Experimental Investigation of Reactive Bubbly Flows—Influence of Boundary Layer Dynamics on Mass Transfer and Chemical Reactions

First published in
Fluid mechanics and its applications 
Number in series
128
Start Page
267
End Page
307
Citation
Reactive Bubbly Flows. Fluid Mechanics and Its Applications 128: 267-307 (2021)
Publisher DOI
10.1007/978-3-030-72361-3_12
Scopus ID
2-s2.0-85111851754
Publisher
Springer
Bubbly flows are extensively used processes in the chemical industry. Since the complex interaction of fluid dynamics, mass transfer and chemical reaction is not yet fully understood, a reliable prediction of yield and selectivity is not possible. Within this work different benchmark experiments are developed, allowing the investigation of the interplay of mixing and chemical reactions. For precise predictions of the chemical process, a detailed knowledge about the intrinsic kinetics is essential. Therefore, the guiding measure “SuperFocus Mixer” (SFM) has been developed and successfully tested by determining the kinetics of a model system and of the oxidation of a temperature sensitive copper complex. In a second step, the identified reaction is transferred into the Taylor bubble setup, marking the second benchmark system. Here the effect of mixing on the production of the products in consecutive and competitive-consecutive reaction is investigated. The conducted experiments show significant influence of the mixing intensity on the production of the first reaction product MNIC and the side product DNIC, favoring the first product at intensified mixing. Finally, the local mass transfer at freely ascending bubbles superimposed by a chemical reaction is determined by applying planar-LIF, and the influence of bubble–bubble bouncing is quantified. In addition, a novel method, the Time Resolved Scanning-LaserInduced Fluorescence (TRS-LIF) for the visualization of 3D concentration fields, is introduced and tested at single rising oxygen bubbles.