Dynamic Heat and Water Transfer Through Layered Fabrics

A model of heat and water transfer through layered fabrics, such as wearing clothing, is developed in this paper. All particular properties of recently developed fabrics are considered: hydrophobic or hydrophilic treatment, membranes glued onto a layer. and surface modification of the textile (abrading). Physical phenomena taken into account are sorption or desorption; free water condensation or evaporation: liquid. vapor, and ad sorbed water diffusion; and heat conduction and contact resistances between layers. The model is dynamic for one-dimensional transfers. Considering this particular porous medium, the energy and mass balance lead to a system of two differential equations (moisture, temperature). The validity of the model is examined in light of basic experi ments existing in the literature. The hygroscopic character of a fabric can be expressed by a diffusion coefficient, which is a function of the water content. Two possible formulations of this property are given.