Analysis of collision characteristics in a 3D gas- solid tapered fluidized bed

This study concerns the dynamic of particle-particle collision characteristics in a threedimensional gas-solid tapered fluidized bed. To this aim, a two-way coupled discrete element method and computational fluid dynamics is used to obtain the position and velocity of particles in the bed. By post-processing of data, the collision characteristics such as the collision frequency, relative collision velocity, and contact time of colliding particles are calculated. Next, the effect of inlet air velocity (v(inlet)) on the particulate flow dynamics and collision characteristics is studied statistically. Predictive equations for collision parameters are obtained in terms of the dimensionless v(inlet) using the regression analysis. Furthermore, it is shown that the relative collision velocity has a Log-normal distribution and its parameters are computed in time. Additionally, the collision characteristics are calculated and analyzed in the different zones of the bed. The results indicate that no collision occurs at heights upper than 350 mm for v(inlet )up to 6.8 times the minimum fluidization velocity. Finally, the particle-particle collision frequencies are compared with the Martin and Gidaspow models where, on average, the minimum differences at v(inlet) = 2.2m/s as 29.7 and 22.6 s(-1) and the maximum ones at v(inlet) = 0.7 m/s as 48.1 and 29s(-1), respectively. (C) 2022 Published by Elsevier Ltd on behalf of Institution of Chemical Engineers.