Characterization of oxygen mass transfer in bubble columns: development of optical-experimental and numerical Euler-Euler methods

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Numerical simulations of bubble flows at the scale of a complete apparatus is, for the moment, only possible with Euler-Euler or Euler- Lagrangian modelling. Many studies exist for the hydrodynamic characterisation of such flows, but mass transfer and mixing have only been treated in a minor number of approaches, especially in the case of simultaneous chemical reaction. Analogically, there exist only little experimental methods for the characterization of bubble flows with mass transfer and chemical reaction at a larger scale, which can deliver data with sufficient temporal and spacial resolution. The aim of this project is the further development of such numerical and experimental methods , which could help to bring mass transfer studies to a level comparable to that, common for hydrodynamics. Especially mixing in the column and the resulting interaction of chemical reaction and hydrodynamic, which is particularly important for reactions with moderate velocity, will be treated in this project. For this, numerical and experimental methods will be developed and validated by comparison with the obtained data. All relevant parameters (concentration of transfered component, bubble size and velocity, liquid phase velocity) will be measured simultaneously with sufficient spacial and temporal resolution. The numerical part will also compare different mass transfer models from literature. The effect of the chemical reaction will be examined for the case of noninstantaneous reactions, for which part of the educts will come to the bulk and only react there and not in the film. In this case the influence of mixing in the bubble column will be significant. The mentionned subjects (mixing, mass transfer and interaction of chemical reaction and hydrodynamics) will be treated by both project partners and the experimental data wil by used as boundary conditions and for validation of the new models. Reversly the numerical results will help for an efficient experimental planning and concentration on the most relevant parameters.