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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

Kinetic parameters estimation for three way catalyst modeling / Karthik Ramanathan in Industrial & engineering chemistry research, Vol. 50 N° 17 (Septembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 17 (Septembre 2011) . - pp. 9960-9979 Titre : Kinetic parameters estimation for three way catalyst modeling Type de document : texte imprimé Auteurs : Karthik Ramanathan, Auteur ; Chander Shekhar Sharma, Auteur Année de publication : 2011 Article en page(s) : pp. 9960-9979 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Modeling  Three  way  catalyst  Parameter  estimation  Kinetic  parameter Résumé : One of the critical needs of a Three Way Catalyst (TWC) model is to be able to predict light-off. This is crucial for application studies and vehicle architectural studies because most of the emissions from a TWC occur before light-off (called cold-start emissions). Laboratory experiments give detailed insights to the reaction mechanism and analytical forms of the rate expressions as they are well-controlled and well-behaved as compared to vehicle tests. However, to predict emissions on a vehicle test, the laboratory-estimated kinetic parameters are not entirely capable because of the various uncertainties in the vehicle tests. In this work, six different vehicle data sets are used to calibrate and validate the TWC global kinetic model. Our emphasis in this work is restricted to predicting the light-off (cold-start emissions) in TWC. The kinetic model is calibrated using 4 vehicle data sets (which use the FTP drive cycle) using iSIGHT software package. The kinetic parameters of the various reactions occurring in the TWC are estimated to match the experimental data through exploratory and local optimization methods. A systematic approach (with increasing complexity) is used to estimate the kinetic parameters. The estimated parameters are then used to validate the model on two different vehicle data sets (one NEDC drive cycle and one FTP drive cycle) with different catalyst compositions and engine power (and hence different engine out exhaust compositions). The model with estimated kinetic parameters predicts the light-off reasonably well for the new data sets. The parameter estimation approach in this work is kept as generic as possible to exhaust aftertreatment devices, and a set of guidelines for parameter estimation (specifically for use in exhaust aftertreatment devices) is presented (in the Appendix). DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24483640 [article] Kinetic parameters estimation for three way catalyst modeling [texte imprimé] / Karthik Ramanathan, Auteur ; Chander Shekhar Sharma, Auteur . - 2011 . - pp. 9960-9979. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 17 (Septembre 2011) . - pp. 9960-9979 Mots-clés : Modeling  Three  way  catalyst  Parameter  estimation  Kinetic  parameter Résumé : One of the critical needs of a Three Way Catalyst (TWC) model is to be able to predict light-off. This is crucial for application studies and vehicle architectural studies because most of the emissions from a TWC occur before light-off (called cold-start emissions). Laboratory experiments give detailed insights to the reaction mechanism and analytical forms of the rate expressions as they are well-controlled and well-behaved as compared to vehicle tests. However, to predict emissions on a vehicle test, the laboratory-estimated kinetic parameters are not entirely capable because of the various uncertainties in the vehicle tests. In this work, six different vehicle data sets are used to calibrate and validate the TWC global kinetic model. Our emphasis in this work is restricted to predicting the light-off (cold-start emissions) in TWC. The kinetic model is calibrated using 4 vehicle data sets (which use the FTP drive cycle) using iSIGHT software package. The kinetic parameters of the various reactions occurring in the TWC are estimated to match the experimental data through exploratory and local optimization methods. A systematic approach (with increasing complexity) is used to estimate the kinetic parameters. The estimated parameters are then used to validate the model on two different vehicle data sets (one NEDC drive cycle and one FTP drive cycle) with different catalyst compositions and engine power (and hence different engine out exhaust compositions). The model with estimated kinetic parameters predicts the light-off reasonably well for the new data sets. The parameter estimation approach in this work is kept as generic as possible to exhaust aftertreatment devices, and a set of guidelines for parameter estimation (specifically for use in exhaust aftertreatment devices) is presented (in the Appendix). DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24483640

Sensitivity analysis and kinetic parameter estimation in a three way catalytic converter / S. Koteswara Rao 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. 3779–3790 Titre : Sensitivity analysis and kinetic parameter estimation in a three way catalytic converter Type de document : texte imprimé Auteurs : S. Koteswara Rao, Auteur ; Rayees Imam, Auteur ; Karthik Ramanathan, Auteur Année de publication : 2009 Article en page(s) : pp. 3779–3790 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Three  way  catalytic  converter  Kinetics  Genetic-algorithm-based  optimization Résumé : A heterogeneous one-dimensional model is used to simulate a three way catalytic converter (TWC). The mathematical model consists of mass and energy balance equations in the gas and solid phases and accounts for 15 heterogeneous chemical reactions. Langmuir−Hinshelwood type kinetics is used to represent most of the reaction rates. In this work, the kinetic parameters of the various reactions occurring in a TWC are estimated using vehicle data based on a genetic-algorithm-based optimization. The method uses the test data to estimate the reaction kinetic parameters by minimizing the deviation between the model predictions and experimental observations. It is found that the objective function based on the cumulative mass of a species that leaves the reactor until a certain time instant is a preferred performance measure for the optimization. The sensitivity of the exit concentration of various species to various kinetic parameters was found. This is used to identify the subset of reactions which have a significant effect on the various species concentrations in the effluent stream and is used to determine the set of kinetic parameters for optimizing the reactor performance. Single parameter and multiple parameters tuning using genetic algorithm have been demonstrated successfully for a TWC application. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801244w [article] Sensitivity analysis and kinetic parameter estimation in a three way catalytic converter [texte imprimé] / S. Koteswara Rao, Auteur ; Rayees Imam, Auteur ; Karthik Ramanathan, Auteur . - 2009 . - pp. 3779–3790. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3779–3790 Mots-clés : Three  way  catalytic  converter  Kinetics  Genetic-algorithm-based  optimization Résumé : A heterogeneous one-dimensional model is used to simulate a three way catalytic converter (TWC). The mathematical model consists of mass and energy balance equations in the gas and solid phases and accounts for 15 heterogeneous chemical reactions. Langmuir−Hinshelwood type kinetics is used to represent most of the reaction rates. In this work, the kinetic parameters of the various reactions occurring in a TWC are estimated using vehicle data based on a genetic-algorithm-based optimization. The method uses the test data to estimate the reaction kinetic parameters by minimizing the deviation between the model predictions and experimental observations. It is found that the objective function based on the cumulative mass of a species that leaves the reactor until a certain time instant is a preferred performance measure for the optimization. The sensitivity of the exit concentration of various species to various kinetic parameters was found. This is used to identify the subset of reactions which have a significant effect on the various species concentrations in the effluent stream and is used to determine the set of kinetic parameters for optimizing the reactor performance. Single parameter and multiple parameters tuning using genetic algorithm have been demonstrated successfully for a TWC application. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801244w