Interfacial mass transfer and bubble hydrodynamics in bubble columns

Abstract

The interaction between gas–liquid or gas–liquid–solid phases exhibit complexity which for years have led researchers to study the intrinsic mechanisms involved. One important branch within multi-phase flow is the interfacial mass transfer which takes place between the relevant phases. A variety of industrial processes depend on the interfacial mass transfer between gas bubbles and the liquid phase in which the bubbles are dispersed. Relevant processes include distillation, absorption, fermentation, sewage treatment, chemical reactors, and bioreactors. Knowledge about the interfacial mass transfer is crucial when designing, scaling up, and optimizing industrial processes. Enhanced understanding of the complex interfacial mass transfer phenomena is necessary for developing and improving models that are essential in industrial applications.

With increased focus on climate and sustainability, the field of biochemical engineering is receiving more attention. In bioprocesses such as fermentation, the viscosity of the fermentation fluids is affected by the presence of cells, substrate, and product concentrations. A variety of fermentation processes therefore involve highly viscous liquids and liquids which possess non-Newtonian rheological behavior. The bubble hydrodynamics and the interfacial mass transfer are affected by the liquid rheology, which can lead to reduced process performance.

The dissertation aims to enhance the fundamental understanding of the interfacial mass transfer phenomena by investigating single bubbles and bubble swarms in bubble columns. The first part of the work focuses on the interfacial mass transfer and bubble hydrodynamics of single CO2 bubbles rising in stagnant water. The second part of this work investigates the interfacial mass transfer and bubble hydrodynamics of bubble swarms in liquids exhibiting both Newtonian and non-Newtonian rheological behavior.