Analytical solution of the mass conservation equations in gas-liquid systems / Elena M. Cachaza in Industrial & engineering chemistry research, Vol. 47 N° 13 (Juillet 2008)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4510–4522 Titre : Analytical solution of the mass conservation equations in gas-liquid systems : applicability to the evaluation of the volumetric mass transfer coefficient (kLa) Type de document : texte imprimé Auteurs : Elena M. Cachaza, Auteur ; M. Elena Díaz, Auteur ; Francisco J. Montes, Auteur ; Miguel A. Galán, Auteur Année de publication : 2008 Article en page(s) : p. 4510–4522 Note générale : Bibliogr. p. 4520-4522 Langues : Anglais (eng) Mots-clés : Mass conservation equations  Gas-liquid systems  Analytical solution Résumé : In the present work, a simple analytical solution of the simplified mass conservation equations applicable to the calculation of the volumetric mass transfer coefficient (kLa) in gas–liquid systems, named the absorption model (ABM), has been proposed and compared to the classical and less complete continuous stirred tank reactor model (CSTR). A partially aerated 2D bubble column has been used in order to study the hydrodynamics and mass transfer at varying superficial gas velocities and aspect ratios (H/W) and examine the benefits of the proposed model. In addition to its simplicity and on the contrary to the CSTR model, the ABM is able to capture the variation of kLa with H/W caused by the formation of additional liquid circulation cells as H/W is increased. Furthermore, the ABM kLa resulting values, that are comparable with previously reported ones, increase with increasing axial positions as a result of higher aeration at upper sections of the bubble column. Also, kL values, not frequently reported in the literature, were calculated. The results show that kL remains approximately constant (≈5.5 × 10−4 m/s) and, therefore, independent of UG in the considered range. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800135h [article] Analytical solution of the mass conservation equations in gas-liquid systems : applicability to the evaluation of the volumetric mass transfer coefficient (kLa) [texte imprimé] / Elena M. Cachaza, Auteur ; M. Elena Díaz, Auteur ; Francisco J. Montes, Auteur ; Miguel A. Galán, Auteur . - 2008 . - p. 4510–4522. Bibliogr. p. 4520-4522 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4510–4522 Mots-clés : Mass conservation equations  Gas-liquid systems  Analytical solution Résumé : In the present work, a simple analytical solution of the simplified mass conservation equations applicable to the calculation of the volumetric mass transfer coefficient (kLa) in gas–liquid systems, named the absorption model (ABM), has been proposed and compared to the classical and less complete continuous stirred tank reactor model (CSTR). A partially aerated 2D bubble column has been used in order to study the hydrodynamics and mass transfer at varying superficial gas velocities and aspect ratios (H/W) and examine the benefits of the proposed model. In addition to its simplicity and on the contrary to the CSTR model, the ABM is able to capture the variation of kLa with H/W caused by the formation of additional liquid circulation cells as H/W is increased. Furthermore, the ABM kLa resulting values, that are comparable with previously reported ones, increase with increasing axial positions as a result of higher aeration at upper sections of the bubble column. Also, kL values, not frequently reported in the literature, were calculated. The results show that kL remains approximately constant (≈5.5 × 10−4 m/s) and, therefore, independent of UG in the considered range. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800135h

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Simultaneous computational fluid dynamics (CFD) simulation of the hydrodynamics and mass transfer in a partially aerated bubble column / Elena M. Cachaza in Industrial & engineering chemistry research, Vol. 48 N° 18 (Septembre 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8685–8696 Titre : Simultaneous computational fluid dynamics (CFD) simulation of the hydrodynamics and mass transfer in a partially aerated bubble column Type de document : texte imprimé Auteurs : Elena M. Cachaza, Auteur ; M. Elena Díaz, Auteur ; Francisco J. Montes, Auteur Année de publication : 2010 Article en page(s) : pp. 8685–8696 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Simultaneous hydrodynamics Mass-transfer computational fluid dynamics Aerated bubble column Résumé : In this work, simultaneous hydrodynamics and mass-transfer computational fluid dynamics (CFD) studies in a rectangular partially aerated bubble column were conducted. The proposed transient Eulerian−Eulerian model was applied to a two-phase flow composed of polydispersed air and water. Four different kl correlations were implemented in the CFD code, and the results were compared. At superficial gas velocity values ranging from 2.4 mm/s to 21.3 mm/s, the developed flow regimes were experimentally characterized by means of visual observations, global gas holdup, plume oscillation period, and Sauter mean bubble diameter measurements. Simultaneously, the transfer of oxygen from the disperse phase to the initially deoxygenized water was characterized by the measurement of the evolution of the dissolved oxygen concentration with time. Comparison between the experimental and simulated parameters previously mentioned allows for the validation of the computational model. According to the results presented in this work, experimental and simulated hydrodynamic and mass-transfer results show a remarkable agreement at all studied superficial gas velocity values. In addition, mass-transfer results reveal (1) no influence on the developed hydrodynamics, (2) the adequacy of the selected kl correlations obtained by an attentive simplification of mass-transfer equations, and (3) the enhancement of mass-transfer processes when using partially aerated bubble columns. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900314s [article] Simultaneous computational fluid dynamics (CFD) simulation of the hydrodynamics and mass transfer in a partially aerated bubble column [texte imprimé] / Elena M. Cachaza, Auteur ; M. Elena Díaz, Auteur ; Francisco J. Montes, Auteur . - 2010 . - pp. 8685–8696. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8685–8696 Mots-clés : Simultaneous hydrodynamics Mass-transfer computational fluid dynamics Aerated bubble column Résumé : In this work, simultaneous hydrodynamics and mass-transfer computational fluid dynamics (CFD) studies in a rectangular partially aerated bubble column were conducted. The proposed transient Eulerian−Eulerian model was applied to a two-phase flow composed of polydispersed air and water. Four different kl correlations were implemented in the CFD code, and the results were compared. At superficial gas velocity values ranging from 2.4 mm/s to 21.3 mm/s, the developed flow regimes were experimentally characterized by means of visual observations, global gas holdup, plume oscillation period, and Sauter mean bubble diameter measurements. Simultaneously, the transfer of oxygen from the disperse phase to the initially deoxygenized water was characterized by the measurement of the evolution of the dissolved oxygen concentration with time. Comparison between the experimental and simulated parameters previously mentioned allows for the validation of the computational model. According to the results presented in this work, experimental and simulated hydrodynamic and mass-transfer results show a remarkable agreement at all studied superficial gas velocity values. In addition, mass-transfer results reveal (1) no influence on the developed hydrodynamics, (2) the adequacy of the selected kl correlations obtained by an attentive simplification of mass-transfer equations, and (3) the enhancement of mass-transfer processes when using partially aerated bubble columns. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900314s

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