EXPERIMENTAL INVESTIGATION ON TRANSCRITICAL CO2 HEAT PUMP SYSTEM WITH EJECTOR IN OFF-DESIGN CONDITIONS

摘要

The use of ejectors is one of the most promising methods to improve performance of transcritical CO_2 heat pump systems. However, in this experimental study, transcritical CO_2 heat pump system with ejector (TCHSE) is found to be inferior to conventional transcritical CO_2 heat pump system (TCHS) in coefficient of performance (COP) when hot water outlet temperature is higher than a certain value. Thus, the use of ejector in CO_2 heat pump water heater might not be beneficial under some working conditions. In this paper, off-design performance characteristics of the systems are analysed. Experimental investigations and assessments on performance of TCHS and TCHSE in off-design conditions are also carried out.