非饱和土壤热湿迁移对地埋管换热特性的影响研究

Study on the effect of heat and moisture migration in unsaturated soil on heat transfer characteristics of buried pipes

本文提出了一种考虑温度因素的预测土壤热导率模型,通过与Campbell和de V-1模型的计算结果比较,该模型能更准确计算土壤热导率大小,平均相对均方差≤15%;其次,建立了基于Matlab平台的地埋管换热器周围非饱和土壤热湿耦合迁移模型,研究了土壤初始温度、初始含湿量及孔隙率对地埋管在放热工况下温湿度场的影响,结果表明:土壤初始温度对钻孔壁处含湿量影响较小,而钻孔壁处温度场与土壤初始含湿量成反比,且其湿度场下降速率均呈现先增后减的趋势;当土壤孔隙率<0.2时,土壤含湿量下降速率明显增加。

In this paper,a model for predicting soil thermal conductivity and considering temperature factors was proposed.Comparing with the results of Campbell and de V-1 models,the proposed model could calculate the soil thermal conductivity more accurately with an average relative mean square deviation of less than 15%.Moreover,the coupled heat and moisture migration model of unsaturated soil around buried pipes heat exchanger was established,and the model was solved based on the Matlab.The effects of initial soil temperature,soil moisture content and soil porosity on heat transfer temperature and humidity field of the buried pipe under exothermic condition were studied.The results show that initial soil temperature has little effect on the moisture content of borehole wall.In addition,the temperature field at the borehole wall is in reverse ratio to the initial soil content,and the decreasing rate of moisture field shows a trend of increasing and decline then.For the soil porosity,when it is less than 0.2,the decreasing rate of soil moisture content will increase significantly.