地下水补给区季节温度变化对地埋管换热性能的影响

摘要

A three-dimensional model of a borehole heat exchanger(BHE)under seasonal temperature fluctuation of groundwater in the recharge area is established.The heat transfer performance of BHE in summer is simulated numerically, and the influence factors including the seepage velocity,the thickness of aquifers and the distance from the recharge area are analyzed.The results show that for the sites near the recharge area of groundwater,the seasonal temperature fluctuation of aquifers around the BHE becomes bigger,where the heat transfer performance of the BHE tends to be determined by the coupled effect of both groundwater temperature fluctuation and the seepage velocity. The heat transfer rate per borehole depth increases linearly with the increase of the thickness of aquifers.%建立了地下水补给区季节温度变化条件下地埋管换热器的三维模型.以夏季工况为例,进行了传热过程数值模拟,并定量分析了含水层渗流速度、含水层厚度、补给区距离等因素的影响.结果表明,距离地下水补给区越近,地埋管周围含水层温度的年周期变化幅度越大,换热性能更倾向于受季节水温变化与渗流速度变化的二者耦合影响,且表现出不同程度的季节效应.随含水层厚度增加,地埋管单位井深换热量总体上呈线性增大趋势.