同轴地埋管换热器岩土热响应试验研究

EXPERIMENTAL STUDY ON GEOTECHNICAL THERMAL RESPONSE TEST OF COAXIAL BOREHOLE HEAT EXCHANGER

岩土热物理性质是影响地源热泵系统设计和运营的关键因素,对位于武汉市洪山区的2口不同深度的同轴地埋管换热孔分别进行48 h的热响应试验,并对同轴地埋管换热器内外管之间环形空间中的平均流体温度进行测试。根据同轴地埋管换热器的几何特性,以简便实用的方式测量同轴地埋管换热器环状空间传热流体的平均温度,结合同轴地埋管换热器钻孔热阻的解析解和无限长线热源理论,提出一种利用同轴地埋管换热器现场热响应试验获取岩土热物理性质的方法。将该方法获得的岩土热物理性质与室内试验结果相比,一致性较好,表明该方法切实可行。

Geotechnical thermophysical properties are the key factors affecting the design and operation of ground source heat pump(GSHP)system. Two thermal response tests lasted 48 h were performed in two experimental coaxial borehole heat exchangers with different depths located in Hongshan District of Wuhan City,and the average fluid temperature in the annular space between inner tube and outer tube of coaxial borehole heat exchangers was measured. A simple in-situ method to obtain ground thermal properties was presented,which combines the analytical solution of borehole thermal resistance with the infinite line source model(ILSM),according to the geometric characteristics of coaxial borehole heat exchanger. Compared with the laboratory test results,the thermal physical properties of rock and soil obtained by this method are in good agreement,which indicates that the proposed method is feasible.