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Effects of particle size and field orientation on the yield stress of magnetostabilized fluidized beds / J. M. Valverde in Industrial & engineering chemistry research, Vol. 51 N° 23 (Juin 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 23 (Juin 2012) . - pp. 8134-8140 Titre : Effects of particle size and field orientation on the yield stress of magnetostabilized fluidized beds Type de document : texte imprimé Auteurs : J. M. Valverde, Auteur ; M.A.S. Quintanilla, Auteur ; M. J. Espin, Auteur Année de publication : 2012 Article en page(s) : pp. 8134-8140 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Fluidized  bed  Fluidization  Yield  stress  Particle  size Résumé : In this work, we present experimental measurements of the yield stress of gas-fluidized beds of magnetizable particles stabilized by an externally imposed magnetic field. Powder samples consist of spherical magnetite particles 35―65 μm in size. The magnetic field is applied in the bubbling regime and the gas velocity is decreased. At a critical gas velocity, particle chains that have formed due to attractive magnetostatic forces become jammed and the bed transits to a solidlike expanded state with a non-negligible yield stress. Our experimental setup allows us for taking measurements of the yield stress of the bed stabilized by a magnetic field oriented either in the vertical or horizontal direction (co-flow and cross-flow field configurations, respectively). In the cross-flow field configuration, the magnetic yield stress is increased with particle size. On the other hand, the magnetic yield stress is decreased in the co-flow field configuration as particle size is increased. This is interpreted as due to the dependence of the interparticle magnetostatic force on the interparticle contact angle with the field, which is, on average, affected by particle size in the jammed bed subjected to small consolidations. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25990326 [article] Effects of particle size and field orientation on the yield stress of magnetostabilized fluidized beds [texte imprimé] / J. M. Valverde, Auteur ; M.A.S. Quintanilla, Auteur ; M. J. Espin, Auteur . - 2012 . - pp. 8134-8140. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 23 (Juin 2012) . - pp. 8134-8140 Mots-clés : Fluidized  bed  Fluidization  Yield  stress  Particle  size Résumé : In this work, we present experimental measurements of the yield stress of gas-fluidized beds of magnetizable particles stabilized by an externally imposed magnetic field. Powder samples consist of spherical magnetite particles 35―65 μm in size. The magnetic field is applied in the bubbling regime and the gas velocity is decreased. At a critical gas velocity, particle chains that have formed due to attractive magnetostatic forces become jammed and the bed transits to a solidlike expanded state with a non-negligible yield stress. Our experimental setup allows us for taking measurements of the yield stress of the bed stabilized by a magnetic field oriented either in the vertical or horizontal direction (co-flow and cross-flow field configurations, respectively). In the cross-flow field configuration, the magnetic yield stress is increased with particle size. On the other hand, the magnetic yield stress is decreased in the co-flow field configuration as particle size is increased. This is interpreted as due to the dependence of the interparticle magnetostatic force on the interparticle contact angle with the field, which is, on average, affected by particle size in the jammed bed subjected to small consolidations. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25990326

Electrofluidization of silica nanoparticle agglomerates / M.A.S. Quintanilla in Industrial & engineering chemistry research, Vol. 51 N° 1 (Janvier 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 1 (Janvier 2012) . - pp. 531–538 Titre : Electrofluidization of silica nanoparticle agglomerates Type de document : texte imprimé Auteurs : M.A.S. Quintanilla, Auteur ; J. M. Valverde, Auteur ; M. J. Espin, Auteur Année de publication : 2012 Article en page(s) : pp. 531–538 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Fluidization  Nanoparticles Résumé : Fluidization of nanostructured powders, potentially providing extremely high gas–solids contact efficiency, has become of interest in a number of emerging applications. Usually, nanopowders are characterized by the existence of large agglomerates of nanoparticles (NPs), whose size and density determine the fluidizability of the powder. Moreover, because of contact and tribocharging mechanisms, insulating nanopowders may accumulate large amounts of electrostatic charge due to their high specific surface area, which can lead to potential hazards when they are handled in industry. The system studied in this work is a silica nanopowder fluidized in a polycarbonate vessel. We show results from a noninvasive visualization technique able to automatically track NP agglomerate trajectories in the fluidized bed excited by an externally applied alternating field. This technique enables us to measure NP agglomerate properties such as their size, charge, and density. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200538v [article] Electrofluidization of silica nanoparticle agglomerates [texte imprimé] / M.A.S. Quintanilla, Auteur ; J. M. Valverde, Auteur ; M. J. Espin, Auteur . - 2012 . - pp. 531–538. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 1 (Janvier 2012) . - pp. 531–538 Mots-clés : Fluidization  Nanoparticles Résumé : Fluidization of nanostructured powders, potentially providing extremely high gas–solids contact efficiency, has become of interest in a number of emerging applications. Usually, nanopowders are characterized by the existence of large agglomerates of nanoparticles (NPs), whose size and density determine the fluidizability of the powder. Moreover, because of contact and tribocharging mechanisms, insulating nanopowders may accumulate large amounts of electrostatic charge due to their high specific surface area, which can lead to potential hazards when they are handled in industry. The system studied in this work is a silica nanopowder fluidized in a polycarbonate vessel. We show results from a noninvasive visualization technique able to automatically track NP agglomerate trajectories in the fluidized bed excited by an externally applied alternating field. This technique enables us to measure NP agglomerate properties such as their size, charge, and density. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200538v