CFD Simulation of Gas-Liquid Flow in Bubble Column with Two-bubble Phase Population Balance Model
A two-bubble phase population balance model (TBPBM) was proposed by treating gas phase (bubbles) as two groups consisting of small and large bubbles, i.e. accounting for small and large bubble phases in terms of different laws of bubble dynamics based on the sizes of bubbles, in which the population balance model was applied and solved respectively for each bubble group to predict the bubble Sauter diameters. The use of two-fluid model coupled with the TBPBM has been tested to simulate hydrodynamics in a bubble column of 440 mm in diameter at the superficial gas velocity of 0.1 m/s. Bubble classes holdup-based probability distribution, radial profiles of time-averaged axial liquid velocity and gas holdup and bubble size distribution for each phase were obtained. The simulation has demonstrated that the predicted profiles of mean gas holdup and liquid velocity are in good agreement with the experimental data and the existing results reported in the literature. The simulation also indicates that the TBPBM model is superior to the SBPBM and mean bubble size models in bubble column hydrodynamics simulation. The error of the predicted overall gas holdup caused by using TBPBM model is 5.7%, while the errors by using SBPBM model and mean bubble size model are 27.2% and 17.3%, respectively.