Documents disponibles écrits par cet auteur

Development of anisotropic permeability during coalbed methane production / Yu Wu in Journal of natural gas science and engineering, Vol. 2 N° 4 (Septembre 2010) 

Public ISBD [article]  in Journal of natural gas science and engineering > Vol. 2 N° 4 (Septembre 2010) . - pp. 197–210 Titre : Development of anisotropic permeability during coalbed methane production Type de document : texte imprimé Auteurs : Yu Wu, Auteur ; Jishan Liu, Auteur ; Elsworth, Derek, Auteur Année de publication : 2012 Article en page(s) : pp. 197–210 Note générale : Génie Chimique Langues : Anglais (eng) Mots-clés : CBM  Dual  poroelasticity  Directional  permeability  Numerical  modelling Résumé : Although coal–gas interactions have been comprehensively investigated, prior studies have focused on one or more component processes of effective stress in driving only isotropic changes in coal permeability. In our previous work (Wu et al., 2009) a general porosity and permeability model was developed to represent the behavior of both the primary medium (coal matrix) and the secondary medium (fractures) under conditions of variable stress. In this study the permeability model is extended to define the evolution of gas sorption-induced permeability anisotropy under the full spectrum of mechanical conditions spanning prescribed in situ stresses through constrained displacement. These models are implemented into a fully coupled model of coal deformation, gas flow and transport in the matrix system, and gas flow and transport in the fracture system. The model separately accommodates compressible gas flow and transport in the coal matrix and fracture systems and rigorously accommodates the role of mechanical deformations for a dual-porosity continuum. Since mechanical interactions and the role of sorption-induced strains are rigorously accommodated, these micro-mechanical models are capable of following the evolution of porosity and permeability in both the coal matrix and the fracture network. This model represents important non-linear responses due to the effective stress effects that cannot be recovered where mechanical influences are not rigorously coupled with the transport system. The permeability model for fractures is verified against the analytical solution for a constant volume reservoir and applied to successfully match a suite of field data from the San Juan Basin. The fully coupled model for coal deformation and gas flow has been applied to quantify the impacts of fracture spacing and in situ ground stresses on coal properties and active processes: those involving shrinkage, swelling and direct changes in effective stress. Model results demonstrate the complex interactions of fracture–matrix induced by CBM production. ISSN : 1875-5100 En ligne : http://www.sciencedirect.com/science/article/pii/S1875510010000508 [article] Development of anisotropic permeability during coalbed methane production [texte imprimé] / Yu Wu, Auteur ; Jishan Liu, Auteur ; Elsworth, Derek, Auteur . - 2012 . - pp. 197–210. Génie Chimique Langues : Anglais (eng) in Journal of natural gas science and engineering > Vol. 2 N° 4 (Septembre 2010) . - pp. 197–210 Mots-clés : CBM  Dual  poroelasticity  Directional  permeability  Numerical  modelling Résumé : Although coal–gas interactions have been comprehensively investigated, prior studies have focused on one or more component processes of effective stress in driving only isotropic changes in coal permeability. In our previous work (Wu et al., 2009) a general porosity and permeability model was developed to represent the behavior of both the primary medium (coal matrix) and the secondary medium (fractures) under conditions of variable stress. In this study the permeability model is extended to define the evolution of gas sorption-induced permeability anisotropy under the full spectrum of mechanical conditions spanning prescribed in situ stresses through constrained displacement. These models are implemented into a fully coupled model of coal deformation, gas flow and transport in the matrix system, and gas flow and transport in the fracture system. The model separately accommodates compressible gas flow and transport in the coal matrix and fracture systems and rigorously accommodates the role of mechanical deformations for a dual-porosity continuum. Since mechanical interactions and the role of sorption-induced strains are rigorously accommodated, these micro-mechanical models are capable of following the evolution of porosity and permeability in both the coal matrix and the fracture network. This model represents important non-linear responses due to the effective stress effects that cannot be recovered where mechanical influences are not rigorously coupled with the transport system. The permeability model for fractures is verified against the analytical solution for a constant volume reservoir and applied to successfully match a suite of field data from the San Juan Basin. The fully coupled model for coal deformation and gas flow has been applied to quantify the impacts of fracture spacing and in situ ground stresses on coal properties and active processes: those involving shrinkage, swelling and direct changes in effective stress. Model results demonstrate the complex interactions of fracture–matrix induced by CBM production. ISSN : 1875-5100 En ligne : http://www.sciencedirect.com/science/article/pii/S1875510010000508

Fabrication and characterization of TiO2 nanotube – epoxy nanocomposites / Yu Wu in Industrial & engineering chemistry research, Vol. 50 N° 21 (Novembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 21 (Novembre 2011) . - pp. 11988–11995 Titre : Fabrication and characterization of TiO2 nanotube – epoxy nanocomposites Type de document : texte imprimé Auteurs : Yu Wu, Auteur ; Lei Song, Auteur ; Yuan Hu, Auteur Année de publication : 2011 Article en page(s) : pp. 11988–11995 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Nanocomposite  Titanium  oxide Résumé : A systematic study has been conducted to investigate the polymer matrix properties resulting from the introduction of TiO2 nanotubes (1-5% by weight) that had been surface-modified with phenyl dichlorophosphate (PDCP), into an epoxy resin. The thermal, mechanical, and combustion properties of the nanocomposites and the neat resin were measured by thermogravimetric analysis, dynamic mechanical thermal analysis, and microscale combustion calorimetry. The nanofiller infusion improved the thermal and mechanical properties of the epoxy resin. The nanocomposites resulted in an increase in the storage modulus and glass transition temperature compared to those of the neat epoxy resin. In addition, the combustion characteristics of the epoxy polymer were effectively improved by addition of the surface-modified nanotubes. Thermogravimetric analysis/infrared spectrometry and direct pyrolysis mass spectrometry confirmed that the TiO2 nanotubes were able to improve the thermal stability and combustion behavior of the polymer matrix because the TNTs retard the release of inflammable gas and change the degradation pathway. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24697519 [article] Fabrication and characterization of TiO2 nanotube – epoxy nanocomposites [texte imprimé] / Yu Wu, Auteur ; Lei Song, Auteur ; Yuan Hu, Auteur . - 2011 . - pp. 11988–11995. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 21 (Novembre 2011) . - pp. 11988–11995 Mots-clés : Nanocomposite  Titanium  oxide Résumé : A systematic study has been conducted to investigate the polymer matrix properties resulting from the introduction of TiO2 nanotubes (1-5% by weight) that had been surface-modified with phenyl dichlorophosphate (PDCP), into an epoxy resin. The thermal, mechanical, and combustion properties of the nanocomposites and the neat resin were measured by thermogravimetric analysis, dynamic mechanical thermal analysis, and microscale combustion calorimetry. The nanofiller infusion improved the thermal and mechanical properties of the epoxy resin. The nanocomposites resulted in an increase in the storage modulus and glass transition temperature compared to those of the neat epoxy resin. In addition, the combustion characteristics of the epoxy polymer were effectively improved by addition of the surface-modified nanotubes. Thermogravimetric analysis/infrared spectrometry and direct pyrolysis mass spectrometry confirmed that the TiO2 nanotubes were able to improve the thermal stability and combustion behavior of the polymer matrix because the TNTs retard the release of inflammable gas and change the degradation pathway. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24697519