CFD simulation of cohesive solid particles' interaction in fluidized bed for determining a regime map of fluidization for cohesive powders

This thesis explored the fluidization behavior of cohesive solid particles within fluidized beds by means of computational fluid dynamics (CFD) simulations. We utilized a developed rheological model for granular materials within a two-fluid model (TFM) simulation, known for its cost-effectiveness and efficiency. Our objective was to construct a regime map for the fluidization of cohesive powders, considering different degrees of particle cohesion, as characterized by the Bond number and tensile stress prefactor. A series of simulations were conducted across a range of particle cohesion levels, employing a particle size of 300 µm and using different fluidization velocities. The outcomes of the simulations revealed the formation of four distinct regimes: bubbling flow, bubbling-clustering flow, bubbleless expansion, and a stationary bed. The boundaries defining these regimes were determined quantitatively based on the ratio of shear-to-yield stress for the solid particles. Importantly, it was observed that these threshold values for demarcating the regimes remained consistent regardless of particle size and fluidization number. The research outcomes enhance our comprehension of the behavior of cohesive powders within fluidized beds. Furthermore, a regime map has been established, which holds the potential to aid operators in predicting and regulating flow patterns.