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Cfd simulation of bubble column reactor using population balance / Kalekudithi Ekambara in Industrial & engineering chemistry research, Vol. 47 n°21 (Novembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p. 8505–8516 Titre : Cfd simulation of bubble column reactor using population balance Type de document : texte imprimé Auteurs : Kalekudithi Ekambara, Auteur ; Kumar Nandakuma, Auteur ; Jyeshtharaj B. Joshi, Auteur Année de publication : 2008 Article en page(s) : p. 8505–8516 Langues : Anglais (eng) Résumé : In this paper, we have presented a comprehensive analysis of the development of flow pattern in a bubble column reactor by the introduction of a population balance equation combined with the three-dimensional two-fluid model (Reynolds stress model). The multiple size group (MUSIG) model has been used to account for the nonuniform bubble size distribution in a gas−liquid mixture. The coalescence and breakage effects of the gas bubbles are modeled according to the coalescence by the random collision driven by turbulence and wake entrainment while for bubble breakage by the impact of turbulent eddies. Local radial distributions of the gas hold-up, Sauter mean bubble diameter, axial liquid velocity, turbulent kinetic energy, turbulent energy dissipation rate, and Reynolds stresses for superficial gas velocity of 20 mm/s are compared against experimental data in a bubble column reactor. The development of flow pattern were examined at six axial locations H/D = 0.2, 1.4, 2.6, 3.9, 5.0, and 6.2. Good quantitative agreement with the experimental data is obtained with three different models (i.e., k−ε, RSM with constant bubble size, and RSM with population balance). The model prediction shows better agreement with the experimental data with population balance than constant bubble diameter predictions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071393e [article] Cfd simulation of bubble column reactor using population balance [texte imprimé] / Kalekudithi Ekambara, Auteur ; Kumar Nandakuma, Auteur ; Jyeshtharaj B. Joshi, Auteur . - 2008 . - p. 8505–8516. Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p. 8505–8516 Résumé : In this paper, we have presented a comprehensive analysis of the development of flow pattern in a bubble column reactor by the introduction of a population balance equation combined with the three-dimensional two-fluid model (Reynolds stress model). The multiple size group (MUSIG) model has been used to account for the nonuniform bubble size distribution in a gas−liquid mixture. The coalescence and breakage effects of the gas bubbles are modeled according to the coalescence by the random collision driven by turbulence and wake entrainment while for bubble breakage by the impact of turbulent eddies. Local radial distributions of the gas hold-up, Sauter mean bubble diameter, axial liquid velocity, turbulent kinetic energy, turbulent energy dissipation rate, and Reynolds stresses for superficial gas velocity of 20 mm/s are compared against experimental data in a bubble column reactor. The development of flow pattern were examined at six axial locations H/D = 0.2, 1.4, 2.6, 3.9, 5.0, and 6.2. Good quantitative agreement with the experimental data is obtained with three different models (i.e., k−ε, RSM with constant bubble size, and RSM with population balance). The model prediction shows better agreement with the experimental data with population balance than constant bubble diameter predictions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071393e

Hydrodynamic simulation of horizontal slurry pipeline flow using ANSYS-CFX / Kalekudithi Ekambara in Industrial & engineering chemistry research, Vol. 48 N° 17 (Septembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 17 (Septembre 2009) . - pp. 8159–8171 Titre : Hydrodynamic simulation of horizontal slurry pipeline flow using ANSYS-CFX Type de document : texte imprimé Auteurs : Kalekudithi Ekambara, Auteur ; R. Sean Sanders, Auteur ; K. Nandakumar, Auteur Année de publication : 2009 Article en page(s) : pp. 8159–8171 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Solid−liquid  (slurry)  pipeline  flows  Three-dimensional  hydrodynamic  model  ANSYS-CFX Résumé : The behavior of horizontal solid−liquid (slurry) pipeline flows was predicted using a transient three-dimensional (3D) hydrodynamic model based on the kinetic theory of granular flows. Computational fluid dynamics (CFD) simulation results, obtained using a commercial CFD software package, ANSYS-CFX, were compared with a number of experimental data sets available in the literature. The simulations were carried out to investigate the effect of in situ solids volume concentration (8 to 45%), particle size (90 to 500 μm), mixture velocity (1.5 to 5.5 m/s), and pipe diameter (50 to 500 mm) on local, time-averaged solids concentration profiles, particle and liquid velocity profiles, and frictional pressure loss. Excellent agreement between the model predictions and the experimental data was obtained. The experimental and simulated results indicate that the particles are asymmetrically distributed in the vertical plane with the degree of asymmetry increasing with increasing particle size. Once the particles are sufficiently large, concentration profiles are dependent only on the in situ solids volume fraction. The present CFD model requires no experimentally determined slurry pipeline flow data for parameter tuning, and thus can be considered to be superior to commonly used, correlation-based empirical models. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801505z [article] Hydrodynamic simulation of horizontal slurry pipeline flow using ANSYS-CFX [texte imprimé] / Kalekudithi Ekambara, Auteur ; R. Sean Sanders, Auteur ; K. Nandakumar, Auteur . - 2009 . - pp. 8159–8171. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 17 (Septembre 2009) . - pp. 8159–8171 Mots-clés : Solid−liquid  (slurry)  pipeline  flows  Three-dimensional  hydrodynamic  model  ANSYS-CFX Résumé : The behavior of horizontal solid−liquid (slurry) pipeline flows was predicted using a transient three-dimensional (3D) hydrodynamic model based on the kinetic theory of granular flows. Computational fluid dynamics (CFD) simulation results, obtained using a commercial CFD software package, ANSYS-CFX, were compared with a number of experimental data sets available in the literature. The simulations were carried out to investigate the effect of in situ solids volume concentration (8 to 45%), particle size (90 to 500 μm), mixture velocity (1.5 to 5.5 m/s), and pipe diameter (50 to 500 mm) on local, time-averaged solids concentration profiles, particle and liquid velocity profiles, and frictional pressure loss. Excellent agreement between the model predictions and the experimental data was obtained. The experimental and simulated results indicate that the particles are asymmetrically distributed in the vertical plane with the degree of asymmetry increasing with increasing particle size. Once the particles are sufficiently large, concentration profiles are dependent only on the in situ solids volume fraction. The present CFD model requires no experimentally determined slurry pipeline flow data for parameter tuning, and thus can be considered to be superior to commonly used, correlation-based empirical models. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801505z