关键词: 固定床反应器, 管径比, 数值模拟, 空隙率, 流体流动特性

Abstract: To accurately characterize the hydrodynamic behavior in fixed-bed reactors, cylindrical packed-bed models with different tube-to-particle diameter ratios D/d_p, defined as the ratio of reactor diameter D to particle diameter d_p, were constructed using rigid-body dynamics in Blender. Numerical simulations were then performed in Fluent to investigate the effects of D/d_p on bed flow characteristics.The results show that, at a given D/d_p, both radial voidage and gas-phase velocity exhibit oscillatory distributions, with higher values near the wall and lower values near the bed center, indicating wall-induced structural heterogeneity and flow maldistribution. As D/d_p increases, the fluctuation amplitudes of voidage and gas velocity decrease, suggesting a weakened wall effect and improved radial uniformity. Under the same superficial air velocity, the bed pressure drop increases with increasing D/d_p.Compared with the voidage predicted by the de Klerk correlation and the pressure drop calculated using the Eisfeld modified correlation, the Blender-generated packed-bed model shows better agreement with experimental data, demonstrating its improved accuracy in representing local packing structure and flow behavior in fixed beds.

Key words: fixed-bed reactor, tube-to-particle diameter ratio, numerical simulation, voidage, fluid flow characteristics