城市轨道交通车站套管式地下换热器换热性能影响参数分析

Analysis of Heat Transfer Performance Influencing Parameters for Casing Underground Heat Exchanger in Urban Rail Transit Station

套管式地下换热器的换热性能是限制地源热泵技术在城市轨道交通车站环控系统推广应用的难点之一。通过与室内模型试验结果进行对比,验证了套管式地下换热器换热过程数值计算模型结果的准确性;选取多个影响参数,采用该数值计算模型,计算得到了各参数值对套管式地下换热器换热性能的影响。设计了正交试验,分析了各影响参数的显著性水平。结果表明:提高回填材料导热系数和进水温度,增加地下换热器直径,均可提高单位井深换热量;提高土体初始温度、增加地下换热器地埋管长度,单位井深换热量呈下降趋势。土体初始温度和进水温度对单位井深换热量的影响最为显著,回填材料导热系数和地下换热器直径对单位井深换热量影响较为显著,地下换热器地埋管长度对单位井深换热量的影响较小。

The heat transfer performance of the casing underground heat exchanger is one of the technical difficulties limiting its application in urban rail transit station environmental control system.Compared with the indoor model test results,the accuracy of the numerical calculation model results of the heat transfer process for the casing underground heat exchanger is verified.Multiple influencing parameters are selected,and the numerical calculation model is used to calculate the influence of each parameter value on the heat transfer performance of the casing underground heat exchanger.Orthogonal tests are designed to analyze the significance level of each influencing parameter.The results show that the heat exchange per unit well depth increases with the increase of thermal conductivity coefficient of backfilling material,inlet water temperature and exchanger diameter,while it decreases with the increase of initial soil temperature and the exchanger buried tube length.The initial soil temperature and the inlet water temperature have the most significant effect on the heat exchange per unit well depth,and the thermal conductivity coefficient of backfilling material and the exchanger diameter also have a relatively significant effect.However,the exchanger buried tube length has a relatively small influence.