Emissions Control for Lean Gasoline Engines · Emissions Control for Lean Gasoline Engines. This presentation does not contain any proprietary, confidential, or otherwise restricted

Managed by UT-Battellefor the Department of Energy

Jim Parks, Shean Huff, Kevin Norman, John Thomas, Vitaly Prikhodko, Bill

Partridge, Jae-Soon Choi

Oak Ridge National Laboratory

Emissions Control for Lean Gasoline Engines

This presentation does not contain any proprietary, confidential, or otherwise restricted information

ACE018

2010 U.S. DOE Vehicle Technologies Program Annual Merit Review and Peer

Evaluation Meeting

June 7-10, 2010

Gurpreet Singh and Ken HowdenAdvanced Combustion Engine Program

U.S. Department of Energy

2 Managed by UT-Battellefor the Department of Energy

Overview

• Timeline– Project start date: Oct. 2009– Project end date: not set– % Complete: Ongoing– Note: this project is a recent adaptation

from a previously funded project that focused on Lean NOx Trap catalysts for diesel engines

• Barriers– Cost-effective emission control

for lean gasoline engine vehicles

• Budget– FY2010: $200k

• Collaborations/Interactions– DOE Vehicle Technologies

Program– Cross-Cut Lean Exhaust

Emissions Reduction Simulations (CLEERS)

– General Motors– Loan of Euro spec Lean GDI

BMW vehicle


Objectives / Relevance

• Objective: Address technical challenges of enabling market penetration of lean gasoline engine vehicles by studying emission control approaches to achieve emission regulation compliance

• Relevance: U.S. passenger car fleet is dominated by gasoline-fueled vehicles. Enabling introduction of more efficient lean gasoline engines can provide significant reductions in passenger car fuel consumption (thereby lowering petroleum use and reducing greenhouse gases).


Milestones

• Characterization of exhaust from the LNT system of a lean gasoline engine vehicle including reductants produced for LNT regeneration and reporting of information to the CLEERS community. (September 30, 2010)


Approach

• Study emission control devices on multi-cylinder lean gasoline engine on engine dynamometer; potential emission control devices include:

– Lean NOx Trap (LNT) catalyst– Selective Catalytic Reduction (SCR) catalyst

• Urea-based• Hydrocarbon-based

– Three-way catalyst (TWC) [likely as part of system]– Oxidation catalyst [or oxidative function of catalysts]– Hydrocarbon trap catalysts [or cold start specific technologies]– Combinations of catalysts (e.g. LNT+SCR)

• Complement engine-based studies with bench flow reactor studies and other catalyst characterization tools

• Communicate results to stakeholders with CLEERS being a primary conduit for information exchange


Technical Accomplishments and Progress

Beginnings of project are focused on gaining information on lean gasoline engine emissions with end goal of engine dynamometer experimental platform

• Chassis-dynamometer experiments performed to characterize exhaust from MY2008 BMW 120i vehicle which uses TWC + LNT technology for European emissions compliance

– Leveraging with Vehicle Systems program

• Bench flow reactor studies of CLEERS LNT (a lean gasoline catalyst) under lean gasoline engine exhaust conditions [ongoing]

• Acquire a modern lean gasoline engine vehicle suitable for engine dynamometer studies [in progress]

– Targeting same BMW engine with associated LNT exhaust system– Plan to develop Drivven control system for full control of engine operation


Accomplishments – Chassis-Dynamometer Study• Engine specs (N43B20)

– 2.0l 4-cylinder – Lean burn combustion– 200bar direct Injection– 170 hp (130 kW) at 6,700 rpm,– 210 Nm (155 ft.lbf) at 4,250 rpm– 12:1 compression ratio – Dual VVT and EGR

• Exhaust– Split TWCs– LNT

TWCTWC

LNT

muffler

Engine Outtemp/pressureO2 boss1/4" exhaust3/8" exhaust

LNT Inlettemp/pressure O2 boss1/4" exhaust new 1/4" NPT for FTIR return

LNT Inlettemp/pressureO2 boss1/4" exhaust3/8" exhaustSpaciMS


Engine Out(Cyl 2&3)

Engine Out(Cyl 1&4)

TWC Out/LNT In

Tailpipe

Split TWCs

LNT (underfloor)


Accomplishments – Experimental Focus• Emissions and Reductant Species (this project)

– UEGOs for both exhaust manifold legs– General emissions analyzers at engine out and

tailpipe positions– Reductant focused emissions analysis at LNT

inlet position• FTIR (NO, NO2, N2O, NH3, HCs, CO, etc)• SpaciMS (H2, O2)• Note: some measurement at other positions with

these tools

• Vehicle Systems Program project– Overall efficiency and emissions

• Transient drive cycles• Steady-state conditions

– Mapping of engine for database– Start-stop feature– Mild hybridization (Intelligent alternator)– See “Light-Duty Lean GDI Vehicle Technology

Benchmark” (presentation VSS17) for more information

TWCTWC

LNT

muffler


LNT Inlettemp/pressure O2 boss1/4" exhaust new 1/4" NPT for FTIR return

LNT Inlettemp/pressureO2 boss1/4" exhaust3/8" exhaustSpaciMS


Engine Out(Cyl 2&3)

Engine Out(Cyl 1&4)

TWC Out/LNT In

Tailpipe

Split TWCs

LNT (underfloor)


Accomplishments: Drive Cycle Results

Stoich Lean Lean with Start/Stop

Lean with Start/Stop And Inteligent Alt.

Fuel Consumption [MPG] 26.02 29.52 30.50 31.25

Improvement [%] 0 13.5 17.2 20.1

• Fuel Economy Benefit of Lean Operation = 4-14% depending on drive cycle• FTP: 13% better fuel economy with lean

operation

• HFET: 14% better fuel economy with lean operation

• US06: 4% better fuel economy with lean operation

• Tailpipe NOx emissions exceed US Tier II Bin 5 Standard

2008 BMW 1 Series Fuel Economy

26.0 40.5 30.230.5 46.7 32.331.646.429.6 32.431.3 46.320

25

30

35

40

45

50

FTP HFET US06

MPG

Stoich.

Lean

Lean with Start/Stop

Lean, Start/Stop &Smart Alt.

2008 BMW 1 Series - NOx Emissions

0.11 0.11 0.350.12 0.12 0.260.02

0.000.03

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

FTP HFET US06

g/m

i

Stoich

Lean

Lean & micro hybrid

US Tier II Standard 50k Bin 5 = 0.05(g/mi)

EU Standard (new vehicle)Euro4 = 0.13 (g/mi)

Lean engine improves fuel economy but fails to meet US emission standards


Accomplishments: Conditions for data collection

• Transient drive cycles:– FTP, HFET, US06

• Matrix of driving conditions examined for mapping purposes– Vehicle speed =

• 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 6000, 7000 RPM

– Load = • 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%

• Will focus on 3500 RPM load sweep data for today’s review

Large amount of data acquired; analysis ongoing


Accomplishments: AFR as function of load (3500 rpm)

0

10

20

30

40

50

60

70

80

90

100

10

12

14

16

18

20

22

24

26

28

30

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Pow

er (h

p)

AFR

Engine Load

Engine Out AFR

Power (hp)

• Lean operation up to 60% load– (leaner at lower loads)

• Rich LNT regeneration at similar AFR

Note: order of load sweep=60%,50%,70%,40%,80%,30%,90%,20%,10%

Lean operation at lower loads; stoich for high loads

Lean

Rich (LNT Regeneration)

(Steady-state operation)

Stoich


Accomplishments: Catalyst temperatures• LNT temperatures generally between 300 and 500ºC

• TWC temperatures generally between 500 and 820ºC

300

400

500

600

700

800

900

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Cata

lyst

Tem

pera

ture

(C)

Engine Load

LNT

TWC (1&4)

TWC (2&3)

LNT SV~55-60k/hr

Temperature Range = 300-500ºC

3500 rpm


Accomplishments: NOx Concentration

0

500

1000

1500

2000

2500

3000

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

NO

x (p

pm)

Engine Load

Engine Out (Lean/Stoich)Engine Out (Rich)TWC Out/LNT In (Lean/Stoich)TWC Out/LNT In (Rich)Tailpipe/LNT Out (Lean/Stoich)Tailpipe/LNT Out (Rich)

• LNT adds TWC-function at stoich conditions

• Challenging high concentration of NOx for LNT

• LNT out NOx significant (lean and rich)

Very high NOxconcentration (vs. diesels)

Note:NOx is primarily NO

3500 rpm


Accomplishments: NOx concentration at 20% load• Significant NOx breakthrough occurs even during short cycle

• Large NOx emissions during rich operation for regeneration

0

500

1000

1500

2000

2500

1120 1130 1140 1150 1160 1170 1180 1190

NO

x (p

pm)

Time (sec)

Engine Out (1&4)

Tailpipe (LNT Out)

NOx profiles show significant NOx breakthrough and desorption during regeneration

3500 rpm


Accomplishments: Lean-Rich cycle period• Short lean period due to filling of LNT (15 sec limit?)

• Rich period varies with load (temp?)

0

0.5

1

1.5

2

2.5

3

3.5

4

0

5

10

15

20

25

30

35

40

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Ric

h Pe

riod

(sec

)

Lean

Per

iod

(sec

)

Engine Load

Lean Period

Rich Period

Short time for lean operation due to high NOx levels

3500 rpm


Accomplishments: Reductant Chemistry

0

0.5

1

1.5

2

2.5

3

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Red

ucta

nt C

once

ntra

tion

(%)

Engine Load

H2 (Lean)H2 (Rich)CO (Lean)CO (Rich)NH3 (Lean)NH3 (Rich)NH3 (Rich) x10

• H2 present at higher levels than CO during rich period– Water-gas-shift over TWC

• NH3 detected at small levels can perform some reduction on LNT

Primary reductants areH2, CO, NH3

Note: Hydrocarbons not detected at significant levels

3500 rpm


Accomplishments: Reductants at 30% load• Sharp peaks of reductants from rich operation

• H2, CO, and NH3 are main reductants

0

200

400

600

800

1000

1200

1400

1600

0

0.5

1

1.5

2

2.5

3

3.5

4

850 860 870 880 890 900 910 920 930

NH

3 Co

ncen

trat

ion

(ppm

)

H2

and

CO C

once

ntra

tion

(%)

Time (sec)

H2 (TWC Out/LNT In)

CO (TWC Out/LNT In)

NH3 (TWC Out/LNT In)

Temporal profiles for reductants are similar

3500 rpm


Accomplishments: Reductant Chemistry- TWC Effects• CO concentration drops over TWC during rich operation

– Water-gas-shift over TWC

• More analysis to come

0

0.5

1

1.5

2

2.5

3

3.5

4

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Red

ucta

nt C

once

ntra

tion

(%)

Engine Load

H2 (TWC Out/LNT In, Rich)

CO (Engine Out, Rich)

CO (TWC Out/LNT In, Rich)

Evidence of Water-gas-shift over TWC

3500 rpm


Accomplishments: Drive Cycle Data • Reductant species at LNT

inlet positions during transient drive cycle (LA4)

• (4) regeneration events shown

• LNT regeneration at AFR of ~13

• H2, CO, and NH3 present at LNT inlet

– H2:CO ratio higher than observed in diesel case

– Significant NH3 observed (product of TWC)

10

15

20

25

30

35

400 450 500 550 600

Engi

ne O

ut A

FR

Time (sec)

AFR

0

5000

10000

15000

20000

25000

400 450 500 550 600

LNT

Inle

t Con

cent

rati

on (

ppm

)

Time (sec)

H2

NH3

COTransient regenerations appear similar to steady-

state observations…more analysis coming


Collaboration

• Collaboration with Vehicle Systems program (internal project) which will support PSAT program

• Intend to work in CLEERS structure to share results and identify research needs

• General Motors (loan of Euro spec Lean GDI BMW vehicle)

• Catalyst manufacturers– Open to study of new formulations


Future Work

• Remainder of FY2010– Continue analysis of results from BMW 120i chassis-dynamometer

experiments• Supply information to CLEERS via website database

– Continue bench flow reactor capacity examination of CLEERS LNT– Acquire and setup lean gasoline engine with controls

• FY2011 and beyond– Characterization of reductant production for LNT regeneration at

various operating conditions (controlled AFR, etc)– Examine LNT+SCR approach for NOx control

• Carry forward from experience gained on diesel-based project


Summary

• Project focus is emission control for lean gasoline engines• Potential for significant reduction in petroleum use in U.S. passenger

vehicle fleet

• Chassis-dynamometer based experiments on European lean gasoline engine vehicle with LNT technology for NOx control• Analysis ongoing; results to be shared in CLEERS

• Acquisition of lean gasoline engine for engine-dynamometer experiments underway

Jim [email protected]

Documents

Emissions Control for Lean Gasoline Engines · Emissions Control for Lean Gasoline Engines. This presentation does not contain any proprietary, confidential, or otherwise restricted