Research Of Uniformity Evaluation Model Based On Entropy And Clustering In The Microwave Heating Processes

The "Energy-saving emission reduction" strategy has become a solid foundation for the national economy sustainable development, which as one of the basic national policy of China. The microwave energy can be widely application in the high energy consuming industries. In the future, the microwave energy can effectively alleviate the tension of energy supply and reducing emissions of waste. Thus, it’s a great significance for the "Energy-saving emission reduction" strategy when widely used the microwave energy.The Microwave heating is different to the conventional heating, which through the microwave penetration to the interior of the materials to make rapid heating. Microwave heating has the characteristics of high efficiency, fast speed, and to the materials of solid or liquid can be better heating. However, the factors of material dielectric properties、the distribution of electromagnetic field、the resonator parameters and other internal or external factors, which can prone to overheating in the process of microwave heating and even produce the thermal runaway phenomenon. Thus, the phenomenon of the overheating and the thermal runaway can seriously restricting the industrial application of microwave energy. Therefore, the solution of the temperature uniform distribution in materials during microwave heating has become an important research topic in the widespread industrial application of microwave energy.To lay the foundation for analyzing the temperature distribution in material microwave heating. Firstly, the microwave heating control system has been designed, which based on the analysis of microwave heating theory. Secondly, the microwave output power can be stabilized by choose the mature control algorithm. Thirdly, the uniformity evaluation model has been proposed by combined with the concept of entropy and spectral clustering, which considered the basis of the Maxwell’s equations and the heat transfer equations. Finally, the uniformity evaluation model has been used into analyze the distribution of material temperature field uniformity in the microwave heating process. At the same time, a solution of causes the localized overheating can be analyze by the model.Firstly, the joint simulation combined COMSOL with MATLAB software has established a real system dimension model. The data of temperature field、electric field amplitude、magnetic field amplitude、coordinate information and others has been obtained by the COMSOL simulation. Secondly, some laws have been found through using the uniformity evaluation model to deal with the data. And then, the results of experimental in microwave heating control system, which is consistent with the model results. It can provide new guidance for microwave research and proof the correctness and effectiveness for the model. The research results show that: the microwave heating uniformity depends on the materials characteristics and the electromagnetic field distribution uniformity in the microwave resonant cavity. When the initial material temperature is constant and the microwave input power at increasing, the uniformity of temperature distribution in the material is not deteriorated only at the input power at 600 W or more. The temperature uniformity of material can be better, when the input power is constant and the initial temperature of materials becomes increase. The minimum uniformity evaluation results and the best material heating uniformity can be obtained, when the center coordinates at(14/20*do, 5/20*wo) by changing the position of cylindrical material in the microwave resonator. The best effect material heating can be obtained, when the coordinates at(0, 11/20 * d0, 3/14 * h0) by changing the position of waveguide port.Overall, the characteristics of temperature distribution in the microwave heating processes can be effectively analyzed by the uniformity evaluation model. At the same time, the model can be validated by the control system of the microwave heating.