Thermal and isothermal performance analyses for heat and moisture transfer in unsaturated porous media in emitting and extracting modes

This study focuses on conducting a comprehensive assessment of the thermal characteristics of unsaturated soils, specifically in relation to temperature and moisture content. The investigation aims to analyze the influence of several key soil properties, namely specific heat capacity, heat emission coefficient, thermal conductivity, porosity, overall heat conduction coefficient and heat emission coefficient of the media. To evaluate the impact of these parameters, sensitivity analyses are conducted, and the results are presented graphically for both heat emitting and extracting modes, considering the variations in temperature and moisture content. The evaluation of equations relevant to heat and moisture flows in unsaturated soils is performed using the finite element method, specifically addressing the three primary equivalents of mass survival for the liquid and gas phases, as well as energy survival. Based on the obtained results, it can be concluded that the aforementioned parameters play a significant role in determining the thermal behavior of soils. For instance, in the emitting mode, the percentages of the temperature increase at the end of the tenth day for the highest total heat capacity and the lowest one is computed to be 13% and 9%, respectively. Also, in the extracting mode, the percentages of the temperature reduction for the highest and least total heat capacity are obtained with the values of 3% and 12%, respectively.