Efficient microwave processing of oil–water emulsion cylinders with lateral and radial irradiations

A detailed theoretical analysis has been carried out to assess the role of lateral and radial irradiations on the microwave heating of 2D cylinders for both o/w and w/o emulsion samples. Lateral irradiation represents the sample incident at one direction with the source at infinity whereas radial irradiation represents the situation where the sample is incident with microwave radiations from the coaxial cylindrical cavity at infinity. For both of lateral and radial irradiations, the effective microwave incidence from the source is assumed to be identical. A preliminary analysis on the microwave heating of samples has been carried out via average power within a sample vs. sample diameter for emulsions with various ϕϕ values (volume fraction of the disperse phase). The samples with smaller diameter are found to have larger average power with radial irradiation for both o/w and w/o emulsion samples. The hot spot formation within a sample is found to be a strong function of lateral/radial irradiation for various emulsion compositions. The radial irradiation or conventional microwave heating with turntable rotation in ovens is not favorable especially for large w/o samples as the hot spot occurs at the center resulting in larger thermal gradient. The present work provides guideline on the heating policy based on either lateral or radial irradiation depending on the sample size and emulsion dielectric properties.