The Research On Improving Microwave Heating Uniformity By Hyperbolic Metamaterials

Compared with the traditional heating method,microwave heating has the characteristics of high efficiency and energy saving,choosing heating to start and stop at any time,eco-friendly and portability of equipment and processes.Based on these characteristics,microwave heating is widely used in various fields,such as home microwave ovens have become a common kitchen appliance in every household.However,The poor uniformity of microwave heating,a chronic problem of microwave heating,has become one of the main factors affecting the user experience and hindering the promotion of microwave heating in other industrial fields where uniformity is required.Existing microwave ovens usually use the following two technical ways to improve microwave heating uniformity.One is the turntable microwave oven,this microwave oven by setting up a rotating glass tray in the cavity to enrich the trajectory of the object being heated,thereby improving microwave heating uniformity,but there are often problems such as poor stability of the glass tray,the cavity is not easy to clean.Another is the flat plate make microwave ovens,flat plate microwave ovens are widely sought after because of their beauty,food pickup and easy cleaning of the cavity.At present,the domestic market share of flat-panel microwave ovens up to more than 90%,and continue to expand,the microwave oven manufacturers represented by the Midea also focus on research and development to the flat-panel microwave ovens,but the heating uniformity of flat-panel microwave ovens has been to be improved.This paper studies the laws and methods of using metamaterials to regulate the spatial distribution of the average power density of electromagnetic fields in microwave cavities,and provides a new technical way to improve the uniformity of electromagnetic fields in cavities.The main research results and innovations of this paper include:(1)A method to improve the uniformity of microwave heating using metamaterials is proposed.By optimizing the design of the microstructure of the metamaterial,it can effectively reduce the spatial coherence of the electromagnetic field in the cavity and stimulate more working modes in the cavity.By designing the movement of the electromagnetic metamaterial,it makes the resonant cavity work alternately between the working modes with good spatial complementarity of electromagnetic power density,improves the spatial uniformity of the average electromagnetic power density in the cavity.And makes the average microwave absorbed by each part of the treated material power is approximately equal,so as to achieve the purpose of improving the uniformity of microwave processing.Simulation and experimental results show that the design of hyperbolic metamaterial electromagnetic stirrer using this method can improve the heating uniformity of the original microwave treatment device from 20.9% to 41.8%.(2)The effect law of hyperbolic metamaterial modified microwave cavity wall on the uniformity of microwave heating was studied.Based on the addition of hyperbolic metamaterial electromagnetic stirrer,the hyperbolic metamaterial was further used to modify the microwave cavity wall.The effect of the length of hyperbolic metamaterials,cavity wall attachment position and rotation angle on the heating uniformity was systematically investigated,and a better hyperbolic metamaterial modification structure was optimized.The experimental results showed that the heating uniformity of the microwave treatment device was further improved from 41.8% to 54.2% after the hyperbolic metamaterial modification.