竖直地埋管热相似试验台原理及试验验证

Principle and verification of a similar experiment system for vertical ground heat exchangers

以考虑岩土竖向分层的竖直地埋管换热器传热模型为基础,通过热相似原理对该传热模型进行相似转换,得到了几何、时间、流速等相似倍数的关系。以某工程为例,基于相似准则,搭建了竖直单U地埋管相似模型试验台。通过该试验台地埋管运行24h(相当于原型运行64d)的测试数据,对已建的三维数值模型(相似模型和原型)计算结果进行验证。结果表明,地埋管出口温度平均相对误差为1%,进出口温差平均相对误差为8%,土壤温度相对误差为3%。该试验台实现了以较小成本和可控短期运行时间对复杂工况下地埋管长期换热规律的研究。

Based on a heat transfer model of vertical ground heat exchanger considering soil vertical stratification, similarly converts the heat transfer model by the thermal similarity principle, obtains the similarity ratios such as flow velocity, geometry and time. Based on a project and the similarity criteria, develops a vertical single U-shape pipe similarity model experiment system. Using the test data of experiment system in 24 hours running （equivalent to 64 days of prototype operation）, verifies the calculated results of the three-dimensional numerical model （similar model and prototype model）. The results show that the average relative error of the outlet temperature of the buried pipe is 1%, the average relative error of the temperature difference between the inlet and outlet is 8%, and the relative error of the soil temperature is 3%. The similar experiment system realizes the study of the long-term heat transfer characteristics of buried pipes under complex conditions with relative low costs and controlled short-term operating time.