Experimental study on coupled heat and moisture transfer in soils during heat absorption and release processes

Abstract

Heat and mass migration during the process of heat absorption and release in soil, as a randomly distributed porous medium, is different. The main objective of this work was to comparatively analyze the difference in heat and moisture transfer during the process of heat absorption and release in different soil. In this paper, an experimental study on heat and moisture migration in soils (coarse sand, gravel, and loam) was carried out, during heat absorption and release processes under the same excess temperature. Results showed that moisture migration nonlinearly increases with the excess temperature and initial moisture content, temperature variation linearly increases with the excess temperature, and hardly changes with the initial moisture content. There would be obvious deviation in temperature distribution during the process of heat absorption and release in gravel, loam and coarse sand with an initial moisture content of 15.4%, 20.4%\\23.3% and 23.3%, under the excess temperature of ±20 °C. The temperature variation and moisture migration during heat absorption process are all greater than those during heat release process. The final temperature distribution deviation of loam is the largest, reaches 15.7%, the final moisture migration difference of gravel is the largest, reaches 31.7%, and the moisture migration difference increases with soil porosity.