ABSTRACT

With respect to heat transfer, fibrous assemblies must be treated as a special case of porous media. Over that, the textiles of hygroscopic fibers containing absorbed water and placed in a temperature gradient are porous media with a phase change. Absorbed water evaporates in the region with higher temperature consuming energy. The vapor then diffuses toward the lower temperature region and condenses again. Thus, an additional heat transfer mechanism occurs in hygroscopic textiles. The contribution of this mechanism to the total heat transport is quantitatively studied and conclusions with respect to thermal insulating properties are formulated.