Documents disponibles écrits par cet auteur

Experimental and numerical studies of water droplet impact on a porous surface in the film-Boiling regime / Zhao Yu in Industrial & engineering chemistry research, Vol. 47 N° 23 (Décembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N° 23 (Décembre 2008) . - p. 9174–9182 Titre : Experimental and numerical studies of water droplet impact on a porous surface in the film-Boiling regime Type de document : texte imprimé Auteurs : Zhao Yu, Auteur ; Wang, Fei, Auteur ; L.-S. Fan, Auteur Année de publication : 2009 Article en page(s) : p. 9174–9182 Note générale : Chemistry engineering Langues : Anglais (eng) Mots-clés : Experimental  and  Numerical  Studies  Water  Droplet  Film-Boiling  Regime Résumé : An experimental and numerical study of the water droplet in collision with a porous surface in the film-boiling regime is reported. The porous substrate with a porosity of 34% and pore size of 76 nm is heated to 300 °C, and the motion of the droplet is recorded by a high-speed digital camera. A new three-dimensional (3-D) numerical model is developed to account for the transport phenomenon both inside and outside the porous media, by coupling the flow field with the heat and mass transfer process. The vapor layer model is used as a subgrid model to calculate the induced vapor pressure in the narrow region between the droplet and the surface. The vapor mass transfer is modeled considering the vapor generation and transport mechanisms in different domains. Direct numerical simulation is performed under the same conditions as the experiment, and the simulation results for the droplet behavior are in good agreement with the experimental results. The collision of a water droplet on the porous surface shows similar features to those on nonporous surfaces in the film-boiling regime, probably because of the small pore size of the material used in the current study. However, the droplet has a longer residence time, and it also seems to be less stable on the porous surface. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800479r [article] Experimental and numerical studies of water droplet impact on a porous surface in the film-Boiling regime [texte imprimé] / Zhao Yu, Auteur ; Wang, Fei, Auteur ; L.-S. Fan, Auteur . - 2009 . - p. 9174–9182. Chemistry engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N° 23 (Décembre 2008) . - p. 9174–9182 Mots-clés : Experimental  and  Numerical  Studies  Water  Droplet  Film-Boiling  Regime Résumé : An experimental and numerical study of the water droplet in collision with a porous surface in the film-boiling regime is reported. The porous substrate with a porosity of 34% and pore size of 76 nm is heated to 300 °C, and the motion of the droplet is recorded by a high-speed digital camera. A new three-dimensional (3-D) numerical model is developed to account for the transport phenomenon both inside and outside the porous media, by coupling the flow field with the heat and mass transfer process. The vapor layer model is used as a subgrid model to calculate the induced vapor pressure in the narrow region between the droplet and the surface. The vapor mass transfer is modeled considering the vapor generation and transport mechanisms in different domains. Direct numerical simulation is performed under the same conditions as the experiment, and the simulation results for the droplet behavior are in good agreement with the experimental results. The collision of a water droplet on the porous surface shows similar features to those on nonporous surfaces in the film-boiling regime, probably because of the small pore size of the material used in the current study. However, the droplet has a longer residence time, and it also seems to be less stable on the porous surface. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800479r

Mixing performance of the novel kar dynamic mixer impeller in small laboratory-scale systems / Zhao Yu in Industrial & engineering chemistry research, Vol. 51 N° 46 (Novembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 46 (Novembre 2012) . - pp. 15282–15292 Titre : Mixing performance of the novel kar dynamic mixer impeller in small laboratory-scale systems Type de document : texte imprimé Auteurs : Zhao Yu, Auteur ; Richard F. Cope, Auteur ; Kishore K. Kar, Auteur Année de publication : 2013 Article en page(s) : pp. 15282–15292 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Laboratory  scale  Agitator  Mixer  Mixing Résumé : Small (<100 mL) lab-scale systems for rapid screening are widely employed in research and development in chemistry and biology, but commonly encounter significant mixing challenges. Researchers from the Engineering and Process Sciences Laboratory of The Dow Chemical Company developed and patented a novel Kar Dynamic Mixer (KDM) impeller for overhead mixing within such unbaffled systems. This impeller consists of multiple twisted ribbon elements mounted on a rotating shaft. Through laboratory experiments and computational fluid dynamics (CFD) simulations, the performance of the KDM impeller was compared to that of vendor-offered impellers in three different lab-scale mixing systems. In fluid viscosities ranging from 5000 to 30 000 cP, the KDM impeller produced the desired mixing in significantly less time than each commercially offered impeller system. Experiments and simulations characterized KDM impeller operations and yielded the recommended ratios of KDM diameter-to-vial diameter (D/T), liquid submergence-to-KDM diameter (s/D), and off-bottom clearance-to-KDM diameter (c/D). The optimal speed at which the KDM impeller rotates depends on the fluid system of interest. The design of the KDM impeller was refined for the applications described in this work by optimizing the length-to-diameter ratio (L/D) of the impeller elements, as well as the number of repeated KDM elements so as to meet the recommended values of s/D, c/D, and L/D. Other crucial features of the optimized KDM design included twisting all elements in the same direction (be it clockwise or counter-clockwise), and the 90 degree offset angle between adjacent elements. The KDM impeller is well suited to laboratory scales, but its high relative mass could make it impractical at some larger scales, depending on fluids of interest and materials of construction. Identifying the size at which the KDM becomes impractical was beyond the current effort. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26679649 [article] Mixing performance of the novel kar dynamic mixer impeller in small laboratory-scale systems [texte imprimé] / Zhao Yu, Auteur ; Richard F. Cope, Auteur ; Kishore K. Kar, Auteur . - 2013 . - pp. 15282–15292. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 46 (Novembre 2012) . - pp. 15282–15292 Mots-clés : Laboratory  scale  Agitator  Mixer  Mixing Résumé : Small (<100 mL) lab-scale systems for rapid screening are widely employed in research and development in chemistry and biology, but commonly encounter significant mixing challenges. Researchers from the Engineering and Process Sciences Laboratory of The Dow Chemical Company developed and patented a novel Kar Dynamic Mixer (KDM) impeller for overhead mixing within such unbaffled systems. This impeller consists of multiple twisted ribbon elements mounted on a rotating shaft. Through laboratory experiments and computational fluid dynamics (CFD) simulations, the performance of the KDM impeller was compared to that of vendor-offered impellers in three different lab-scale mixing systems. In fluid viscosities ranging from 5000 to 30 000 cP, the KDM impeller produced the desired mixing in significantly less time than each commercially offered impeller system. Experiments and simulations characterized KDM impeller operations and yielded the recommended ratios of KDM diameter-to-vial diameter (D/T), liquid submergence-to-KDM diameter (s/D), and off-bottom clearance-to-KDM diameter (c/D). The optimal speed at which the KDM impeller rotates depends on the fluid system of interest. The design of the KDM impeller was refined for the applications described in this work by optimizing the length-to-diameter ratio (L/D) of the impeller elements, as well as the number of repeated KDM elements so as to meet the recommended values of s/D, c/D, and L/D. Other crucial features of the optimized KDM design included twisting all elements in the same direction (be it clockwise or counter-clockwise), and the 90 degree offset angle between adjacent elements. The KDM impeller is well suited to laboratory scales, but its high relative mass could make it impractical at some larger scales, depending on fluids of interest and materials of construction. Identifying the size at which the KDM becomes impractical was beyond the current effort. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26679649