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Scale-up in laminar and transient regimes of a multi-stage stirrer, a CFD approach

Letellier, Bertrand and Xuereb, Catherine and Swaels, Philippe and Hobbes, Phillippe and Bertrand, Joël Scale-up in laminar and transient regimes of a multi-stage stirrer, a CFD approach. (2002) Chemical Engineering Science, Volume 57 (n°21). pp.4617-4632. ISSN 0009-2509

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Official URL: http://dx.doi.org/10.1016/S0009-2509(02)00371-8

Abstract

A multi-stage industrial agitator system adapted to the mixing of a mixture whose viscosity varies during the process has been characterized by using CFD. In the entire study the mixture is supposed to have a Newtonian behavior even though it is rarely the case. It is shown that the well-adapted propeller is able to e7ciently blend high viscous media provided the Reynolds number is not too low. A scale-up study of the agitated system has also been carried out by respecting the classical scale-up rules such as the geometrical similarity and the conservation of the power per volume in the particular case of viscous media. Using an Eulerian approach, the hydrodynamics of three di9erent scales with geometrical similarity have been numerically characterized by the energy curve (power number versus Reynolds number) and by the Metzner and Otto constant in which both are required for scale-up procedure. Experimental power measurements have been carried out at the smaller scale so that simulations have been partially validated. New hydrodynamic criteria have also been introduced in order to quantify the =ows in the case of a multi-stage stirrer running at low Reynolds number. It has been shown how this hydrodynamic di9ers dramatically from one scale to another when scale-up at constant energy per volume is applied. From the CFD results, recommendations about the widely used scale-up rules have been suggested and modi>cations of stirring geometry have been proposed in order to reduce the =ow pattern variations during scale-up. ? 2002 Elsevier Science Ltd. All rights reserved.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available athttp://www.sciencedirect.com/science?_ob=ArticleListURL&_method=list&_ArticleListID=958626096&_sort=r&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=d5997f69ec2d816c2cc4a9580b2b0cc6
Audience (journal):International peer-reviewed journal
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Institution: Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
French research institutions > Centre National de la Recherche Scientifique - CNRS
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Deposited By:Catherine XUEREB

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