Documents disponibles écrits par cet auteur

Determination of agglomeration kinetics in nanoparticle dispersions / Herbert Loria in Industrial & engineering chemistry research, Vol. 50 N° 14 (Juillet 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 14 (Juillet 2011) . - pp. 8529-8535 Titre : Determination of agglomeration kinetics in nanoparticle dispersions Type de document : texte imprimé Auteurs : Herbert Loria, Auteur ; Pedro Pereira-Almao, Auteur Année de publication : 2011 Article en page(s) : pp. 8529-8535 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Dispersion  Nanoparticle  Kinetics  Agglomeration Résumé : The direct application of nanoparticles as nonsupported adsorbents and catalysts is of high interest since they offer high surface areas with reduced mass transfer limitations. However, the natural tendency of these materials to aggregate, even faster when at high temperatures, makes the agglomeration process an important phenomenon to be studied, understood and, eventually controlled. A method to obtain the kinetics of nanoparticle agglomeration processes is presented in this paper. This analysis was based on the change of particle diameter during aggregation. The kinetic expression was validated with a series of experiments where the growth of Fe2O3 nanoparticles immersed in base oil was followed at different times, temperatures, and particle concentrations. Results revealed the nature of the particle agglomeration process in the ranges of the experimental conditions; they indicated that physical adhesion, more than chemical binding, is the determining mechanism for agglomeration of Fe2O3 nanoparticles immersed in base oil. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24346894 [article] Determination of agglomeration kinetics in nanoparticle dispersions [texte imprimé] / Herbert Loria, Auteur ; Pedro Pereira-Almao, Auteur . - 2011 . - pp. 8529-8535. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 14 (Juillet 2011) . - pp. 8529-8535 Mots-clés : Dispersion  Nanoparticle  Kinetics  Agglomeration Résumé : The direct application of nanoparticles as nonsupported adsorbents and catalysts is of high interest since they offer high surface areas with reduced mass transfer limitations. However, the natural tendency of these materials to aggregate, even faster when at high temperatures, makes the agglomeration process an important phenomenon to be studied, understood and, eventually controlled. A method to obtain the kinetics of nanoparticle agglomeration processes is presented in this paper. This analysis was based on the change of particle diameter during aggregation. The kinetic expression was validated with a series of experiments where the growth of Fe2O3 nanoparticles immersed in base oil was followed at different times, temperatures, and particle concentrations. Results revealed the nature of the particle agglomeration process in the ranges of the experimental conditions; they indicated that physical adhesion, more than chemical binding, is the determining mechanism for agglomeration of Fe2O3 nanoparticles immersed in base oil. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24346894

A model to predict the concentration of dispersed solid particles in an aqueous medium confined inside horizontal cylindrical channels / Herbert Loria in Industrial & engineering chemistry research, Vol. 48 N° 8 (Avril 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4088–4093 Titre : A model to predict the concentration of dispersed solid particles in an aqueous medium confined inside horizontal cylindrical channels Type de document : texte imprimé Auteurs : Herbert Loria, Auteur ; Pedro Pereira-Almao, Auteur Année de publication : 2009 Article en page(s) : pp. 4088–4093 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Cylindrical  channels  Solid  particles  Two-dimensional  convective-dispersive  model Résumé : The deposition of solid particles in cylindrical channels has received considerable attention, because of its direct application in industry. However, an adequate mathematical expression that studies the separation and suspension of dispersed particles present in horizontal cylindrical channels is still missing. In this paper, we developed and solved a time-dependent, two-dimensional convective-dispersive model that simulates the deposition and suspension of dispersed particles immersed in a fluid medium inside the cross section of a horizontal cylindrical channel in a stagnant situation. The results of the modeling are compared with a series of experiments that permit one to know the concentration of the particles in different points in the cross section of a horizontal cylinder. These experiments were performed using particles in the micrometer range dispersed in an aqueous medium. The conditions that permit to control the suspension and deposition of the particles inside a liquid medium with cylindrical geometry are unveiled by the presented model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801518p [article] A model to predict the concentration of dispersed solid particles in an aqueous medium confined inside horizontal cylindrical channels [texte imprimé] / Herbert Loria, Auteur ; Pedro Pereira-Almao, Auteur . - 2009 . - pp. 4088–4093. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4088–4093 Mots-clés : Cylindrical  channels  Solid  particles  Two-dimensional  convective-dispersive  model Résumé : The deposition of solid particles in cylindrical channels has received considerable attention, because of its direct application in industry. However, an adequate mathematical expression that studies the separation and suspension of dispersed particles present in horizontal cylindrical channels is still missing. In this paper, we developed and solved a time-dependent, two-dimensional convective-dispersive model that simulates the deposition and suspension of dispersed particles immersed in a fluid medium inside the cross section of a horizontal cylindrical channel in a stagnant situation. The results of the modeling are compared with a series of experiments that permit one to know the concentration of the particles in different points in the cross section of a horizontal cylinder. These experiments were performed using particles in the micrometer range dispersed in an aqueous medium. The conditions that permit to control the suspension and deposition of the particles inside a liquid medium with cylindrical geometry are unveiled by the presented model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801518p

A model to predict the concentration of submicrometer solid particles in viscous media confined inside horizontal cylindrical channels / Herbert Loria in Industrial & engineering chemistry research, Vol. 48 N° 8 (Avril 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4094–4100 Titre : A model to predict the concentration of submicrometer solid particles in viscous media confined inside horizontal cylindrical channels Type de document : texte imprimé Auteurs : Herbert Loria, Auteur ; Pedro Pereira-Almao, Auteur Année de publication : 2009 Article en page(s) : pp. 4094–4100 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ultradispersed  particles  Cylindrical  channel  Viscosity  Dispersion  coefficient Résumé : As light oil reserves dwindle, the extraction and processing of heavy crude oils are becoming increasingly important. The use of ultradispersed catalysts (nanometric catalytic particles dispersed in the oil) is considered to be a promising way to upgrade these materials. To simulate such processes, mass transfer of the ultradispersed particles must be estimated. However, an adequate mathematical expression to describe the motion of these particles through viscous media in a horizontal cylindrical channel is still missing. In this paper, we developed and solved a time-dependent, two-dimensional convective−dispersive model, which simulates the transient deposition and suspension of ultradispersed particles immersed in a viscous medium, inside the cross section of a horizontal cylindrical channel in a stagnant situation. The results of the modeling are compared with a series of experiments that permit knowledge of the concentration of the ultradispersed particles inside a horizontal cylinder. These experiments were performed using particles in the submicrometer range (average sizes of 198 nm) and fluid media with diverse densities and viscosities. The effect of the fluid medium properties and the initial particle concentration in the calculation of the dispersion coefficient was also studied. The conditions needed to maintain the solid particles suspended in the liquid medium, contained in a vessel with cylindrical geometry, are also unveiled by the presented model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801519e [article] A model to predict the concentration of submicrometer solid particles in viscous media confined inside horizontal cylindrical channels [texte imprimé] / Herbert Loria, Auteur ; Pedro Pereira-Almao, Auteur . - 2009 . - pp. 4094–4100. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4094–4100 Mots-clés : Ultradispersed  particles  Cylindrical  channel  Viscosity  Dispersion  coefficient Résumé : As light oil reserves dwindle, the extraction and processing of heavy crude oils are becoming increasingly important. The use of ultradispersed catalysts (nanometric catalytic particles dispersed in the oil) is considered to be a promising way to upgrade these materials. To simulate such processes, mass transfer of the ultradispersed particles must be estimated. However, an adequate mathematical expression to describe the motion of these particles through viscous media in a horizontal cylindrical channel is still missing. In this paper, we developed and solved a time-dependent, two-dimensional convective−dispersive model, which simulates the transient deposition and suspension of ultradispersed particles immersed in a viscous medium, inside the cross section of a horizontal cylindrical channel in a stagnant situation. The results of the modeling are compared with a series of experiments that permit knowledge of the concentration of the ultradispersed particles inside a horizontal cylinder. These experiments were performed using particles in the submicrometer range (average sizes of 198 nm) and fluid media with diverse densities and viscosities. The effect of the fluid medium properties and the initial particle concentration in the calculation of the dispersion coefficient was also studied. The conditions needed to maintain the solid particles suspended in the liquid medium, contained in a vessel with cylindrical geometry, are also unveiled by the presented model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801519e

Model to predict the concentration of ultradispersed particles immersed in viscous media flowing through horizontal cylindrical channels / Herbert Loria in Industrial & engineering chemistry research, Vol. 49 N° 4 (Fevrier 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 4 (Fevrier 2010) . - pp 1920–1930 Titre : Model to predict the concentration of ultradispersed particles immersed in viscous media flowing through horizontal cylindrical channels Type de document : texte imprimé Auteurs : Herbert Loria, Auteur ; Pedro Pereira-Almao, Auteur Année de publication : 2010 Article en page(s) : pp 1920–1930 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Ultradispersed  particles  Viscous  Horizontal  cylindrical  channels. Résumé : An innovative way to upgrade heavy crude oils is the use of ultradispersed catalysts; however, an adequate mathematical expression that describes the mass transfer on this process is still missing. This paper studies the separation and suspension of ultradispersed particles based on their motion through diverse viscous media enclosed in horizontal cylindrical channels. A time-dependent, three-dimensional convective−dispersive model which simulates the transient deposition and suspension of these particles immersed in viscous media inside a horizontal cylinder was developed and solved. This model was also experimentally validated, and its results unveiled the particle and fluid media properties that are necessary to control particle deposition. The experiments were performed using Fe2O3 particles (average sizes of 198 nm) immersed in water−glycerol mixtures with different densities and viscosities subject to different fluid velocities. The effect of the fluid medium properties, the initial particle concentration, and fluid velocity on the dispersion coefficient was also studied. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901232p [article] Model to predict the concentration of ultradispersed particles immersed in viscous media flowing through horizontal cylindrical channels [texte imprimé] / Herbert Loria, Auteur ; Pedro Pereira-Almao, Auteur . - 2010 . - pp 1920–1930. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 4 (Fevrier 2010) . - pp 1920–1930 Mots-clés : Ultradispersed  particles  Viscous  Horizontal  cylindrical  channels. Résumé : An innovative way to upgrade heavy crude oils is the use of ultradispersed catalysts; however, an adequate mathematical expression that describes the mass transfer on this process is still missing. This paper studies the separation and suspension of ultradispersed particles based on their motion through diverse viscous media enclosed in horizontal cylindrical channels. A time-dependent, three-dimensional convective−dispersive model which simulates the transient deposition and suspension of these particles immersed in viscous media inside a horizontal cylinder was developed and solved. This model was also experimentally validated, and its results unveiled the particle and fluid media properties that are necessary to control particle deposition. The experiments were performed using Fe2O3 particles (average sizes of 198 nm) immersed in water−glycerol mixtures with different densities and viscosities subject to different fluid velocities. The effect of the fluid medium properties, the initial particle concentration, and fluid velocity on the dispersion coefficient was also studied. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901232p

Prediction of density and viscosity of bitumen using the Peng−Robinson equation of state / Herbert Loria in Industrial & engineering chemistry research, Vol. 48 N° 22 (Novembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 22 (Novembre 2009) . - pp. 10129–10135 Titre : Prediction of density and viscosity of bitumen using the Peng−Robinson equation of state Type de document : texte imprimé Auteurs : Herbert Loria, Auteur ; Pedro Pereira-Almao, Auteur ; Marco Satyro, Auteur Année de publication : 2010 Article en page(s) : pp. 10129–10135 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Bitumen  Thermodynamic  models  Peng−Robinson  equation Résumé : Density and viscosity are important quantities required in engineering design for production, fluid transportation, and processing. However, there is no satisfactory theory for the calculation of these properties for bitumen. The principal objective of this paper is to obtain thermodynamic models to predict the density and viscosity of bitumen on the basis of the translated version of the Peng−Robinson equation of state. In the density calculation, a consistent correction to improve the liquid-phase volume estimation was applied. The density model evidenced a small percent average absolute error regarding experimental data (less than 1%). The model for viscosity was based on a modification of the Enskog’s equation. This modification allowed the prediction of bitumen viscosity using an equation of state along with a substance- and temperature-dependent parameter; this approach showed good accuracy with respect to experimental data. An important advantage of these models is the possibility of estimating viscosities at different pressures. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901031n [article] Prediction of density and viscosity of bitumen using the Peng−Robinson equation of state [texte imprimé] / Herbert Loria, Auteur ; Pedro Pereira-Almao, Auteur ; Marco Satyro, Auteur . - 2010 . - pp. 10129–10135. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 22 (Novembre 2009) . - pp. 10129–10135 Mots-clés : Bitumen  Thermodynamic  models  Peng−Robinson  equation Résumé : Density and viscosity are important quantities required in engineering design for production, fluid transportation, and processing. However, there is no satisfactory theory for the calculation of these properties for bitumen. The principal objective of this paper is to obtain thermodynamic models to predict the density and viscosity of bitumen on the basis of the translated version of the Peng−Robinson equation of state. In the density calculation, a consistent correction to improve the liquid-phase volume estimation was applied. The density model evidenced a small percent average absolute error regarding experimental data (less than 1%). The model for viscosity was based on a modification of the Enskog’s equation. This modification allowed the prediction of bitumen viscosity using an equation of state along with a substance- and temperature-dependent parameter; this approach showed good accuracy with respect to experimental data. An important advantage of these models is the possibility of estimating viscosities at different pressures. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901031n