Multi-scale analysis of gas-liquid interaction and CFD simulation of gas-liquid flow in bubble columns

The ratio of effective drag coefficient to bubble diameter is of critical importance for CFD simulation of gas-liquid flow in bubble columns. In this study, a novel model is proposed to calculate the ratio on the basis of the Dual-Bubble-Size (DBS) model. The motivation of the study is that a stability condition reflecting the compromise between different dominant mechanisms can serve for a closure in addition to mass and momentum conservative constraints, and the interphase momentum transfer should be related to different paths of energy dissipation. With the DBS model, we can first offer a physical interpretation on macro-scale regime transition via the shift of global minimum point of micro-scale energy dissipation from one potential trough to the other. Then the proposed drag model is integrated into a CFD simulation. Prior to this integration, we investigate the respective effects of bubble diameter and correction factor and found that the effect of bubble diameter is limited, whereas the correction factor due to the bubble swarm effect is eminent and appropriate correction factor has to be selected for different correlations of standard drag efficient to be in accord with experiments. By contrast, the DBS drag model can well predict the radial gas holdup distribution, the total gas holdup as well as the two-phase flow field without the need to adjust model parameters, showing its great potential and advantage in understanding the complex nature of multi-scale structure of gas-liquid flow in bubble columns. (C) 2011 Elsevier Ltd. All rights reserved.

[1]  Wei Ge,et al.  Focusing on the meso-scales of multi-scale phenomena-In search for a new paradigm in chemical engineering , 2010 .

[2]  Rodney O. Fox,et al.  CFD predictions for flow‐regime transitions in bubble columns , 2005 .

[3]  Wei Ge,et al.  Explorations on the multi-scale flow structure and stability condition in bubble columns , 2007 .

[4]  Wei Ge,et al.  Modeling of Regime Transition in Bubble Columns with Stability Condition , 2009 .

[5]  Wei Ge,et al.  Analytical multi-scale method for multi-phase complex systems in process engineering—Bridging reductionism and holism , 2007 .

[6]  J.A.M. Kuipers,et al.  Euler-Euler Modeling of Flow, Mass Transfer, and Chemical Reaction in a Bubble Column , 2009 .

[7]  M. Fialová,et al.  Duality of the gas-liquid flow regimes in bubble column reactors , 1997 .

[8]  Wei Ge,et al.  A conceptual model for analyzing the stability condition and regime transition in bubble columns , 2010 .

[9]  Gabriel Wild,et al.  Influence of coalescence behaviour of the liquid and of gas sparging on hydrodynamics and bubble characteristics in a bubble column , 1999 .

[10]  F. White.  Viscous Fluid Flow , 1974 .

[11]  Wei Ge,et al.  Computational Fluid Dynamics Simulation of Regime Transition in Bubble Columns Incorporating the Dual-Bubble-Size Model , 2009 .

[12]  R. F. Mudde,et al.  Uniform Flow in Bubble Columns , 2009 .

[13]  Jinghai Li,et al.  Exploring complex systems in chemical engineering - the multi-scale methodology , 2003 .

[14]  Wei Ge,et al.  CFD simulation of concurrent-up gas-solid flow in circulating fluidized beds with structure-dependent drag coefficient , 2003 .

[15]  Jinghai Li,et al.  Eulerian Simulation Incorporating a Dual-bubble-size Drag Model for a Bubble Column , 2010 .

[16]  Wei Ge,et al.  Simulation of Heterogeneous Structure in a Circulating Fluidized-Bed Riser by Combining the Two-Fluid Model with the EMMS Approach , 2004 .

[17]  Liang-Shih Fan,et al.  Flow structure in a three‐dimensional bubble column and three‐phase fluidized bed , 1994 .

[18]  Rajamani Krishna,et al.  Size, structure and dynamics of “large” bubbles in a two-dimensional slurry bubble column , 1996 .

[19]  N. Cheremisinoff,et al.  Shapes and velocities of single drops and bubbles moving freely through immiscible liquids. , 1976 .

[20]  Annalisa Manera,et al.  Influence of the lift force on the stability of a bubble column , 2005 .