Effect of rotation on temperature uniformity of microwave processed low - high viscosity liquids: A computational study with experimental validation

Abstract

Microwave processing of liquid foods is a recent trend with volumetric heating effect compared to conventional processing. A certain temperature non-uniformity is, however, still observed due to non-uniform electric field distribution. This is especially significant in high viscous products due to the difficulty in creating natural convection mixing. Enabling rotational effects to liquid might be an approach to obtain a uniform temperature distribution. Therefore, the objectives were to develop a mathematical model for microwave processing of liquid foods, experimentally validate it and demonstrate rotation on temperature uniformity. A multi-physics finite element program was used for model development, and experimental studies were carried out in a batch system at 2.5 rpm. Validated model was then used to demonstrate the improved temperature uniformity in low - high viscous liquids with rotation (0 to 20 rpm). Considering the recent trend in the use of continuous microwave system for the industrial production, this study is expected to give a certain sight for rotational effects on microwave processing. The experimentally validated model is now to be expanded for further design and optimization studies for industrial scale continuous systems.