套管式地下换热器传热模型及其特性分析

通过对套管式地下换热器传热过程的分析,在已有套管式地下换热器传热模型基础上,考虑管内流动和传热,提出了集管内流动与土壤导热相耦合的传热分析模型,并利用有限元数值计算方法进行了传热特性的分析。讨论了埋管管径组合和流体流速对流体出口温度及单位埋管换热量的影响。此外,还系统地研究了连续运行模式和可变负荷运行模式的地下传热特性,阐述了地下换热器高效运行的控制策略和影响。

Modeling for coaxial tubes underground heat exchanger and analysis of heat transfer

To analyze deeply the heat transfer of the coaxial tubes underground heat exchanger(UHE),a new model to couple the fluid flow in the collecting tubes and the heat transfer between the tubes and the soil was proposed based on the existing equivalent model.The heat transfer characteristics and the performance of the coaxial tubes UHE were analyzed by means of the finite element method.The effects of the size of the buried tubes and the flow velocity in the tube on the fluid temperature at the pipe outlet and the heat exchange per unit pipe.Moreover,the underground heat transfer characteristics under two kinds of the operation mode,the continuous operation mode and the variable load operation mode,were studied systematically.The effect of the control strategy on the operation of the UHE was discussed and a control strategy for the efficient operation of the UHE was presented.