地下水对地埋管换热器换热的影响分析

针对传统传热模型无法反映地下水对地埋管换热器换热的影响,结合黄土高原地区的地质条件,通过Fluent流体仿真软件建立地埋管换热器的三维非稳态分层渗流传热模型,并利用实验数据验证该模型的准确性.在不同的地下水流速和岩土体孔隙率的条件下,通过数值模拟的方法,研究以含水层厚度为特征长度的贝克莱数与地埋管换热器换热之间的关系.结果表明:单位井深换热量增加率与贝克莱数成对数关系;当贝克莱数较大时,地下水对地埋管换热器换热有促进作用;当贝克莱数较小时,地下水对地埋管换热的强化作用不明显,甚至起到抑制作用.同时,对含水层处的导热系数进行修正,得到新的分层渗流传热模型.

Analysis on Influence of Groundwater on Heat Exchange of Ground Heat Exchanger

The traditional heat transfer model cannot reflect the heat exchange influence of groundwater on the ground heat exchanger,in order ro slove the problem, based on the geological conditions of the Loess Plateau Region, the three-dimensional unsteady layered seepage heat transfer model of the ground heat exchanger is established by Fluent fluid simulation software, and the accuracy of the model is verified by the experimental data. Under the conditions of different groundwater flow velocity and geotechnical porosity, the relationship between Peclet number with aquifer thickness as the characteristic length and the heat exchange of the ground heat exchanger is studied by numerical simulation method. The results show that there is a pairing-number relationship between heat exchange increase rate per unit well depth and Peclet number. When the Peclet number is large, the groundwater can promote the heat exchange of ground heat exchanger. When the Peclet number is small, the effect of groundwater heat exchange enhancement is not obvious, and even reverse. The new layered seepage heat transfer model is obtained by modifying the thermal conductivity at the aquifer.