The Design Of Microwave Field Uniformity And Numerical Simulation Of Drying Process

The microwave drying technology appeared in 1940s. Through several dozens of years'research and practice, the fundamental research has made great strides, and the application scope has already spreaded widely day by day. Because of microwave drying's unique mechanism, which makes it have many special characteristics, such as high efficiency, short time, high energy usage rate, low pollution, good product quality and so on, it has already gradually obtained widespread approval and application.At first, this article introduces some elementary knowledge of microwave drying, summarizes and analyses comprehensively the relative information about the concept and the characteristics of microwave, the principle and the characteristics of microwave drying. And then introducing some theory knowledge about heat transfer & mass transfer which is used in the simulation of microwave drying. Finally, this article conducts the research mainly about three parts of contents, which are the design of rectangular resonant cavity, the vector distribution of the electric field and the magnetic field in the rectangular resonant cavity vector as well as the numerical simulation of the microwave drying.In the process of microwave drying, the microwave field uniformity has an extremely important influence to the drying result. One of the methods for obtaining uniform microwave field is to maximize the resonant model number in the cavity. Under specific microwave resonance frequency, the resonant model number mainly is decided by the resonant cavity size. Through programming, extracting the most large model number under the specific resonance frequency, thus obtaining the corresponding resonant cavity size. In the foundation about the rectangular resonant cavity structure size design, simulating the vector distribution of the electric field and the magnetic field in the microwave field with the aid of ANSYS, and carries on the theoretical analysis to the electric field and the magnetic field vector distribution. The microwave drying process is an extremely complex heat transfer & mass transfer process which is mainly conducted in the resonant cavity. This article uses the approximate processing method, choosing carrot as drying medium to carry on the microwave drying numerical simulation. Through changing parameters, such as microwave power, frequency and medium coefficient and so on, to obtain the corresponding medium temperature and the moisture content which are changed with time, and then making the comparison with the hot air drying method, obtains that, comparing with the hot air drying, the microwave drying has some characteristics such as quick temperature rising, short drying time, low material moisture content and so on.