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Angle-resolved particle image velocimetry measurements of flow and turbulence fields in small-scale stirred vessels of different mixer configurations / Kenneth H. K. Chung in Industrial & engineering chemistry research, Vol. 48 N°2 (Janvier 2009)

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°2 (Janvier 2009) . - p. 1008–1018 Titre : Angle-resolved particle image velocimetry measurements of flow and turbulence fields in small-scale stirred vessels of different mixer configurations Type de document : texte imprimé Auteurs : Kenneth H. K. Chung, Auteur ; Simmons, Mark J. H., Auteur ; Mostafa Barigou, Auteur Année de publication : 2009 Article en page(s) : p. 1008–1018 Note générale : chemical engineering Langues : Anglais (eng) Mots-clés : Angle-Resolved  Particle  Image  --configurations Résumé : Angle-resolved particle image velocimetry measurements were conducted at one degree intervals in miniature vessels of four different configurations used in high-throughput experimentation. The four vessels—standard fully baffled, unbaffled, off-center or eccentric impeller, and square section—were agitated by an up-pumping six-blade 45° pitched blade turbine (PBT). The effect of periodicity was revealed in all configurations but was restricted to the impeller discharge and inflow regions. The square vessel achieved the strongest axial-radial flow field among all configurations. The smallest overestimation in the computation of turbulent kinetic energy by the ensemble time average method, otherwise referred to as pseudoturbulence, was achieved in the eccentric and square configurations. The up-pumping PBT shed trailing vortices mainly in a radial direction with relatively little axial movement. The highest axial vortex position was achieved in the square vessel, which may be partly responsible for its lower mixing time compared to other configurations. The measurements obtained here in the high-transitional regime suggest that the square configuration performs better than other configurations and can be a good replacement for the fully baffled vessel in commercial high-throughput experimentation units where baffles are usually prohibited. This result was confirmed from mixing time measurements made using planar laser induced fluorescence where the superiority of the square vessel was demonstrated. [article] Angle-resolved particle image velocimetry measurements of flow and turbulence fields in small-scale stirred vessels of different mixer configurations [texte imprimé] / Kenneth H. K. Chung, Auteur ; Simmons, Mark J. H., Auteur ; Mostafa Barigou, Auteur . - 2009 . - p. 1008–1018. chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°2 (Janvier 2009) . - p. 1008–1018 Mots-clés : Angle-Resolved  Particle  Image  --configurations Résumé : Angle-resolved particle image velocimetry measurements were conducted at one degree intervals in miniature vessels of four different configurations used in high-throughput experimentation. The four vessels—standard fully baffled, unbaffled, off-center or eccentric impeller, and square section—were agitated by an up-pumping six-blade 45° pitched blade turbine (PBT). The effect of periodicity was revealed in all configurations but was restricted to the impeller discharge and inflow regions. The square vessel achieved the strongest axial-radial flow field among all configurations. The smallest overestimation in the computation of turbulent kinetic energy by the ensemble time average method, otherwise referred to as pseudoturbulence, was achieved in the eccentric and square configurations. The up-pumping PBT shed trailing vortices mainly in a radial direction with relatively little axial movement. The highest axial vortex position was achieved in the square vessel, which may be partly responsible for its lower mixing time compared to other configurations. The measurements obtained here in the high-transitional regime suggest that the square configuration performs better than other configurations and can be a good replacement for the fully baffled vessel in commercial high-throughput experimentation units where baffles are usually prohibited. This result was confirmed from mixing time measurements made using planar laser induced fluorescence where the superiority of the square vessel was demonstrated.

Combined use of PEPT and ERT in the study of aluminum hydroxide precipitation / Iwan Edwards in Industrial & engineering chemistry research, Vol. 48 N°2 (Janvier 2009)

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°2 (Janvier 2009) . - p 1019–1028 Titre : Combined use of PEPT and ERT in the study of aluminum hydroxide precipitation Type de document : texte imprimé Auteurs : Iwan Edwards, Auteur ; Sean A. Axon, Auteur ; Mostafa Barigou, Auteur ; Hugh Stitt, Auteur Année de publication : 2009 Article en page(s) : p 1019–1028 Note générale : chemical engineering Langues : Anglais (eng) Mots-clés : Aluminum  Hydroxide--Study Résumé : The application of multimodal tomographic techniques to the in situ study of the semibatch precipitation of aluminum hydroxide, an industrially important alumina precursor, has been developed. For the first time Electrical Resistance Tomography (ERT) and Positron Emission Particle Tracking (PEPT) have been used concomitantly to study precipitation and hydrodynamics. This combination of techniques allows a step change in our ability to understand industrial precipitation processes. The semibatch precipitation of aluminum hydroxide was investigated in a stirred vessel operated with different configurations. Mixing conditions during semi batch precipitation have been shown to determine particle properties. Variables such as impeller design, power input, and feed location were used to provide different mixing conditions at the feed point where the reagents contact and precipitation takes place. The mixing performance during precipitation can be analyzed using ERT, with information of how the feed plume is dispersed under different mixing conditions. The flow conditions in the feed region can be characterized using PEPT. Together, the techniques can establish how the feed plume is dissipated into the bulk fluid. [article] Combined use of PEPT and ERT in the study of aluminum hydroxide precipitation [texte imprimé] / Iwan Edwards, Auteur ; Sean A. Axon, Auteur ; Mostafa Barigou, Auteur ; Hugh Stitt, Auteur . - 2009 . - p 1019–1028. chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°2 (Janvier 2009) . - p 1019–1028 Mots-clés : Aluminum  Hydroxide--Study Résumé : The application of multimodal tomographic techniques to the in situ study of the semibatch precipitation of aluminum hydroxide, an industrially important alumina precursor, has been developed. For the first time Electrical Resistance Tomography (ERT) and Positron Emission Particle Tracking (PEPT) have been used concomitantly to study precipitation and hydrodynamics. This combination of techniques allows a step change in our ability to understand industrial precipitation processes. The semibatch precipitation of aluminum hydroxide was investigated in a stirred vessel operated with different configurations. Mixing conditions during semi batch precipitation have been shown to determine particle properties. Variables such as impeller design, power input, and feed location were used to provide different mixing conditions at the feed point where the reagents contact and precipitation takes place. The mixing performance during precipitation can be analyzed using ERT, with information of how the feed plume is dispersed under different mixing conditions. The flow conditions in the feed region can be characterized using PEPT. Together, the techniques can establish how the feed plume is dissipated into the bulk fluid.