12th Diesel Engine-Efficiency and Emissions Research (DEER) Conference August 20-24, 2006, Detroit, Michigan LNT or Urea SCR Technology: Which is the right technology for TIER 2 BIN 5 passenger vehicles? Richard Dorenkamp Diesel Engine Development, Volkswagen AG, Wolfsburg
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LNT or Urea SCR Technology: Which is the right technology ... · LNT or Urea SCR Technology: Which is the right ... • Comparison LNT and SCR Technique • Conclusion. ... LNT or
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12th Diesel Engine-Efficiency and Emissions Research (DEER) ConferenceAugust 20-24, 2006, Detroit, Michigan
LNT or Urea SCR Technology:
Which is the right technology forTIER 2 BIN 5 passenger vehicles?
Latin AmericaLatin AmericaCostsCosts,,MobilityMobility
ChinaChinaEmissionsEmissions,,EnergyEnergy
Low fuelconsumption Low emissions
(noise, smell,exhaust gas)
Sufficientpower output /
torque
Long service life
High comfort(low vibrations)
Compatible withbiogenic fuels
Good operability
Low consumptionof lubricants
Low servicecostsLow production
costs
Customer Demands on Modern Diesel Engines
Low emissions(noise, smell,exhaust gas)
European Emission Results
Emission trends in VW diesel engines in Europewith the Rabbit/Golf as an example
North America Region Emission Results
Emission trends in VW dieselengines in North America
with the Jetta as an example
Low fuelconsumption
Low emissions(noise, smell,exhaust gas)
Sufficientpower output /
torque
Long service life
High comfort(low vibrations)
Betrieb mit biogenenKraftstoffen
Good operability
Low consumptionof lubricants
Low servicecostsLow production
costs
NOx-CatalystNOx-Catalyst
DieselParticulate Filter
DieselParticulate Filter
OxidationCatalyst
OxidationCatalyst
Diesel FuelDiesel Fuel
EngineEngine
Components of Diesel Development
Measures on the Engine
Combustion
Exhaust gasrecirculation
Turbocharging
Injection
Homogenization
Temperaturemanagement
Engine Improvements
• Injection system• Combustion process• Air management• Turbocharging• EGR system
50%50%50%
• HC- CO- conversion at low temperature• Exotherme in exhaust gas system (necessary for PM trap NSC)
COHC
(O2)
H2OCO2
Ceramic monolith Precious metal coating
Metal casing Cellular structure
Oxidation Catalyst Principle
620°C 620°C
750°C
720°C
DOC + CSF close to the engine
CSF close to engine with integrated oxicat
HCI close to engine with ext. fuel injection
CSF away from engine + retarded post injection
620°C
750°C
620°C 520°C
750°C
700°C
Fuel metering
Different Particle Traps
570°C
750°C
650°C150
250
350
450
550
650
0 5 10 15 20Time [min]
Exh.gas temp. before particulate filter [°C]
Post injection period
General Conditions for NOx Catalytic Converter Systems
1. NOx-storage catalytic converter (discontinuous)λ > 1 : NOx storage (formation of Nitrates)λ < 1 : NOx release and reduction• Low sulfur fuel (S < 10 ppm) necessary• Additional fuel consumption as a result of
catalytic converter regeneration
2. Urea SCR catalytic converter (continuous)- Hydrolysis and thermolysis of urea → formation of NH3
- Reduction of NOx in the SCR catalyst using NH3
• Logistics necessary for the reduction agent, urea• Customer-friendly topping up of urea at filling stations
• Catalyst temperature
• Space velocity
• Current NOx load
• Regeneration frequency (⇔ fuel consumption)
• Thermal ageing
• Sulphur poisoning
Impacts on NOx Efficiency for NOx Storage Cat
Impacts: Thermal Ageing and Sulphur Poisoning
Temperature field for DeSOx
Temperature limit of NSC
Tmax for DeSOx
Requirements for desulphation• catalyst temperature (600°C < T < 750°C)• λ ≤ 1• secondary emissions (λ-control)
Desulphation (DeSOx)
Tλ
timeHeat-condition DeSOx-condition
λ = 1
Temperature NSC
OSC refill heat up coolingheat up
λ in Front of NSC
λ behind NSC
Durability Run with Desulphation
Touran 74 kW EU4 (4000 lbs) with CSF cc + NSC underfloor
NOx Conversion at FTP cycle (engine out NOx 0.35 g/mi)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
014
.771
26.25
231
.520
36.70
246
.958
57.26
710
8.604
149.7
2214
9.722
149.7
0414
9.722
154.8
2015
4.838
Mileage [km]
NO
x-C
onve
rsio
n
60% efficiency
Oven ageingat 800 °C, 24h
Correlation between Bench and Vehicle Ageing
NOx Conversion at FTP cycle Golf class, 3500 lbs
0
10
20
30
40
50
60
70
80
90
100
Fresh Vehicle 120.000 mi Bench ageing120.000 mi
NO
x-C
onve
rsio
n[%
]
SCR-System Structure
AdBlue Tank
Heating
AdBlue Pipe
Metering Valve
T Sensor ECU NOx Sensor
ECU control line
Components of SCR-System
Urea Metering ValveMixer
SCR Catalyst
Conversion at a Function of:• Temperature• Mass flow• NO/NO2 Balance• NH3 Distribution and NOx /NH3 Ratio• Ageing of the catalyst