A one-dimensional instationary heterogeneous mass transfer model for gas absorption in multiphase systems.

For a physically correct analysis (and prediction) of the effect of fine, dispersed phase drops or particles on the mass transfer rate in multiphase systems, it was demonstrated that only 3-D instationary, heterogeneous mass transfer models should be used. Existing models are either homogeneous, stationary or single particle models. As a first step, a 1-D, instationary, heterogeneous multi-particle mass transfer model was developed. With this model the influence of several system parameters was studied and problems and pitfalls in the translation of modeling results for heterogeneous models into a prediction of absorption fluxes are discussed. It was found that only those particles located closely to the gas–liquid interface determine mass transfer. For these particles the distance of the first particle to the gas–liquid interface and the particle capacity turned out to be the most important parameters. Comparisons with a homogeneous model and experimental results are presented. Typical differences in results comparing a homogeneous model with the 1-D heterogeneous model developed in this work could be attributed to a change in the near interface geometry. Future work in this field should therefore be directed towards near interface phenomena. Three dimensional mass transfer models, of which a preliminary result is presented, are indispensable for this.