Microwave processing of materials has been found to deliver enormous advantages over\nconventional processing methods in terms of mechanical and physical properties of the materials.\nHowever, the non-uniform temperature distribution is the key problem of microwave processing,\nwhich is related to the structure of the cavity, and the placement and physical parameters of the\nmaterial. In this paper, a new microwave cavity structure with a sliding short based on phase-shifting\nheating is creatively proposed to improve the temperature uniformity. An electronic mathematical\nmodel based on the Finite Element Method (FEM) is built to predict the temperature distribution.\nMeanwhile, a new computational approach based on the theory of transformation optics is first\nprovided to solve the problem of the moving boundary in the model simulation. At first, the\nexperiment is carried out to validate the model, and heating results from the experiment show\ngood agreement with the modelââ?¬â?¢s prediction. Based on the verified model, materials selected\namong a wide range of dielectric constants are treated by stationary heating and phase-shifting\nheating. The coefficient of variation (COV) of the temperature and temperature difference has\nbeen compared in detail between stationary heating and phase-shifting heating. A significant\nimprovement in heating uniformity can be seen from the temperature distribution for most of\nthe materials. Furthermore, three other materials are also treated at high temperature and the\nheating uniformity is also improved. Briefly, the strategy of phase-shifting heating plays a significant\nrole in solve the problem of non-uniform heating in microwave-based material processing. A\n25%ââ?¬â??58% increase in uniformity from adapting the phase-shifting method can be observed for the\nmicrowave-processed materials.
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