Wicking and Drying in Fibrous Porous Materials

The drying process of fibrous porous media such as textile, paper and filters is substantially significant to the manufacturing cost of these materials. Development of faster and inexpensive procedures for drying fibrous materials is an increasing need in modern industry, so understanding of the enhanced drying processes including the heat and mass transfer mechanisms is urgent. In particular, passive wicking-driven drying in fibrous porous materials has received increasing attention in broader applications including performance garments, heat pipes, electronics cooling and solar steam generation. In fibrous porous systems, the wicking or capillary filling is widely described by the Lucas-Washburn equation. However, the volatile fluid evaporates or dries up at the surface of fibrous porous structures, slowing and hindering the wicking process by deviating the flow dynamics from the Lucas-Washburn relationship. This chapter discusses the basic drying processes together with combined wicking and drying transport phenomena in fibrous porous materials. Optimization of fibrous porous structures for enhanced wicking and drying is also conducted and analyzed. The modeling and optimization results advance the understanding of heat and mass transfer in drying processes in fibrous porous media and will facilitate the engineering of fibrous architectures for various applications.