Documents disponibles écrits par cet auteur

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]  in Industrial & 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

Mass transfer rates from oscillating bubbles in bubble columns operating with viscous fluids / Mariano Martin in Industrial & engineering chemistry research, Vol. 47 N° 23 (Décembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N° 23 (Décembre 2008) . - p. 9527–9536 Titre : Mass transfer rates from oscillating bubbles in bubble columns operating with viscous fluids Type de document : texte imprimé Auteurs : Mariano Martin, Auteur ; Francisco J. Montes, Auteur ; Miguel A. Galán, Auteur Année de publication : 2009 Article en page(s) : p. 9527–9536 Note générale : Chemistry engineering Langues : Anglais (eng) Mots-clés : Transfer  rates  Bubble  columns  Viscous  fluids Résumé : In spite of the work on bubble columns, their design and scale-up is still a difficult task due to the lack of understanding of bubble dispersions and mass transfer mechanisms. Even less known are viscous or non-Newtonian fluids. Therefore, a theoretical model for predicting the volumetric mass transfer coefficient, kLa, in bubble columns operating with viscous fluids has been proposed. The model consists of a population balance coupled with a theoretical equation for the Sherwood number for oscillating bubbles, considering the effect of liquid viscosity on both. Experimental results for Newtonian and non-Newtonian viscous liquids from the literature are used to validate the model. Bubble dispersions have been simulated with good agreement using the Weber critical number, Wec, as a parameter to account for the effect of liquid viscosity, which increases bubble stability. A correlation between the liquid viscosity and Wec has also been proposed. The mass transfer resistance is calculated taking into account the hydrodynamic processes involving bubbles (collisions, breakup, coalescence, detachment) because they provide initial oscillation amplitudes. However, bubble oscillation decays in viscous liquids because the oscillating energy is absorbed as viscous dissipation. Good agreement is found between the experimental and the predicted kLa when considering that bubble oscillations do not decay completely by viscous dissipation due to the continuous bubble collisions, breakup, and coalescence. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801077s [article] Mass transfer rates from oscillating bubbles in bubble columns operating with viscous fluids [texte imprimé] / Mariano Martin, Auteur ; Francisco J. Montes, Auteur ; Miguel A. Galán, Auteur . - 2009 . - p. 9527–9536. Chemistry engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N° 23 (Décembre 2008) . - p. 9527–9536 Mots-clés : Transfer  rates  Bubble  columns  Viscous  fluids Résumé : In spite of the work on bubble columns, their design and scale-up is still a difficult task due to the lack of understanding of bubble dispersions and mass transfer mechanisms. Even less known are viscous or non-Newtonian fluids. Therefore, a theoretical model for predicting the volumetric mass transfer coefficient, kLa, in bubble columns operating with viscous fluids has been proposed. The model consists of a population balance coupled with a theoretical equation for the Sherwood number for oscillating bubbles, considering the effect of liquid viscosity on both. Experimental results for Newtonian and non-Newtonian viscous liquids from the literature are used to validate the model. Bubble dispersions have been simulated with good agreement using the Weber critical number, Wec, as a parameter to account for the effect of liquid viscosity, which increases bubble stability. A correlation between the liquid viscosity and Wec has also been proposed. The mass transfer resistance is calculated taking into account the hydrodynamic processes involving bubbles (collisions, breakup, coalescence, detachment) because they provide initial oscillation amplitudes. However, bubble oscillation decays in viscous liquids because the oscillating energy is absorbed as viscous dissipation. Good agreement is found between the experimental and the predicted kLa when considering that bubble oscillations do not decay completely by viscous dissipation due to the continuous bubble collisions, breakup, and coalescence. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801077s