Tuning the standard SCR reaction kinetics to model NO conversion in a diesel engine exhaust SCR catalyst system under steady state conditions in 1D and 3D geometries using ammonia gas as the reductant

Stephen F. Benjamin, M. Gall, Carol A. Roberts

    Research output: Book/ReportOther report

    3 Citations (Scopus)
    26 Downloads (Pure)

    Abstract

    Removal of NOx from lean Diesel exhaust can be achieved
    by the use of selective catalytic reduction technology. The
    supplied reductant is often ammonia, either as urea or as
    ammonia gas released from a storage medium. Experiments
    have been carried out on an engine test rig run to steady state
    conditions using NOx composed mainly of NO, with
    ammonia gas as the reductant. This was essentially a 1D
    study because a long 10 degree diffuser was used to provide
    uniform temperature and velocity profile to the SCR catalyst
    brick in the test exhaust system. Tuning of the standard
    reaction, the NO SCR reaction, in a kinetic scheme from the
    literature and adjustment of the ammonia adsorption kinetics
    achieved improved agreement between the measurements and
    CFD simulations. This was carried out for studies at exhaust
    gas temperatures between 200 and 300 °C. The effect of
    diffuser geometry upstream of the SCR catalyst on NOx
    conversion was then investigated experimentally using a 180
    degree sudden expansion as a 3D diffuser. These were also
    steady state studies with the exhaust NOx composed mostly
    of NO. The SCR brick was short, 45 mm in length, to provide
    a rigorous test of the kinetics. Observed NOx conversion
    profiles for ammonia supplied in quantities ranging from
    deficient to excess showed that the combined influence of
    temperature and velocity profiles upstream of the SCR was
    apparent in this 3D case. 2D axially symmetric CFD
    simulations have been carried out to model the 3D case and
    the predictions are discussed and compared with engine test
    data in this paper.
    Original languageEnglish
    PublisherSAE
    DOIs
    Publication statusPublished - 2012

    Publication series

    NameSAE Technical Papers
    PublisherSAE

    Fingerprint

    Exhaust systems (engine)
    Thyristors
    Reaction kinetics
    Diesel engines
    Ammonia
    Tuning
    Catalysts
    Geometry
    Gases
    Engines
    Selective catalytic reduction
    Kinetics
    Brick
    Urea
    Adsorption
    Temperature

    Bibliographical note

    Paper presented at SAE 2012 International Powertrains, Fuels & Lubricants Meeting, September 18-20, 2012. Malmo, Sweden.
    SAE paper 2012-01-1636 Copyright © 2012 SAE International. This paper is posted on this site with permission from SAE International. Further use or distribution of this paper is not permitted without permission from SAE.

    Keywords

    • nitric oxide
    • diesel exhaust
    • catalytic reduction technology

    Cite this

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    title = "Tuning the standard SCR reaction kinetics to model NO conversion in a diesel engine exhaust SCR catalyst system under steady state conditions in 1D and 3D geometries using ammonia gas as the reductant",
    abstract = "Removal of NOx from lean Diesel exhaust can be achievedby the use of selective catalytic reduction technology. Thesupplied reductant is often ammonia, either as urea or asammonia gas released from a storage medium. Experimentshave been carried out on an engine test rig run to steady stateconditions using NOx composed mainly of NO, withammonia gas as the reductant. This was essentially a 1Dstudy because a long 10 degree diffuser was used to provideuniform temperature and velocity profile to the SCR catalystbrick in the test exhaust system. Tuning of the standardreaction, the NO SCR reaction, in a kinetic scheme from theliterature and adjustment of the ammonia adsorption kineticsachieved improved agreement between the measurements andCFD simulations. This was carried out for studies at exhaustgas temperatures between 200 and 300 °C. The effect ofdiffuser geometry upstream of the SCR catalyst on NOxconversion was then investigated experimentally using a 180degree sudden expansion as a 3D diffuser. These were alsosteady state studies with the exhaust NOx composed mostlyof NO. The SCR brick was short, 45 mm in length, to providea rigorous test of the kinetics. Observed NOx conversionprofiles for ammonia supplied in quantities ranging fromdeficient to excess showed that the combined influence oftemperature and velocity profiles upstream of the SCR wasapparent in this 3D case. 2D axially symmetric CFDsimulations have been carried out to model the 3D case andthe predictions are discussed and compared with engine testdata in this paper.",
    keywords = "nitric oxide, diesel exhaust, catalytic reduction technology",
    author = "Benjamin, {Stephen F.} and M. Gall and Roberts, {Carol A.}",
    note = "Paper presented at SAE 2012 International Powertrains, Fuels & Lubricants Meeting, September 18-20, 2012. Malmo, Sweden. SAE paper 2012-01-1636 Copyright {\circledC} 2012 SAE International. This paper is posted on this site with permission from SAE International. Further use or distribution of this paper is not permitted without permission from SAE.",
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    AU - Gall, M.

    AU - Roberts, Carol A.

    N1 - Paper presented at SAE 2012 International Powertrains, Fuels & Lubricants Meeting, September 18-20, 2012. Malmo, Sweden. SAE paper 2012-01-1636 Copyright © 2012 SAE International. This paper is posted on this site with permission from SAE International. Further use or distribution of this paper is not permitted without permission from SAE.

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    N2 - Removal of NOx from lean Diesel exhaust can be achievedby the use of selective catalytic reduction technology. Thesupplied reductant is often ammonia, either as urea or asammonia gas released from a storage medium. Experimentshave been carried out on an engine test rig run to steady stateconditions using NOx composed mainly of NO, withammonia gas as the reductant. This was essentially a 1Dstudy because a long 10 degree diffuser was used to provideuniform temperature and velocity profile to the SCR catalystbrick in the test exhaust system. Tuning of the standardreaction, the NO SCR reaction, in a kinetic scheme from theliterature and adjustment of the ammonia adsorption kineticsachieved improved agreement between the measurements andCFD simulations. This was carried out for studies at exhaustgas temperatures between 200 and 300 °C. The effect ofdiffuser geometry upstream of the SCR catalyst on NOxconversion was then investigated experimentally using a 180degree sudden expansion as a 3D diffuser. These were alsosteady state studies with the exhaust NOx composed mostlyof NO. The SCR brick was short, 45 mm in length, to providea rigorous test of the kinetics. Observed NOx conversionprofiles for ammonia supplied in quantities ranging fromdeficient to excess showed that the combined influence oftemperature and velocity profiles upstream of the SCR wasapparent in this 3D case. 2D axially symmetric CFDsimulations have been carried out to model the 3D case andthe predictions are discussed and compared with engine testdata in this paper.

    AB - Removal of NOx from lean Diesel exhaust can be achievedby the use of selective catalytic reduction technology. Thesupplied reductant is often ammonia, either as urea or asammonia gas released from a storage medium. Experimentshave been carried out on an engine test rig run to steady stateconditions using NOx composed mainly of NO, withammonia gas as the reductant. This was essentially a 1Dstudy because a long 10 degree diffuser was used to provideuniform temperature and velocity profile to the SCR catalystbrick in the test exhaust system. Tuning of the standardreaction, the NO SCR reaction, in a kinetic scheme from theliterature and adjustment of the ammonia adsorption kineticsachieved improved agreement between the measurements andCFD simulations. This was carried out for studies at exhaustgas temperatures between 200 and 300 °C. The effect ofdiffuser geometry upstream of the SCR catalyst on NOxconversion was then investigated experimentally using a 180degree sudden expansion as a 3D diffuser. These were alsosteady state studies with the exhaust NOx composed mostlyof NO. The SCR brick was short, 45 mm in length, to providea rigorous test of the kinetics. Observed NOx conversionprofiles for ammonia supplied in quantities ranging fromdeficient to excess showed that the combined influence oftemperature and velocity profiles upstream of the SCR wasapparent in this 3D case. 2D axially symmetric CFDsimulations have been carried out to model the 3D case andthe predictions are discussed and compared with engine testdata in this paper.

    KW - nitric oxide

    KW - diesel exhaust

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