Abstract A Multiphysics numerical model was developed using COMSOL Multiphysics to study the effect of size, shape and position of catalyst bed within the microwave reactor (2450 MHz). The dielectric properties of HZSM-5 catalyst were measured at different frequencies and nine different temperatures ranging from 25 °C to 370 °C. The heat transfer in porous media was coupled with RF electromagnetics module and flow-through porous media by extracting the heat source term Q for the heat transfer problem from the electromagnetics. A solid-fluid thermal non-equilibrium condition was modelled as the heat is generated within the catalyst. It was observed that sample position, shape and size of the sample, all significantly affect the heating profile and temperature gradient inside the porous media. The experimental results and the predicted temperatures were in good agreement. Microwave heating had higher total internal energy but conventional heating had lower temperature gradient after reaching steady state. Brick-shaped sample heats more uniformly compared to cylindrical sample. If the radius of the sample is decreased, while maintaining the volume of the sample, microwaves penetrate deeper inside the sample, and more uniform temperature distribution is observed throughout the length of the sample.

中文翻译：

---

多孔催化剂床微波加热的数值模拟

摘要 使用 COMSOL Multiphysics 开发了多物理场数值模型，以研究微波反应器 (2450 MHz) 内催化剂床的尺寸、形状和位置的影响。HZSM-5 催化剂的介电性能在不同频率和 25 °C 至 370 °C 的九个不同温度下进行测量。通过从电磁学中提取热源项 Q，将多孔介质中的传热与射频电磁学模块和流通多孔介质耦合。当热量在催化剂内产生时，固体-流体热非平衡条件被建模。观察到样品的位置、形状和尺寸都显着影响多孔介质内部的加热曲线和温度梯度。实验结果与预测温度吻合良好。微波加热具有较高的总内能，而常规加热达到稳态后温度梯度较低。与圆柱形样品相比，砖形样品加热更均匀。如果减小样品的半径，同时保持样品的体积，微波会深入样品内部，并且在整个样品长度上观察到更均匀的温度分布。