The Design Of Microwave Chemical Reactor System-"Yangshao-Ⅰ"

Microwave chemistry is one of the fastest developing scientific fields. And microwave chemical reactor plays an important role in microwave chemical engineering. However, the design of microwave chemical reactor is a complicated engineering problem and demands not only microwave techniques but also chemical theories. So far, various microwave chemical reactors have been developed by a lot of manufacturers domestic and abroad. Though those reactors can effectively heat the chemical reaction, the power absorbed by the reaction can not be obtained exactly in most of reactors. However, the study on mechanism of microwave chemical reaction depends much upon the power absorbed by the reaction. To solve this problem, a novel microwave chemical reactor called "Yangshao — I " is investigated in this paper. That microwave chemical reaction system is designed based on BJ-9 rectangular waveguide and operates at 915MHz.First, finite difference time domain (FDTD) method is used to calculate the electromagnetic field distribution in the waveguide. After get the steady-state data, two methods based on Poynting vector and standing wave ratio (SWR) respectively are studied to obtain S-parameters. The S-parameters calculated by those two methods are compared with those derived from transmission line theory. Good agreement can be observed. It shows that the two methods are valid and practical for the FDTD simulation.Second, leakage of the "Yangshao— I " system is computed. Results show that the leakage is far smaller than the international standard — 1mW/cm2, and itis impossible to be detected by instrument.Third, the electromagnetic field and power distribution in the waveguide loaded with a beaker of water are simulated by using FDTD. Conclusion drawn from simulation results is: the smaller the radius of water is, the more homogeneous the electromagnetic field and power distribution are.Finally, the S-parameters for different radius of beaker at different temperature are studied. The complex relative permittivity of water changes greatly with temperature. As a result, S-parameters vary with both the temperature and radius of water nonlinearly.