Influence of restitution and friction coefficients on the velocity field of polydisperse TiO2 agglomerates in a conical fluidized bed by the adhesive CFD-DEM simulation

The hydrodynamic behavior of cohesive TiO2 nanoparticle agglomerates was studied in a conical fluidized bed. The effects of size, particle polydispersity, and airflow velocity were analyzed in the transition regime from heterogeneous to homogeneous and turbulent fluidization. The simple-agglomerates size was -25-75 ?m with fractal dimensions of -1.95-2.50. Adhesive CFD-DEM simulations were performed to study the interaction between the simple-agglomerates by combining Mindlin-Dersiewicz and Johnson-Kendall-Roberts (JKR) contact models. The effects of restitution and friction coefficients, probability density function, and coordination number of agglomerates were studied on the particle velocity profiles in the spout and annular zones. The error analysis results showed that bed dynamics is more sensitive to a change in the friction coefficient than in the restitution coefficient. A good agreement between the results was found for friction and restitution coefficients close to one, which is evidence of nearly elastic collisions between TiO2 agglomerates. (C) 2021 Elsevier B.V. All rights reserved.