Documents disponibles écrits par cet auteur

Influence of the top impeller diameter on the gas dispersion in a sparged multi - impeller stirred tank / Yuyun Bao in Industrial & engineering chemistry research, Vol. 51 N° 38 (Septembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 38 (Septembre 2012) . - pp. 12411-12420 Titre : Influence of the top impeller diameter on the gas dispersion in a sparged multi - impeller stirred tank Type de document : texte imprimé Auteurs : Yuyun Bao, Auteur ; Jie Yang, Auteur ; Lei Chen, Auteur Année de publication : 2012 Article en page(s) : pp. 12411-12420 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Stirred  vessel  Dispersion  Agitator Résumé : The impeller configuration with a hollow half-elliptical blade dispersing turbine below two up-pumping wide-blade hydrofoils, identified as HEDT+2WHU and recommended in previous work, was used in this study. The effect of the top impeller diameter, ranging from 0.33T to 0.50T, on gas―liquid flow in a stirred tank of 0.48 m diameter was investigated by experimental and CFD methods. Power consumption, total gas holdup, and local void fraction were measured for the impeller configurations with different top impeller diameters. Results show that while the ratio of top impeller diameter to tank diameter (Dtop/T) increases from 0.33 to 0.50, the relative power demand (RPD) in a gas―liquid system decreases slightly. The increase of total gas holdup with rising gas flow rate becomes less evident as Dtop/T increases from 0.33 to 0.50. Local void fractions at the measurement points above the height of 0.8T increase significantly with the increase of top impeller diameter. When Dtop/T = 0.50, there is an extremely large voidage of about 50% just above the top impeller. The maximum voidage decreases with the decrease of top impeller diameter and almost disappears when Dtop/T = 0.33. CFD simulation based on the two-fluid model along with the population balance model (PBM) was used to investigate the effect of top impeller diameter on the gas―liquid flows. The power consumption, total gas holdup, and local void fraction predicted by the CFD approach were in reasonably good agreement with the experimental data. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26399692 [article] Influence of the top impeller diameter on the gas dispersion in a sparged multi - impeller stirred tank [texte imprimé] / Yuyun Bao, Auteur ; Jie Yang, Auteur ; Lei Chen, Auteur . - 2012 . - pp. 12411-12420. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 38 (Septembre 2012) . - pp. 12411-12420 Mots-clés : Stirred  vessel  Dispersion  Agitator Résumé : The impeller configuration with a hollow half-elliptical blade dispersing turbine below two up-pumping wide-blade hydrofoils, identified as HEDT+2WHU and recommended in previous work, was used in this study. The effect of the top impeller diameter, ranging from 0.33T to 0.50T, on gas―liquid flow in a stirred tank of 0.48 m diameter was investigated by experimental and CFD methods. Power consumption, total gas holdup, and local void fraction were measured for the impeller configurations with different top impeller diameters. Results show that while the ratio of top impeller diameter to tank diameter (Dtop/T) increases from 0.33 to 0.50, the relative power demand (RPD) in a gas―liquid system decreases slightly. The increase of total gas holdup with rising gas flow rate becomes less evident as Dtop/T increases from 0.33 to 0.50. Local void fractions at the measurement points above the height of 0.8T increase significantly with the increase of top impeller diameter. When Dtop/T = 0.50, there is an extremely large voidage of about 50% just above the top impeller. The maximum voidage decreases with the decrease of top impeller diameter and almost disappears when Dtop/T = 0.33. CFD simulation based on the two-fluid model along with the population balance model (PBM) was used to investigate the effect of top impeller diameter on the gas―liquid flows. The power consumption, total gas holdup, and local void fraction predicted by the CFD approach were in reasonably good agreement with the experimental data. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26399692

Numerical simulation of gas dispersion in an aerated stirred reactor with multiple impellers / Jian Min in Industrial & engineering chemistry research, Vol. 47 N°18 (Septembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°18 (Septembre 2008) . - p. 7112–7117 Titre : Numerical simulation of gas dispersion in an aerated stirred reactor with multiple impellers Type de document : texte imprimé Auteurs : Jian Min, Auteur ; Yuyun Bao, Auteur ; Lei Chen, Auteur Année de publication : 2008 Article en page(s) : p. 7112–7117 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Aerated  tank  Hollow-blade  disk  turbine  Euler-Euler  computation Résumé : The flow field and void fraction distribution in an aerated tank of 0.45 m diameter with a three-impeller agitator have been numerically simulated and validated against prior experimental data. An asymmetric deep hollow-blade disk turbine (BT-6) was used as bottom impeller to disperse the incoming gas, with two up-pumping, four-blade, Maxflo (MFU) hydrofoils above to ensure effective axial mixing from top to bottom of the tank. The standard Eulerian−Eulerian formulation of the k−ε turbulence model with multiple frames of reference (MFR) was used in the simulation. A population balance model (PBM) combined with a multiple size group (MUSIG) model has been implemented using the commercial CFX code. Bubble breakup and coalescence have been modeled fundamentally using isotropic turbulence theory. An alternative approach was provided by an Euler−Euler computation assuming a constant single average bubble diameter (SABD), set to 4 mm. These SABD results were compared with those predicted by the MUSIG model and also with experiment. The liquid and gas flow fields, gas void fraction distribution, average bubble diameter, and spatial distribution of bubbles of differing diameter were computed and partially compared with available experimental data. The gas void fraction distribution is strongly affected and controlled by the flow field. There is a region with very high local gas holdup near the tank wall, just above the level of the top impeller. This was correctly predicted by the MUSIG model in good agreement with the experimental results. The results when using the assumption of a single average bubble diameter did not fit the experimental data quite as well. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800490j [article] Numerical simulation of gas dispersion in an aerated stirred reactor with multiple impellers [texte imprimé] / Jian Min, Auteur ; Yuyun Bao, Auteur ; Lei Chen, Auteur . - 2008 . - p. 7112–7117. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°18 (Septembre 2008) . - p. 7112–7117 Mots-clés : Aerated  tank  Hollow-blade  disk  turbine  Euler-Euler  computation Résumé : The flow field and void fraction distribution in an aerated tank of 0.45 m diameter with a three-impeller agitator have been numerically simulated and validated against prior experimental data. An asymmetric deep hollow-blade disk turbine (BT-6) was used as bottom impeller to disperse the incoming gas, with two up-pumping, four-blade, Maxflo (MFU) hydrofoils above to ensure effective axial mixing from top to bottom of the tank. The standard Eulerian−Eulerian formulation of the k−ε turbulence model with multiple frames of reference (MFR) was used in the simulation. A population balance model (PBM) combined with a multiple size group (MUSIG) model has been implemented using the commercial CFX code. Bubble breakup and coalescence have been modeled fundamentally using isotropic turbulence theory. An alternative approach was provided by an Euler−Euler computation assuming a constant single average bubble diameter (SABD), set to 4 mm. These SABD results were compared with those predicted by the MUSIG model and also with experiment. The liquid and gas flow fields, gas void fraction distribution, average bubble diameter, and spatial distribution of bubbles of differing diameter were computed and partially compared with available experimental data. The gas void fraction distribution is strongly affected and controlled by the flow field. There is a region with very high local gas holdup near the tank wall, just above the level of the top impeller. This was correctly predicted by the MUSIG model in good agreement with the experimental results. The results when using the assumption of a single average bubble diameter did not fit the experimental data quite as well. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800490j

Temperature effects on gas dispersion and solid suspension in a three-phase stirred reactor / Yuyun Bao in Industrial & engineering chemistry research, Vol. 47 n°12 (Juin 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4270–4277 Titre : Temperature effects on gas dispersion and solid suspension in a three-phase stirred reactor Type de document : texte imprimé Auteurs : Yuyun Bao, Auteur ; Lei Chen, Auteur ; Zhengming Gao, Auteur ; Xinnian Zhang, Auteur Année de publication : 2008 Article en page(s) : p. 4270–4277 Note générale : Bibliogr. p. 4277 Langues : Anglais (eng) Mots-clés : Gas  dispersion;  Solid  suspension;  Impeller  combination;  Stirred  tank Résumé : Temperature effects on gas dispersion and solid suspension have been investigated in a fully baffled, dished-base stirred tank of 0.48 m diameter holding 0.145 m3 of liquid stirred by a triple-impeller combination. The impeller combination consisted of a half-elliptical disk turbine below two up-pumping wide-blade hydrofoils (WHU). This configuration is efficient for both gas dispersion and solid suspension. Power consumption, gas holdup, and the critical off-bottom just-suspension agitation speed have been measured at solid concentrations up to 21 vol % at six different temperatures ranging from 24 to 95 °C in increments of about 14 °C. The results confirm significant effects of temperature on the hydrodynamic characteristics. The relative power demand increases somewhat at increased temperature, although this effect is less when more solids are present. Gas holdup decreases significantly at higher temperatures, again an effect that is reduced at higher solid concentrations. The critical impeller speed for off-bottom just suspension (NJSG) increases with increasing gas rates over the whole temperature range of this work, though the effect of the gas rate on NJSG is less at higher temperatures. The effects of the temperature on power consumption, gas holdup, and NJSG have been quantified in a series of correlations that are relevant for the design and operation of hot-sparged three-phase reactors. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701726e [article] Temperature effects on gas dispersion and solid suspension in a three-phase stirred reactor [texte imprimé] / Yuyun Bao, Auteur ; Lei Chen, Auteur ; Zhengming Gao, Auteur ; Xinnian Zhang, Auteur . - 2008 . - p. 4270–4277. Bibliogr. p. 4277 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4270–4277 Mots-clés : Gas  dispersion;  Solid  suspension;  Impeller  combination;  Stirred  tank Résumé : Temperature effects on gas dispersion and solid suspension have been investigated in a fully baffled, dished-base stirred tank of 0.48 m diameter holding 0.145 m3 of liquid stirred by a triple-impeller combination. The impeller combination consisted of a half-elliptical disk turbine below two up-pumping wide-blade hydrofoils (WHU). This configuration is efficient for both gas dispersion and solid suspension. Power consumption, gas holdup, and the critical off-bottom just-suspension agitation speed have been measured at solid concentrations up to 21 vol % at six different temperatures ranging from 24 to 95 °C in increments of about 14 °C. The results confirm significant effects of temperature on the hydrodynamic characteristics. The relative power demand increases somewhat at increased temperature, although this effect is less when more solids are present. Gas holdup decreases significantly at higher temperatures, again an effect that is reduced at higher solid concentrations. The critical impeller speed for off-bottom just suspension (NJSG) increases with increasing gas rates over the whole temperature range of this work, though the effect of the gas rate on NJSG is less at higher temperatures. The effects of the temperature on power consumption, gas holdup, and NJSG have been quantified in a series of correlations that are relevant for the design and operation of hot-sparged three-phase reactors. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701726e