低温模式下地下换热器管土结构冻胀变形特性研究

为研究地下换热器的运行温度(低于0℃)对地下换热器管土结构冻胀变形的影响,通过建立地下换热器管土结构冻胀变形过程的数值模型,以单U型地下换热器管土结构为研究对象,模拟其在不同恒温温度和不同进、出水温差工况下的冻胀变形过程,分析冻胀土体应力、管体变形和管截面的变化特征,以此考察地下换热器的安全运行特性。结果表明:对于恒温运行模式,在土体冻结范围基本一致的情况下,低温运行模式可产生更小的冻胀力、管体变形和管截面减小程度;对于不同的进、出水温差运行模式,在平均运行温度一致的降温模式下,较小的温差可产生较小的冻胀力、出水管管体变形量和管截面减小程度。该研究将冻胀模型应用于地下换热技术领域,可为合理选择地下换热器运行方式以预防冻害提供参考。

Research on Frost Heave Deformation Characteristics of Pipe Soil Structure of Underground Heat Exchanger under Low Temperature Mode

This paper sets up a frost heave numerical model to study the effect of operating temperature(below 0℃) on frost heave deformation of the pipe soil structure of underground heat exchanger.The paper establishes the numerical model of frost heave deformation preocess of the pipe soil structure of the underground heat exchanger and takes soil structure of the single U-shaped pipe underground heat exchanger as the analysis object.And the paper investigates the safe operation characteristics of underground heat exchanger by simulating the frost heave processes with different operating temperature mode and investigating the variation of freezing soil stresses,pipe deformation and flow area variation of pipe section.The results show that with the constant temperature mode and basically same freezing range,lower temperature can bring smaller soil stress,pipe deformation and reduction degree of pipe section.with the declining temperature mode and the same average operating temperature,smaller temperature difference between inlet and outlet pipe can bring smaller soil stress,outlet pipe deformation and reduction degree of pipe section.In this study,the frost heave numerical model is applied in the field of underground heat transfer technology,which can provide a reference for a proper operating mode to prevent freezing damage.