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Electrically heated catalysts for hybrid applications / Karthik Ramanathan 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. 8444-8467 Titre : Electrically heated catalysts for hybrid applications : mathematical modeling and analysis Type de document : texte imprimé Auteurs : Karthik Ramanathan, Auteur ; Se H. Oh, Auteur ; Edward J. Bissett, Auteur Année de publication : 2011 Article en page(s) : pp. 8444-8467 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Modeling  Catalyst Résumé : In view of the significant cold-start hydrocarbon emission reduction potential of the electrically heated converter (EHC) technology for conventional stoichiometric gasoline engines, there is considerable interest in better understanding of the thermal and emission performance characteristics and optimizing the design/operating aspects of an EHC system as applied to plug-in hybrid electric vehicles (PHEVs) and extended-range electric vehicles (EREVs). The application of the EHC technology to these hybrid vehicles is unique in that catalyst cooling to below reaction temperatures can occur during extended periods of electric vehicle driving (with engine off) or during intermittent engine stops/starts, and the EHC can be heated prior to engine start (preheating) for enhanced emission reduction. In this study, the design aspects and heating strategies of an EHC system have been analyzed using a transient monolith converter model which accounts for the resistive heating of an inert metal-substrate monolith placed ahead of a conventional three-way catalytic converter. The results of model calculations presented here quantify the effects of various heating strategies on the emission performance of hybrid vehicles during the first 250 s of the Federal Test Procedure (FTP) drive cycle. It is also shown that there exists an optimum electric heater volume for cases with either preheating only or a combination of pre- and postheating. For the latter case, the emission performance can be further improved by adding a smaller electric heater (downstream of the existing heater) which is capable of heating the gas rapidly and efficiently during postheating. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24346885 [article] Electrically heated catalysts for hybrid applications : mathematical modeling and analysis [texte imprimé] / Karthik Ramanathan, Auteur ; Se H. Oh, Auteur ; Edward J. Bissett, Auteur . - 2011 . - pp. 8444-8467. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 14 (Juillet 2011) . - pp. 8444-8467 Mots-clés : Modeling  Catalyst Résumé : In view of the significant cold-start hydrocarbon emission reduction potential of the electrically heated converter (EHC) technology for conventional stoichiometric gasoline engines, there is considerable interest in better understanding of the thermal and emission performance characteristics and optimizing the design/operating aspects of an EHC system as applied to plug-in hybrid electric vehicles (PHEVs) and extended-range electric vehicles (EREVs). The application of the EHC technology to these hybrid vehicles is unique in that catalyst cooling to below reaction temperatures can occur during extended periods of electric vehicle driving (with engine off) or during intermittent engine stops/starts, and the EHC can be heated prior to engine start (preheating) for enhanced emission reduction. In this study, the design aspects and heating strategies of an EHC system have been analyzed using a transient monolith converter model which accounts for the resistive heating of an inert metal-substrate monolith placed ahead of a conventional three-way catalytic converter. The results of model calculations presented here quantify the effects of various heating strategies on the emission performance of hybrid vehicles during the first 250 s of the Federal Test Procedure (FTP) drive cycle. It is also shown that there exists an optimum electric heater volume for cases with either preheating only or a combination of pre- and postheating. For the latter case, the emission performance can be further improved by adding a smaller electric heater (downstream of the existing heater) which is capable of heating the gas rapidly and efficiently during postheating. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24346885

Improved transfer coefficients for wall-flow monolithic catalytic reactors / Margaritis Kostoglou in Industrial & engineering chemistry research, Vol. 51 N° 40 (Octobre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 40 (Octobre 2012) . - pp. 13062-13072 Titre : Improved transfer coefficients for wall-flow monolithic catalytic reactors : Energy and momentum transport Type de document : texte imprimé Auteurs : Margaritis Kostoglou, Auteur ; Edward J. Bissett, Auteur ; Athanasios G. Konstandopoulos, Auteur Année de publication : 2012 Article en page(s) : pp. 13062-13072 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Transport  process  Momentum  Catalytic  reactor  Monolithic  construction Résumé : Wall-flow monolithic (WFM) catalytic reactors occupy an ever increasing important position in environmental and industrial catalysis as well as in energy applications. Their performance is very frequently determined by transport (momentum, energy, and mass) limitations, driven by the market needs for lower pressure drop, efficient heat exploitation, and miniaturization. In the present problem we address the problem of deriving the appropriate single channel equations that describe heat transfer in a wall-flow monolithic (WFM) reactor with porous channels of square-cross section. The first step of the study involves setting up a self-similar hydrodynamic problem for the two-dimensional flow field in the channel cross section. This flow field depends only on the so-called wall Reynolds number. It is shown that the self-similarity fails for large values of wall Reynolds number. The second step involves setting up the Graetz problem for the flow velocity profile found in the first step and solving for the asymptotic Nusselt number. This Nusselt number depends on the Prandtl number in addition to the wall Reynolds dependence through the flow-field. Correlations for the Nusselt number as a function of wall Reynolds and Prandtl numbers are given to facilitate the inclusion of these effects into standard practice. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26451455 [article] Improved transfer coefficients for wall-flow monolithic catalytic reactors : Energy and momentum transport [texte imprimé] / Margaritis Kostoglou, Auteur ; Edward J. Bissett, Auteur ; Athanasios G. Konstandopoulos, Auteur . - 2012 . - pp. 13062-13072. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 40 (Octobre 2012) . - pp. 13062-13072 Mots-clés : Transport  process  Momentum  Catalytic  reactor  Monolithic  construction Résumé : Wall-flow monolithic (WFM) catalytic reactors occupy an ever increasing important position in environmental and industrial catalysis as well as in energy applications. Their performance is very frequently determined by transport (momentum, energy, and mass) limitations, driven by the market needs for lower pressure drop, efficient heat exploitation, and miniaturization. In the present problem we address the problem of deriving the appropriate single channel equations that describe heat transfer in a wall-flow monolithic (WFM) reactor with porous channels of square-cross section. The first step of the study involves setting up a self-similar hydrodynamic problem for the two-dimensional flow field in the channel cross section. This flow field depends only on the so-called wall Reynolds number. It is shown that the self-similarity fails for large values of wall Reynolds number. The second step involves setting up the Graetz problem for the flow velocity profile found in the first step and solving for the asymptotic Nusselt number. This Nusselt number depends on the Prandtl number in addition to the wall Reynolds dependence through the flow-field. Correlations for the Nusselt number as a function of wall Reynolds and Prandtl numbers are given to facilitate the inclusion of these effects into standard practice. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26451455