Impact of carbon dioxide injection on oxygen dissolution rate during oxygen additions in a bubble column. http://dx.doi.org/10.1016/j.cej.2013.07.081

Abstract

Oxygen additions are common practice during oenological fermentations. Since oxygen dissolutionunder winemaking conditions is not completely understood, these additions are performed empirically. Inparticular, the influence of carbon dioxide produced by yeast cells on the oxygen dissolution rate remainsunclear. In this paper, we present an oxygen mass balance model that describes the evolution of dissolvedoxygen in a laboratory scale carbon dioxide bubbling column emulating wine fermentation hydrodynamicconditions during oxygen additions. The model consists of two partial differential equations for the liquid andgas phases and considers liquid recirculation and mixing. Considering only one fitting parameter, the modelcan reproduce well the observed dissolved oxygen evolution at different locations in the column. We foundthat carbon dioxide bubbling has two simultaneous antagonist effects: it enhances the volumetric masstransfer coefficient and decreases the oxygen equilibrium concentration mainly due to the dilution effect inthe gas phase. Overall, the latter effect is shown to be more important and explains the reduction of almost 60% of the oxygen dissolution rate for high carbon dioxide bubbling conditions. The model developed herewill help to design better oxygen addition systems for oenological fermentations.