Experimental Study of Soil Heat Storage and Solar Assisted Geothermal Heat Pump System

Abstract

This study is performed to analyze the performance of a heat pump system with hybrid heat sources (solar and geothermal) for a school building and assess the soil heat storage in various models. Based on the experimental data, the changing law of ground temperature with heat storage in non-heating and heating seasons and the controllable influencing factors of the system performance have been discussed. The results show that ground temperature can increase by an average of 1.0? for seven days by solar-soil heat storage, while the average increasing temperature is decreased to 0.3? after the temperature is recovered to stable condition for 88 hours. The heat storage effect below 70m is significantly worse than that above 70m for the influence of the shallow surface water and uneven distribution of rock in Tianjin. The coefficient of performance of the heat pump can be improved 0.2~0.25 with the assistance of solar compared to the single source heat pump. And there is an optimal flow rate group of the fluid in the fan-coil and the borehole heat exchanger (BHE), which is (1.83, 2.54), m3/h, for the present system.