Abstract
The authors analyzed the performance for the CO2 heat pumps equipped in the hot water supply systems of each house based on the results of field measurements. This paper presents the measurement results on the thermal and energy efficiency of heat pumps through the winter season. As the results, the average results of coefficient of performance (COP) on the heat pumps are shown based on the characteristics of hot water usage and outdoor temperature, etc. And, the efficiency of the steady and the unsteady running condition and the defrosting condition of heat pumps are analyzed by the factors of outdoor temperature and humidity of heat pump unit. Finally, the authors clarify the COP of the hot water supply system in winter.
