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]  inIndustrial & 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

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