Numerical simulation of temperature distribution in multi-phase materials as a result of selective heating by microwave energy.

In order to discuss the temperature distributions due to microwave (MW) selective heating of multi-phase solids, numerical analysis was conducted. The simulation was performed assuming the dielectric heating mechanism in a dual phase solid in which one phase has much larger permittivity (loss factor) than the other In addition, an electric (E-) field inside the solid was assumed to be homogeneous, the value of which was estimated by a macroscopic electromagnetic (EM) simulation of the solid body placed in a TE10 cavity. In this EM simulation, a single phase solid body having an averaged permittivity value of the dual-phase is assumed. Next, heat transfer calculations were performed in order to obtain the temperature distribution in the dual phase solid, assigning different permittivity values to the phases giving rise different heat source terms in the thermal conduction equation. The boundary conditions were either adiabatic or considering the thermal energy dissipation by radiation to obtain the realistic temperature in the model solid. It was shown that a larger temperature difference resulted in larger particle size. The model considering the temperature dependence of the permittivity predicted a largest temperature difference during several ten milli-seconds.