Effect of Turbulence Model on the Hydrodynamics of Gas–solid Fluidized Bed

Abstract

AbstractFluidized bed reactors have been extensively employed in processing industries as it provides perfect mixing, efficient operation, and large heat and mass transfer rates. Understanding the particle–fluid interaction inside the bed is a significant parameter for the effective operation of the fluidized bed. This work aims to study the effect of the turbulence model on the mean solids volume fraction and mean flow field at different operating parameters (static bed height, inlet velocity). In the current numerical study, the unsteady multiphase simulations are performed in a three-dimensional fluidized bed (Gao et al. 2012) using the two-fluid model (TFM) with the kinetic theory of granular flow (KTGF) option. k-ℇ is selected to model the turbulence. Gidaspow, Syamlal and O’Brien and energy minimization multiscale (EMMS) drag models are considered for modeling the interphase momentum exchange coefficient. The three-dimensional models could capture the flow behavior inside the turbulent fluidized bed. The numerically predicted time-averaged solid volume fraction fits well with the experimental data at the center compared to the wall using the incorporation of EMMS drag with the k-ℇ turbulence model. Similar to the experiments, a dense region is observed with descending particles near the wall and the dilute region near the center portion of the bed. It can be noted that close numerical predictions can be obtained using the selection of an appropriate drag model and turbulence model.KeywordsCFDDragGas–solid fluidized bedHydrodynamicsTurbulence model