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]  inIndustrial & 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 ; Mark J. H. Simmons, 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 ; Mark J. H. Simmons, 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.

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Influence of rheological model on the processing of yoghurt / Mullineux, Glen in Journal of food engineering, Vol. 84 N°2 (Janvier 2008)  

Public ISBD [article]  inJournal of food engineering > Vol. 84 N°2 (Janvier 2008) . - 250-257 p. Titre : Influence of rheological model on the processing of yoghurt Type de document : texte imprimé Auteurs : Mullineux, Glen, Auteur ; Mark J. H. Simmons, Auteur Année de publication : 2008 Article en page(s) : 250-257 p. Note générale : Génie Chimique Langues : Anglais (eng) Mots-clés : Power law Herschel–Bulkley model Yoghurt Loi de puissance Modèle Herschel-Bulkley Yaourt Index. décimale : 664 Résumé : The power law and the Herschel–Bulkley model are common ways of representing the behaviour of a number of food materials. The underlying relations contain parameters which are obtained by fitting to experimental results. There is evidence to suggest that both models can represent materials equally well and this is investigated. With the Herschel–Bulkley model, it is shown that good fits can be obtained to data points with significantly different values of the parameters, including the particular case of the power law. This arises due to a linear relation between certain logarithmic terms. This is characterised and used to provide a means for converting between good triples of Herschel–Bulkley parameters. The fact that the two models behave equally well raises the question as to whether it is better to use the power law (being the simpler) for predictive work in the design of production systems where the materials experience medium to high shear rates in pipelines. La loi de puissance et le modèle de Herschel-Bulkley sont des manières communes de représenter le comportement d'un certain nombre de matériaux de nourriture. Les relations fondamentales contiennent les paramètres qui sont obtenus par l'ajustement aux résultats expérimentaux. Il y a d'évidence pour suggérer que les deux modèles puissent représenter le puits de matériaux également et ceci est étudié. Avec le modèle de Herschel-Bulkley, on lui montre que de bons ajustements peuvent être obtenus aux points de repères avec des valeurs sensiblement différentes des paramètres, y compris le cas particulier de la loi de puissance. Ceci surgit en raison d'une relation linéaire entre certaines limites logarithmiques. Ceci est caractérisé et employé pour fournir des moyens pour convertir entre de bons triples de paramètres de Herschel-Bulkley. Le fait que les deux modèles se comportent des augmenter également bons la question de savoir si il vaut mieux d'employer la loi de puissance (étant le plus simple) pour le travail prédictif dans la conception des systèmes de production où les matériaux éprouvent le milieu au cisaillement élevé évalue dans les canalisations. DEWEY : 664 ISSN : 0260-8774 RAMEAU : Yogourt En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T8J-4NSMMM1-2&_user=1 [...] [article] Influence of rheological model on the processing of yoghurt [texte imprimé] / Mullineux, Glen, Auteur ; Mark J. H. Simmons, Auteur . - 2008 . - 250-257 p. Génie Chimique Langues : Anglais (eng) in Journal of food engineering > Vol. 84 N°2 (Janvier 2008) . - 250-257 p. Mots-clés : Power law Herschel–Bulkley model Yoghurt Loi de puissance Modèle Herschel-Bulkley Yaourt Index. décimale : 664 Résumé : The power law and the Herschel–Bulkley model are common ways of representing the behaviour of a number of food materials. The underlying relations contain parameters which are obtained by fitting to experimental results. There is evidence to suggest that both models can represent materials equally well and this is investigated. With the Herschel–Bulkley model, it is shown that good fits can be obtained to data points with significantly different values of the parameters, including the particular case of the power law. This arises due to a linear relation between certain logarithmic terms. This is characterised and used to provide a means for converting between good triples of Herschel–Bulkley parameters. The fact that the two models behave equally well raises the question as to whether it is better to use the power law (being the simpler) for predictive work in the design of production systems where the materials experience medium to high shear rates in pipelines. La loi de puissance et le modèle de Herschel-Bulkley sont des manières communes de représenter le comportement d'un certain nombre de matériaux de nourriture. Les relations fondamentales contiennent les paramètres qui sont obtenus par l'ajustement aux résultats expérimentaux. Il y a d'évidence pour suggérer que les deux modèles puissent représenter le puits de matériaux également et ceci est étudié. Avec le modèle de Herschel-Bulkley, on lui montre que de bons ajustements peuvent être obtenus aux points de repères avec des valeurs sensiblement différentes des paramètres, y compris le cas particulier de la loi de puissance. Ceci surgit en raison d'une relation linéaire entre certaines limites logarithmiques. Ceci est caractérisé et employé pour fournir des moyens pour convertir entre de bons triples de paramètres de Herschel-Bulkley. Le fait que les deux modèles se comportent des augmenter également bons la question de savoir si il vaut mieux d'employer la loi de puissance (étant le plus simple) pour le travail prédictif dans la conception des systèmes de production où les matériaux éprouvent le milieu au cisaillement élevé évalue dans les canalisations. DEWEY : 664 ISSN : 0260-8774 RAMEAU : Yogourt En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T8J-4NSMMM1-2&_user=1 [...]

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Selective hydrogenation of 1 - heptyne in a mini trickle bed reactor / Mansour Al-Herz in Industrial & engineering chemistry research, Vol. 51 N° 26 (Juillet 2012)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 8815-8825 Titre : Selective hydrogenation of 1 - heptyne in a mini trickle bed reactor Type de document : texte imprimé Auteurs : Mansour Al-Herz, Auteur ; Mark J. H. Simmons, Auteur ; Joseph Wood, Auteur Année de publication : 2012 Article en page(s) : pp. 8815-8825 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Trickle bed reactor Hydrogenation Résumé : The selective hydrogenation of 1-heptyne over a 2 wt % Pd/Al2O3 catalyst was studied in a trickle bed reactor operating in both batch recycle and continuous modes. The reaction was studied in a range of different solvents, including isopropanol, hexane, mixtures of these two solvents, and also isopropanol with small quantities of water and base (NaOH) added. It was found that the rate of reaction was fastest in hexane, owing to the higher hydrogen solubility in this solvent. However, the selectivity toward 1-heptene was higher in isopropanol, with over 95% selectivity being maintained for 120 min of the total 240 min reaction time. The addition of water or base led to an increase in reaction rate, possibly through modification of the adsorption equilibria at the catalyst surface or direct involvement in the reaction. The hydrodynamics of trickle flow upon the reaction were investigated, showing that increasing liquid flow rate led to enhancement of reaction rate, although a plateau was eventually reached at the higher flows. The higher flows led to improved catalyst wetting, liquid hold up, and mass transfer rates, thus explaining the enhanced reaction rate. The concentration profiles were fitted according to a Langmuir―Hinshelwood kinetic expression. Operation in continuous flow was demonstrated, although a long residence time was required for high conversion, leading to lower 1-heptene selectivity compared with batch recycle operation. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26107435 [article] Selective hydrogenation of 1 - heptyne in a mini trickle bed reactor [texte imprimé] / Mansour Al-Herz, Auteur ; Mark J. H. Simmons, Auteur ; Joseph Wood, Auteur . - 2012 . - pp. 8815-8825. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 8815-8825 Mots-clés : Trickle bed reactor Hydrogenation Résumé : The selective hydrogenation of 1-heptyne over a 2 wt % Pd/Al2O3 catalyst was studied in a trickle bed reactor operating in both batch recycle and continuous modes. The reaction was studied in a range of different solvents, including isopropanol, hexane, mixtures of these two solvents, and also isopropanol with small quantities of water and base (NaOH) added. It was found that the rate of reaction was fastest in hexane, owing to the higher hydrogen solubility in this solvent. However, the selectivity toward 1-heptene was higher in isopropanol, with over 95% selectivity being maintained for 120 min of the total 240 min reaction time. The addition of water or base led to an increase in reaction rate, possibly through modification of the adsorption equilibria at the catalyst surface or direct involvement in the reaction. The hydrodynamics of trickle flow upon the reaction were investigated, showing that increasing liquid flow rate led to enhancement of reaction rate, although a plateau was eventually reached at the higher flows. The higher flows led to improved catalyst wetting, liquid hold up, and mass transfer rates, thus explaining the enhanced reaction rate. The concentration profiles were fitted according to a Langmuir―Hinshelwood kinetic expression. Operation in continuous flow was demonstrated, although a long residence time was required for high conversion, leading to lower 1-heptene selectivity compared with batch recycle operation. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26107435

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