composition of PM and %
solid fraction--SOL / carbon soot (carbon and ash)soluble organic fraction--SOF (from oil and fuel)sulfate particulates--SO4 (sulfuric acid,water)? SOF%:? load, ? EGR, active DPF regenerationhigh load high speed, low PM emission(?)
what is "filtration"?
1, depth ~ : PM accumulated on filter porosity2, cake ~: PM forms a prosity layer
why choose honeycomb structure?
? surface? efficiency (modify back P-> ? v of gas passing-> time ?-> ?
why asymmetric DPF cell designs? usually use?
haigher soot storage, lower pressure drop with high soot loadingactagon/squre
what mechanisms of particles deposition does depth filtration rely on?
diffusional deposition inertial depositionflow-line interception
3 phrases of regeneration, and reactions
filtrationpassive regeneration 300~400?C(slow) :NO2+C->NO+CO, NO2+C->0.5N2+CO2active regeneration 600?C(fast) :C+O2->CO2/CO (with fuel add Ce, Fe can be 380~450?C)*J.M.CRT:C+NO2->NO+CO/CO2, but not good for PV, regen time=30min, need sulfur deactive catalyst
What is the effect of fuel additive
without fuel add is for-life solution (>20000km)with fuel add is maintenance required.
what control the activation of regeneration?what is the objective of strategy of O2based?what strategy can use?
air flow meter sensor, inlet DPF temp sensor, DPF press drop sensormonitoring PM loading, inlet T>600, O2>5%pilot & main inj. timing retarded, after & post injection activation(IDLE:also multiple inj), inj P variation, EGR reduction or deactivationinlet fresh air reduction(?)Torque correction
what assessment used for catalyzed DPF critical regeneration events?
thermal shock test (activation of RGN at 1750rpm 1,5bar for 2 min, until the combustion start--P drop peak)measurement of DPF T evolution
why DPF regeneration management is more critical if use BIODIESEL on standard diesel engines without modification?
regeneration rate of BDF is twice as fast as that of Diesel. (higher regeneration efficiency)Biofuel has lower soot mass limit than conventional diesel.higher max T and T gradient
DPF requirement:
high filtration efficiency (>90%)high thermal resistance (no damage up to 1200?C)high mechanical resistance (isostatic strength>4 Mpa)high chemical inertiahigh porosity (>42%)low pressure drop (<7kPa @ 600 m3/h)
the function of filter wall active "layer
catalyze soot combustion during RGN, minimize residual sootreduce CO&HC emission during regeneration
DPF design preferance
volume: ?better for technical function (?RGN frequency & ?P, ? oil change interval & ash tolerance), worse for cost ,wight, vehicle intergrationLength/diameter:?better for reliability, RGN frequency, ?P ????
the material used for DPFoutside canmatmonolith?why)segment
outside can: metallicmat: ceramic(??????monolith: cement(flexible enough when temperature change, componsate the stress)segment: SiC
why use Close Coupled PDF from E4 to Euro 5?
1) 50?C increase of exhaust T <- exhaust T is a function of distance from outlet turbine 2) -35% time to reach the same reg T3) ? viscosity, ? oil dilution
1)ECU sensors for DPF? 2)Vehicle mission profile will have impact on? 3)What is Soot Loading Driving Parameters? 4)What is regeneration activation driving Parameters? 5)When will RGN activated? 6)What parameters have impact on RGN duration?
1) 2 ex gas T: outlet pre cat, inlet DPF Pressure: DPF P drop2) soot loading estimation, regeneration efficiency3) Mission Profile, Car inertial weight, Car Road Load4) DFP Soot Load, Mission Profile, No perception by driver5) when most favorable condition is detected & accelerator pedal is released to minimize T variation6) RGN duration is optimized for each mission profile, only effective when TinDPF>580?C, and is interrupted if time > 20min
other 2 statistical model for ECU
1) residual soot map2) oil quality driving parameter
Why additive DPF?
additive is added in the fuel not just on the monolith, so the contact is optimized, get higher T
additive should make sure the optimal DP regeneration behavior. what kind of behaviour?
Faster soot oxidation with additive.lower soot burn off with additive.fast, uniform and complete soot combustion(should provide high surface area->small cristallite size)
2 different chemical species of fuel additive
1,organometallic salts: Fe2O3 (highly efficient to decrease combustion temperature) 2,Eolys: Ce-Ce/Fe-Fe (a colloidal dispersion of a iron oxide--ensure perfect dispersion and stability)
what is add blue? what's difference between it with fuel additive?
add blue is for SCR, selective catalytic reduction sys, it is (NH2)2CO, it is added after DOC fuel additive is added in fuel tank(i think), it is Fe2O3 or others.
all reaction functions
DOC(catalyst): NO+CO->CO2+N2, HC + O2 -> CO2 + H2O, CO + O2 -> CO2DFP(reduce soot)(regeneration):CO+O2->CO2, C+O2-> CO2 [for catalysed filter: C+NO2->CO2+NO, NO+O2->NO2]3way catalyst oxygen sorageCO+CeO2 ->CeO3+CO2, Ce2O3+O2->CeO2
recently development of FBC:
New Eolys: reduce on-board volume, better inter gration, extend maintaenance interval, reduce ashOn-Board Multifunction FBC: co-additive: flexible to different fuel qualities new Octosquare design: more ash storage
1)stability check for FBC, 2)trap regeneration test
1)the stability is checked by following the evolution of the active matter(Fe-Ce) concentration during ageing test2)draw profile, important point: start of regeneration, soot burn rat @50%, soot burn rate@100%masure: back pressurecriteria: constant back pressure at end of regeneration
effect of FBC
loading decrease before regenerationlong intervallow back PBUT: may reduce regeneration target T ->fuel penalty + oil dilution
comparasion between catalysed DPF and Eoly A-DPF
EOLY A-DPF: more contact points with soot, high porouslonger regeneration intervals and lower TC-DPF:risk of non homogeneous regeneration:hot spot and future uncontrolled, partial regeneration with DP residual->fuel penaltyso, need higher maintenance, secondary emissions
solution for commercial vehicles and heavy duty vehicles(sweeper, excavator, dumper)
DPF and DeNOx combinationspecial ECU like plug-inMicro thermal injector