一种现场测定土壤源热泵岩土热物性的新方法

A METHOD FOR MEASURING THERMAL PROPERTIES OF GROUND

利用现有土壤源热泵实验台测定了岩土热物性参数,采用传热学反问题的方法对实验数据进行分析。测试过程中从岩土取热,U型地埋管换热器形成一个线热汇,使其在测试过程中与热泵实际运行时的工作状态相接近,测试更准确,节省测量过程的耗电量。以每个采样时刻作为计算节点,取平均值作为计算结果。测定结果显示岩土导热系数为3.2W/(m·K),回填材料导热系数为2.0W/(m·K),岩土热扩散率为0.85×10^(-6)m^2/s。可靠性分析表明:其标准误差分别为0.08W/(m·K),0.04W/(m·K)和0.039×10^(-6) m^2/s。

Thermal properties of ground have been measured by using a ground source heat pump experiment plate. The calculation is an inverse problem of heat transfer, and a method was used to solve this problem. Heat transfer in the bore hole was simplified by using the equivalent cylinder method. Heat transfer out of the bore hole was calculated by using the Ingersoll line heat source model. The heat pump extracts heat from the ground, and the U-tube acts as a heat sink. Thus, heat exchange process in the bore hole is more similar to the operating condition. Each group of sample data is used to calculate the thermal properties, and the average value is taken as the result. Thermal conductivity of ground is 3.2W/（m·K）, thermal conductivity of back fill is 2.0W/（m·K）, thermal diffusivity of ground is 0.85 × 10-6m2/s. Re-liability of those data are analyzed in this paper. Uncertainty degree of them are 0.08W/（m·K）, 0.04W/（m·K）, 0.039 ×10-6m2/s, respectively.