土壤冻结对地热换热器传热的影响

研究了土壤 冻结对地源热泵系统中的地热换热器与其周围土壤的热交换过程的影响。探讨了土壤水分含量、斯蒂芬数、土壤初始温度（即地温）等对周围土壤温度分布、冻结锋面发展等的影响，并与不考虑土壤冻结情况作了对比分析。当考虑土壤中水分冻结时，由于冻结时放出大量的潜热，且冰的导热系数大，因此计算出地下埋管周围的土壤平均温度高，传热热阻小，设计的地热换热器规模可以变小，亦即可以减小钻孔的深度 或钻孔的数量，从而可以减小地热泵系统的 初投资。另外也扩大了地下回路中防冻液的选择范围。当土壤含湿量大、土壤初始温度高时，对于系统的设计与运行是 有利的。

The influence of soil freezing on the heat transfer between heat exchanger of ground-source heat pumps and its ambient

This paper has analyzed the heat transfer of a buried heat exchanger of ground source heat pumps (GSHP) with its ambient soil. The influences of soil freezing are probed into. It has studied the effects of such factors as the Stef an number, moisture content of soil, etc., on the ambient soil temperature distribution, the freezing front development, and so on. It has also analyzed the deviation caused by ignoring the moisture freezing under the same boundary and initial conditions. When soil freezing is considered, the calculated temperature distribution of the ambient ground is higher and the total heat resistance of the geothermal heat exchanger is less due to the release of latent heat and the larger heat conductivity of ice. Thus the size of the geothermal heat exchanger will be reduced, and also the initial costs of GSHP system will be cut down. On the other hand, the selection ranges of circulate fluids, anti-freezing solutions and heat pumps will be enlarged. More moisture content and higher soil initial temperature are favorable to the design and operation of GSHP systems.