Abstract:

In this paper, based on the DEM method, the flow of two kinds of nanoparticles with different particle sizes in the rotating fluidized bed was simulated by using MFIX software.Comparing the simulation results with previous experimental results, it is found that the results are in good agreement, which verifies the accuracy and reliability of the rotating fluidized bed model. The movement process of nanoparticles in a rotating fluidized bed is numerically simulated. Adding the van der Waals force, the distribution of nanoparticles, the velocity vector distribution of nanoparticles and the pressure drop of the nanoparticle bed layer changing with gas velocity under different centrifugal accelerations were simulated. The results indicate that a small fraction of nanoparticles become entrained in the upper region of the rotating fluidized bed, while the majority of particles follow the movement of the bed. When the nanoparticles reach an angle of approximately 60°, they experience a downward motion followed by repeated cycles due to particle accumulation. The bed pressure drop in the rotating fluidized bed increases with increasing centrifugal acceleration and gas velocity. Under the same conditions, the bed pressure drop for TiO₂ particles is higher than that of Al₂O₃ particles, and Al₂O₃ particles reach a steady state earlier compared to TiO₂ particles.

Key words: DEM method, nanoparticles, rotating fluidized bed, numerical simulation

摘要：

基于DEM方法利用MFIX软件分别模拟了两种不同粒径纳米颗粒在旋转流化床内的流动。模拟结果与以往实验结果进行比较发现结果吻合较好，验证了旋转流化床模型的准确性和可靠性。对纳米颗粒在旋转流化床中的运动过程进行数值模拟，加入范德华力，得到了纳米颗粒分布、纳米颗粒速度矢量分布以及纳米颗粒床层压降在不同离心加速度下随气速的变化。结果表明，少部分纳米颗粒在旋转流化床上部游离，其余颗粒随旋转流化床运动，当纳米颗粒上升到60°旋转角附近时，颗粒出现回落，然后进行反复运动，由于纳米颗粒的运动受到颗粒堆积的影响，最终纳米颗粒在旋转流化床底部往复循环。纳米颗粒在旋转流化床内的压降均随离心加速度和气速的增加而增加，相同条件下TiO₂颗粒的床层压降大于Al₂O₃颗粒的床层压降，而且与TiO₂相比Al₂O₃ 颗粒先达到稳定状态。

关键词: DEM方法, 纳米颗粒, 旋转流化床, 数值模拟