Non-Newtonian fluidisation of spherical particles |
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Authors: | Delphine CicéronJacques Comiti Rajendra P ChhabraMaurice Renaud |
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Affiliation: | a GEPEA, UMR CNRS 6144, Université de Nantes, CRTT, BP 406, 44602 Saint-Nazaire Cedex, France b Department of Chemical Engineering, Indian Institute of Technology, Kanpur, 208016 India c Laboratoire de Génie des Procédés Papetiers, UMR 5518, Ecole Française de Papeterie et des Industries Graphiques, B.P. 65, 38402 Saint Martin d'Hères, France |
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Abstract: | This work presents the development of a new model based on the submerged object concept in order to characterise the expansion of spherical particles fluidised by non-Newtonian purely viscous liquids, especially at intermediate and high bed void fractions values. In order to take the interactions between the particles into account a parameter called hydraulic tortuosity is introduced which is a function of the Reynolds number and porosity. A method allowing its evaluation is proposed. Based on the test of a lot of experimental data from our laboratory and from previous works, this model is shown to give satisfactory results for porosities values larger than 0.6. In order to cover the entire range of porosities corresponding to the particles expansion a capillary-type model is proposed for the lower values of the porosities. This model is found to give satisfactory results in the range of bed void fraction comprised between the value corresponding to the minimum of fluidisation εmf and ε=0.65. The combination of the two models tested on 21 independent sets of data concerning viscoinelastic shear-thinning liquids leads to a mean error of 16%. It is also shown to give accurate predictions for Newtonian liquids. A comparison is also presented with the prediction of some of the widely used equations available in literature. |
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Keywords: | Fluidisation Non-Newtonian fluids Spherical particle Capillary representation Submerged object model |
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