Heating concentrations of microwaves in spherical and cylindrical foods. Part One: in planes waves.

摘要

A comprehensive and systematic study of internal focusing of microwaves during heating in spherical and cylindrical materials was conducted, based on theoretical analysis and numerical investigations for plane waves. Along with penetration depth, wavelength was introduced as a parameter for characterization of microwave heating of foods. Based on theoretical analysis, the distributions of power density in a radial direction were studied for various groups of foods and food simulants with radii ranging from 0.5 to 13.5 cm, including vegetables and meats. At 2.45 GHz the focusing areas were pronounced in terms of dielectric properties and the radii were then presented as heating diagrams. For example, the smallest radius that could lead to heating concentration of microwaves was found to be 0.5 cm for any food material, and the upper limit of the radius that incurred central heating of unfrozen foods was 13.5 cm.