Modelling of Bubbly Flow in Bubble Column Reactors with an Improved Breakup Kernel Accounting for Bubble Shape Variations

Abstract

Bubble shapes have been assumed to be spherical in the currently available breakup models such as the one developed by Luo and Svendsen (1996). This particular breakup model has been widely accepted and implemented into CFD modelling of gas-liquid two-phase flows. However, simulation results obtained based on this model usually yield unreliable predictions about the breakage of very small bubbles. The incorporation of bubble shape variation into breakup models has rarely been documented in the study but the bubble shape plays an important role when considering the interactions with the surrounding turbulent eddies in turbulent bubbly flows, especially when the effects of bubble deformation, distortion and bubble internal pressure change are considered during the events of eddy-bubble collision. Thus, the assumption of spherical bubbles seems to be no longer appropriate in reflecting this phenomenon. This study proposes and implements an improved bubble breakup model, which accounts for the variation of bubble shapes when solving the population balance equations for CFD simulation of gas-liquid two-phase flows in bubble columns.