Mack CSM 2010 - Exhaust Aftertreatment System Components and Operations; Selective Catalytic Reduction (SCR)

170Mack,EmissionsSolution
ExhaustAftertreatmentSystemComponentsand
Operations
SelectiveCatalyticReduction(SCR)
SelectiveCatalyticReduction(SCR)isanemissions-reductiontechnologywiththeability
todelivernear-zeroemissionsofnitrogenoxides(NOx),asmog-causingpollutantand
greenhousegas.SCR’sperformancehasbeenprovedinmillionsofkilometersofreal-world
trucksinothercountries,aswellasinlong-termeldtestsintheU.S.
SCRreducesNOxemissionstoverylowlevels,whileatthesametimedeliveringexcellent
fueleconomyandreliability.Thesystemdoesn’tchangethedesignorofthebasicengine.
Rather,SCRisanaftertreatmentsystemwhichconvertsNOxintheexhauststreaminto
harmlessgases.Moderndieselsalreadyuseexhaustaftertreatmentsystems,calleddiesel
particulatelters,tocontrolemissionsofanotherpollutant,soot(alsoknownasparticulate
matterorPM).
SCRworksbyinjectingDieselExhaustFluid(DEF)intotheexhaust.DEFisasolutionof
ultra-purewaterandurea.DEFworkswiththeheatoftheexhaustandacatalysttoconvert
NOxintonitrogenandwatervapor-twoharmlessandnaturalcomponentsoftheairwe
breathe.Theendresultiscleanerair,excellentfuelefciencyandareliableemissions
controlsystemfortoday’smoderndieselengine.
W2061387
1.DieselEngine
2.AftertreatmentDEFTank
3.AftertreatmentDEFPump
4.AftertreatmentDEFDosingUnit
5.SelectiveCatalyticReduction(SCR)Catalyst
6.AftertreatmentDEFTankGauge