Liao Yinhong, Lan Junqing, Zhang Chun, Hong Tao, Yang Yang, Huang Kama, Zhu Huacheng
College of Electronic and Information Engineering, Sichuan University, Chengdu 610065, China.
College of Electronic Engineering, Chengdu University of Information Technology, Chengdu 610065, China.
Materials (Basel). 2016 Apr 25;9(5):309. doi: 10.3390/ma9050309.
Microwave processing of materials has been found to deliver enormous advantages over conventional processing methods in terms of mechanical and physical properties of the materials. However, the non-uniform temperature distribution is the key problem of microwave processing, which is related to the structure of the cavity, and the placement and physical parameters of the material. In this paper, a new microwave cavity structure with a sliding short based on phase-shifting heating is creatively proposed to improve the temperature uniformity. An electronic mathematical model based on the Finite Element Method (FEM) is built to predict the temperature distribution. Meanwhile, a new computational approach based on the theory of transformation optics is first provided to solve the problem of the moving boundary in the model simulation. At first, the experiment is carried out to validate the model, and heating results from the experiment show good agreement with the model's prediction. Based on the verified model, materials selected among a wide range of dielectric constants are treated by stationary heating and phase-shifting heating. The coefficient of variation (COV) of the temperature and temperature difference has been compared in detail between stationary heating and phase-shifting heating. A significant improvement in heating uniformity can be seen from the temperature distribution for most of the materials. Furthermore, three other materials are also treated at high temperature and the heating uniformity is also improved. Briefly, the strategy of phase-shifting heating plays a significant role in solve the problem of non-uniform heating in microwave-based material processing. A 25%-58% increase in uniformity from adapting the phase-shifting method can be observed for the microwave-processed materials.
人们发现，在材料的机械和物理性能方面，材料的微波处理相对于传统处理方法具有巨大优势。然而，温度分布不均匀是微波处理的关键问题，这与腔体结构以及材料的放置和物理参数有关。本文创造性地提出了一种基于相移加热的带有滑动短路器的新型微波腔体结构，以提高温度均匀性。建立了基于有限元方法（FEM）的电子数学模型来预测温度分布。同时，首次提供了一种基于变换光学理论的新计算方法来解决模型模拟中的移动边界问题。首先进行实验以验证模型，实验得到的加热结果与模型预测结果吻合良好。基于经过验证的模型，对从广泛介电常数范围内选择的材料进行静态加热和相移加热处理。详细比较了静态加热和相移加热之间温度和温差的变异系数（COV）。从大多数材料的温度分布可以看出加热均匀性有显著改善。此外，还对另外三种材料进行了高温处理，加热均匀性也得到了提高。简而言之，相移加热策略在解决基于微波的材料处理中的加热不均匀问题方面发挥了重要作用。对于微波处理的材料，采用相移方法可使均匀性提高25% - 58%。
