Multiphysics Modeling to Assist Microwave Cavity Design for Food Processing

Abstract

Microwave technology has many current applications. It is very useful for food processing, including domestic cooking and warming-up and industrial heating and drying. It heats faster than conventional applications; however, in most cases result in non-uniform temperature distribution. Adequate cavity and equipment designs can reduce the impact of these heterogeneities and using multiples magnetrons is a possibility to mitigate hot and cold spots. Yet, the literature lacks methods to evaluate and compare multiple magnetrons designs. This study aimed to develop a procedure to evaluate the number and position of magnetrons connected to an application cavity using multiphysics modelling and simulation of the microwave distribution and heating of a food model. It was based on evaluating the electric field distribution into a selected working volume filled with air or a mixture of air-potato and the consequent effective power absorbed and temperature distribution into the air-potato medium. The assisted methodology with process simulation offers an insight into food temperature distribution, which would be very difficult to obtain experimentally or in any equipment design methodology. In this case study, it was found that up to 6 magnetrons are good enough when active in approximately 0.16 m3 cavity with a load that fills 10% of its volume.

Raw Kernels Packaged for Toasting: A Current Challenge for Microwave Technology

“…The narrow and stable bandwidth of the solid-state generator produces a single standing wave pattern, resulting in stable and predictable food heating patterns, inferring that the available information provides fundamental insights into solid-state microwave heating [32]. Considering the magnetron as a fundamental element in microwave technology, it is estimated that the increase in magnetrons in specific positions makes it possible to overcome the problem of non-uniform temperature distribution in the cavity [33]. Concerning the non-uniform electromagnetic field distribution caused by reflection at the cavity walls, its geometry seems to be decisive in how microwave heating is distributed, so sample rotational movement, cavity geometry, and frequency can affect temperature and electromagnetic field distribution at the industrial scale [30].…”