Theoretical Analysis of Heat-Mass Transport and Pressure in Unsaturated Porous Material: Under Microwave Energy (Influence of Particle Size, Electric Field Intensity and Frequency)

Abstract

In this study, a multiphase porous media model was developed to predict heat transfer and moisturetransport during microwave drying of unsaturated porous material. A total gas pressure equation wasintroduced to address internal vapor generation in microwave drying. The resulting governing equationswere numerically solved with the finite volume method. All the physical, thermodynamic, thermal, transport,and dielectric properties used in the simulation were for unsaturated porous material (composed ofglass beads, water and air) and were either from our measurements or from the literature. The resultsshowed that variation of particle size, electric field intensity and frequency gave strong effect on overalldrying kinetics. The moisture profile in the unsaturated porous material suggests the importance of capillaryflow in microwave drying. The results could provide a basis for fundamental understanding of microwavedrying of unsaturated porous materials and they could be applied as a useful tool for exploring practicalproblems.

Keywords : Unsaturated Porous Material / Particle Size / Electric Field Intensity / Frequency