On the Computational Modeling of Unfluidized and Fluidized Bed Dynamics

Two factors of great importance when considering gas-solid fluidized bed dynamics are pressure drop and void fraction, which is the volume fraction of the gas phase. It is, of course, possible to obtain pressure drop and void fraction data through experimentation, but this tends to be costly and time consuming. It is much preferable to be able to efficiently computationally model fluidized bed dynamics. In the present work, ANSYS FLUENT is used to simulate fluidized bed dynamics using an Eulerian-Eulerian multiphase flow model. By comparing the simulations using FLUENT to experimental data as well as to data from other fluidized bed codes such as Multiphase Flow with Interphase eXchanges (MFIX), it is possible to show the strengths and limitations of FLUENT with respect to multiphase flow modeling. The simulations described herein will focus on modeling of beds in the unfluidized regime, where the inlet gas velocity is less than the minimum fluidization velocity, and will deem to shed some light on the discrepancies between experimental data and FLUENT results. In addition, this paper will also include comparisons between experimental data and simulation data in the fluidized regime based on void fraction contours and profiles.