Experimental performance analysis of a solar assisted ground source heat pump system under different heating operation modes

This paper presents an experimental study on the influence of operation modes on the heating performance of a solar assisted ground source heat pump system (SAGSHPS). Through experiments conducted in January, the characteristics of the SAGSHPS were investigated under different heating operation modes. The results indicate that the solar thermal could be used to accelerate the soil recovery when the heat pump unit is turned off, but the duration of solar use to recharge boreholes should be optimized according to the water temperature in the solar heat storage water tank to avoid unnecessary power consumption of the circulation pump. In addition, the solar heat storage water tank is beneficial for the stable operation of the SAGSHPS. The volumetric flow rate in the water tank has a significant impact on the electricity consumption of the SAGSHPS. From comprehensive analysis of the integral effect of the SAGSHPS under different modes, the mode in which the water tank is connected with the ground heat exchangers (GHES) in series is the recommended mode for the SAGSHPS in the coldest month in Dalian.