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.