Advanced NOx Aftertreatment System And Controls For On-Highway Heavy Duty Diesel Engines

Hu, Haoran; Reuter, Johannes; Yan, John; McCarthy, James E.

doi:10.4271/2006-01-3552

Cited by 31 publications

(10 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(Graphical results for the cases not discussed here are given in the Appendix.) Figure 1 compares the computed and observed outlet gas compositions for the case in which the inlet flow contained 500 ppm NO 2 and 1750 ppm CO. Clearly, the agreement is quite good, even for the minor species N 2 O, although there are some discrepancies at the lowest temperatures. Figure 2 presents an additional kind of comparison for the case in which 500 ppm NO 2 was fed along with 5000 ppm H 2 .…”

Section: Resultsmentioning

confidence: 99%

“…This involves the same ten gas-phase species considered in our previous paper (O 2 As before, the precious metal phase is referred to as platinum, with the understanding that this really accounts for the palladium and rhodium components as well. This phase is assumed to be populated by 14 distinct species:…”

Section: Reaction Mechanismmentioning

confidence: 99%

“…These aftertreatment devices have an inherent advantage over those based on selective catalytic reduction (SCR) in that the latter require NH 3 , which is generated on board from thermolysis and hydrolysis of urea and thus requires additional hardware. In the past few years, hybrid LNT-SCR systems have been proposed [1][2][3][4] as a way of eliminating the need to carry urea for the SCR catalyst. In such systems, NH 3 generated and not consumed during the rich phase of LNT operation is stored and then used by the SCR catalyst to reduce any NO x exiting the LNT.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, this likely represents the first truly microkinetic model that accounts successfully for the roles of both NO x species (NO and NO 2 ), both principal reductants (CO and H 2 ), all three reduction products (N 2 …”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Microkinetic Modeling of Lean NO<sub>x</sub> Trap Storage and Regeneration

Larson

Chakravarthy

Pihl

et al. 2011

View full text Add to dashboard Cite

A microkinetic chemical reaction mechanism capable of describing both the storage and regeneration processes in a fully formulated lean NO x trap (LNT) is presented. The mechanism includes steps occurring on the precious metal, barium oxide (NO x storage), and cerium oxide (oxygen storage) sites of the catalyst. The complete reaction set is used in conjunction with a transient plug flow reactor code (including boundary layer mass transfer) to simulate not only a set of long storage/regeneration cycles with a CO/H 2 reductant, but also a series of steady flow temperature sweep experiments that were previously analyzed with just a precious metal mechanism and a steady state code neglecting mass transfer. The results show that, while mass transfer effects are generally minor, NO x storage is not negligible during some of the temperature ramps, necessitating a re-evaluation of the precious metal kinetic parameters. The parameters for the entire mechanism are inferred by finding the best overall fit to the complete set of experiments. Rigorous thermodynamic consistency is enforced for parallel reaction pathways and with respect to known data for all of the gas phase species involved. It is found that, with a few minor exceptions, all of the basic experimental observations can be reproduced with the transient simulations. In addition to accounting for normal cycling behavior, the final mechanism should provide a starting point for the description of further LNT phenomena such as desulfation and the role of alternative reductants. 4 ACKNOWLEDGMENTSThe authors thank Dr. Andrew Lutz, formerly of Sandia, for initial development of the Chemkinbased transient plug flow reactor code (TPLUG).

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Reaction Mechanismmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Microkinetic Modeling of Lean NO<sub>x</sub> Trap Storage and Regeneration

Larson

Chakravarthy

Pihl

et al. 2011

View full text Add to dashboard Cite

show abstract

“…These aftertreatment devices have an inherent advantage over those based on selective catalytic reduction (SCR) in that the latter require NH 3 , which is generated on board from thermolysis and hydrolysis of urea and thus requires additional hardware. In the past few years, hybrid LNT-SCR systems have been proposed (Bevan and Taylor, 2006;Hu et al, 2006;Parks et al, 2009;Theis and Gulari, 2006) as a way of eliminating the need to carry urea for the SCR catalyst. In such systems, NH 3 generated and not consumed during the rich phase of LNT operation is stored and then used by the SCR catalyst to reduce any NO x exiting the LNT.…”

Section: Introductionmentioning

confidence: 99%

Simulation of lean NOx trap performance with microkinetic chemistry and without mass transfer.

Larson¹,

Daw

Pihl

et al. 2011

View full text Add to dashboard Cite

A microkinetic chemical reaction mechanism capable of describing both the storage and regeneration processes in a fully formulated lean NO x trap (LNT) is presented. The mechanism includes steps occurring on the precious metal, barium oxide (NO x storage), and cerium oxide (oxygen storage) sites of the catalyst. The complete reaction set is used in conjunction with a transient plug flow reactor code to simulate not only conventional storage/regeneration cycles with a CO/H 2 reductant, but also steady flow temperature sweep experiments that were previously analyzed with just a precious metal mechanism and a steady state code. The results show that NO x storage is not negligible during some of the temperature ramps, necessitating a re-evaluation of the precious metal kinetic parameters. The parameters for the entire mechanism are inferred by finding the best overall fit to the complete set of experiments. Rigorous thermodynamic consistency is enforced for parallel reaction pathways and with respect to known data for all of the gas phase species involved. It is found that, with a few minor exceptions, all of the basic experimental observations can be reproduced with these purely kinetic simulations, i.e., without including mass-transfer limitations. In addition to accounting for normal cycling behavior, the final mechanism should provide a starting point for the description of further LNT phenomena such as desulfation and the role of alternative reductants. 4 ACKNOWLEDGMENTSThe authors thank Dr. Andrew E. Lutz, formerly of Sandia, for initial development of the Chemkin-based transient plug flow reactor code (TPLUG). The efforts at Oak Ridge were sponsored by the U.S.

show abstract

Development and Investigation of Diesel Fuel Reformer for LNT Regeneration

Wittka

Müller

Dittmann

et al. 2015

Emiss. Control Sci. Technol.

View full text Add to dashboard Cite

In the present work, an exhaust after treatment system combining Lean NO X Trap (LNT) plus exhaust bypass, passive catalyst for selective catalytic reduction (SCR), and engine independent LNT reductant supply by on-board exhaust fuel reforming was developed. To demonstrate the mobile production of synthesis gas with focus on automotive application, an outline fuel reformer has been developed which is predominantly operated using engine exhaust gas. The reformer concept and design are described in detail. The reaction process is a variable superposition of exothermic catalyzed partial oxidation (CPOx) and endothermic steam (steam reforming (SR)) and CO 2 (dry reforming (DR)) reformation. This strong dependence of the reformer operation on the engine's exhaust gas composition was intensively studied by steady-state experiments on an engine test bench. Besides operating the reformer within thermal limits, the control strategy is designed in terms of low hydrocarbon emissions and high energetic efficiency. In comparison to pure CPOx, exhaust gas reforming showed favorable thermal behavior as well as efficiency benefits of up to 20 % due to the endothermic part of the reaction. The reformer could achieve a reductant yield of above 50 %, whereas only 10-25 % for medium engine load and up to 45 % for high engine load could be realized by engine-rich operation. For the investigated diesel engine-rich calibrations, the undesired HC emission reached a percentage share of the reductants of 15-55 %, whereas the reformer showed only up to 12 %.

show abstract

Advanced NOx Aftertreatment System And Controls For On-Highway Heavy Duty Diesel Engines

Cited by 31 publications

References 10 publications

Microkinetic Modeling of Lean NO<sub>x</sub> Trap Storage and Regeneration

Microkinetic Modeling of Lean NO<sub>x</sub> Trap Storage and Regeneration

Simulation of lean NOx trap performance with microkinetic chemistry and without mass transfer.

Development and Investigation of Diesel Fuel Reformer for LNT Regeneration

Contact Info

Product

Resources

About