Experimental investigation of transcritical CO2 heat pump for simultaneous water cooling and heating

Abstract

This paper presents the experimental performances of a transcritical CO2 heat pump prototype for simultaneous water cooling and heating applications. System behavior and performances such as cooling capacity, heating capacity, and system coefficient of performance (COP) have been studied experimentally for various operating parameters such as water mass flow rate, water inlet temperature for both evaporator and gas cooler, and expansion valve opening. Performance is also compared with previous test data. Test indicates that the expansion valve opening has a significant effect as well near the full valve closing condition (up to 20°). Study shows that both the water mass flow rate and inlet temperature have significant effect on system performances. Test results show that, at gas cooler pressure of 90 bar, the effect of evaporator water mass flow rate on the system performances is more pronounced (COP increases 0.6 for 1 kg/min.) compared to the gas cooler water mass flow rate (COP increases 0.4 for 1 kg/min.) and the effect of gas cooler water inlet temperature is more significant (COP decreases 0.48 for given ranges) compared to the evaporator water inlet temperature (COP increases 0.43 for given ranges).