conditions. Cyclic tests were performed to simulate the operating conditions that are likely to be encountered in heat-pump installations in the UK, where operation is restricted to the heating mode only. The heat pump used is of the split-type air-to-water design and is equipped with a fully hermetic reciprocating compressor and a thermostatic expansion valve with maximum operating pressure characteristics. The results suggest that the cyclic losses associated with refrigerant migration during the off cycle and the employment of a suction accumulator represent a 5% and 4% respective decrease in the system COP when compared with the case where refrigerant migration was controlled.