Diffusion thermo-hydrique dans les materiaux de construction.

Abstract

The present study concerns coupled mass and thermal transfers in tow simple and multilayered walls, by using constant and variable boundary conditions. The thermal mechanism transfer is presumed by conduction and that of mass is assumed by diffusion. We have adopted thermal conductivity and mass diffusivity which are variable and are functions of water content. Temperature, moisture content, thermal and mass flux continuity is used at the level of layer contact surfaces for multilayered wall. To better know the influence of the variation of the outside conditions on the behavior of the thermal transfer and the evolution of the temperature in the wall. We have adopted external boundary conditions as periodic and sinusoidal form. In order to be much closer from reality, we have studied the transfers in a simple wall made of concrete and in another one which is multilayered. Basing on finite volumes method, some simulations have been realized, using a code of calculation by Fortran 90. The results are validated by comparing them with other studies recently published. They show that: - The transfer coefficients are strongly coupled, and the physical medium characteristics make the thermal transfer unsteady. - The boundary conditions strongly influence the evolution of the temperature in the wall and also the thermal flux densities at the level of wall interior surface.