Transport Properties in the Drying of Solids

Abstract

Diffusion in solids during drying is a complex process that may involve molecular diffusion, capillary flow, Knudsen flow, hydrodynamic flow, or surface diffusion. Diffusion of gases, vapors, and liquids in solids, however, is a more complex process than the diffusion in fluids because of the heterogeneous structure of the solid and its interactions with the diffusing components. The method uses a drying experimental apparatus and estimates the heat and mass transport properties as parameters of a drying model that incorporates these properties. In the process model, each mechanism of heat and mass transfer is expressed using a driving force and a transport property as a coefficient of proportionality between the rate and the corresponding driving force. The transport properties are estimated as parameters of the process model by fitting it to experimental data. Only the properties of the controlling mechanisms can be obtained.

Topics & Concepts