DETERMINATION OF FLOW REGIMES IN BUBBLE COLUMNS USING CFD

Computational fluid dynamics (CFD) simulation, deals with the solution of fluid dynamic equations on digital computers, requiring relatively few restrictive assumptions and thus giving a complete description of the hydrodynamics of bubble columns. This detailed predicted flow field gives an accurate insight to the fluid behaviors.3D simulation computational fluid dynamics (CFD) is applied using ANSYS-CFX Euler-Euler model to measure the hydrodynamic of an airlift reactor, and comparing with experimental data of Baten et. al., (1999). Also by comparing the hydrodynamics of airlift reactor within bubble column reactor, of air/water and in the homogeneous bubble flow regime, it can be noticed that the liquid circulation velocities are more significant in the airlift configuration than in bubble columns, leading to significantly lower gas holdups. Within the riser of the airlift, the gas and liquid phases are virtually in plug flow, whereas in bubble column the gas and liquid phases follow parabolic velocity distribution. The transition regime appears at high superficial gas velocity in airlift reactors because of its ability to operate in the homogeneous bubble flow regime till much higher superficial gas velocities.