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Studies of a Heavy-Duty Diesel Aftertreatment System Based on the NOX Storage and Reduction Technology

Papadakis, Klaus LU (2006)
Abstract (Swedish)
Popular Abstract in Swedish

Gränsvärden för NOX-utsläppen i avgaserna från tunga dieselmotorer kommer att minskas i den Europeiska Unionen från 3,5 g/kWh (Euro IV) idag till 2,0 g/kWh (Euro V) år 2008. I USA och Japan är trenden likadan och utveckling av ett avgassystem för tunga dieselfordon verkar oundviklig. I detta arbetet har en motorrigg byggts upp som bestod av en 11 l dieselmotor och ett avgasrenings-system baserat på NOX-lagringstekniken. Avgasreningssystemet bestod av BaO-baserade NOX-lagringskatalysatorer på totalt 16.8 l och oxidationskatalysatorer på totalt 8,4 l för att oxidera NO till NO2 och föroxidera insprutade kolväten.



Denna teknik har redan tillämpats i samband med... (More)
Popular Abstract in Swedish

Gränsvärden för NOX-utsläppen i avgaserna från tunga dieselmotorer kommer att minskas i den Europeiska Unionen från 3,5 g/kWh (Euro IV) idag till 2,0 g/kWh (Euro V) år 2008. I USA och Japan är trenden likadan och utveckling av ett avgassystem för tunga dieselfordon verkar oundviklig. I detta arbetet har en motorrigg byggts upp som bestod av en 11 l dieselmotor och ett avgasrenings-system baserat på NOX-lagringstekniken. Avgasreningssystemet bestod av BaO-baserade NOX-lagringskatalysatorer på totalt 16.8 l och oxidationskatalysatorer på totalt 8,4 l för att oxidera NO till NO2 och föroxidera insprutade kolväten.



Denna teknik har redan tillämpats i samband med lean-burn-bensinmotorer där en NOX-reduktionsgrad av 80 % uppnåddes. Därmed är den ett lovande alternativ för minskningen av NOX i dieselavgaser. I NOX-lagringstekniken lagras NOX som Ba(NO3)2 under långa magra förhållanden (1-2 min) och den desorberas och reduceras under korta rika förhållanden (0-10 s). Syftet med denna avhandling var att optimera avgassystemet med hänsyn till en hög NOX-reduktionsgrad och ett lågt bränslestraff samt att modellera katalysatorerna. Modellerna kan sedan användas för att reglera NOX-reduktionsprocessen under transienta förhållanden.



Stationära NOX-reduktionsförsök har utförts i motorriggen. NOX-reduktionsgraden uppgick då maximalt till cirka 60 %. Denna är beroende av ett flertal parametrar som katalysatorns temperatur, insprutningstiden, cykeltiden och den insprutade mängden kolväten (dieselbränsle). För att erhålla ett lågt bränslestraff har ett förbiledningssystem installerats som förbileder cirka 90 % av avgasflödet under regenerationstiderna. Perioden då avgasflödet genom katalysatorn minskas (förbilednings-tiden) har påvisats som en viktig parameter för att uppnå en hög NOX-reduktionsgrad vid låg temperatur utan att öka bränslestraffet. Optimeringen av NOX-reduktionsgraden gjordes med hjälp av designförsök vid olika temperaturer. Optimeringens resultat användes som bas för den temperaturbaserade doseringsstrategin som reglerade insprutningarna under transienta driftsbetingelser. I en Europeisk Transientcykel (ETC)-körning har en NOX-reduktionsgrad av 60 % uppnåts med 6,6 % bränslestraff.



En första modell av NOX-fällan har utvecklats och testats i stationära försök. En mean-field-modell av oxidationskatalysatorn, placerad uppströms NOX-lagringskatalysatorn, har också skappats och testats med god överenstämmelse i en ETC-körning. (Less)
Abstract
The legislative limits for NOX emissions in the exhaust gas from heavy-duty diesel engines will be decreased in the European Union from today 3.5 g/kWh (Euro IV) to 2.0 g/kWh in 2008 (Euro V). In the USA and Japan a similar trend can be seen. Accordingly, the development of an exhaust aftertreatment system for heavy-duty trucks seems unavoidable. In this work, an 11 l diesel engine rig has been built up including an aftertreatment system which is based on the NOX storage and reduction approach. BaO-based NOX storage and reduction catalysts of in total 16.8 l were used and also oxidation catalysts of in total 8.4 l to oxidise NO to NO2 and pre-oxidise the injected hydrocarbons.



The NOX storage and reduction technology has... (More)
The legislative limits for NOX emissions in the exhaust gas from heavy-duty diesel engines will be decreased in the European Union from today 3.5 g/kWh (Euro IV) to 2.0 g/kWh in 2008 (Euro V). In the USA and Japan a similar trend can be seen. Accordingly, the development of an exhaust aftertreatment system for heavy-duty trucks seems unavoidable. In this work, an 11 l diesel engine rig has been built up including an aftertreatment system which is based on the NOX storage and reduction approach. BaO-based NOX storage and reduction catalysts of in total 16.8 l were used and also oxidation catalysts of in total 8.4 l to oxidise NO to NO2 and pre-oxidise the injected hydrocarbons.



The NOX storage and reduction technology has already been applied in lean-burn gasoline vehicles and has shown NOX reduction degrees of 80 % and above. It is thus a promising alternative for the reduction of NOX in diesel truck exhausts. In the NOX storage and reduction concept, NOX is stored as Ba(NO3)2 under long lean periods (1-2 min) and released and reduced under short rich periods (0-10 s). It is the aim of this project to both optimise the aftertreatment system with respect to a high NOX reduction and a low fuel penalty and also create models of the catalysts which may be used to control the NOX reduction performance under transient conditions.



Stationary NOX reduction experiments have been performed on the engine rig. The maximal degree of NOX reduction was approximately 60 % under stationary operation. The degree of NOX reduction depends on a number of parameters as the catalyst temperature, the injection time, the cycle time or the dosed amount of hydrocarbons (diesel fuel). To keep the fuel penalty low, a bypass system has been installed, which bypassed approximately 90 % of the exhaust flow under the regeneration periods. The period when the flow through the catalyst is reduced, the bypass time, has turned out to be an important parameter to achieve an improved low temperature NOX reduction without increasing the fuel penalty. An optimisation of the NOX reduction performance has been done at different temperatures using Design of Experiments. The optimisation results served as the base of a temperature dependent dosing strategy which controlled the injections under transient conditions. In a European Transient Cycle (ETC), a 60 % NOX conversion was achieved with a fuel penalty of 6.6 %.



A first model for the NOX storage and reduction catalyst has been developed and tested under stationary conditions. A mean-field model of the oxidation catalyst placed upstream of the NOX storage and reduction catalyst has also been created and tested successfully in an ETC. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Forzatti, Pio, Politecnico di Milano Technical University, Italy
organization
publishing date
type
Thesis
publication status
published
subject
keywords
fuel penalty, injection parameters, DoE, design of experiments, exhaust, diesel engine, NO oxidation, simulation, modelling, oxidation catalyst, NOX trap, NOX storage and reduction, NSR, Kemiteknik och kemisk teknologi, Chemical technology and engineering, dosing strategy, system optimisation
pages
203 pages
publisher
Department of Chemical Engineering, Lund University
defense location
Room K:E, Center of Chemistry and Chemical Engineering, Getingevägen 60, Lund Institute of Technology
defense date
2006-02-24 10:15
ISBN
91-628-6684-2
language
English
LU publication?
yes
id
72cc9956-9a40-4a7b-a14c-4434a4dd0638 (old id 546122)
date added to LUP
2007-10-13 11:28:02
date last changed
2016-09-19 08:45:12
@phdthesis{72cc9956-9a40-4a7b-a14c-4434a4dd0638,
  abstract     = {The legislative limits for NOX emissions in the exhaust gas from heavy-duty diesel engines will be decreased in the European Union from today 3.5 g/kWh (Euro IV) to 2.0 g/kWh in 2008 (Euro V). In the USA and Japan a similar trend can be seen. Accordingly, the development of an exhaust aftertreatment system for heavy-duty trucks seems unavoidable. In this work, an 11 l diesel engine rig has been built up including an aftertreatment system which is based on the NOX storage and reduction approach. BaO-based NOX storage and reduction catalysts of in total 16.8 l were used and also oxidation catalysts of in total 8.4 l to oxidise NO to NO2 and pre-oxidise the injected hydrocarbons.<br/><br>
<br/><br>
The NOX storage and reduction technology has already been applied in lean-burn gasoline vehicles and has shown NOX reduction degrees of 80 % and above. It is thus a promising alternative for the reduction of NOX in diesel truck exhausts. In the NOX storage and reduction concept, NOX is stored as Ba(NO3)2 under long lean periods (1-2 min) and released and reduced under short rich periods (0-10 s). It is the aim of this project to both optimise the aftertreatment system with respect to a high NOX reduction and a low fuel penalty and also create models of the catalysts which may be used to control the NOX reduction performance under transient conditions.<br/><br>
<br/><br>
Stationary NOX reduction experiments have been performed on the engine rig. The maximal degree of NOX reduction was approximately 60 % under stationary operation. The degree of NOX reduction depends on a number of parameters as the catalyst temperature, the injection time, the cycle time or the dosed amount of hydrocarbons (diesel fuel). To keep the fuel penalty low, a bypass system has been installed, which bypassed approximately 90 % of the exhaust flow under the regeneration periods. The period when the flow through the catalyst is reduced, the bypass time, has turned out to be an important parameter to achieve an improved low temperature NOX reduction without increasing the fuel penalty. An optimisation of the NOX reduction performance has been done at different temperatures using Design of Experiments. The optimisation results served as the base of a temperature dependent dosing strategy which controlled the injections under transient conditions. In a European Transient Cycle (ETC), a 60 % NOX conversion was achieved with a fuel penalty of 6.6 %.<br/><br>
<br/><br>
A first model for the NOX storage and reduction catalyst has been developed and tested under stationary conditions. A mean-field model of the oxidation catalyst placed upstream of the NOX storage and reduction catalyst has also been created and tested successfully in an ETC.},
  author       = {Papadakis, Klaus},
  isbn         = {91-628-6684-2},
  keyword      = {fuel penalty,injection parameters,DoE,design of experiments,exhaust,diesel engine,NO oxidation,simulation,modelling,oxidation catalyst,NOX trap,NOX storage and reduction,NSR,Kemiteknik och kemisk teknologi,Chemical technology and engineering,dosing strategy,system optimisation},
  language     = {eng},
  pages        = {203},
  publisher    = {Department of Chemical Engineering, Lund University},
  school       = {Lund University},
  title        = {Studies of a Heavy-Duty Diesel Aftertreatment System Based on the NOX Storage and Reduction Technology},
  year         = {2006},
}