Modeling of Reactive Mass-Transfer in Bubbly Flows

CFD simulations of dispersed bubbly flow on the scale of technical equipment are feasible within the Eulerian two-fluid framework of interpenetrating continua. However, accurate numerical predictions rely on suitable closure models. Concerning the fluid dynamics of bubbly flows a certain degree of predictive capability has been reached recently. However, concerning mass transfer both with and without an accompanying chemical reaction only few studies have been performed to date.
The present contribution focusses on the so-called enhancement factor which describes the effect of a chemical reaction on the mass transfer. Different models available from the literature are compared. The reactive absorption of CO2 in aqueous NaOH is considered as an example. Simulations are compared with a set of experimental data reported by Darmana et al. [Chemical Engineering Science 62 (2007), 2556 - 2575]. Using an adequate model for the enhancement factor and taking into account the complete reaction network, an improved match with the data is obtained. Experimental conditions are suggested, for which further aspects of the system behavior become manifest.