Impacts of solid-phase wall boundary condition on CFD simulation of conical spouted beds containing heavy zirconia particles

Abstract

The gas–solid flow behavior of a conical spouted bed including heavy particles, zirconia, with density of 6050kg/m3 that typically encountered in chemical vapor deposition (CVD) was studied by the CFD technique. An Eulerian–Eulerian two-fluid model (TFM) in conjunction with the kinetic theory of granular flows (KTGF) was used in a full 3D computational framework. To reduce the computational time, while maintaining the accuracy of the results, polyhedral mesh structure was utilized. Parametric studies of the specularity coefficient and particle–wall restitution coefficient were also performed. The hydrodynamics parameters including particle velocity and solid volume fraction profiles at different bed levels were evaluated, and the overall behavior of particles in the bed was studied. The simulation results showed that the specularity coefficient significantly affects the CFD results, while the impact of small changes in the particle–wall restitution coefficient is not noticeable. Furthermore, a small specularity coefficient of 0.05 provides suitable predictions that are in agreement of the experimental data. Incoherent spouting was also properly predicted by the present CFD model, which was shown to be in agreement with the experimental observations. It was also found that both the no-slip boundary condition and the specularity of φ=1 wall boundary condition predict roughly the same results. Finally, the influences of the drag function and particle–particle restitution coefficient on the CFD results were studied, and the new findings were discussed.