Performance Analysis of a Hot Water Supply System with a CO2 Heat Pump by Numerical Simulation (2nd Report, Modeling of Hot Water Storage Tank and Analysis of System)

Abstract

Heat pumps using CO2 as a natural refrigerant have been developed and are expected to contribute to energy saving in hot water supply. In residential applications, CO2 heat pumps are used in combination with hot water storage tanks. The objective of this series of papers is to analyze the overall performance of a hot water supply system composed of a CO2 heat pump and a hot water storage tank by numerical simulation. In the 2nd report, a simulation model of a hot water storage tank is created and the performance of a hot water supply system is analyzed. The performance calculated is compared with that measured, and the simulation model is validated. The trade-off relationship between the system efficiency and the volume of hot water unused through the operational condition on the inlet water temperature is clarified quantitatively.