Optimal design of catalytic converters for minimizing cold-start emissions

Ramanathan, Karthik; West, David; Balakotaiah, Vemuri

doi:10.1016/j.cattod.2004.08.003

Cited by 52 publications

(37 citation statements)

References 23 publications

(39 reference statements)

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“…Later, simplified catalyst modeling approaches have been introduced (e.g. (Please et al 1994), (Leighton & Chang 1995), (Ramanathan et al 2004), (Keith et al 2001)). Such approaches have provided insights into catalyst parameters optimization (void fraction, material, precious metal loading distribution, .…”

Section: Reduced Modelmentioning

confidence: 99%

Model-based temperature control of a diesel oxidation catalyst

Lepreux¹,

Creff²,

Petit³

2012

Journal of Process Control

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To cite this version:Olivier Lepreux. Model-based Temperature Control of a Diesel Oxidation Catalyst . Mathematics T H E S E pour obtenir le grade de DOCTEUR DE L'ECOLE NATIONALE SUPERIEURE DES MINES DE PARIS RésuméLe problème étudié dans cette thèse est la commande d'un système DOC (Diesel Oxidation Catalyst) tel qu'utilisé dans les systèmes de dépollution des gaz d'échappement des moteurs Diesel automobiles.Ce système est par nature un système à paramètres répartis en raison de sa géométrie allongée parcourue par un flux gazeux en contact avec un catalyseur réparti. Après avoir étudié expérimenta-lement ce système, nous avons décidé de prendre en compte cette nature répartie, qui comme on le montre, se retrouve également dans les autres systèmes de dépollution (filtres à particules, pièges à NOx, SCR).Une première contribution du manuscrit consiste en un modèle du système DOC. Celui-ci est obtenu par des simplifications successives, justifiées expérimentalement (observations, estimations des ordres de grandeurs) ou par analyse des équations régissant la dynamique du système (déve-loppements asymptotiques, changements de variables). Ce modèle permet de rendre compte de la complexité de la réponse de la température de sortie du DOC à des variations des grandeurs d'entrée. En particulier, les effets de réponses inverses et de retards sont bien représentés.Une seconde contribution est un ensemble d'algorithmes de commande (précompensation, rétro-action, et synchronisation) permettant de maîtriser les phénomènes thermiques dans le DOC.Ces deux contributions ont été testées expérimentalement et validées. En conclusion, les performances obtenues sont évaluées. En résumé, en utilisant l'approche présentée dans ce manuscrit, il est possible de commander, en conditions réelles, la température de sortie du DOC à ±15 • C. 6 SummaryThe problem studied in this thesis is the control of a DOC (Diesel Oxidation Catalyst) as used in aftertreatment systems of diesel vehicles.This system is inherently a distributed parameter system due to its elongated geometry where a gas stream is in contact with a distributed catalyst. After having studied this system experimentally, we decided to take into account its distributed nature, which as shown, is also found in other aftertreatment devices (particulate filters, NOx traps, SCR).A first contribution of the thesis is a model for the DOC system. It is obtained by successive simplifications justified either experimentally (from observations, estimates of orders of magnitudes) or by an analysis of governing equations (through asymptotic developments, change of variables). This model can account for the complexity of the temperature response of DOC output to changes in input variables. In particular, the effects of inverse responses and delays are well represented.A second contribution is a combination of algorithms (feedback, feedforward, and synchronization) to control the thermal phenomena in the DOC.Both contributions have been tested and validated experimentally. In conclusion, the o...

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Section: Reduced Modelmentioning

confidence: 99%

Model-based temperature control of a diesel oxidation catalyst

Lepreux¹,

Creff²,

Petit³

2012

Journal of Process Control

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“…Understanding the low temperature performance of the LNT is especially important for vehicles that are only driven a short distance (insufficient time for engine/exhaust to heat up). Ramanathan et al 18 used a transient one-dimensional two-phase model to obtain an explicit light-off criterion that was used to predict the nature of ignition (front-end, middle, or back-end) in catalytic converters (TWC), to minimize cold-start emissions. Similar developments are needed for the more complex LNT, but the measurement of comprehensive performance data are critical, which is the motivation for this study.…”

Section: Introductionmentioning

confidence: 99%

Performance features of Pt/BaO lean NOx trap with hydrogen as reductant

2009

Self Cite

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in Wiley InterScience (www.interscience.wiley.com).The performance of a model Pt/BaO/Al 2 O 3 monolith catalyst was studied using H 2 as the reductant. The dependence of product selectivities on operating parameters is reported, including the durations of regeneration and storage times, feed composition and temperature, and monolith temperature. The data are explained in terms of a phenomenological model factoring in the transport, kinetic, and spatio-temporal effects. The Pt/BaO catalyst exhibits high cycle-averaged NOx conversion above 1008C, generating a mixture of N 2 and byproducts NH 3 and N 2 O. The cycle-averaged NOx conversion exhibits a maximum at about 3008C corresponding to the NOx storage maximum. The N 2 selectivity exhibits a maximum at a somewhat higher temperature, at which point the NH 3 selectivity exhibits a minimum. This trend conveys the intermediate role of NH 3 in reacting with stored NOx. Both N 2 and N 2 O are also formed during the storage steps from the oxidation of NH x species produced during the regeneration.

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“…1 presents a scheme of the catalyst under consideration. It is composed of two separated monoliths [18] in charge of oxidizing carbon monoxides and hydrocarbons into carbon dioxide and water, and reducing nitrogen oxides to nitrogen and oxygen 2 . For experimental studies and comparisons, the catalyst has been instrumented with two internal temperature sensors.…”

Section: Experimental Set-upmentioning

confidence: 99%