Determination of micromixing times in commercially available continuous-flow mixers: evaluation of the incorporation and interaction by exchange with the mean model

Abstract

To understand and predict the effect of mixing in a mixer or reactor, characterization is essential. The Villermaux-Dushman system of competitive parallel reactions is one of the most frequently used methods to obtain details on the micromixing behavior in mixers and reactors. For quantitative information, a model can convert experimental data into a universal micromixing time, which can be used to compare set-ups and reaction conditions. Different modeling approaches have been developed over time and complicate the comparison of results with newfound micromixing times. In this work, these different modeling approaches are elaborated upon to show the significant differences that can arise between these models. Special attention goes out to a model for continuous-flow mixers, which operates differently and has different characteristics compared to mixing in conventional batch reactors. The volume fractions of the two phases being mixed are generally closer to one another in flow mixers, requiring adaptations in the experimental and modeling approach. Several models were tested, after which the interaction by exchange with the mean (IEM) model was selected. Using this model, micromixing times were determined for a variety of continuous-flow mixers under different operating conditions.