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Analysis of the conditions for the inception of natural pulsing flow in cocurrent packed columns / Talgat A. Akramov in Industrial & engineering chemistry research, Vol. 47 N°19 (Octobre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7424–7432 Titre : Analysis of the conditions for the inception of natural pulsing flow in cocurrent packed columns Type de document : texte imprimé Auteurs : Talgat A. Akramov, Auteur ; Petr Stavarek, Auteur ; Vladimir Jiricny, Auteur Année de publication : 2008 Article en page(s) : p. 7424–7432 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Packed-bed  column--mass  balance  Holdup  formation  Hydrodynamic  regime Résumé : Functional analysis of mass balances in a cocurrent packed-bed column has been carried in conjunction with analysis of the locally linear relationship between liquid holdup and phase velocities and first-order kinetics of the rate of holdup formation. The analysis indicates that the stability of the hydrodynamic regime in the bed is limited by the condition k(λ − γ)L < 2. Furthermore, for k(λ − γ)L > 0.5, the amplitude of the pulsations appearing in the bed in response to small flow perturbations was found to amplify. For k(λ − γ)L approaching 2, the flow disturbances are amplified very strongly. Experimental measurement of the liquid holdup, analysis of the kinetics of liquid holdup formation, and determination of the limits of the appearance of natural pulsations from pressure drop fluctuations show that the limit of inception of natural pulsations closely adheres to the line k(λ − γ)L = 2 where our analysis predicts very strong amplification of flow disturbances. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800501q [article] Analysis of the conditions for the inception of natural pulsing flow in cocurrent packed columns [texte imprimé] / Talgat A. Akramov, Auteur ; Petr Stavarek, Auteur ; Vladimir Jiricny, Auteur . - 2008 . - p. 7424–7432. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7424–7432 Mots-clés : Packed-bed  column--mass  balance  Holdup  formation  Hydrodynamic  regime Résumé : Functional analysis of mass balances in a cocurrent packed-bed column has been carried in conjunction with analysis of the locally linear relationship between liquid holdup and phase velocities and first-order kinetics of the rate of holdup formation. The analysis indicates that the stability of the hydrodynamic regime in the bed is limited by the condition k(λ − γ)L < 2. Furthermore, for k(λ − γ)L > 0.5, the amplitude of the pulsations appearing in the bed in response to small flow perturbations was found to amplify. For k(λ − γ)L approaching 2, the flow disturbances are amplified very strongly. Experimental measurement of the liquid holdup, analysis of the kinetics of liquid holdup formation, and determination of the limits of the appearance of natural pulsations from pressure drop fluctuations show that the limit of inception of natural pulsations closely adheres to the line k(λ − γ)L = 2 where our analysis predicts very strong amplification of flow disturbances. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800501q

Minimum energy dissipation under cocurrent flow in packed beds / Talgat A. Akramov in Industrial & engineering chemistry research, Vol. 50 N° 18 (Septembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 18 (Septembre 2011) . - pp. 10824-10832 Titre : Minimum energy dissipation under cocurrent flow in packed beds Type de document : texte imprimé Auteurs : Talgat A. Akramov, Auteur ; Petr Stavarek, Auteur ; Vladimir Jiricny, Auteur Année de publication : 2011 Article en page(s) : pp. 10824-10832 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Packed  bed  Cocurrent  flow  Energy  dissipation  Minimum  energy Résumé : Functional analysis of mass balances on gas and liquid, and pressure drop equations describing the concurrent flow in packed beds has yielded two criteria. Positive values of these criteria has been shown sufficient to achieve energy savings by synchronized periodic pulsations of inlet gas and liquid velocities or by liquid velocity only compared to the situation under the same mean steady inlet phase velocities. This, however, is not the case of pulsation by gas inlet velocity alone. The developed criteria have been evaluated from data obtained by experimental measurement of liquid holdup and gas pressure drop in a column 0.05 m in diameter packed to 1 m by 0.003 m glass spheres using water/air and toluene/air system. Our experiments showed these criteria to be fulfilled in the whole domain of gas and liquid velocities tested. Evaluation of the energy savings under pulsations relative to the steady state operation showed that the savings for water/air system may reach up to 4% with the maximum in region of high and intermediate liquid velocities and low gas velocities. For the toluene/air system the savings are somewhat lower and occur in the same velocity domain. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24523899 [article] Minimum energy dissipation under cocurrent flow in packed beds [texte imprimé] / Talgat A. Akramov, Auteur ; Petr Stavarek, Auteur ; Vladimir Jiricny, Auteur . - 2011 . - pp. 10824-10832. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 18 (Septembre 2011) . - pp. 10824-10832 Mots-clés : Packed  bed  Cocurrent  flow  Energy  dissipation  Minimum  energy Résumé : Functional analysis of mass balances on gas and liquid, and pressure drop equations describing the concurrent flow in packed beds has yielded two criteria. Positive values of these criteria has been shown sufficient to achieve energy savings by synchronized periodic pulsations of inlet gas and liquid velocities or by liquid velocity only compared to the situation under the same mean steady inlet phase velocities. This, however, is not the case of pulsation by gas inlet velocity alone. The developed criteria have been evaluated from data obtained by experimental measurement of liquid holdup and gas pressure drop in a column 0.05 m in diameter packed to 1 m by 0.003 m glass spheres using water/air and toluene/air system. Our experiments showed these criteria to be fulfilled in the whole domain of gas and liquid velocities tested. Evaluation of the energy savings under pulsations relative to the steady state operation showed that the savings for water/air system may reach up to 4% with the maximum in region of high and intermediate liquid velocities and low gas velocities. For the toluene/air system the savings are somewhat lower and occur in the same velocity domain. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24523899