Numerical investigation of subcritical and supercritical carbon dioxide fluidized beds using two fluid model and discrete element method

Abstract

Fluidization state of ambient, subcritical and supercritical carbon dioxide (CO2) fluid fluidized beds are simulated using Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) and Two-Fluid Model (TFM) combined with Low Density Ratio-Kinetic Theory of Granular Flow (LDR-KTGF). Quantitative and qualitative analysis were executed between TFM and CFD-DEM simulation results. Fluidization process using two methods coincides with predictions of stability function and different criteria for distinguishing from particulate and aggregative fluidizations. A transitional fluidization with the wave-like and chunk-like flows occurs in subcritical CO2 fluid fluidized bed, and the bubble-like and particle aggregative-like flows are observed in ambient and supercritical states, respectively. The discrepancies in volume fractions and velocities obtained using TFM and CFD-DEM approaches were small, while the predicted turbulent kinetic parameters and bubble-like kinetic energy show sensitivity to the turbulence model. Statistical analysis of the turbulent normal Reynolds stresses indicated an anisotropic flow of particles.