Documents disponibles écrits par cet auteur

An empirical correlation of drag coefficient for a single bubble rising in non-newtonian liquids / Zhang, Li. 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. 9767–9772 Titre : An empirical correlation of drag coefficient for a single bubble rising in non-newtonian liquids Type de document : texte imprimé Auteurs : Zhang, Li., Auteur ; Chao Yang, Auteur ; Zai-Sha Mao, Auteur Année de publication : 2009 Article en page(s) : p. 9767–9772 Note générale : Chemistry engineering Langues : Anglais (eng) Mots-clés : Empirical  correlation  Drag  coefficient  Non-Newtonian  liquids Résumé : The motion of a single bubble rising unsteadily and steadily in a quiescent non-Newtonian liquid was investigated experimentally. By using a charged coupled device camera to follow the rising bubble, the sequences of the recorded frames were digitized and analyzed using image analysis software, and the measurements of the acceleration and steady motion of bubbles were obtained. Using the experimental data, we proposed an empirical correlation to predict the total drag coefficient calculated from the accelerating motion to the steady motion with the added mass force and history force included. This correlation is an extension of our previous work with non-Newtonian fluids. This new correlation represents very well the experimental data of the total drag force in a wide range covering both unsteady accelerating motion and steady motion in non-Newtonian fluids. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8010319 [article] An empirical correlation of drag coefficient for a single bubble rising in non-newtonian liquids [texte imprimé] / Zhang, Li., Auteur ; Chao Yang, Auteur ; Zai-Sha Mao, Auteur . - 2009 . - p. 9767–9772. Chemistry engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N° 23 (Décembre 2008) . - p. 9767–9772 Mots-clés : Empirical  correlation  Drag  coefficient  Non-Newtonian  liquids Résumé : The motion of a single bubble rising unsteadily and steadily in a quiescent non-Newtonian liquid was investigated experimentally. By using a charged coupled device camera to follow the rising bubble, the sequences of the recorded frames were digitized and analyzed using image analysis software, and the measurements of the acceleration and steady motion of bubbles were obtained. Using the experimental data, we proposed an empirical correlation to predict the total drag coefficient calculated from the accelerating motion to the steady motion with the added mass force and history force included. This correlation is an extension of our previous work with non-Newtonian fluids. This new correlation represents very well the experimental data of the total drag force in a wide range covering both unsteady accelerating motion and steady motion in non-Newtonian fluids. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8010319

CFD modeling of nucleation, growth, aggregation, and breakage in continuous precipitation of barium sulfate in a stirred tank / Jingcai Cheng in Industrial & engineering chemistry research, Vol. 48 N° 15 (Août 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6992–7003 Titre : CFD modeling of nucleation, growth, aggregation, and breakage in continuous precipitation of barium sulfate in a stirred tank Type de document : texte imprimé Auteurs : Jingcai Cheng, Auteur ; Chao Yang, Auteur ; Zai-Sha Mao, Auteur Année de publication : 2009 Article en page(s) : pp. 6992–7003 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Barium  sulfate  (BaSO4)  Continuous  stirred  tank  reactor  Single-phase  Reynolds  Navier−Stokes  equations Résumé : In this work, the precipitation of barium sulfate (BaSO4) in a continuous stirred tank reactor (CSTR) is modeled. The flow field is obtained through solving the single-phase Reynolds averaged Navier−Stokes equations with a standard single-phase k−ε turbulence model. The population balance equation is solved through the standard method of moments (SMM) and the quadrature method of moments (QMOM) both with and without aggregation and breakage terms. In the cases of precipitation simulation without aggregation and breakage, the results predicted from 2-node QMOM, 3-node QMOM, and SMM are very close. Thus, 2-node QMOM could replace SMM and be well-incorporated into an in-house CFD code to simulate the precipitation in CSTR with acceptable accuracy. The predicted area-averaged crystal size d32 decreases almost linearly with increasing feed concentration, and the deviation from experimental data becomes significant at high feed concentration. Numerical simulation using 2-node QMOM with the Brownian motion and shear-induced aggregation kernels as well as a power-law breakage kernel indicates that the predicted d32 shows good qualitative agreement with experimental results, and the quantitative agreement is achieved when the appropriate breakage rate equation is adopted. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004282 [article] CFD modeling of nucleation, growth, aggregation, and breakage in continuous precipitation of barium sulfate in a stirred tank [texte imprimé] / Jingcai Cheng, Auteur ; Chao Yang, Auteur ; Zai-Sha Mao, Auteur . - 2009 . - pp. 6992–7003. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6992–7003 Mots-clés : Barium  sulfate  (BaSO4)  Continuous  stirred  tank  reactor  Single-phase  Reynolds  Navier−Stokes  equations Résumé : In this work, the precipitation of barium sulfate (BaSO4) in a continuous stirred tank reactor (CSTR) is modeled. The flow field is obtained through solving the single-phase Reynolds averaged Navier−Stokes equations with a standard single-phase k−ε turbulence model. The population balance equation is solved through the standard method of moments (SMM) and the quadrature method of moments (QMOM) both with and without aggregation and breakage terms. In the cases of precipitation simulation without aggregation and breakage, the results predicted from 2-node QMOM, 3-node QMOM, and SMM are very close. Thus, 2-node QMOM could replace SMM and be well-incorporated into an in-house CFD code to simulate the precipitation in CSTR with acceptable accuracy. The predicted area-averaged crystal size d32 decreases almost linearly with increasing feed concentration, and the deviation from experimental data becomes significant at high feed concentration. Numerical simulation using 2-node QMOM with the Brownian motion and shear-induced aggregation kernels as well as a power-law breakage kernel indicates that the predicted d32 shows good qualitative agreement with experimental results, and the quantitative agreement is achieved when the appropriate breakage rate equation is adopted. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004282

Chitosan/functionalized multiwalled carbon nanotubes multilayer hollow microspheres prepared via layer-by-layer assembly technique / Chao Yang in Industrial & engineering chemistry research, Vol. 51 N° 41 (Octobre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 41 (Octobre 2012) . - pp. 13346-13353 Titre : Chitosan/functionalized multiwalled carbon nanotubes multilayer hollow microspheres prepared via layer-by-layer assembly technique Type de document : texte imprimé Auteurs : Chao Yang, Auteur ; Peng Liu, Auteur Année de publication : 2012 Article en page(s) : pp. 13346-13353 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Microsphere  Multiple  layer Résumé : Novel multilayer hollow microspheres were fabricated via the layer-by-layer (LBL) assembly technique by the electrostatic interaction between the polycation chitosan (CHI) and the anion carboxyl-functionalized multiwalled carbon nanotubes (f-MWNTs) on sacrificial polystyrene sulfonate (PSS) microsphere templates. The successful stepwise growth of the CHI/f-MWNTs multilayers in different pH media was compared by zeta potential measurement and scanning electron microscopy (SEM) analysis. The morphologies of the hollow microspheres were characterized by transmission electron microscopy (TEM) and SEM. The swelling and collapse of the hollow microspheres occurred during the template removal by dissolution and the drying process. It was found that more f-MWNTs had been deposited onto the surface of the PSS microspheres at pH 3 than at pH 5, confirmed by SEM and thermogravimetric analysis (TGA). Furthermore, this result is consistent with the differences of the electrical conductivities of the hollow microspheres obtained from the different pH media. It is also found that in the etching process, the different etching reagents, such as DMF and toluene, obviously affected the electrical conductivity of the final hollow microspheres. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26493629 [article] Chitosan/functionalized multiwalled carbon nanotubes multilayer hollow microspheres prepared via layer-by-layer assembly technique [texte imprimé] / Chao Yang, Auteur ; Peng Liu, Auteur . - 2012 . - pp. 13346-13353. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 41 (Octobre 2012) . - pp. 13346-13353 Mots-clés : Microsphere  Multiple  layer Résumé : Novel multilayer hollow microspheres were fabricated via the layer-by-layer (LBL) assembly technique by the electrostatic interaction between the polycation chitosan (CHI) and the anion carboxyl-functionalized multiwalled carbon nanotubes (f-MWNTs) on sacrificial polystyrene sulfonate (PSS) microsphere templates. The successful stepwise growth of the CHI/f-MWNTs multilayers in different pH media was compared by zeta potential measurement and scanning electron microscopy (SEM) analysis. The morphologies of the hollow microspheres were characterized by transmission electron microscopy (TEM) and SEM. The swelling and collapse of the hollow microspheres occurred during the template removal by dissolution and the drying process. It was found that more f-MWNTs had been deposited onto the surface of the PSS microspheres at pH 3 than at pH 5, confirmed by SEM and thermogravimetric analysis (TGA). Furthermore, this result is consistent with the differences of the electrical conductivities of the hollow microspheres obtained from the different pH media. It is also found that in the etching process, the different etching reagents, such as DMF and toluene, obviously affected the electrical conductivity of the final hollow microspheres. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26493629

Experimental study on surface aerators stirred by triple impellers / Xiangyang Li in Industrial & engineering chemistry research, Vol. 48 N° 18 (Septembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8752–8756 Titre : Experimental study on surface aerators stirred by triple impellers Type de document : texte imprimé Auteurs : Xiangyang Li, Auteur ; Gengzhi Yu, Auteur ; Chao Yang, Auteur Année de publication : 2010 Article en page(s) : pp. 8752–8756 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Stirred  vessel  Gas-liquid  mass  transfer  Triple-impeller  Surface  aeration Résumé : In a stirred vessel with the aspect ratio of 2.4, the gas−liquid mass transfer characteristics of triple-impeller configurations with surface aeration have been studied. The way by adding one or more impellers below the aerating impeller could not overcome the problem of poor gas dispersion in the region close to the bottom of the gas−liquid vessel stirred only by a surface aerator. With the combination of surface aeration and sparger aeration, gas dispersion is greatly improved. Triple-impeller configurations and volumetric gas flow rates are optimized based on the volumetric mass transfer coefficient per power consumption. It is found that the sparging gas has only a little effect on the surface aeration, because the vessel is stirred by the triple-impeller configuration and with a larger aspect ratio. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900623m [article] Experimental study on surface aerators stirred by triple impellers [texte imprimé] / Xiangyang Li, Auteur ; Gengzhi Yu, Auteur ; Chao Yang, Auteur . - 2010 . - pp. 8752–8756. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8752–8756 Mots-clés : Stirred  vessel  Gas-liquid  mass  transfer  Triple-impeller  Surface  aeration Résumé : In a stirred vessel with the aspect ratio of 2.4, the gas−liquid mass transfer characteristics of triple-impeller configurations with surface aeration have been studied. The way by adding one or more impellers below the aerating impeller could not overcome the problem of poor gas dispersion in the region close to the bottom of the gas−liquid vessel stirred only by a surface aerator. With the combination of surface aeration and sparger aeration, gas dispersion is greatly improved. Triple-impeller configurations and volumetric gas flow rates are optimized based on the volumetric mass transfer coefficient per power consumption. It is found that the sparging gas has only a little effect on the surface aeration, because the vessel is stirred by the triple-impeller configuration and with a larger aspect ratio. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900623m

Large eddy simulation of turbulent flow and mixing time in a gas – liquid stirred tank / Qinghua Zhang in Industrial & engineering chemistry research, Vol. 51 N° 30 (Août 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 30 (Août 2012) . - pp. 10124-10131 Titre : Large eddy simulation of turbulent flow and mixing time in a gas – liquid stirred tank Type de document : texte imprimé Auteurs : Qinghua Zhang, Auteur ; Chao Yang, Auteur ; Zai-Sha Mao, Auteur Année de publication : 2012 Article en page(s) : pp. 10124-10131 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Stirred  vessel  Mixing  time  Turbulent  flow  Large  eddy  simulation Résumé : Mixing time is a key parameter relevant to the scale-up and design of agitated reactors. Although there have been many published papers on mixing times in stirred tanks predicted by computational fluid dynamics (CFD), there are few reports on the large eddy simulation (LES) based prediction of the mixing time in a gas―liquid stirred tank. In this work, an LES method based on an Eulerian―Eulerian model is presented for predicting the mixing time in a gas―liquid stirred tank agitated by a Rushton turbine. In order to verify the simulated results, mixing time experiments were carried out using a conductivity technique. In the present LES, the Smagorinsky subgrid scale model was used to model the effect of subgrid scale on the resolved scales. The concentration distributions and operating parameters such as feed positions, impeller speeds, and gas flow rates on the mixing time were examined It is shown that the predicted concentration distributions of tracers are more irregular and realistic by using LES. Also, the mixing time decreases with the increase of impeller speed. However, with increasing gas flow rate, the mixing time first increases and then levels off. The predicted mixing time by the LES method shows good agreement with the measured values. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26201427 [article] Large eddy simulation of turbulent flow and mixing time in a gas – liquid stirred tank [texte imprimé] / Qinghua Zhang, Auteur ; Chao Yang, Auteur ; Zai-Sha Mao, Auteur . - 2012 . - pp. 10124-10131. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 30 (Août 2012) . - pp. 10124-10131 Mots-clés : Stirred  vessel  Mixing  time  Turbulent  flow  Large  eddy  simulation Résumé : Mixing time is a key parameter relevant to the scale-up and design of agitated reactors. Although there have been many published papers on mixing times in stirred tanks predicted by computational fluid dynamics (CFD), there are few reports on the large eddy simulation (LES) based prediction of the mixing time in a gas―liquid stirred tank. In this work, an LES method based on an Eulerian―Eulerian model is presented for predicting the mixing time in a gas―liquid stirred tank agitated by a Rushton turbine. In order to verify the simulated results, mixing time experiments were carried out using a conductivity technique. In the present LES, the Smagorinsky subgrid scale model was used to model the effect of subgrid scale on the resolved scales. The concentration distributions and operating parameters such as feed positions, impeller speeds, and gas flow rates on the mixing time were examined It is shown that the predicted concentration distributions of tracers are more irregular and realistic by using LES. Also, the mixing time decreases with the increase of impeller speed. However, with increasing gas flow rate, the mixing time first increases and then levels off. The predicted mixing time by the LES method shows good agreement with the measured values. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26201427

Numerical simulation of barium sulfate precipitation process in a continuous stirred tank with multiple-time-scale turbulent mixer model / Qinghua Zhang in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009) 

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Water-dispersed conductive polypyrroles doped with lignosulfonate and the weak temperature dependence of electrical conductivity / Chao Yang in Industrial & engineering chemistry research, Vol. 48 N° 21 (Novembre 2009) 

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