Evaluation of Interphase Drag Models for the Determination of Gas Hold-Up of an Air-Water System in a Spouted Bed using CFD

Abstract

Abstract: The hydrodynamics of a dispersed air-water system within a spouted column with a concentric draft tube and a conical base is simulated using CFD based on a two–fluid Euler–Euler (E-E) modeling framework and k-ε two-equation turbulence closures. The interaction between the dispersed gas phase and the continuous liquid phase is characterized by bubble–liquid interphase forces (drag, turbulent dispersion and lift forces). The Ishii-Zuber drag model [1] and Grace adjusted drag model [2], the latter represented by: GraceDpg Grace dense D C  C , , are compared for their capability to match experimental gas hold- up. Numerical results of Reynolds-averaged Navier-Stokes equations with k-ε two-equation turbulence closures models when compared with Pironti experimental data [3] indicated that both drag models, predicted the air hold-up within experimental error. Furthermore, Ishii-Zuber liquid-gas drag model consistently provided better agreement of experimental results; it correctly determines the hold-up within 0.14%. Numerical agreement with adjusted Grace liquid-gas drag model, is exponent dependent 4  p  0.5, turning down that the best computed hold-up is within 0.44%. for p  0.5.