Assessment of drag models in simulating bubbling fluidized bed hydrodynamics

Abstract

The hydrodynamic behavior of gas–solid flow is investigated in a 2-D bubbling fluidized bed reactor filled with 530μm particles. The Computational Fluid Dynamics (CFD) is used to simulate the complex transient behavior of gas–solid flow. The CFD simulation of the bed hydrodynamics is based on the concept of Euler–Euler two-fluid model in combination with Kinetic Theory of Granular Flow (KTGF). In the present study, four different drag models are used to determine the drag force between the two phases and the results are compared. It is observed that the drag model has a significant effect on the simulation of gas–solid flow. The Gidaspow drag model and Syamlal–O'Brien model could predict the core-annulus structure of the bed very well. In comparison, the energy minimization multi-scale (EMMS) model and McKeen model cannot clearly predict the core-annulus structure of the flow. The Gisadpow model was found to provide better agreement with the experimental results of time-averaged particle velocity. On the other hand, the Syamlal–O'Brien model and EMMS model predicted the time-averaged granular temperature comparatively well. The effect of turbulence modeling on the flow behavior is also studied by incorporating the RNG k–ε turbulence model. The results showed that the effect of turbulence modeling on the bed hydrodynamics is not very significant.