Multiphysics Simulation And Experiment Of Industrial Microwave Oven

As a green and efficient energy source,the microwave has been widely used in the industry and is often used in microwave extraction and other fields requiring liquid heating.In general,the convection of the liquid will contribute to the uniform heating of the liquid,but microwave heating is different.When the liquid is heated by microwave,the top temperature is always found to be the highest.The uneven temperature distribution of liquid heated by microwaves has greatly influenced the application of microwave in the chemical industry such as microwave extraction.On the other hand,in most microwave energy industrial applications,multiple magnetrons are often used to increase microwave power at a low cost.However,when multiple magnetrons simultaneously supply energy,there must be mutual influence between magnetrons,which requires more elaborate design and matching to improve efficiency,uniformity,and safety.Aiming at the above problems,this paper mainly does the following work:1.The coupling simulation model of the electromagnetic field,temperature field,and flow field was established in COMSOL Multiphysics,taking into account the dielectric property,heat transfer property,and fluid property of the heated object that would change with the temperature.The simulation analysis and experimental verification of microwave reheating rice,water,and alcohol were carried out.The phenomenon that the temperature of the top layer is higher than that of the bottom layer when the liquid is heated by microwave is explained.2.The ordinary glass was improved by using a cut-off waveguide.The effects of different heights of water and different lengths of cut-off waveguides on the uniformity and efficiency of microwave-heated water are analyzed by means of multi-physical field simulation.The simulation results show that the uniformity and efficiency of microwave heating water are improved in some cases.3.The ordinary glass was plated with silver through the silver mirror reaction,and the water was heated by microwave using the silver-plated glass.The temperature difference between the top layer and the bottom layer has dropped from 7.8? to 0.5?.4.The energy absorption rate of 4 magnetron industrial microwave ovens was optimized in HFSS,and the cavity height,tuning screw radius,and insertion depth were mainly adjusted.The energy absorption between 2.448 GHz and 2.468 GHz increased by 6% after the final optimization.5.The multi-physical coupling simulation of the electromagnetic field,temperature field,and flow field were carried out for the water heating load of the optimized 4 magnetrons industrial microwave oven.The simulation results showed that the average temperature of the water load of the optimized model increased by 5.4% compared with the original model after heating for the 60 s.