Simulation Study On Heating Efficiency And Uniformity Of High Power Rectangular Microwave Reactor

Microwave heating has been widely used in the production and daily life, as its speediness, high efficiency, homogeneity, strong penetrating, choosability. An important standard to measure the performance of microwave reactor is Microwave heating efficiency and uniformity. Different material and size heating object will affect the reaction cavity distribution in the electromagnetic field, and then appear different heating efficiency and uniformity. Therefore exploring the distribution of the microwave reaction cavity of heating the different object in the electromagnetic field helps the Optimizing design of microwave reactor. Based on high frequency electromagnetic simulation software HFSS, the thesis studied heating efficiency and uniformity of a kind of high power rectangular microwave reactor when it is loaded with different materials and different shapes. The main job description as follows:Overviewing the basic theory of microwave heater, it includes dielectric polarization, Microwave heating principle and characteristics, Microwave transmission in the medium, rectangular resonant cavity theory, perturbation theory, finite element theory and HFSS in the application of the microwave heater design.After selecting the right dimensions of microwave reaction cavity,then use HFSS electromagnetic simulation software to simulate the feed Angle,feed length, feed distance, load size and distance from the cavity bottom when loaded with fly ash and glass material, which will affect the heating efficiency. The results showed that:(1)When the cylinder,sphere and cuboids are loaded with fly ash, if you want the highest heating efficiency, the feed mouth Angle should be 162o、102o、82o; when loaded with glass material, the feed mouth Angle should be 134o、60o、174o.(2) When the feed length is more than 50 mm, its impact on the heating efficiency remains unchanged.(3)When loaded with the fly ash, the high heating efficiency could be obtained as the distance from the feed to the center of the cavity top is between 60 mm ~ 70 mm;when loaded with the glass material, feed distance to cylinder, cuboids,sphere should be 44 mm, 104 mm, 63 mm.(4) The cylinder and the cuboids will have higher heating efficiency when the loading thickness is about 110 mm; the sphere shaped fly ash and glass material will have higher heating efficiency when its radius is 60 mm or 95 mm.(5)When loaded with fly ash, the higher heating efficiency will appear under the condition that the distance from the cylinder and the cuboids to the cavity bottom is between 0 ~ 20 mm, for sphere the distance is 50 mm; when loaded with the glass material, the distance for cylinder and sphere is between 10 ~ 20 mm,while the distance for cuboids is 35 mm or 75 mm. After optimization, when loaded with fly ash, the heat efficiency of the cylinder and the cuboids are more than 98%, when the highest was 99.7%.For sphere, the heat efficiency is up to 88.82%; when loaded with the glass material, the heat efficiency is more than 90%, and up to 96.38%.Studying the feed quantity’s influence on the heating uniformity, under the precondition of giving consideration to the heating efficiency, we get the following conclusion. For fly ash material, increasing the feed quantity can obtain more uniform electromagnetic field distribution; for glass materials, increasing the feed quantity instead lead to poor heating uniformity.