Heating performance analysis of the region control method for heat pump with thermal storage system

Abstract

A heat pump with thermal storage system comprises a heat pump and a thermal storage tank. Heat pumps store thermal energy in the thermal storage tank during the night; this then allows for the stored thermal energy and heat pump to meet the heating load demands during the day. This system contributes to the stabilization of the electric power supply and demand as well as makes it possible to realize the economic benefit of using inexpensive electric power during the night. Control strategies include the use of conventional control methods such as thermal storage priority and heat pump priority methods and region control methods. The region control method combines the advantages of both conventional methods. In this study, the system comprises a heat pump with a latent thermal storage tank. The heating load is that required for an office building and was calculated using the TRNSYS software. The power consumption and electricity cost were analyzed by conducting experiments according to the heating load size and each of the three control methods. The region control method was performed at the optimal operating ratio, which was the best in terms of electricity cost. It was noted that the utilization ratio of the thermal storage tank was also high. When comparing the region control method at 80 % design load with the thermal storage priority method, the heat pump coefficient of performance was higher and the power cost was lower by 5.7 %. However, the utilization ratio of thermal storage was higher than the heat pump priority method and the power cost was 5.2 % lower. Therefore, it is confirmed that the region control method is more effective than the conventional methods.