Microwave phase control heating

Abstract

Food processors are increasingly looking towards new microwave-based technologies to deliver competitive advantage in the market place, reduce operational costs, allow greater product innovation and increase flexibility without the need for large capital investments. The technical barriers to the widespread exploitation of microwave heating, and opportunities for microwave heating in food processing, are discussed in the context of the need to understand the microwave field/material/process interaction. It is shown how a new application of interference techniques, called phase control microwave heating, may offer opportunities for enhanced heat transfer in food processing, especially for direct control of the spatial power deposition within a foodstuff. Simulations of phase control heating using a 3D FETD microwave model, validation of experimental findings and examples in other applications are presented.

Modeling and Simulation of Microwave Heating of Foods Under Different Process Schedules

“…Several systems dealing with the direct control of product heating have been investigated (Bows et al 1999;Gerling 2000). To this respect, the interference of electromagnetic waves (IEW) was employed in order to obtain uniform temperature profiles during heating.…”

A classification system for microwave heating of food

“…Bows et al . (1999) , Fritz (1988) and Lau & Sheppard (1990) showed that this is readily achieved with travelling wave single mode applicators, where it was possible to generate many different heating patterns at any instant in time.…”

“…Bows et al . (1999) described a travelling wave waveguide system to generate conditions for vector addition heating, where the heating pattern in various materials was controlled by changing the phase of one microwave signal relative to the other.…”

“…(1999) described a travelling wave waveguide system to generate conditions for vector addition heating, where the heating pattern in various materials was controlled by changing the phase of one microwave signal relative to the other. Using a low loss material (100 mm length, 72 × 34 mm cross section) and the WR284 waveguide circuit described in Bows et al . (1999) , various heating patterns were generated by changing the phase of one signal relative to the other in 20 ° increments.…”

“… Thermal images along centre plane of a low‐loss food material under phase control heating conditions ( Bows et al ., 1999 ). Relative to the left most image, each subsequent image is heated in 20 ° phase steps.…”