The drying of capillary porous materials by microwave with rectangular waveguide has been investigated numerically and experimentally. Most importantly, it focuses on the investigation of the distributions of electric field, temperature and moisture profiles within the capillary porous materials. The measurements of temperature and moisture distributions within the capillary porous materials provide a good basis for understanding of the microwave drying process. The mathematical model gives qualitatively comparable trends to experimental data. The calculations of electromagnetic fields inside the rectangular waveguide and the capillary porous materials show that the variation of particle sizes and initial moisture content changes the degree of penetration and rate of microwave power absorbed within the sample. Further, the small particle size leads to much higher capillary pressure resulting in a faster drying time.

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The melting of frozen packed beds by a microwave with a rectangular waveguide has been investigated numerically and experimentally. It was performed for the two different layers, which consist of frozen and unfrozen layers. This paper focuses on the prediction of the temperature field, as well as the microwave energy absorbed, and the melting front within the layered packed beds. Based on the combined model of the Maxwell and heat transport equations, the results show that the direction of melting against the incident microwave strongly depends on the structural layered packed beds because of the difference in the dielectric properties between water and ice.Index Terms-FDTD method, layered packed beds, microwave melting, moving boundary, rectangular waveguide.

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