Dynamic modelling and simulation of the multi-phase flow in bubble columns

Abstract

The aims of this PhD project are to investigate bubble column bubbly flow and bubble column three-phase flow using Euler/Euler large eddy simulation (LES) approach, focusing on LES sub-grid-scale (SGS) modelling which implements the modifications of the dynamic responses of the rising bubbles and solid particles to their surrounding turbulent eddies into the SGS models for modelling the gas-liquid two-phase and gas-solid-liquid three-phase flows in bubble column reactors. Current status of LES modelling of two or three-phase flows in bubble columns together with the corresponding experimental studies has been comprehensively reviewed in Chapter 1. As two or three phase flows in bubble column reactors involve complicated transport phenomena such as strong interactions between bubbles and turbulent eddies, solid particles modification on turbulent eddies, the coupling between the interfacial mass transfer and momentum transfer, the hydrodynamics and mass transfer involved cannot be predicted using LES with the standard Smagorinsky SGS model without considering the aforementioned couplings and modifications, especially when the interfacial force closures based on spatial-filtering are concerned. Although several eddy viscosity models and SGS interfacial forces models have been proposed and successfully implemented into LES of multiphase flows in bubble column reactors in the frame of Eulerian-Eulerian approach in the previous studies, it still remains very challengeable by using the Euler/Euler LES for accurate predicting those important parameters for multiphase flows in the bubble columns such as liquid velocities, bubble volume fraction, turbulent kinetic energy spectrum, species concentration spectrum, modified force models contribution and flow patterns, particularly when comparing the simulation results with the existing experimental data available from the open literature. The present PhD project has attempted to consider the effects of SGS bubble-eddy interaction in bubble column bubbly flows, bubble-eddy and particle-eddy interactions in slurry bubble column, and SGS turbulent dispersion and SGS added mass stress force terms on both the hydrodynamics and mass transfer (e.g. take CO2 adsorption in a reactive bubble column as the example). By employing the proposed models in the Euler/Euler LES modelling as reported from Chapter 2 to Chapter 6, it has been clearly demonstrated that the predictions of those important parameters either in bubble column bubbly flows or three-phase flow in slurry bubble column have been significantly improved.

Date of Award	9 Jul 2022
Original language	English
Awarding Institution	University of Nottingham
Supervisor	Xiaogang Yang (Supervisor), Xuerui Mao (Supervisor) & Jie Yang (Supervisor)