Research and Development of Thermal Properties Test Device of Deep Ground Soil for Ground Source Heat Pump

摘要

By analyzing the unsteady heat transfer of vertical embedded pipe for ground source heat pump, a transient cylindrical source model is verified based on the thermal response experiment. Meanwhile, the thermal shortcircuit modification is also applied to correct the mean temperature of the circulating water. Besides, a new model to predict the temperature of the borehole wall is developed for reference based on the semi-infinite theory. With the thermal response test device developed by ourselves, two experimental boreholes located in Shanghai were tested in summer. The interior relations among the thermal property parameters are discussed based on the experimental data, of which the change of density specific heat capacity in normal range has little effect on the calculation results of ground conductivity and borehole thermal resistance, so it's considered constant, while the other two parameters need to be determined by calculation. Other influence factors, including selection of the initial time and thermal short-circuit, are researched as well. Through comparing the calculation result of the mean circulating temperature with the experimental data, the accuracy of the thermal property parameters calculated is verified.