Development of an integrated multi-grid 3D FDTD and finite-difference heat transfer code to simulate microwave drying in multimode cavities

In this paper, we describe the development of a unified code for simulating microwave processing of materials in multimode cavities. The integrated codes include a multi-grid 3D FDTD code and a finite difference heat transfer program. The code was used to simulate various feed options for the microwave cavity to help control and improve the uniformity of heating. The heat transfer code together with knowledge of the dielectric properties of materials as a function of temperature, which is also measured in our laboratory, provide significant information that help design controlled and high-yield microwave drying processes. Simulation results from both the multi-grid FDTD and the heat transfer codes are described, and suggestions for optimizing the drying uniformity discussed.