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Effect of interface contamination on particle–bubble collision

Huang, Zhujun and Legendre, Dominique and Guiraud, Pascal Effect of interface contamination on particle–bubble collision. (2012) Chemical Engineering Science, 68 (1). 1-18. ISSN 0009-2509

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Official URL: http://dx.doi.org/10.1016/j.ces.2011.07.045

Abstract

This study focuses on the impact of the interface contamination on the collision efficiency between bubbles and inertial particles. The bubble's surface mobility has been integrated into the collision modelling by using the hydrodynamics stagnant-cap model, in which the clean angle O clean is used to characterise the interface contamination level. Direct numerical simulations have been performed for various bubble's Reynolds numbers (1≤Reb≤100), particle to bubble size ratio (0:001≤rp/rb≤0:02) and particle's Stokes numbers (0:001<Stp<1). The Lagrangian tracking was performed for the solid particles by solving the full particle trajectory equation, in order to find the critical grazing trajectory. The collision efficiency was then calculated, as the ratio of the number of particles located in the body of revolution made by critical trajectory to that of particles located in the cylinder formed by bubble’s projection area. The magnitude of hydrodynamic force (buoyancy, drag, shear lift, added mass and history forces) as well as surface forces (electrostatic, Van der Waals and hydrophobic forces) are compared to propose a simplified trajectory equation. The surface contamination was found to play an important effect on the behavior of collision efficiency, especially near O clean. Analysis of collision angle showed that there is a critical angle O crit, depending on the bubble's Reynolds number. For the bubble with O clean > O crit, the contact point of the "grazing trajectory" can only be situated on the mobile interface, while for O clean < O crit, the contact point may be on both mobile and immobile part of the interface and only the positive inertial effect is observed. A simple model has been proposed that makes possible the description of collision efficiency for clean or contaminated bubbles.

Item Type:Article
HAL Id:hal-00921117
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
French research institutions > Institut National de la Recherche Agronomique - INRA (FRANCE)
Université de Toulouse > Institut National des Sciences Appliquées de Toulouse - INSA (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
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Deposited By: Dominique LEGENDRE
Deposited On:19 Dec 2013 15:49

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