Simultaneous transfer of heat and moisture in porous media

TLDR

These equations generalize those derived by Philip and de Vries (1957). The study develops simultaneous differential equations for heat and moisture transfer in porous media under gravity and temperature and moisture gradients. The equations distinguish liquid and vapor moisture changes and analyze steady‑state heat‑moisture interaction for clay loam and medium sand soils. The behavior depends on moisture‑transfer boundary conditions, temperature‑gradient direction, and the ratio of two moisture diffusivities.

Abstract

Simultaneous differential equations for the transfer of heat and moisture in porous media under the combined influence of gravity and gradients of temperature and moisture content are developed. These equations are a generalization of those derived by Philip and de Vries [1957]. In particular a consistent distinction is made between changes of moisture content in the liquid and the vapor phase. The interaction between heat and moisture transfer in steady state heat conduction is discussed in detail using numerical values for two soils, a clay loam and a medium sand. The behavior is found to be dependent on the boundary conditions for moisture transfer, on the direction of the temperature gradient and on the ratio of two moisture diffusivities enterbag in the analysis.