Experiment Study on Ground Temperature Recovery and Operating Performance of Intermittent Heat Storage in GSHP System

The ground source heat pump system (GSHP) continuous operation will result in heat accumulation of the soil around the underground heat exchangers leading the descend operation performance of heat pump system. Based on experiment of GSHP system in summer season, the temperature distribution of humid soil around the vertical boreholes, the power consumption of the heat pump unit, the water temperature in the inlet and outlet of the underground heat exchangers, the heat release rate of per unit length of the buried pipes in humid soil and the cooling coefficient of performance (COP) for the heat pump unit were acquired during the different intermittent heat storage modes. This study investigated the impact of soil temperature change around the borehole wall on the performance of heat pump operation, the influence of intermittent heat storage on the soil temperature near the borehole wall and the performance of heat pump unit, and the effect of intermittent heat storage process on the recovery rate of soil temperature. The results showed that proper control of the operation and interval time of GSHP can effectively improve the soil temperature field around the underground heat exchangers and enhance the performance of GSHP system, thus achieving high efficiency operation of heat pump units.