Documents disponibles écrits par cet auteur

CFD–DEM study of the effect of particle density distribution on the multiphase flow and performance of dense medium cyclone / K. W. Chu in Minerals engineering, Vol. 22 N° 11 (Octobre 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 893–909 Titre : CFD–DEM study of the effect of particle density distribution on the multiphase flow and performance of dense medium cyclone Type de document : texte imprimé Auteurs : K. W. Chu, Auteur ; B. Wang, Auteur ; A. B. Yu, Auteur Année de publication : 2009 Article en page(s) : pp. 893–909 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Dense  medium  cyclone  Discrete  element  method  Computational  fluid  dynamics  Coal  preparation Résumé : A mathematical model is developed to study the coal-medium flow in a dense medium cyclone (DMC) of 1000 mm body diameter. In the model, the motion of coal particles is obtained using the Discrete Element Method (DEM) facilitated with the concept of “parcel–particle” while the flow of medium as a liquid-magnetite mixture Computational Fluid Dynamics (CFD) based on the local averaged Navier–Stokes equations. In addition the Reynolds Stress Model (RSM) is adopted to describe the anisotropic turbulence, the Volume of Fluid (VOF) model is used to describe the air-core position and multiphase mixture model used to estimate the flow of fine magnetite particles. The simulated medium and coal flows allow estimates to be made of pressure drop, efflux stream medium densities and partition curves for coal particles of different sizes and densities. These estimates are compared favourably with industrial scale measurements of a 1000 mm DMC operating under similar conditions. On this base, the effect of particle density distribution that represents the major difference between two major coal type, i.e., coking coal and thermal coal, is studied. The results are analysed in terms of medium flow pattern, particle flow pattern, partition performance and particle–fluid, particle–wall and particle–particle interaction forces. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001150 [article] CFD–DEM study of the effect of particle density distribution on the multiphase flow and performance of dense medium cyclone [texte imprimé] / K. W. Chu, Auteur ; B. Wang, Auteur ; A. B. Yu, Auteur . - 2009 . - pp. 893–909. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 893–909 Mots-clés : Dense  medium  cyclone  Discrete  element  method  Computational  fluid  dynamics  Coal  preparation Résumé : A mathematical model is developed to study the coal-medium flow in a dense medium cyclone (DMC) of 1000 mm body diameter. In the model, the motion of coal particles is obtained using the Discrete Element Method (DEM) facilitated with the concept of “parcel–particle” while the flow of medium as a liquid-magnetite mixture Computational Fluid Dynamics (CFD) based on the local averaged Navier–Stokes equations. In addition the Reynolds Stress Model (RSM) is adopted to describe the anisotropic turbulence, the Volume of Fluid (VOF) model is used to describe the air-core position and multiphase mixture model used to estimate the flow of fine magnetite particles. The simulated medium and coal flows allow estimates to be made of pressure drop, efflux stream medium densities and partition curves for coal particles of different sizes and densities. These estimates are compared favourably with industrial scale measurements of a 1000 mm DMC operating under similar conditions. On this base, the effect of particle density distribution that represents the major difference between two major coal type, i.e., coking coal and thermal coal, is studied. The results are analysed in terms of medium flow pattern, particle flow pattern, partition performance and particle–fluid, particle–wall and particle–particle interaction forces. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001150

Modeling the multiphase flow in a dense medium cyclone / B. Wang in Industrial & engineering chemistry research, Vol. 48 N° 7 (Avril 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 7 (Avril 2009) . - pp. 3628–3639 Titre : Modeling the multiphase flow in a dense medium cyclone Type de document : texte imprimé Auteurs : B. Wang, Auteur ; K. W. Chu, Auteur ; A. B. Yu, Auteur Année de publication : 2009 Article en page(s) : pp. 3628–3639 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Multiphase  flow  Dense-medium  cyclone  Fluid  multiphase  model  Reynolds  stress  model Résumé : A mathematical model is proposed to describe the multiphase flow in a dense-medium cyclone (DMC). In this model, the volume of fluid multiphase model is first used to determine the shape and position of the air core, and then the mixture multiphase model is employed to describe the flow of the dense medium (comprising finely ground magnetite in water) and the air core, where the turbulence is described by the Reynolds stress model. The results of fluid flow are finally used in the simulation of coal particle flow described by the stochastic Lagrangian particle tracking model. The validity of the proposed approach is verified by the reasonably good agreement between the measured and predicted results under different conditions. The flow features in a DMC are then examined in terms of factors such as flow field, pressure drop, particle trajectories, and separation efficiency. The results are used to explain the key characteristics of flow in DMCs, such as the origin of a short-circuit flow, the flow pattern, and the motion of coal particles. Moreover, the so-called surging phenomenon is examined in relation to the instability of fluid flow. The model offers a convenient method to investigate the effects of variables related to geometrical and operational conditions on the performance of DMCs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801175c [article] Modeling the multiphase flow in a dense medium cyclone [texte imprimé] / B. Wang, Auteur ; K. W. Chu, Auteur ; A. B. Yu, Auteur . - 2009 . - pp. 3628–3639. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 7 (Avril 2009) . - pp. 3628–3639 Mots-clés : Multiphase  flow  Dense-medium  cyclone  Fluid  multiphase  model  Reynolds  stress  model Résumé : A mathematical model is proposed to describe the multiphase flow in a dense-medium cyclone (DMC). In this model, the volume of fluid multiphase model is first used to determine the shape and position of the air core, and then the mixture multiphase model is employed to describe the flow of the dense medium (comprising finely ground magnetite in water) and the air core, where the turbulence is described by the Reynolds stress model. The results of fluid flow are finally used in the simulation of coal particle flow described by the stochastic Lagrangian particle tracking model. The validity of the proposed approach is verified by the reasonably good agreement between the measured and predicted results under different conditions. The flow features in a DMC are then examined in terms of factors such as flow field, pressure drop, particle trajectories, and separation efficiency. The results are used to explain the key characteristics of flow in DMCs, such as the origin of a short-circuit flow, the flow pattern, and the motion of coal particles. Moreover, the so-called surging phenomenon is examined in relation to the instability of fluid flow. The model offers a convenient method to investigate the effects of variables related to geometrical and operational conditions on the performance of DMCs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801175c

A numerical model for the liquid flow in a sputnik coal distributor / B.Y. Guo in Minerals engineering, Vol. 22 N° 1 (Janvier 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 1 (Janvier 2009) . - pp. 78–87 Titre : A numerical model for the liquid flow in a sputnik coal distributor Type de document : texte imprimé Auteurs : B.Y. Guo, Auteur ; K. J. Dong, Auteur ; K. W. Chu, Auteur Année de publication : 2009 Article en page(s) : pp. 78–87 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Coal  preparation  Coal  distributor  Fluid  flow  Numerical  modeling  Computational  fluid  dynamics Index. décimale : 622 Industrie minière Résumé : Sputnik coal distributors are widely applied in coal separation plants and biased outputs are frequently encountered. The present paper aims to develop a numerical model for simulating the flow of the carrier liquid within a distributor chamber. The model uses simple homogeneous multi-phase flow model and performs well in terms of successfully predicting the important phenomena within the distributor chamber, such as the strong vortex in the upper chamber and channeling through the slots on the orifice plate, as observed experimentally. The model provides necessary information for particle flow modeling and offers a useful tool to trouble-shooting of operations and optimization of design for such type of devices. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687508001088 [article] A numerical model for the liquid flow in a sputnik coal distributor [texte imprimé] / B.Y. Guo, Auteur ; K. J. Dong, Auteur ; K. W. Chu, Auteur . - 2009 . - pp. 78–87. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 1 (Janvier 2009) . - pp. 78–87 Mots-clés : Coal  preparation  Coal  distributor  Fluid  flow  Numerical  modeling  Computational  fluid  dynamics Index. décimale : 622 Industrie minière Résumé : Sputnik coal distributors are widely applied in coal separation plants and biased outputs are frequently encountered. The present paper aims to develop a numerical model for simulating the flow of the carrier liquid within a distributor chamber. The model uses simple homogeneous multi-phase flow model and performs well in terms of successfully predicting the important phenomena within the distributor chamber, such as the strong vortex in the upper chamber and channeling through the slots on the orifice plate, as observed experimentally. The model provides necessary information for particle flow modeling and offers a useful tool to trouble-shooting of operations and optimization of design for such type of devices. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687508001088

Numerical simulation of the gas-solid flow in three-dimensional pneumatic conveying bends / K. W. Chu 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. 7058–7071 Titre : Numerical simulation of the gas-solid flow in three-dimensional pneumatic conveying bends Type de document : texte imprimé Auteurs : K. W. Chu, Auteur ; A. B. Yu, Auteur Année de publication : 2008 Article en page(s) : p. 7058–7071 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Gas-solid  flow  Pneumatic  conveying  bend Résumé : The laden gas−solid flow in a pneumatic conveying bend is featured with intensive gas−solid, particle−particle, and particle−wall interactions, which are however difficult to quantify experimentally. In this work, these interactions are obtained by use of a three-dimensional combined continuum and discrete model. The model is achieved by combining our code for discrete element method for solid phase with the commercial software package Fluent for computational fluid dynamics for gas phase. The applicability of the approach is first qualitatively verified by comparing the simulated results with the observations in the literature in terms of typical flow features in bends such as roping, particle segregation, particle velocity reduction, particle recirculation, and pressure fluctuation. The gas−solid, particle−particle, and particle−wall interaction forces are then analyzed to understand their role in governing the complicated flow. It is found that the intensive gas−particle interaction at the outer wall makes the peak of the axial velocity shift from the outer wall to the inner wall of a pipe. Correspondingly, the so-called secondary flow is suppressed in the outer wall region but enhanced along the side wall. The spatial distribution of particle−wall interaction is obtained and shown to correspond to the wearing pattern in a bend. This distribution is also found in the particle−particle interaction close to the bend wall. Not only gas−solid interaction but also particle−particle interaction contributes to the dispersion of a rope. Finally, simulations are also conducted to investigate the effects of inlet conditions such as gas and solid flow rates on these interaction forces. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800108c [article] Numerical simulation of the gas-solid flow in three-dimensional pneumatic conveying bends [texte imprimé] / K. W. Chu, Auteur ; A. B. Yu, Auteur . - 2008 . - p. 7058–7071. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°18 (Septembre 2008) . - p. 7058–7071 Mots-clés : Gas-solid  flow  Pneumatic  conveying  bend Résumé : The laden gas−solid flow in a pneumatic conveying bend is featured with intensive gas−solid, particle−particle, and particle−wall interactions, which are however difficult to quantify experimentally. In this work, these interactions are obtained by use of a three-dimensional combined continuum and discrete model. The model is achieved by combining our code for discrete element method for solid phase with the commercial software package Fluent for computational fluid dynamics for gas phase. The applicability of the approach is first qualitatively verified by comparing the simulated results with the observations in the literature in terms of typical flow features in bends such as roping, particle segregation, particle velocity reduction, particle recirculation, and pressure fluctuation. The gas−solid, particle−particle, and particle−wall interaction forces are then analyzed to understand their role in governing the complicated flow. It is found that the intensive gas−particle interaction at the outer wall makes the peak of the axial velocity shift from the outer wall to the inner wall of a pipe. Correspondingly, the so-called secondary flow is suppressed in the outer wall region but enhanced along the side wall. The spatial distribution of particle−wall interaction is obtained and shown to correspond to the wearing pattern in a bend. This distribution is also found in the particle−particle interaction close to the bend wall. Not only gas−solid interaction but also particle−particle interaction contributes to the dispersion of a rope. Finally, simulations are also conducted to investigate the effects of inlet conditions such as gas and solid flow rates on these interaction forces. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800108c

Numerical studies of the effects of medium properties in dense medium cyclone operations / B. Wang in Minerals engineering, Vol. 22 N° 11 (Octobre 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 931–943 Titre : Numerical studies of the effects of medium properties in dense medium cyclone operations Type de document : texte imprimé Auteurs : B. Wang, Auteur ; K. W. Chu, Auteur ; A. B. Yu, Auteur Année de publication : 2009 Article en page(s) : pp. 931–943 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Dense  medium  cyclone  Multiphase  flow  Computational  fluid  dynamics  Separations Résumé : A mathematical approach is proposed to describe the multiphase flow in a 1000 mm industrial dense medium cyclone. A mixture multiphase model is employed to describe the flow of the dense medium (comprising finely ground magnetite contaminated with non-magnetic material in water) and the air core, where the turbulence is described by the well established Reynolds stress model. The stochastic Lagrangian particle tracking method is used to simulate the flow of coal particles. The proposed approach was qualitatively validated using literature and industrial data and then used to study the effects of medium properties including medium density, magnetite type and non-magnetic content. It is found that as the medium density increases, the pressure drop increases, resulting in a high pressure gradient force on coal particles and reduced separating efficiencies. The segregation of magnetite particles becomes serious as magnetite particle size increases, which leads to a high density differential and a high off-set. The viscosity of medium decreases and the segregation of magnetite particles become significant with the decrease of non-magnetic content, resulting in a high density differential and off-set. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001009 [article] Numerical studies of the effects of medium properties in dense medium cyclone operations [texte imprimé] / B. Wang, Auteur ; K. W. Chu, Auteur ; A. B. Yu, Auteur . - 2009 . - pp. 931–943. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 931–943 Mots-clés : Dense  medium  cyclone  Multiphase  flow  Computational  fluid  dynamics  Separations Résumé : A mathematical approach is proposed to describe the multiphase flow in a 1000 mm industrial dense medium cyclone. A mixture multiphase model is employed to describe the flow of the dense medium (comprising finely ground magnetite contaminated with non-magnetic material in water) and the air core, where the turbulence is described by the well established Reynolds stress model. The stochastic Lagrangian particle tracking method is used to simulate the flow of coal particles. The proposed approach was qualitatively validated using literature and industrial data and then used to study the effects of medium properties including medium density, magnetite type and non-magnetic content. It is found that as the medium density increases, the pressure drop increases, resulting in a high pressure gradient force on coal particles and reduced separating efficiencies. The segregation of magnetite particles becomes serious as magnetite particle size increases, which leads to a high density differential and a high off-set. The viscosity of medium decreases and the segregation of magnetite particles become significant with the decrease of non-magnetic content, resulting in a high density differential and off-set. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001009