微波多模腔金属边界移动对加热的影响研究

微波加热作为一种新型、高效的加热方法,在化学催化及材料处理等方面有着巨大的优势,但是微波加热的非均匀性限制了其在化工等行业中的大规模应用.本文设计了一种可移动金属壁的微波加热多模腔.在加热过程中,通过单向移动微波多模腔的金属壁,实现腔体内电场分布的不断改变,从而达到提高加热均匀性的目的.在仿真计算中,通过使用移动网格方法实现了整个加热过程的模拟计算.通过与离散位置的电场值和端口反射系数比较,验证了计算方法的准确性.通过比较被加热物质的温度变异系数(COV),可以看出移动金属壁的微波多模腔的加热均匀性相对于固定尺寸的多模腔的提高了近18%~38%.同时,本文分析了不同金属壁移动方式对加热效果的影响,提出可根据材料的属性和要求,计算选择理想的金属壁移动方式,获得更优的处理结果.

Study on the Influence of Metal Boundary Movement on the Heating of Microwave Multimode Cavity

As a new and efficient heating method, microwave has a great advantage in chemical catalysis and material processing. However, the non-uniformity of microwave heating has limited its application in the chemical industry. A multi-mode microwave cavity with moving metal wall is designed in this paper. In the heating process, the electric field distribution of the cavity is constantly changing by moving the metal wall of the cavity, thereby achieving the purpose of improving the heating uniformity. In the simulation, by using the moving mesh method, the simulation of the whole heating process can be realized by a continuous algorithm. The accuracy of the algorithm is verified by comparing with the electric field distribution of the cavity and reflection coefficient of the port with that of the discrete position. By comparing the temperature coefficient of variation (COV) of the heated material, it can be considered that the heating uniformity of the microwave multimode cavity with a moving metal wall is increased by 18%-38% compared to that of the fixed size multimode cavity. Meanwhile, we analyzed the effect of different metal wall movement modes on the heating effect, and concluded that one can choose the metal wall movement mode according to the properties of the material and other requirements.