Effect of load on the heating efficiency and temperature uniformity in multi-mode cavity applicators

In this paper, we investigate the effect of load size, geometry and properties on microwave heating efficiency and heating uniformity during microwave processing of materials using multi-mode cavity applicators. For this purpose, a numerical technique based on finite element method and implemented using COMSOL Multiphysics package is deployed to compute heating efficiency expressed in terms of power absorbed by the material divided by the input power. Both field variations and resulting temperature evolutions are computed for each size and shape studied. Results show that heating efficiency and temperature uniformity are dependent on the size, the geometry and the properties of the material to be treated and can be controlled to a large extent by just changing these material characteristics without the need of external impedance matching components. The model is experimentally validated and good agreement between the theoretical and experimental results is obtained.