Key Words:Mass transfer;Computational fluid dynamics - Flow patterns - Phase interfaces
Abstract:The mass transfer process inside bubbles is an important, but easily overlooked, component of the global mass transfer process. Bubble deformation influences the internal flow pattern and the mass transfer area. Furthermore, the internal flow impacts on the concentration distribution. This paper presents the results of a study on the mass transfer process inside bubbles and the interactions among the above factors using a computational fluid dynamics model. The accuracy of the model is verified by an experiment with a chromogenic reaction. Gas-interface mass transfer processes with and without internal flow are compared to show the positive effects of the shape change and the flow. A mass transfer enhancement factor, which is related to the concentration gradient and the mass transfer area, is presented to quantitatively analyze the effects. The results show that various internal flow patterns and concentration distributions can occur in different bubbles. The change in the average mass fraction and the average mass transfer coefficient of the process including internal flow are 2.8 times and 28.0% higher than those of the process without any internal flow. The enhancement factors are greater than 1.0, which indicates that a stronger internal flow intensifies the mass transfer process.<br/> © 2019 Author(s).
Volume:31
Issue:11
Translation or Not:no