Documents disponibles écrits par cet auteur

Influence of templates on the overgrowth of MCM-41 over HY and the hydrodesulfurization performances of the supported Ni-Mo catalysts / Xiang Li in Industrial & engineering chemistry research, Vol. 48 N° 6 (Mars 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2870–2877 Titre : Influence of templates on the overgrowth of MCM-41 over HY and the hydrodesulfurization performances of the supported Ni-Mo catalysts Type de document : texte imprimé Auteurs : Xiang Li, Auteur ; Feng Zhou, Auteur ; Anjie Wang, Auteur Année de publication : 2009 Article en page(s) : pp. 2870–2877 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : MCM-41  HY  zeolite  Ni-Mo  sulfides  Hydrodesulfurization Résumé : Overgrowth of MCM-41 on HY zeolite was performed using different templates [cetyltrimethylammonium bromide (CTABr) and cetyltrimethylammonium chloride (CTACl)]. The hydrodesulfurization (HDS) performances of Ni−Mo sulfides supported over these synthesized composites were evaluated with dibenzothiophene (DBT) as the model sulfur-containing molecule. TEM and STEM images revealed that zeolite HY overgrown with an MCM-41 layer (less than 20 nm) was obtained using CTABr as the template [MY(Br)], and the MCM-41 pore channels were assumed to be oriented outward from the inner HY core. Nevertheless, for the samples synthesized using CTACl [MY(Cl)], the HY crystals were buried independently in the MCM-41 phase. Both Ni−Mo/MY(Br) and Ni−Mo/MY(Cl) showed higher HDS activity and reducibility than Ni−Mo/MCM-41. The hydrogenation activity of Ni−Mo/MCM-41 was enhanced more than the direct desulfurization activity by the introduction of HY zeolite. Ni−Mo/MY(Br) and Ni−Mo/MY(Cl) exhibited hydrocracking activities equivalent to that of Ni−Mo/MCM-41, indicating that the HDS of DBT predominantly takes place in the mesopores of Ni−Mo/MY(Br) and Ni−Mo/MY(Cl). Because the active species located in the mesopores cannot have close contact with the strong acid sites of the HY zeolite, it is suggested that the spillover hydrogen might play an essential role in the HDS reaction over the supported Ni−Mo sulfides. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801389w [article] Influence of templates on the overgrowth of MCM-41 over HY and the hydrodesulfurization performances of the supported Ni-Mo catalysts [texte imprimé] / Xiang Li, Auteur ; Feng Zhou, Auteur ; Anjie Wang, Auteur . - 2009 . - pp. 2870–2877. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2870–2877 Mots-clés : MCM-41  HY  zeolite  Ni-Mo  sulfides  Hydrodesulfurization Résumé : Overgrowth of MCM-41 on HY zeolite was performed using different templates [cetyltrimethylammonium bromide (CTABr) and cetyltrimethylammonium chloride (CTACl)]. The hydrodesulfurization (HDS) performances of Ni−Mo sulfides supported over these synthesized composites were evaluated with dibenzothiophene (DBT) as the model sulfur-containing molecule. TEM and STEM images revealed that zeolite HY overgrown with an MCM-41 layer (less than 20 nm) was obtained using CTABr as the template [MY(Br)], and the MCM-41 pore channels were assumed to be oriented outward from the inner HY core. Nevertheless, for the samples synthesized using CTACl [MY(Cl)], the HY crystals were buried independently in the MCM-41 phase. Both Ni−Mo/MY(Br) and Ni−Mo/MY(Cl) showed higher HDS activity and reducibility than Ni−Mo/MCM-41. The hydrogenation activity of Ni−Mo/MCM-41 was enhanced more than the direct desulfurization activity by the introduction of HY zeolite. Ni−Mo/MY(Br) and Ni−Mo/MY(Cl) exhibited hydrocracking activities equivalent to that of Ni−Mo/MCM-41, indicating that the HDS of DBT predominantly takes place in the mesopores of Ni−Mo/MY(Br) and Ni−Mo/MY(Cl). Because the active species located in the mesopores cannot have close contact with the strong acid sites of the HY zeolite, it is suggested that the spillover hydrogen might play an essential role in the HDS reaction over the supported Ni−Mo sulfides. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801389w

Obtaining closure for fin-and-tube heat exchanger modeling based on volume averaging theory (VAT) / Feng Zhou in Journal of heat transfer, Vol. 133 N° 11 (Novembre 2011) 

Public ISBD [article]  in Journal of heat transfer > Vol. 133 N° 11 (Novembre 2011) . - pp. [111802/1-8] Titre : Obtaining closure for fin-and-tube heat exchanger modeling based on volume averaging theory (VAT) Type de document : texte imprimé Auteurs : Feng Zhou, Auteur ; Nicholas E. Hansen, Auteur ; David J. Geb, Auteur Année de publication : 2012 Article en page(s) : pp. [111802/1-8] Note générale : Physique Langues : Anglais (eng) Mots-clés : Volume  averaging  theory  Closure  Heat  exchanger  Length  scale Index. décimale : 536 Chaleur. Thermodynamique Résumé : Modeling a fin-and-tube heat exchanger as porous media based on volume averaging theory (VAT), specific geometry can be accounted for in such a way that the details of the original structure can be replaced by their averaged counterparts, and the VAT based governing equations can be solved for a wide range of heat exchanger designs. To complete the VAT based model, proper closure is needed, which is related to a local friction factor and a heat transfer coefficient of a representative elementary volume. The present paper describes an effort to model a fin-and-tube heat exchanger based on VAT and obtain closure for the model. Experiment data and correlations for the air side characteristics of fin-and-tube heat exchangers from the published literature were collected and rescaled using the “porous media” length scale suggested by VAT. The results were surprisingly good, collapsing all the data onto a single curve for friction factor and Nusselt number, respectively. It was shown that using the porous media length scale is very beneficial in collapsing complex data yielding simple heat transfer and friction factor correlations and that by proper scaling, closure is a function of the porous media, which further generalizes macroscale porous media equations. The current work is a step closer to our final goal, which is to develop a universal fast running computational tool for multiple-parameter optimization of heat exchangers. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JHTRAO000133000011 [...] [article] Obtaining closure for fin-and-tube heat exchanger modeling based on volume averaging theory (VAT) [texte imprimé] / Feng Zhou, Auteur ; Nicholas E. Hansen, Auteur ; David J. Geb, Auteur . - 2012 . - pp. [111802/1-8]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 133 N° 11 (Novembre 2011) . - pp. [111802/1-8] Mots-clés : Volume  averaging  theory  Closure  Heat  exchanger  Length  scale Index. décimale : 536 Chaleur. Thermodynamique Résumé : Modeling a fin-and-tube heat exchanger as porous media based on volume averaging theory (VAT), specific geometry can be accounted for in such a way that the details of the original structure can be replaced by their averaged counterparts, and the VAT based governing equations can be solved for a wide range of heat exchanger designs. To complete the VAT based model, proper closure is needed, which is related to a local friction factor and a heat transfer coefficient of a representative elementary volume. The present paper describes an effort to model a fin-and-tube heat exchanger based on VAT and obtain closure for the model. Experiment data and correlations for the air side characteristics of fin-and-tube heat exchangers from the published literature were collected and rescaled using the “porous media” length scale suggested by VAT. The results were surprisingly good, collapsing all the data onto a single curve for friction factor and Nusselt number, respectively. It was shown that using the porous media length scale is very beneficial in collapsing complex data yielding simple heat transfer and friction factor correlations and that by proper scaling, closure is a function of the porous media, which further generalizes macroscale porous media equations. The current work is a step closer to our final goal, which is to develop a universal fast running computational tool for multiple-parameter optimization of heat exchangers. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JHTRAO000133000011 [...]

Step response identification under inherent - type load disturbance with application to injection Molding / Tao Liu in Industrial & engineering chemistry research, Vol. 49 N° 22 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11572-11581 Titre : Step response identification under inherent - type load disturbance with application to injection Molding Type de document : texte imprimé Auteurs : Tao Liu, Auteur ; Feng Zhou, Auteur ; Yi Yang, Auteur Année de publication : 2011 Article en page(s) : pp. 11572-11581 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Injection  molding Résumé : Motivated by autotuning of injection velocity in an industrial injection molding machine, a step response identification method is proposed for practical application subject to inherent-type load disturbance. Both models of the process and the inherent-type load disturbance can be simultaneously derived from a step test. Identification algorithms are detailed for obtaining the widely used low-order models of first-order plus dead time (FOPDT) and second-order plus dead time (SOPDT). Based on the identified process and disturbance models, a two-degree-of-freedom (2DOF) internal model control (IMC) structure plus feed-forward control is proposed for improving load disturbance rejection. Analytical controller design formulas and tuning guidelines are developed accordingly. A practical application to the velocity control of an injection molding machine is shown to illustrate the effectiveness and merits of the proposed identification method and control strategy. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23437855 [article] Step response identification under inherent - type load disturbance with application to injection Molding [texte imprimé] / Tao Liu, Auteur ; Feng Zhou, Auteur ; Yi Yang, Auteur . - 2011 . - pp. 11572-11581. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11572-11581 Mots-clés : Injection  molding Résumé : Motivated by autotuning of injection velocity in an industrial injection molding machine, a step response identification method is proposed for practical application subject to inherent-type load disturbance. Both models of the process and the inherent-type load disturbance can be simultaneously derived from a step test. Identification algorithms are detailed for obtaining the widely used low-order models of first-order plus dead time (FOPDT) and second-order plus dead time (SOPDT). Based on the identified process and disturbance models, a two-degree-of-freedom (2DOF) internal model control (IMC) structure plus feed-forward control is proposed for improving load disturbance rejection. Analytical controller design formulas and tuning guidelines are developed accordingly. A practical application to the velocity control of an injection molding machine is shown to illustrate the effectiveness and merits of the proposed identification method and control strategy. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23437855