Designing system cavity geometry and optimizing process variables for continuous flow microwave processing

Abstract

Microwave application is a significant industrial food process applied from thawing to drying and pasteurization – sterilization. While its unique feature is the volumetric heating, the distinct drawback of a microwave process, as a contradiction, is the temperature non-uniformity due to the limited penetration depth. In addition to the effects of sample geometry and physical properties, cavity design is another significant factor for temperature uniformity especially in the continuous flow industrial systems, but this approach did not receive the required attention to prevent this noted contradiction. Therefore, the objective of this study was to demonstrate optimization studies for cavity geometry and process design in industrial scale continuous flow microwave systems. For this purpose, a previously (experimentally) validated mathematical model was used for optimization studies in industrial scale continuous flow systems. These systems had cylindrical (915MHz frequency) and rectangular (2450MHz frequency) cavity geometries. The results demonstrated that the cavity geometry had a significant effect for increasing the process efficiency while the pipe orientation within the system affected the electric field distribution and resulting temperature uniformity. This study also confirmed a different view to the industrial scale continuous flow microwave process for improving the system design and optimizing the process variables.