Coupled thermal-electromagnetic model for microwave heating of temperature-dependent dielectric media

Abstract

Microwave heating processes involve electromagnetic and thermal effects coupled together through the local temperature dependence of the material dielectric properties. This paper presents a one-dimensional model for the coupled electromagnetic-thermal process and demonstrates its solutions for typical problems. The local temperature dependence of the lossy dielectric medium is taken into account in two different time scales. One is the heat-generation time scale due the microwave radiation, and the other is the temperature diffusion time scale. The two timescale approach minimizes the computation time and provides an efficient simulation tool for the analysis of various phenomena. The two-scale model presented in this paper is benchmarked by a comparison of its numerical results with other models published in the literature. Several examples of microwave heating processes in various materials are simulated. Effects of heatwave propagation in matter are predicted by the model. The results show the temporal and spatial evolution of the temperature and power-dissipation profiles. Variations in the (microwave) impedance profile in the medium due to the heating are computed. A further development of this model, including more complicated geometries and various loss mechanisms, may yield useful numerical tools for the synthesis and design of microwave heaters in which the heated material acts as a nonlinear load in the microwave circuit.

Analysis and control of the thermal runaway of ceramic slab under microwave heating

“…Other ceramic parameters related with the HTE were obtained from ref. [19]. Some main parameters in simulation are shown in Table 1.…”

“…In the numerical simulation of thermal runaway, a coupled system of Maxwell's equations and the heat transfer equation (HTE) has to be solved. In 1999, Alpert and Jerby [19] presented a coupling method with two time scales to solve it. Later, a finite element method with an adaptive time step scheme was developed [20] .…”

Microwave material processing—a review

“…82 Later, several works have been reported on power absorptions based on Maxwell's equations. [83][84][85] Spatial analysis of Maxwell's equation has also been carried out for food processing. Maxwell's equations for electromagnetic fields and the heat conduction equation were solved to predict temperature distribution in food processing for the pasteurization of prepared meals.…”

Modeling of microwave heating of particulate metals

“…Elsewhere, a simulation package based on 2-D modeling of microwave heating of ceramics was developed by Craven et al, [18] who used a coupled electromagnetic-thermal model. This approach was further extended by Alpert and Jerby [19] for microwave heating of temperature-dependent dielectric media.…”