Detailed study of single bubble behavior and drag correlations in Newtonian and non-Newtonian liquids for the design of bubble columns

A study of the effects of fluid type (shear-thinning, Newtonian, and shear-thickening) and periodic shape fluctuations of bubbles on the drag coefficient is presented for three bubble sizes (2 mm, 4 mm and 6 mm), three flow consistency indexes (mu(water), 10 mu(water), 100 mu(water)) and three flow behavior indexes (0.8, 1, 1.2). Computational Fluid Dynamics (CFD) simulations were performed in addition to previous measurements to obtain local data of the flow hydrodynamics. The results were used to evaluate 12 different drag coefficient estimation models, which are essential for the design of bubble columns. The Dijkhuizen et al. and Rodrigue correlations are suitable for the prediction of terminal velocity in both Newtonian and non-Newtonian liquids with high or intermediate viscosity. Finally, a modification of the correlations enables the prediction of small bubble terminal velocity also in low-viscosity liquids. (c) 2022 The Author(s). Published by Elsevier Ltd on behalf of Institution of Chemical Engineers. This is an open access article under the CC BY license (http://creativecommons. org/licenses/by/4.0/).

Automated summary

This study investigates the influence of fluid type and bubble shape fluctuations on the drag coefficient, and evaluates the applicability of 12 drag coefficient estimation models. The results indicate that the Dijkhuizen et al. and Rodrigue correlations can effectively predict the terminal velocity of bubbles in different viscosity liquids.