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Bubble size distribution for a bubble column reactor undergoing forced oscillations / Y. G. Waghmare in Industrial & engineering chemistry research, Vol. 48 N°4 (Février 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - pp. 1786–1796 Titre : Bubble size distribution for a bubble column reactor undergoing forced oscillations Type de document : texte imprimé Auteurs : Y. G. Waghmare, Auteur ; C. A. Dorao, Auteur ; H. A. Jakobsen, Auteur Année de publication : 2009 Article en page(s) : pp. 1786–1796 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Oscillations  Bubble  size  distribution  Air-water  system  Breakage  models Résumé : It has recently been shown that low amplitude (0.5−2.5 mm) oscillations at low frequencies (10−25 Hz) can be used to improve bubble column performance. Here, we report the study of bubble size distribution (BSD) in an oscillating bubble column for the air−water system. BSD was measured at different heights in the column, and the effects of various operating parameters such as frequency, amplitude, and gas flow rate were studied. Sauter mean diameter was calculated from BSD data, and it was correlated as a function of power input per unit mass using the Hinze formula. Population balance modeling simulations were performed. Two different breakage models (Martinez−Bazan and Luo−Svendsen) were considered which differ fundamentally in the constitution of the models and as a result predict opposite shapes of daughter size distribution curves. Simulation results were compared against experimental data, and both the models gave good comparisons with the measured Sauter mean bubble diameters. The predictions obtained from the simulation for BSD using the Martinez−Bazan model were in quantitative agreement with the experimental observations suggesting vibrations produce nearly equal size bubble breakage. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801375h [article] Bubble size distribution for a bubble column reactor undergoing forced oscillations [texte imprimé] / Y. G. Waghmare, Auteur ; C. A. Dorao, Auteur ; H. A. Jakobsen, Auteur . - 2009 . - pp. 1786–1796. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - pp. 1786–1796 Mots-clés : Oscillations  Bubble  size  distribution  Air-water  system  Breakage  models Résumé : It has recently been shown that low amplitude (0.5−2.5 mm) oscillations at low frequencies (10−25 Hz) can be used to improve bubble column performance. Here, we report the study of bubble size distribution (BSD) in an oscillating bubble column for the air−water system. BSD was measured at different heights in the column, and the effects of various operating parameters such as frequency, amplitude, and gas flow rate were studied. Sauter mean diameter was calculated from BSD data, and it was correlated as a function of power input per unit mass using the Hinze formula. Population balance modeling simulations were performed. Two different breakage models (Martinez−Bazan and Luo−Svendsen) were considered which differ fundamentally in the constitution of the models and as a result predict opposite shapes of daughter size distribution curves. Simulation results were compared against experimental data, and both the models gave good comparisons with the measured Sauter mean bubble diameters. The predictions obtained from the simulation for BSD using the Martinez−Bazan model were in quantitative agreement with the experimental observations suggesting vibrations produce nearly equal size bubble breakage. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801375h

Mass transfer in a viscous bubble column with forced oscillations / Y. G. Waghmare in Industrial & engineering chemistry research, Vol. 47 n°15 (Août 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5386-5394 Titre : Mass transfer in a viscous bubble column with forced oscillations Type de document : texte imprimé Auteurs : Y. G. Waghmare, Auteur ; Richard G. Rice, Auteur ; F Carl Knopf, Auteur Année de publication : 2008 Article en page(s) : p. 5386-5394 Note générale : Bibliogr. p. 5394 Langues : Anglais (eng) Mots-clés : Viscous  bubble  column;  Oscillations  --  mass  transfer;  carboxymethylcellulose  solutions Résumé : Previously, it was shown that low-amplitude (0.5−2.5 mm) oscillations at moderate frequencies (0−25 Hz) can be used to improve bubble column performance. Literature on pulsed-flow bubble columns has mainly focused on air−water systems. In the present work, the effects of oscillations on mass transfer in a pulsed-flow bubble column were studied for various carboxymethylcellulose solutions giving an effective viscosity range of 1−62 cP. As in our previous work on air−water systems, the viscous system exhibits an initial increase in mass-transfer coefficient as a function of frequency and then leveled to a plateau. This asymptotic behavior can be attributed to the Bjerknes force acting on a bubble, which slows the bubble rise as frequency is increased. The shape of the curve for mass-transfer coefficient vs frequency was unchanged for viscous systems, but the absolute value of the mass-transfer coefficient decreased as a function of increasing viscosity. A theory was developed from first principles to show how the volumetric mass-transfer coefficient changes as a function of operating parameters, such as the frequency and amplitude of vibrations, gas superficial velocity, and viscosity of the fluid. The comparison with experiments was quite good for a large range of velocities and viscosities. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800041k [article] Mass transfer in a viscous bubble column with forced oscillations [texte imprimé] / Y. G. Waghmare, Auteur ; Richard G. Rice, Auteur ; F Carl Knopf, Auteur . - 2008 . - p. 5386-5394. Bibliogr. p. 5394 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5386-5394 Mots-clés : Viscous  bubble  column;  Oscillations  --  mass  transfer;  carboxymethylcellulose  solutions Résumé : Previously, it was shown that low-amplitude (0.5−2.5 mm) oscillations at moderate frequencies (0−25 Hz) can be used to improve bubble column performance. Literature on pulsed-flow bubble columns has mainly focused on air−water systems. In the present work, the effects of oscillations on mass transfer in a pulsed-flow bubble column were studied for various carboxymethylcellulose solutions giving an effective viscosity range of 1−62 cP. As in our previous work on air−water systems, the viscous system exhibits an initial increase in mass-transfer coefficient as a function of frequency and then leveled to a plateau. This asymptotic behavior can be attributed to the Bjerknes force acting on a bubble, which slows the bubble rise as frequency is increased. The shape of the curve for mass-transfer coefficient vs frequency was unchanged for viscous systems, but the absolute value of the mass-transfer coefficient decreased as a function of increasing viscosity. A theory was developed from first principles to show how the volumetric mass-transfer coefficient changes as a function of operating parameters, such as the frequency and amplitude of vibrations, gas superficial velocity, and viscosity of the fluid. The comparison with experiments was quite good for a large range of velocities and viscosities. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800041k