地埋管换热器周围土壤冻结温度场的模拟研究

Simulation Research on Soil Freezing Temperature Field Surrounding Ground Heat Exchanger

考虑了未冻水质量分数对冻结土壤传热特性的影响,采用控制容积法建立了地埋管换热器周围土壤冻结温度场的数学模型,分析了土壤冻结对土壤物性参数和土壤温度分布的影响,探讨了不同液态水质量分数下土壤冻结温度场的变化。随着土壤温度的降低,冻结土壤的单位体积定压热容减小,热导率增大。由于土壤冻结过程中释放出相变潜热,考虑冻结计算出的土壤温度比未考虑冻结的土壤温度高,土壤中液态水质量分数越大,土壤冻结时释放的潜热量越大,有利于土壤源热泵的运行。

The impact of unfrozen water mass fraction on heat transfer characteristics of frozen soil is taken into account, and the mathematical model of soil freezing temperature field surrounding ground heat exchanger is established by control volume method. The influence of soil freezing on soil physical parameters and temperature distribution is analyzed, and the variation of soil freezing temperature field under different liquid water mass fractions is discussed. The pressurization heat capacity per unit volume of frozen soil declines and the heat conductivity of frozen soil increases with the decreasing of soil temperature. Due to the latent heat of phase change is released during soil freezing, the soil temperature with consideration of soil freezing is higher than that of without consideration of soil freezing. The higher the liquid water mass fraction in soil, the higher the latent heat released during soil freezing, which is favora- ble for operation of ground-source heat pump.