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Managed by UT-Battellefor the Department of Energy
Impacts of Advanced Combustion, Fuels and Aftertreatment Technologies on Diesel PM Emissions and Mobile Source Air Toxics:
A Ten-Year Retrospective
February 11, 2009
Chairman’s Air Pollution Seminar Series
California Air Resources Board
Sacramento, CA
John StoreyFuels, Engines, and Emissions
Research [email protected]
865-946-1232
2 Managed by UT-Battellefor the Department of Energy Presentation_name
Acknowledgements
• FEERC team: – Ron Graves (Director), Brian West, Jim Parks,
Sam Lewis, Bruce Bunting, Stuart Daw, Scott Sluder, Robert Wagner, Teresa Barone, Norberto Domingo and many others
• DOE support: Office of Vehicle Technologies– James Eberhardt, Gurpreet Singh, Ken Howden,
Kevin Stork, John Fairbanks
• EPA support: OTAQ– Dennis Johnson and Jim Blubaugh
• CARB – Alberto Ayala for inviting me
3 Managed by UT-Battellefor the Department of Energy Presentation_name
Diesel and light-duty diesel have specific challenges in public, regulatory acceptance
1979 Cadillac Diesel Sedan
1981 VW Rabbit Diesel Pickup
•1970’s-90’s tough for diesel
•GM diesel problems
•“Dump Dirty Diesel”Campaign
•CARB interest in diesel replacement with natural gas
•1998+ Government Response to Diesel Issues
•DEER conference
•Consent decree between OEMs, EPA
•Fuel sulfur rule
•EPA releases Diesel PM Toxicity
4 Managed by UT-Battellefor the Department of Energy Presentation_name
Who invented the diesel engine?
• Rudolf Diesel 1858-1913
• Much more efficient than steam engines of the time
• Original vision – to run on vegetable oils! – biodiesel isn’t such a
new idea
• Died mysteriously on ferry to England 1913
5 Managed by UT-Battellefor the Department of Energy Presentation_name
• Motivation, background of DOE and diesel
• Approach to lowering PM– Engine Hardware– Diesel Particulate Filters
• Current State-of-the-Art– Putting it all together into today’s vehicle– Retrofit PM control– Ultralow sulfur diesel and Biodiesel
• Future– Modeling Emissions Control Systems– Advanced combustion modes– Link to CO 2 emissions and climate change
The path forward…..
6 Managed by UT-Battellefor the Department of Energy Presentation_name
• Began as part of the Manhattan Project
• Nation’s largest multiprogram energy laboratory
• World’s first nuclear reactor and now leading producer of medical radioisotopes
• Nation’s largest unclassified scientific computing facility
• Nation’s largest science facility,the $1.4B Spallation Neutron Source
• Nation’s largest concentration of open source materials research
Oak Ridge National Laboratory
National TransportationResearch Center
High Temperature Materials Laboratory
Relevant Facilities
7 Managed by UT-Battellefor the Department of Energy Presentation_name
Transportation technology
Generation Storage and distribution Consumption
Transportation system analysis
Alternativefuels
Refining
Hydrogenproduction
Hydrogen storageand transport
Batteries &Power electronics
Internal combustion
Fuel cells
Hybrid Electric Vehicle
8 Managed by UT-Battellefor the Department of Energy Presentation_name
Fuels, Engines, & Emissions Research Center…. a comprehensive laboratory for internal combustion engine technology
• A DOE National User Facility in the NTRC
• Focusing on alternative fuels, advanced combustion, and emission control R&D
• Unique or extraordinary diagnostic and analytical tools for engine/emission control R&D
• R&D from bench-scale to vehicle– Chemical/analytical labs– 9 dynamometer stands: 25-600
hp– Chassis dynamometer– Full-pass engine controls
support research – Emissions analysis with high
resolution of time and species – Non-invasive optical and mass-
spec diagnostics – Modeling & simulation
Chassis dyno lab
Engine Cells
Chassis Dyno Lab
Analytical Labs
Offsite Projects
9 Managed by UT-Battellefor the Department of Energy Presentation_name
The DOE’s Transportation Agenda
• Energy Security, Energy Efficiency– Energy Data Book and http://www.fueleconomy.gov– Energy Independence and Security Act (EISA, 2007)
• 36 Billion gal/yr of renewable fuels (2022)• Limits to corn-based ethanol• Focus on cellulosic ethanol
• Office of Vehicle Technologies– Light-duty engine efficiency goal: 42% (2007) 45% (2010)– Heavy-duty efficiency goal: 50% (2006); 55% (2013)– Meet applicable emissions
• Office of Biomass Programs– Production via Cellulosic sources (biomass)
• Office of Hydrogen, Fuel cells, and Infrastructure Technologies– Automotive fuel cell emphasis
10 Managed by UT-Battellefor the Department of Energy Presentation_name
So why bring up the DOE vision?
• DOE saw diesel engines as meeting their goal of energy efficiency and security– Heavy-duty engine efficiency program– Light Truck Clean Diesel program
• Emissions control was the enabling technology for diesel
• 1998. DEER conference in Maine– Diesel Engine Emissions control Research– Organized by DOE (John Fairbanks)– < 100 attendees
• 2008 DEER conference in Dearborn– > 1300 attendees
http://www1.eere.energy.gov/vehiclesandfuels/resour ces/proceedings/index.html
11 Managed by UT-Battellefor the Department of Energy Presentation_name
DEER conferences are comprehensive
• Industry, academia, National Labs, non-profit– Special session for environmental advocacy
organizations
• Thrusts included health effects– First U.S. discussion of nanoparticles and health
• NOx and PM control sessions
• Now large focus on advanced combustion and energy efficiency
12 Managed by UT-Battellefor the Department of Energy Presentation_name
0
5
10
15
0 0.1 0.25 0.6 1.0
Evolution of Heavy Duty Diesel Engine Emission Control
Source – Pat Flynn, DEER 20001974 EPA (HC + NOx)
19881978 (HC + NOx)
1990
19911994
1998
1987 ModelsRetard TimingLower IMTShorten HRRLow Friction
1988 ModelsRetard TimingInc. Inj. PressHigher BoostHigher CR
1991 ModelsRetard TimingLow IMT/High IMPInc. Inj. Press.Variable Inj. Timing
Particulate [g/(HP-hr)]
NO
x [g
/(H
P-h
r)]
2004(2002)
CooledEGR
13 Managed by UT-Battellefor the Department of Energy Presentation_name
EPA’s emissions standards require substantial PM and NOx reductions for automotive diesels, too.
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
FTP NOx Emissions (g/mi)
FTP
PM
Em
issi
ons
(g/m
i)
5
Bin 8
Tier 1, Through 2003
Tier 2 StandardsPhase-in 2004-2009
CurrentDiesel
Technology
14 Managed by UT-Battellefor the Department of Energy Presentation_name
• Motivation, background of DOE and diesel
• Approach to lowering PM– Engine Hardware– Diesel Particulate Filters
• Current State-of-the-Art– Putting it all together into today’s vehicle– Retrofit PM control– Ultralow sulfur diesel and Biodiesel
• Future– Modeling Emissions Control Systems– Advanced combustion modes– Link to CO 2 emissions and climate change
The path forward…..
15 Managed by UT-Battellefor the Department of Energy Presentation_name
Diesel Engine
(compression ignition)
Gasoline Engine
(spark ignited)
hot flame region:
nitric oxides
spark plug
hot flame region:
nitric oxides +
smoke
fuel injector
How do diesels work, anyway?
Source:Caterpillar, 2003
16 Managed by UT-Battellefor the Department of Energy Presentation_name
Fuel injection - key subsystem of diesel
• Pump-line-nozzle (“ancient”)
• Unit injectors
• Common rail (state of art)
• Piezo (combined with
common rail emerging)
Source: Dieselnet.com
Injectortip
17 Managed by UT-Battellefor the Department of Energy Presentation_name
Injection pressure being increased to aid emission compliance
• Mechanical unit injector=1000 bar (1981)
• “HEUI” =up to 1450 bar
• Early generation common rail=1350 bar
• Latest piezo common rail=1800 bar
• The future (Bosch and others) 2000 bar = 29,000 psi
• WHY?– Tiny, tiny holes (<200 µm) needed to make a fine
spray, smaller particles– But , then pass ~ 1 gallon/hr through each hole!
One bar=14.5 psi
One Mpa=10 bar
18 Managed by UT-Battellefor the Department of Energy Presentation_name
Sequence of diesel fuel injection and beginning of combustion
19 Managed by UT-Battellefor the Department of Energy Presentation_name
NOx PM Trade-off curve has been moving
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
NOx Emissions (g/mi)
PM
Em
issi
ons
(g/m
i)
5
Bin 8
Tier 1, Through 2003
CurrentDiesel
Technology
20 Managed by UT-Battellefor the Department of Energy Presentation_name
• Motivation, background of DOE and diesel
• Approach to lowering PM– Engine Hardware – Diesel Particulate Filters
• Current State-of-the-Art– Putting it all together into today’s vehicle– Retrofit PM control– Ultralow sulfur diesel and Biodiesel
• Future– Modeling Emissions Control Systems – Advanced combustion modes– Link to CO 2 emissions and climate change
The path forward…..
21 Managed by UT-Battellefor the Department of Energy Presentation_name
Diesel PM control – Diesel Particulate Filters (DPF) and Diesel Oxidation Catalysts (DOC)
• DOCs use precious metal catalyst to burn off organi c fraction– Typical PM mass reduction is 30%– Used on heavy-duty pickup trucks in 90’s
• First DPF on a car – 1985 Mercedes 300 for Californi a market (not a success)– Need 700 °C to burn off soot with exhaust O 2
• Electrically-heated DPF’s in early 1990’s
• Early systems used DOC + DPF– NO → NO2, then the NO 2 oxidizes the soot
• Later DPFs use catalytic coating – Catalyst on DPF converts NO to NO 2, NO2 oxidizes soot
22 Managed by UT-Battellefor the Department of Energy Presentation_name
Diesel Particulate Filter uses ceramic honeycomb to trap PM
Trapped PM
Cell Plugs
Exhaust(PM, CO, HC)Enter
Ceramic HoneycombWall
Exhaust (CO 2, H2O)Out
23 Managed by UT-Battellefor the Department of Energy
DPF Assembly can replace muffler
Soot filtersubstrate
V-band +gasket
V-band +gasket
Inlet section withflow distributor
flow
Outlet sectionwith water trap
flow
V-band +gasket
Pre-catalyst
24 Managed by UT-Battellefor the Department of Energy Presentation_name
Early DPF field study in 2001 in NYC
Uncontrolled Regeneration
• Occurs when DPF accumulates excess soot
• Excess soot can be lit off during high load (hill, ex-way).
• If engine drops to idle during this burning, exhaust flow too low
• Internal DPF temperatures high enough to melt ceramic.
Source: B. Bunting, DEER 2001
25 Managed by UT-Battellefor the Department of Energy Presentation_name
Trap failure is very rapid, typically
TRAP FAILURE, BUS 6358, 2/26/01
0100200300400500600700800900
1000
4:33
:10
4:38
:10
4:43
:10
4:48
:10
4:53
:10
4:58
:10
5:03
:10
5:08
:10
5:13
:10
5:18
:10
5:23
:10
5:28
:10
5:33
:10
5:38
:10
5:43
:10
5:48
:10
5:53
:10
TIME OF DAY
TE
MP
ER
AT
UR
E, d
eg.C
0
2
4
6
8
10
trap in C
trap out C
press inhg
TRAP FAILURE, BUS 6358, 2/26/01
0100200300400500600700800900
1000
4:33
:10
4:38
:10
4:43
:10
4:48
:10
4:53
:10
4:58
:10
5:03
:10
5:08
:10
5:13
:10
5:18
:10
5:23
:10
5:28
:10
5:33
:10
5:38
:10
5:43
:10
5:48
:10
5:53
:10
TIME OF DAY
TE
MP
ER
AT
UR
E, d
eg.C
0
2
TRAP FAILURE, BUS 6358, 2/26/01
0100200300400500600700800900
1000
4:33
:10
4:38
:10
4:43
:10
4:48
:10
4:53
:10
4:58
:10
5:03
:10
5:08
:10
5:13
:10
5:18
:10
5:23
:10
5:28
:10
5:33
:10
5:38
:10
5:43
:10
5:48
:10
5:53
:10
TIME OF DAY
TE
MP
ER
AT
UR
E, d
eg.C
0
2
4
6
8
10
trap in C
trap out C
press inhg
Source: B. Bunting, DEER 2001
26 Managed by UT-Battellefor the Department of Energy Presentation_name
Hi Temp - Melting
Temp Gradients - Fracture
What we are trying to prevent What we are trying to prevent --Uncontrolled RegenerationUncontrolled Regeneration
Low load operation Excessive soot loading
High load operation ignites soot UNCONTROLLED REGENERATION
27 Managed by UT-Battellefor the Department of Energy Presentation_name
Configuration 1
Exhaust OutletSoot filter with catalyst
Dieselinjection
Configuration 2
Dieselinjection
Exhaust Outlet
Soot filter with catalystPre-cat
More of a slow burn than a flame thrower
Solution: active regeneration controls when the DPF is regenerated
28 Managed by UT-Battellefor the Department of Energy Presentation_name
………..Evolution into a system…
• Gasoline vehicle emissions control evolved into a system– Tailpipe approach with oxidation – early 70’s– Air pumps added, late 70’s– A/F ratio control + fuel injection – 80’s– Now completely tied together
• Diesel engine system– Better control of fuel injection– DPF with Active Regen– EGR for NOx control
29 Managed by UT-Battellefor the Department of Energy Presentation_name
Fuel – the missing link
• DPF development well on its way by 2001– But PM mass was higher with pump fuel
• Sulfur was the culprit – made sulfate aerosol in the exhaust pipe
• DOE had several large research efforts to address sulfur effects 1999-2002– DECSE (Diesel Emissions Control- Sulfur Effects)– DVECSE (Diesel Vehicle Emissions Control – SE)
• Result: EPA required 15 ppm S in 2006
• Analogous to tetraethyl lead removal – Driven by concerns for catalytic converter– Lower lead levels in people was a byproduct
30 Managed by UT-Battellefor the Department of Energy Presentation_name
• Motivation, background of DOE and diesel
• Approach to lowering PM– Engine Hardware – Diesel Particulate Filters
• Current State-of-the-Art– Putting it all together into today’s vehicle– Retrofit PM control– Ultralow sulfur diesel and Biodiesel
• Future– Modeling Emissions Control Systems– Advanced combustion modes– Link to CO 2 emissions and climate change
The path forward…..
31 Managed by UT-Battellefor the Department of Energy Presentation_name
The dirty diesel of the past is giving way to clean diesel technology
2008 Dodge Ram 2500 Pickup meets 2009 standards
32 Managed by UT-Battellefor the Department of Energy Presentation_name
Clean diesel cars available now
VW Jetta TDI
Mercedes E320 Bluetec
33 Managed by UT-Battellefor the Department of Energy Presentation_name
VW’s emissions controls a marvel of packaging
Source: Internationales Wiener Motorensymposium 2008
34 Managed by UT-Battellefor the Department of Energy Presentation_name
Almost 40% improvement in MPG
2009 Volkswagen Jetta 2009 Volkswagen Jetta
Diesel Vehicle Gasoline Vehicle
New EPA MPG
DIESEL
33 Combined 29
City 40 Hwy
REGULAR GASOLINE
24 Combined 20
City 29 Hwy
Annual Petroleum
Consumption
(1 barrel=42 gallons) 11.9 barrels 14.3 barrels
Source: fueleconomy.gov
35 Managed by UT-Battellefor the Department of Energy Presentation_name
Diesel fuel then and now…
• 1998: Low sulfur diesel rule in effect, largely for PM control. < 500 ppm S, ~450 ppm true– California: ~150 ppm S due to low aromatics
• 2006: Ultralow sulfur diesel for diesel emissions control < 15 ppm S, ~ 8 ppm true– How? The magic of hydrogen. Result is higher
cetane fuel - good for older engines
• Biodiesel: How does it affect PM emissions?– Generally lower PM mass, higher solubles– Alters behavior of DPF → ULSD ≠ B5 ≠ B20
36 Managed by UT-Battellefor the Department of Energy Presentation_name
• Motivation, background of DOE and diesel
• Approach to lowering PM– Engine Hardware – Diesel Particulate Filters
• Current State-of-the-Art– Putting it all together into today’s vehicle– Retrofit PM control– Ultralow sulfur diesel and Biodiesel
• Future– Modeling Emissions Control Systems– Advanced combustion modes– Link to CO 2 emissions and climate change
The path forward…..
37 Managed by UT-Battellefor the Department of Energy Presentation_name
Diesel PM retrofit
• Diesel oxidation catalysts (DOC) popular– Low cost, “bolt-on” solution– ~30% PM reduction
• Diesel Particulate Filters (DPF) offer best PM removal– Require maintenance, off-vehicle regeneration
• Crankcase emissions filtration– Crankcase breather significant source
• ORNL-EPA project examined both– Field-aged DPF from schoolbus– Crankcase PM mass and size
38 Managed by UT-Battellefor the Department of Energy Presentation_name
Extensive setup of 1999 Cummins B5.9 was necessary to carry out project
Engine
DPF
Transient Emissions
System
39 Managed by UT-Battellefor the Department of Energy Presentation_name
PM and HC go down with DPF
0.00200.00350.00660.00550
0.1
0.2
0.3
0.4
0.5
FTP1 FTP2 FTP3 BP-FTP1
BP-FTP2
DPF-FTP1
DPF-FTP2
CDPF-FTP1
CDPF-FTP2
Test Sequence
Em
issi
ons
(g/h
p.hr
)
PMHC
40 Managed by UT-Battellefor the Department of Energy Presentation_name
Time for FTP (sec)
0 300 600 900 1200
Num
ber
Con
cent
ratio
n (#
/cm
3 )
0
2000
4000
6000
8000
10000
12000 Hot FTP 1 (09/04/08)Hot FTP 1 (09/05/08)
Total Particle Number Concentration During FTP Cycles
Downstream of DPF
Outdoor Air Concentration
41 Managed by UT-Battellefor the Department of Energy Presentation_name
Unique sampler design imposes no vacuum or pressure on crankcase
• All of PM collected
• ∆p < 0.5” H 2O observed at inlet of tunnel
• PM as much as 18% of regulated limit
To Roots Blower + Flow Measure
PressureMeasurement
SMPS outlet
HEPA Filter
Twin 70mmFilter Holders
42 Managed by UT-Battellefor the Department of Energy Presentation_name
PM emissions from draft tube significant
0
0.005
0.01
0.015
0.02
0.025
7/01
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stea
dy-s
tate
2000
rpm
, 23
bar
1400
rpm
, 30
bar
1800
rpm
, 30
bar
805r
pm, 0
bar
Cra
nkca
se P
M (
g/hp
.hr)
0
0.05
0.1
0.15
0.2
0.25
Cra
nkca
se P
M (
g/hr
)
Basew. Bpw. DPFSteady StateIdle
*
43 Managed by UT-Battellefor the Department of Energy Presentation_name
dp (nm)
100 101 102 103 104 105
dN/d
logd
p (#
/cm
3 )
0.0
5.0e+7
1.0e+8
1.5e+8
2.0e+8
2.5e+8
SMPSAPS
µg = 114 ± 2 nm Ctot = 2.9 x 107 #/cm3
Crankcase Emissions Number-Size Distribution
dp (nm)
101 102 103 104 105
dN/d
logd
p (#
/cm
3 )
0.0
5.0e+7
1.0e+8
1.5e+8
2.0e+8
2.5e+8
SMPSAPS
µg = 159 ± 2 nm Ctot = 1.4 x 108 #/cm3
Increased Backpressure
Engine Baseline
Backpressure 280 mbarat rated speed (1400 RPM)
Rated Torque1400 RPM, 300 ft.lbs
(similar to 100% A on 13 mode)
44 Managed by UT-Battellefor the Department of Energy Presentation_name
Findings from Retrofit DPF Study
• Field aged DPF (3+ years in service) as received evaluation– DPF very efficiently removing PM– Clean DPF: higher number concentrations until soot layer
builds
• Crankcase emissions – mostly oil droplets– PM mass emissions = 3 X DPF out emissions– PM size shows significantly larger particles
• Crankcase PM treatment complements DPF retrofit
• Model Year 2007 and beyond closes the crankcase
Presentation at 2009 CRC On-Road Emissions Workshop
45 Managed by UT-Battellefor the Department of Energy Presentation_name
• Motivation, background of DOE and diesel
• Approach to lowering PM– Engine Hardware – Diesel Particulate Filters
• Current State-of-the-Art– Putting it all together into today’s vehicle– Retrofit PM control– Ultralow sulfur diesel and Biodiesel
• Future– Modeling Emissions Control Systems– Advanced combustion modes– Link to CO 2 emissions and climate change
The path forward…..
46 Managed by UT-Battellefor the Department of Energy Presentation_name
Modeling used extensively to improve combustion efficiency, emissions
Addressing the fundamental losses of combustion flames
Increased use of computational tools
47 Managed by UT-Battellefor the Department of Energy Presentation_name
Catalyst Modeling takes off from 2000 on….
• Objective to improve ability to simulate advanced emissions controls
• CLEERS (cleers.org) has annual workshops and working groups for NOx and PM control
• Broad participation from industry, academia, labs
• Past presentations available on the web site– Created and maintained by ORNL
Cross-Cut L ean Exhaust E missions R eduction S imulations
48 Managed by UT-Battellefor the Department of Energy Presentation_name
Modeling Extended to Engines, Vehicles
•Modeling the growth of the soot layer in a DPF duri ng a drive cycle
•No active regeneration of the filter (DPF)
0
1
2
3
4
5
6
7
8
0 1372 2744 4116 5488 6860Time (s)
Soo
t Lay
er W
idth
(µµ µµm
)
0
2
4
6
8
10
12
14
16
Eng
ine-
Out
PM
(m
g/s)
Soot layer Width
Engine-out PM
Source: ORNL Systems Modeling, 2008
49 Managed by UT-Battellefor the Department of Energy Presentation_name
• Motivation, background of DOE and diesel
• Approach to lowering PM– Engine Hardware – Diesel Particulate Filters
• Current State-of-the-Art– Putting it all together into today’s vehicle– Retrofit PM control– Ultralow sulfur diesel and Biodiesel
• Future– Modeling Emissions Control Systems– Advanced combustion modes– Link to CO 2 emissions and climate change
The path forward…..
50 Managed by UT-Battellefor the Department of Energy Presentation_name
High Efficiency Clean Combustion (HECC)
• HECC includes– Homogeneous Charge Compression Ignition (HCCI)
– Premixed Charge Compression Ignition (PCCI)
– others
• Improve powertrain system efficiency by lowering performance requirements for post-combustion emissions controls.
Objectives of ORNL efforts
• Detailed emissions characterization for understandi ng combustion regimes and environmental impact.
– Hydrocarbon speciation (MSATs!)
– PM characterization
51 Managed by UT-Battellefor the Department of Energy Presentation_name
Exhaust Gas Recirculation (EGR) key to advanced combustion modes
• EGR on most diesel engines since 2002
• How does EGR work?– Lowers NOx by diluting charge (air) with exhaust ga s
– lowers peak combustion temperature
– Typically increases PM
• High levels of EGR result in lower NOx and PM
52 Managed by UT-Battellefor the Department of Energy Presentation_name
Exhaust
Air
Air HXN
Engine Coolant
DPF
HP
EG
R H
XN
Shaft Work
Turbo
Typical Exhaust Gas Recirculation (EGR)
scheme
53 Managed by UT-Battellefor the Department of Energy Presentation_name
Motivation – 1999 study with VW TDI engine
0
0.4
1.0
1.4
20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0
EGR %
NO
x, P
M g
/hp-
hr
PM
NOx
0
0.4
1.0
1.4
20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0
EGR %
NO
x, P
M g
/hp-
hr
PM
NOx
54 Managed by UT-Battellefor the Department of Energy Presentation_name
Diesel Engine
(compression ignition)
hot flame region:
nitric oxideshot flame region:nitric oxides + smoke
Gasoline Engine
(spark ignited)
HCCI Engine
(Homogeneous Charge
Compression Ignition)
Low temperature combustion
ultra low emissions !!
spark plugfuel injector
What is this High Efficiency Clean Combustion?
Source:Caterpillar, 2003
55 Managed by UT-Battellefor the Department of Energy Presentation_name
Images of Conventional and HCCISource: Caterpillar, DEER Conference, 2002
Conventional Diesel HCCI
PCCI = Pre-mixed charge compression ignition
56 Managed by UT-Battellefor the Department of Energy Presentation_name
Advanced combustion changes the NOx-PM trade-off curve
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
FTP NOx Emissions (g/mi)
FTP
PM
Em
issi
ons
(g/m
i)
5
Bin 8
Tier 1, Through 2003
Tier 2 StandardsPhase-in 2004-2009
CurrentDiesel
Technology
With “advanced”combustion
57 Managed by UT-Battellefor the Department of Energy Presentation_name
0
5.0
10.0
15.0
500 1000 1500 2000 2500 3000 3500
Engine Speed (rpm)
BM
EP
(ba
r)
02
13
4
5
Steady state modes used with HECC to approximate Light-duty FTP cycle.
• BSFC equivalent to baseline operation.
• Emissions lower
0.0
0.5
1.0
NOx PMConventional
HECC
Estimated FTP Emissions Index(Normalized)
What about HCs and CO?
58 Managed by UT-Battellefor the Department of Energy Presentation_name
High EGR = high formaldehyde and acetaldehyde formation.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
22.2 34.9 40.2 44.3 46.3 48.8 54.0 56.0
EGR %
DN
PH
Mas
s C
once
ntra
tion
mg/
s
Formaldehyde Acetaldehyde Acrolein
Propionaldehyde Benzaldehyde
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What are Mobile Source Air Toxics (MSATs)?
Mobile Source Air Toxics (MSATs)
Particulate Matter (PM)
Volatile Organics
Semivolatile Organics
MetalsDiesel PM
Polycyclic organic Matter (POM)
Formaldehyde
Acetaldehyde
1,3-Butadiene
Acrolein
Benzene
Toluene
Ethylbenzene
XylenePolycyclicAromatic
Hydrocarbons (PAHs)
Diesel Exhaust Organic Gases
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Array of Analytical Techniques for MSATs
Catalyst
Dilution
Tunnel SMPSParticle Size Distribution
PM Filters
Total PMSOF/insolubleSOF speciation
EmporeSelective capture of semi-volatiles (C10-C18)
GC/MS speciation
DNPH
Selective capture of carbonyl species
HPLC, UV, ESI/MS separation/speciation
Canisters
Light HC species
Preconcentrator, GC/MS speciation
FTIR
C1-C4 species
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DOC Oxidation of Formaldehyde Not Complete Until ~225ºC
• CO, HC, and formaldehyde oxidation efficiency as a function of catalyst temperature– CO oxidation enables higher
oxidation of HCs and formaldehyde
– Formaldehyde oxidation not complete until 225ºC
• Engine at 1500 rpm/ 1.0 bar during cool down of catalyst from previous higher load operation
0
10
20
30
40
50
60
70
80
90
100
125 150 175 200 225 250
Catalyst Temperature (C)
Con
vers
ion
COHCFormaldehyde
• Thermal management can enable DOC to be kept at tem perature where suitable CO/HC/Formaldehyde oxidation occurs, but…
– What is the efficiency penalty associated with main taining formaldehyde oxidation vs. CO/HC oxidation?
62 Managed by UT-Battellefor the Department of Energy Presentation_name
0
1
2
3
4
5
Formaldehyde Acetaldehyde
Em
issi
ons
Inde
x (g
/kg
fuel
)
1500 rpm, 2.6 bar0
1
2
3
4
5
Formaldehyde Acetaldehyde
Em
issi
ons
Inde
x (g
/kg
fuel
)
1500 rpm, 1.0 bar
Catalyst Temperature
119ºC
256ºC220ºC
Low catalyst temperature presents challenges for tailpipe aldehydes in PCCI mode
Tier 2, Bin 5 formaldehyderegulation 0.24 g/kg fuel
0
1
2
3
4
5
Formaldehyde Acetaldehyde
Em
issi
ons
Inde
x (g
/kg
fuel
)
2000 rpm, 2.0 bar
Conv., Engine OutPCCI, Engine OutPCCI, Catalyst Out
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Particle size measurements
• Why measure particle size?– Nanoparticles linked to health effects
– Number of particles may be more important than mass
• Modern engines reduce PM size to reduce mass
• With DPFs, PM mass measurement difficult– European Union adopting number based regs
– CARB investigating number-based system as well
Engine out DPF out
64 Managed by UT-Battellefor the Department of Energy Presentation_namedp (nm)
1 10 100 1000
dN/d
logd
p (
#/cm
3 )
0
2e+7
4e+7
6e+7
8e+7Conv.: Engine OutPCCI: Engine Out
Number s are similar, but PCCI particles much smaller
PCCI PM smaller in size at low load and medium load
Number of particles > 100 nm decreases
dp (nm)
1 10 100 1000dN
/dlo
gdp
(#/
cm3 )
0
2e+7
4e+7
6e+7
8e+7Conv.: Engine OutPCCI: Engine Out
46 nm23 nm
65 Managed by UT-Battellefor the Department of Energy Presentation_name
• Motivation, background of DOE and diesel
• Approach to lowering PM– Engine Hardware – Diesel Particulate Filters
• Current State-of-the-Art– Putting it all together into today’s vehicle– Retrofit PM control– Ultralow sulfur diesel and Biodiesel
• Future– Modeling Emissions Control Systems– Advanced combustion modes– Link to CO 2 emissions and climate change
The path forward…..
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What does all of this mean for greenhouse gas emissions?
• CO2 directly related to fuel efficiency– Engines have been getting more efficient, but..
– …PM emissions controls reduce efficiency• Backpressure, fuel needed for active regeneration
• N2O and CH4 emissions can be a concern– Catalyst systems can make N 2O
– Advanced combustion can make more CH 4
• 2010 regulations could be paradigm shift– Urea-SCR NOx removal efficiency could allow
higher fuel efficiency
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Summary
• Engines, PM control have advanced considerably in ten years
• DPFs close to 99% efficient
• Retrofits showing good durability
• Packaging of systems remains a challenge
• DOE continues to push technology for better efficiency
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Resources
• DEER presentations– http://www1.eere.energy.gov/vehiclesandfuels/res
ources/proceedings/index.html
• CLEERS– http://cleers.org
• Society of Automotive Engineers– www.sae.org
• Health Effects Institute– 2008 Mobile Source Air Toxics report at
www.healtheffects.org
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Extra slides
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X-Ray Imaging Scouting Study Approach: Measurements with commercial 3D x-ray
X
D
• MDXi400 by 3D-XRAY, Ltd onsite NTRC March-May 08
• Rotating platform & X-ray fan beam give 3D profiles
• Used for defect detection in catalytic monolith production
• Examined cracks, thermal damage, washcoat uniformity, soot & ash DPF deposition
• Responds to CLEERS poll interest in DPF monitoring
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Significant Results (6): Confirmed measurement of DPF soot distribution in-can
0
0.5
1
1.5
2
0 0.2 0.4 0.6 0.8
X-ray response (a.u.)S
oot L
oadi
ng (
g)
• 6-in OD uncoated DPF (in can)• Loaded for 5 hours on
Mercedes 1.7-L engine with ULSD fuel
• Quantitative detection of axial soot loading variations thru can wall
Linear calibration curve
72 Managed by UT-Battellefor the Department of Energy Presentation_name
Significant Results (7): Also confirmed ability to image details of DPF thermal damage
• 150mm DPF in can
• Thermal damage (by OEM) induced near exit
• Expect to be highly useful for model/OBD validation