Modelling of droplet breakage probabilities in an oscillatory baffled reactor

Abstract

The breakage of droplets dispersed in a continuous aqueous phase determines the performance of many mixing devices and reactors that rely on effective contact between two phases, e.g. emulsion mills, liquid–liquid extraction columns, stirred tank reactors and Oscillatory Baffled Reactors. Quantitative knowledge of the mechanisms involved in the breakage provides parameters for design and prediction. In the work presented here, oil was dispersed in water in a continuous OBR, and a High Speed Camera was used to record the events of breakage of individual oil droplets and probabilities of breakage were estimated. It was confirmed that breakage was more sensitive to changes in the amplitude of oscillation than in the frequency of oscillation. A novel integral model was developed based on an analysis of the total work effected on the deforming droplet in order to interpret the results. The quantitative results from direct observation were compared to the model predictions. The model with fitted parameters was finally extrapolated to smaller diameters, in an attempt to predict the critical drop diameter for breakage.