Effect of thermal intensity and initial moisture content on heat and moisture transfer in unsaturated soil

Abstract

Soil is an economical and convenient energy storage medium that can be used for air conditioning and space heating. Thermal intensity and soil initial moisture content are the key factors influencing moisture transfer in soil. In this paper, we investigated the coupled heat and moisture transfer in unsaturated soil under thermal effects, and developed mathematical models in one-dimension for the coupled heat and moisture transfer processes. A series of experiments with different thermal intensities and initial moisture content were carried out to observe temperatures and moisture contents in sandy soil. The model was validated on the basis of experimental data. The soil column experiment results showed that moisture transfer flux was positively correlated with heat source temperature. In addition, under different initial moisture content conditions, the effects on moisture transfer were different even under the same driving force of temperature gradient. Under the same heat source temperature, soil with low moisture content had a strong moisture transfer, thus removing more heat, but the actual process showed that soil with high moisture content had a strong heat transfer, indicating that heat transfer, which indicates that heat conduction played a more important role than moisture transfer.