Multi-physics computer simulation of radio frequency heating to control pest insects in stored-wheat

Radio frequency (RF) selective heating, a novel method to control insect pests in the stored-grains, has many advantages over the existing methods that use pesticides, fumigants, heat, cold, and mechanical pressure. However, there are many variables that can affect the effectiveness of RF selective heating. The finite element method based COMSOL Multiphysics software was used to simulate the selective heating of rusty grain beetle (Cryptolestes ferrungineus, S) in the bulk stored-wheat at 12, 15, and 18% moisture content. The multi-physics – the electric model, and the non-isothermal fluid flow/heat transfer model were coupled, and the transient electrical and the thermal properties of the insect and wheat were used. Only one quadrant of the RF system including the sample was simulated because of the geometric symmetry in the system. The differences between the experimental and the simulated temperatures for the bulk wheat at MC of 12, 15, and 18% were not more than 13.3, 10.2 and 18.1% respectively. The temperature of the insect was 14.1 °C (maximum) higher than the temperature of the host grain. Therefore, there is a potential of this environmentally friendly method in controlling the insect pests in the stored-grains. The non-uniform heating of the samples was observed, and some recommendations to improve the heating uniformity are presented.