FINITE ELEMENT MODELING AND ANALYSIS OF RADIO FREQUENCY HEATING RATE IN MUNG BEANS

Radio frequency (RF) heating has been extensively studied as a novel disinfestation method for dry agricultural products. A major difficulty in using this method is that different heating rates at the corners and edges of materials may cause negative effects on product quality. A systematic analysis of factors that influence the RF heating rate is desirable to help in designing effective treatment protocols. A finite element model using COMSOL Multiphysics software was developed and experimentally validated with 3 kg of mung beans in a 6 kW, 27.12 MHz free-running oscillator RF system to study the influence of sample moisture content, density, specific heat capacity, thermal conductivity, dielectric properties, top electrode voltage, and electrode gap on RF heating rate. Simulation results demonstrated that the variation in sample density and specific heat capacity, especially thermal conductivity, had a relatively slight effect on RF heating rate. The RF heating rate was significantly influenced by electrode gap, top electrode voltage, and the dielectric properties and moisture content of the sample. These heating rate distributions might be valuable in guiding and optimizing RF treatment conditions, which are helpful to improve RF heating uniformity for disinfecting dry products.