Part load ratio characteristics and energy saving performance of standing column well geothermal heat pump system assisted with storage tank in an apartment

A geothermal heat pump (GSHP) system has improved energy efficiency compared to conventional air-source heat pumps due to a more stable underground temperatures through the year. Among various types of GSHP systems, standing column well (SCW) system is a specialized type of open loop system, where water is drawn from the bottom of a deep rock well, passed through a heat pump, and returned to the top of the well, during which it exchanges heat with the surrounding bedrock. In this research a SCW system integrated with heat storage tank was assessed through dynamic energy simulation technique after comprehensive validation process of heat pump performance curves. For this purpose, the detailed analysis on the operational characteristics of SCW heat pump and its energy performance enhancement due to the connection with heat storage tank was performed, such as variations of part load ratios (PLRs), COP and the corresponding energy requirements, compared to window air-conditioner and boiler based conventional system. The results of this study showed that the SCW heat pump system connected with heat storage tank showed an annual energy saving of approximately 62% and 14% compared to the conventional system and the SCW system without heat storage tank, respectively. This indicates that energy efficiency can be significantly improved when SCW heat pump can be properly operated in combination with heat storage tank in residential buildings.