Transport phenomena in porous media: A review

This paper, a review of the state of the art of the drying process in wet porous media, presents an overview of thermodynamic relations in heat treatment of synthetic fiber fabrics. Heat and mass transfer in wet porous media are coupled in a very complicated way. The structure of the solid matrix varies widely in shape. There is, in general, a distribution of void sizes, and the structures may also be locally irregular. Energy transport in such a medium occurs by conduction in all of the phases. Mass transport occurs within voids of the medium. In an unsaturated state, these voids are partially filled with a liquid, whereas the rest of the voids contain some gas. It is a common misapprehension that nonhygroscopic fibers (i.e., those with intrinsically low moisture content) will automatically produce a hydrophobic fabric. The main significance of the fine geometry of a textile structure in contributing to resistance to water penetration can be stated in a different manner.