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?
Richard Dorenkamp
Diesel Engine Development, Volkswagen AG, Wolfsburg
Agenda
• Engine Program and Demands
• Current Emission Results in Europe and NAR
• Engine Reduction Potential
• Comparison LNT and SCR Technique
• Conclusion
VW Diesel Engine Program
VW Diesel Engine Program
VW Diesel Engine Program
0 70 140 210 280 3500
150
300
450
600
Power output [hp]
Torq
ue[lb
*ft]
Global Markets: Future Demands and Developments
North AmericaNorth AmericaEmissionsEmissions,,Performance,Performance,ConsumptionConsumption
EuropeEuropeEmissionsEmissions,,ConsumptionConsumption,,COCO2
JapanJapanEmissionsEmissions,,ConsumptionConsumption,,ComfortComfort
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
Control NH3 Breakthroughby NH3 Barrier Catalyst
SCR Catalyst
Dependence on NO2/NO Relation, Ageing
0
20
40
60
80
100
100 200 300 400 500
Temperature [°C]
NO
x C
onve
rsio
n[%
]
fresh,with NO2 : NO =1:1
without NO2
thermal aged,24h 750°C,with NO2 : NO =1:1,
NH3 Storage Capacity of SCR Catalyst
0
100
200
300
400
500
600
700
800
100 200 300 400 500Temperature [°C]
NH
3St
orag
e[m
g/l]
-0Servicing---Packaging Space-0Error Rate / Complexity---Costs
--0Required Infrastructure0-Fuel Consumption0-HC++NO2 Emissions
++++
+++
NOx Red. Potential (Golf)
FTPUS06NEDC
SCR SystemNOx Storage Cat
System Benchmark Test
NOx Emission Results of SCR and NSC
0
500
1000
1500
2000
2500
0 500 1000 1500 2000Time [s]
cum
. NO
x [m
g]
0
50
100
150
200
250
Tem
pera
ture
[°C
]
FTP cycle
exhaust gas temperature [°C]
mNOx engine out US07
SCR aftertreatment
NSC aftertreatment
in FTP Testcycle
0
500
1000
1500
2000
2500
0 500 1000 1500 2000Time [s]
cum
. NO
x [m
g]
0
50
100
150
200
250
Tem
pera
ture
[°C
]
FTP cycle
exhaust gas temperature [°C]
mNOx engine out US07
SCR aftertreatment
NSC aftertreatment
Focus of developmentin the near future- for both systems,especially for SCR-system
NOx Emission Results of SCR and NSC
FTP test cycle
SCRSCR
System Applicability
LeanLean NONOxx TrapTrap
Vehicle weight
NO
xEm
issi
ons
Emission Limit
Conclusion
• Volkswagen uses leading edge technologies for the development of diesel engines
• Main focus of the diesel engine development is an optimised internalcombustion system to achieve the emission standards
• For the LEV 2/BIN5 limits we need:- a new combustion process- an optimised aftertreatment system- a high standard of fuel quality
• LNT vs. SCR technique: There will be applications for both systems.
Full speed ahead into a clean Diesel future.Full speed ahead into a clean Diesel future.
Thank Youfor Your Attention.Thank Youfor Your Attention.