Boundary/Finite Element Modeling of Three-Dimensional Electromagnetic Heating During Microwave Food Processing

A three-dimensional 3D finite element-boundary integral formulation is presented for the analysis of the electric and magnetic field distribution, power absorption, and temperature distribution in electrically conductive and dielectric materials. The hybrid finite/boundary method represents an optimal approach for modeling of large-scale electromagnetic-thermal materials processing systems in which the volume ratio of the sample over the entire computational domain is small. To further improve the efficiency, the present formulation also incorporates various efficient solvers designed specifically for the solution of large sparse systems of linear algebraic equations. The resulting algorithm with a compressed storage scheme is considered effective and efficient to meet the demand of 3D large scale electromagnetic/thermal simulations required for processing industries. Examples of 3D electromagnetic and thermal analysis are presented for induction and microwave heating systems. Numerical performance of the computer code is assessed for these systems. Computed results are presented for the electric field distribution, power absorption, and temperature distribution in a food load thermally treated in an industrial pilot scale microwave oven designed for food sterilization. Computed temperature distribution in a food package compares well with experimental measurements taken using an infrared image camera.