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]  inIndustrial & 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

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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]  inIndustrial & 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, Éditeur scientifique ; Zai-Sha Mao, Éditeur scientifique ; Chao Yang, Éditeur 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, Éditeur scientifique ; Zai-Sha Mao, Éditeur scientifique ; Chao Yang, Éditeur 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

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