Analysis of microwave heating for cylindrical shaped objects

Microwave heating is very popular in food industries as well as in home and office to warm up foodstuffs quickly. However, this technique provides non-uniform heating within the system. The potential existence of standing wave due to the transmission and reflection from interfaces is responsible for this non-uniform heating. Therefore, it is important to study the coupling between electromagnetic wave propagation and energy transfer in the system to predict the temperature distribution within the foodstuff. In this paper, a closed-form analytic solution is presented to predict the temperature distribution within a cylindrical shaped foodstuff under microwave heating by solving an unsteady energy equation. A simplified Maxwell's equation is solved for electric field distribution within the body. The heat generation by microwave is calculated from the electric field distribution within the body using Poynting theorem. The effects of cylinder radius, heat transfer coefficient and incident frequency are studied for different length of the cylindrical foodstuff. It is found that the temperature within the body is very sensitive to cylinder length and time. The results indicate that uniform and effective heating depend on the proper integration of geometric parameters and dielectric properties of the object as well as the frequency of the incident electromagnetic wave. This rigorous analytic investigation will provide significant insight to understand and overcome the challenge of non-uniformity in temperature distribution in microwave heating.