Improvement of Microwave Heating Efficiency and Uniformity by Controllable Rotary Columns Array

The electromagnetic boundary (EMB) will primarily determine the reflection and distribution of the electromagnetic field. Therefore, a controllable time-varying EMB of microwave reaction cavity (MRC) provides a possibility for improving heating efficiency and uniformity. In this article, a controllable time-varying EMB is fabricated by placing a controllable rotary column array (CRCA) in a conventional cylindrical MRC, where the CRCA consists of 20 circularly arranged controllable eccentric rotary copper columns. The influence of the eccentric distance and the rotating angle of CRCA on the heating efficiency and uniformity are studied by the finite element simulation software—COMSOL Multiphysics. Based on CRCA, angle selection and dynamic rotational heating processes are proposed. Furthermore, the heating uniformity of the angle selection heating process is optimized by using the minimum method of energy loss distribution coefficient of variation (COV). To validate the simulation result, the corresponding heating system is made and the experiments are carried out, and the experiment result agrees very well with the simulations. The simulation result also shows that the heating efficiency and uniformity are improved up to 31.52% and 220.62%, respectively. Finally, the effects of the two heating processes on objects of different shapes and materials are discussed.