基于钻孔内多极模型的岩土热物性参数评估方法

PARAMETER EVALUATING METHOD OF GEOTHERMAL PROPERTIES BASED ON MULTIPOLE MODEL INSIDE BOREHOLE

为准确评估地埋管换热器设计中岩土热物性参数,该文基于钻孔内解析传热模型和钻孔外数值传热模型,提出一种岩土热物性参数评估方法。该方法通过钻孔壁面温度耦合钻孔内外换热,求解流体平均温度,在此基础之上采用单纯形法寻优求解岩土导热系数、热扩散系数及钻孔热阻。并结合实际工程的地源热泵系统热响应测试实验,验证该方法的准确性。相比于纯二维数值模型和p(t)-liner纯解析模型,该方法计算所得的流体出口温度更加接近实测值,其均方根误差分别为0.115、0.252和0.193℃。同时,相比于常用的二维模型,当钻孔内热阻采用多级模型计算时,能够提高计算精度,钻孔热阻误差减少3.9%。

In order to estimate the geothermal parameters accurately in the design of buried pipe heat exchanger, an evaluating method of geothermal properties was proposed based on the analytical thermal conductive model inside borehole and the numerical thermal conductive model outside borehole. The fluid average temperature was calculated by coupling the heat transfer inside and outside borehole through the temperature of borehole wall. On this basis, soil conductivity, soil diffusivity and borehole thermal resistance were solved by simplex search algorithm. The method was validated by thermal response test （TRT） of ground source heat pump system for actual projects. The fluid outlet temperature calculated by this method was more close to the measured value compared to pure 2-D numerical model and p （t）-liner analytical model, the root mean square error was 0.115, 0.252 and 0.193℃, respectively. Meanwhile, compared with general 2-D model, the calculation accuracy could be improved when the muhipole model was used to calculate the thermal resistance in the borehole, and the error of borehole thermal resistance was reduced by 3.9%