Research On Heating Efficiency And Uniformity Of Photonic Crystal Microwave Reaction Cavity

Microwave heating has the advantages of instantaneous,controllable,and efficient,and has been widely used in food,industry,environmental engineering,and medicine.However,microwave heating has problems such as low heating efficiency and poor heating uniformity.These problems become the bottleneck restricting the development of microwave heating.Uneven heating will cause hot spots and thermal runaway,and low heating efficiency will not only waste energy,but also cause excess microwave energy in the reaction chamber to return to the feed port,which may burn out the magnetron or other microwave sources equipment.Therefore,improving the utilization efficiency of microwave energy and improving the uniformity of microwave heating has always been a hot and difficult research topic for experts and scholars.Microwave reaction cavity is the key equipment of microwave heating system,and its performance is of great significance to improve the efficiency and uniformity of microwave heating.Based on the review and analysis of microwave heating theory,photonic crystal theory,dielectric properties theory and other related theories and applications,this paper designs and conducts research on the heating efficiency and heating uniformity of photonic crystal microwave reaction cavity.The main work is as follows:(1)Based on the Bragg scattering properties of photonic crystals for electromagnetic waves,photonic crystals in the microwave band were introduced into traditional cylindrical and rectangular microwave reaction cavities,and the concept of a new type of photonic crystal microwave reaction cavity was proposed.(2)A novel cylindrical photonic crystal microwave reaction cavity is designed.The effects of photonic crystal structure parameters,defect location and number on the heating efficiency and heating uniformity of the reaction cavity were studied by HFSS software simulation in the case of single-fed and double-fed ports.(3)It is proposed to place a trapezoidal photonic crystal structure around the inner wall of a conventional rectangular microwave reaction cavity.COMSOL Multiphysics software is used to simulate and analyze the effects of photonic crystal structure parameters and defect positions on the heating efficiency and heating uniformity of the rectangular microwave reaction cavity when the load shape is rectangular or cylindrical.(4)Two controllable photonic crystal microwave reaction cavities with eccentrically rotatable copper cylinders are designed.During the heating process,the position of the copper cylinders can be changed in real time,and the periodicity of the copper cylinders arrangement in time and the dynamic controllable heating of the photonic crystal microwave reaction cavity are realized.