Influence of Bubble Bouncing on Mass Transfer and Chemical Reaction

• Published in: Chemical engineering & technology 2016-10, Vol.39 (10), p.1955-1962
• Main Authors: Timmermann, Jens, Hoffmann, Marko, Schlüter, Michael
• Format: Article
• Language: English
• Subjects: Bouncing; Boundary layer deformation; Bubbles; Computational fluid dynamics; Fluid flow; Hydrodynamics; Mass transfer; Sherwood number correlation; Sodium sulfite reaction; Turbulence; Turbulent flow
• ISSN: 0930-7516; 1521-4125
• DOI: 10.1002/ceat.201600299

The hydrodynamics of bubbly flows is dominated by bubble‐induced turbulence and bubble‐bubble interactions. Both phenomena influence the gas‐liquid mass transfer as well as the mixing of reactants. If the time scales of mass transfer and mixing are in the same order as the time scales of a parallel‐consecutive reaction, the yield and selectivity will be affected by the local hydrodynamics. An experimental setup is presented that enables the investigation of mass transfer during well‐defined and adjustable bubble collisions. The influence of CO2 bubble collisions on mass transfer is measured and modeled with a modified Sherwood number correlation. Further visualization of the concentration field in the vicinity of O2 bubbles by means of laser‐induced fluorescence demonstrates the dependency of mass transfer from a chemical reaction and permits the development of a first model approach. Bubble‐induced turbulence and bubble‐bubble interactions influence the gas‐liquid mass transfer and mixing of reactants. Bubble bouncing leads to a deformation of the interfaces of two bubbles and is expected to affect the mass transfer rate. A Sherwood number correlation is developed to predict the mass transfer in dependency of the bouncing frequency.