IMPROVEMENT OF THE HEATING PERFORMANCE IN A VARIABLE SPEED HEAT PUMP BY APPLYING THE GAS INJECTION TECHNIQUE INTO A TWIN ROTARY TYPE COMPRESSOR

摘要

For heat pumps used in the cold regions, it is very important to obtain appropriate heating capacity. Several studies have been performed to enhance heating capacity at low ambient temperatures. The heating performance was significantly improved by the application of a variable speed compressor. However, for outdoor temperature conditions below -15°C, it is still difficult to acquire enough heating capacity above the rated heating capacity. In this study, a twin rotary type compressor with gas injection was applied to a heat pump system in order to improve the heating capacity at low ambient temperatures. The heating performance of the gas injection cycle was measured and analyzed by varying outdoor temperature and compressor frequency. The tested heating performance of the gas injection cycle was compared with that of the non-injection cycle. The heating capacity of the gas injection system was increased by 11～23% with the variation of outdoor temperature. The COP based on equal capacity was also improved by 28～35%.