Influence of ceramic supports on microwave heating for composite dielectric food slabs

Abstract

Abstract A detailed theoretical analysis has been carried out to study efficient heating of one‐dimensional (1‐D) composite dielectric food slabs due to microwaves. Current study involves processing of beef with oil layers with/without ceramic support for various cases, such as the support and/or oil layer is directly exposed to microwaves (case 1), the beef layer is directly exposed to microwaves (case 2) and oil‐beef layers and the ceramic supports are exposed to microwaves at both the sides (case 3). A preliminary analysis on microwave heating has been carried out for beef‐oil composite without any support and the maxima in average power corresponding to resonances occur at various sample thicknesses for all cases. The detailed spatial distribution for various cases illustrates that for small oil thicknesses, heating rate is less and greater heating rate would correspond to larger oil thicknesses specially for case 1. The similar analysis has been extended for all cases with oil layer directly attached with ceramic supports (Al 2 O 3 and SiC). The detailed analysis on spatial distribution of temperature and power during one side incidence illustrate that the greater thermal runaway occurs for case 2 with Al 2 O 3 support corresponding to smaller oil thickness whereas SiC support may cause thermal runaway for larger oil thicknesses. For distributed microwave incidences (case 3), it is observed that Al 2 O 3 support may cause thermal runaway whereas SiC support may reduce the thermal runaway, based on suitable distribution of microwaves at both sides. © 2006 American Institute of Chemical Engineers AIChE J, 2006