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

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) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 424-429 Titre : Numerical simulation of barium sulfate precipitation process in a continuous stirred tank with multiple-time-scale turbulent mixer model Type de document : texte imprimé Auteurs : Qinghua Zhang, Editeur scientifique ; Zai-Sha Mao, Editeur scientifique ; Chao Yang, Editeur scientifique Année de publication : 2009 Article en page(s) : P. 424-429 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Barium  sulfate  Mixing  of  reagents  Precipitation  processes Résumé : Mixing of reagents is very important in precipitation processes, as it can significantly affect the size distribution and morphology of products. In this work, the influence of turbulent mixing on the course of barium sulfate precipitation process in a continuous stirred tank was investigated with multiple-time-scale turbulent mixer model. The effect of various operating conditions such as feed concentration, stirrer speed, and mean residence time on the barium sulfate precipitation process was clearly demonstrated. The simulation results were compared to the literature data, and good agreement is observed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800722f [article] Numerical simulation of barium sulfate precipitation process in a continuous stirred tank with multiple-time-scale turbulent mixer model [texte imprimé] / Qinghua Zhang, Editeur scientifique ; Zai-Sha Mao, Editeur scientifique ; Chao Yang, Editeur scientifique . - 2009 . - P. 424-429. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 424-429 Mots-clés : Barium  sulfate  Mixing  of  reagents  Precipitation  processes Résumé : Mixing of reagents is very important in precipitation processes, as it can significantly affect the size distribution and morphology of products. In this work, the influence of turbulent mixing on the course of barium sulfate precipitation process in a continuous stirred tank was investigated with multiple-time-scale turbulent mixer model. The effect of various operating conditions such as feed concentration, stirrer speed, and mean residence time on the barium sulfate precipitation process was clearly demonstrated. The simulation results were compared to the literature data, and good agreement is observed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800722f