关键词: 固定床, 传热, 数值模拟, 颗粒堆积, 微波加热

Abstract:

A three-dimensional, transient gas-solid two-phase fixed bed microwave heating model was established according to the actual experimental setup. The microwave heating effects under four different catalyst particle stacking modes (simple, diamond, cubic, hexagonal) were simulated and calculated, considering the influence of different inlet gas velocities and microwave heating powers. The results indicate that the heat transfer efficiency of the fixed bed reactor is enhanced under microwave heating, with the diamond stacking mode exhibiting the best heat transfer effect among the four stacking modes. The microwave field has a certain directionality, with the highest electric field intensity along the z-axis, resulting in pronounced hotspot effects between particle contact points. In the horizontal direction, there is no strong electric field formed in the y-axis direction perpendicular to the microwave feeding inlet. Based on the diamond stacking model, the calculation results for inlet gas velocity and microwave power suggest that the inlet gas velocity can change the heating rate and the time required to reach equilibrium temperature, while the microwave power only affects the final temperature. As the inlet gas velocity increases, the temperature difference between particles decreases. These findings provide theoretical support for solving the problem of poor heat transfer efficiency in traditional fixed-bed reactors during strong endothermic reactions.

Key words: fixed bed, heat transfer, numerical simulation, particle stacking, microwave heating