Diesel Emission Control Review 2005

DieselEmissionControlReviewTimJohnsonAugust10,2005FullversionforwebsitePresentatonwillbecondensed2•Filtersaremakingsignificantprogresswithsophisticatedregenerationschemesandcontinuousimprovementinbackpressureanddurability.•NOxsolutionslookgood.–HDNTEdictates80%NOxefficiencyat500C–ZeoliteSCRisusedinJapan–HTLNTsemerging•IntegratedsolutionsarehittingBin5andUS2010Summary3Quickwordaboutmixedmodeengines•Mixed-mode:highHCandCO,andlowNOxandPMatlowload;inverseathighload;nominal50%loadthreshold•Formixed-modeengines,allemissioncontrolrequirementschange–LTHC+COcontrolwillbecritical.–Withmixedmodecombustion,filterregenerationcanlargelybepassive.•Ifregenerationisneededatlowload,HCsandCOareavailable–Withmixedmode,HTNOxperformancewillbeemphasized.–IntegratedPMandNOxcontrolenhancedwithmixedmodecombustion.HCandCOControlatLowTemperature•Nottoocriticalfortraditionalcombustion,butverycriticalforHCCIoperationunderlowload•125Cidleand175Cat25%load•Severaloptionsareavailable•Pd-basedcatalystsareofferingbetterPGMmanagementoptions5NewDOCsarebeginningtoaddressCOissuewithpre-mixedcombustionFiat,ATAConf,10-046Backpressureandefficiencytrade-offsfornovelDOCsubstratesaredescribedRelativeefficiencyofthebestdesignis20%betterthanstd.200-csi,butwith35%higherbackpressure.EmitecViennaMotorsymposium,4/05Forcomparison,standard400-csi4milwebhas10%betterrelativeefficiency,butwithsimilarbackpressureas200-csi(CorningSAE2004-01-1419).PMControl•DPFregenerationstrategiesaregettingincreasinglysophisticated(detailsinDEERLDDDPFregenerationpaper).•Filtersystemsfundamentalunderstandingisimproving•Someissuesstillneedtobeaddressed–agedsootmightpresentaproblem–DPFsmighthaveunder-utilizedcatalystinsmallpores–DPFporesizedistributionmightbefurtheroptimized8OEMEmissionSystemStrategiesDOCsonly•Minimumcurrentdieselsystem:DOCsforodorcontrol•VehiclesareabletomeetEUIVlegislationthroughenginemanagement.DOCs+uncatalyzedfilters(DPF)•Firstsystem(1999);IncrementalimprovementsintheFBCformulationanddeliveryandincreasedDPFashstoragecapacityarekeepingthiscompetitive.DOCs+catalyzedfilters•CatalystonfilterimprovesregenerationwhileDOCreducesHC,COandNOx.•Expandsrangeofpassiveregeneration,reducescomplexity.Catalyzedfiltersonly•TargetsystemformanyOEMs:Furthercomplexityreductionandcost.PMandNOxsolution•Mixed-modecombustionsynergiesenablethiscostsavingintegration’04-’062006Î’02-’062008ÎDOC+DPFFuelBorneCatalystDOC+CSFCCCSFDOConlyDPNRorfilter+NOxsolution9SootoxidationratebyNO2isstudied.ThebalancebetweenNOxproduction,NO2conversion,flowrateandsootoxidationrateshowssootoxidationkineticsarecontrollingtherate.Averagesootburningrate(preloadedfillers)onCSFfornormalengineexhaust.T380C,ratecontrolledbysootoxidationkinetics.T380CsootoxidationbyO2begins.HighRPMwith350CexhaustgiveshighestNO2production.WhenengineNOxisdropped70%,sootoxidationrategoesdown.However,thereisstillsomeNO2oractiveO2activityforDPFmanagement.UmicoreSAE2005-01-066310NewDPFcatalystcoatingprocessputDOCfunctiononDPFandaidsregenerationNewcoatingtechnologyputscatalystintothewallratherthanonit.Δpgoesuponly5to30%vs.2-3Xforstandardcoating.•AshsimulationtestsshowlittleimpactonHCandCOconversion.•10g/litersootdropsCOefficiencyfrom88to80%.MinimalimpactonHC.UmicoreSAE2005-01-1756At450C,CDPF6XmoresootthanDOC+CDPFsystem.11Lessthan50%oflubeoilashiscollectedonDPFs,despite99%removalefficiencyofsolidparticles.Pressuredropisnotagoodindicatorofashloading.Only46%ofphosphorousfromconsumedlubeoilwascapturedontheDPF.37%Ca,31%Mg,andonly5%ofBwerecaptured.•20-30%ashcomesfromnon-lubeoilsourcesLubrizol,9thEnginePCSymposium6/05;SAE2005-01-216812CSFagingstudiesshowstrongimpactofashaccumulationUmicoreSAE2005-01-0663%oftheoreticalNO2150-400C.AshcleaninghasbigimpactonNO2formation(~2x).CleaningmighthavetobedonemorefrequentlythanΔPdictatestokeepDPFhealthy13Precaution:Agedsootmaynoteasilyoxidizeandmayunknowinglybuild-upinDPFDifferentialoxidationtemperatureincreaseswithdialkyldithio-phosphoricacid(DDPA)additions.Effectisduetoacidbaseinteractionsanddeactivationofsootactivesites.Ramanspectroscopyshowschangesindieselsootstructurewithagingtemperature.Cummins2004-01-3043•IncreaseinRamanspectraG/Discorrelatedtoreducedoxidationrate(upto90%slower).NCMR,DEER8/04•Topreventbuild-up,occasionalcompleteregenerationsareneeded.14PoresizedistributionofCSFchangeslittlewithwashcoatloadinglevel.Causesinefficiencies.Theporesizedistributionofvariousuncatalyzedfilters(0g/l)isverydifferent,butisoverwhelmedbythewashcoat.Catalystpreferentiallygoesintothesmallpores.Uncatalyzed,left.Catalyzed,right.IbidenSAE2005-01-057815DeepbedDPFshavebettersoot/catalystcontactandthusregeneratebetter.Contactofsootandcatalystisimportant,asisfiltrationmechanism.Deepbedfiltrationgivesbettersoot/catalystcontact.Thelowercatalystloadingoncakefiltershasbettersootoxidationactivity.HighcatalystloadingpreventssomedepthfiltrationDepthfiltershaveporesizes40microns.APTLabSAE2005-01-067016Duetotheexponentialnatureofregenerationdegreewithfuelconsumptionpartialregenerationscansavefuel.APTLabSAE2005-01-06703-5g/litersootload