Ethanol Effects on Lean-Burn and Stoichiometric GDI Emissions
John M.E. Storey, Teresa L. Barone, John F. Thomas, Shean P. Huff, and Samuel A. Lewis Oak Ridge National Laboratory
2011 Directions In Engine Efficiency and Emissions Research Conference
October 3-6, 2011
DOE Sponsor – Vehicle Technologies
James Eberhardt: Health Impacts
Kevin Stork & Steve Przesmitzki: Fuels
Gurpeet Singh & Ken Howden: Catalysts
2 Managed by UT-Battelle for the Department of Energy Data Source: Heyder (2004)
Nanoparticles can penetrate into alveolar region
Particle Size Influences Location of Deposition in Respiratory System
3 Managed by UT-Battelle for the Department of Energy
Comparison of Stoichiometric and Lean GDI Emissions
Stoichiometric GDI Vehicle Pontiac Solstice
“wall-guided”
Lean GDI Vehicle BMW 120i – Euro spec
“spray guided” • Motivation: 1. Understand potential fuel effects on GDI PM emissions. 2. Health implications and ambient air quality issues •Approach •Test cycles: FTP and US06, transient accelerations plus steady state • Fuels: Gasoline and intermediate ethanol blends (E0, E10, E20) • Measurements:
- Particle mass: collection on Teflon-coated quartz-fiber filters and gravimetric analysis -- Particle composition: organic carbon/elemental carbon (OC/EC) - Particle number concentration and size distributions: analysis by SMPS
Particle Emissions Analysis
Catalyst
Mass
Morphology
EEPS
Steady-State
Number-Size Distributions
Transient
Transmission Electron Microscopy;TEM-Sampler
AVL Micro Soot Sensor
Mettler Microbalance
Organic Fraction
Organic to Elemental
Carbon Ratio
Dilution Systems
Full-flow CVS
Partial Flow BG-3
Microtunnel
European PMP
Microwave Reactor Extraction Organic Speciation
Scanning Mobility Particle Sizer
5 Managed by UT-Battelle for the Department of Energy 0
2
4
6
8
10
PM e
mis
sion
s (m
g/m
ile)
E0 E10 E20
FTP
US06
Stoich GDI Lean GDI Stoich GDI Lean GDI
Stoichiometric GDI Vehicle PM emissions more sensitive to fuel and cycle than lean GDI
Tier 2 LDDV PM limit
6 Managed by UT-Battelle for the Department of Energy
Ethanol leads to lower elemental carbon concentrations in the tailpipe
• Less EC implies less soot formation for E10, E20
- Catalyst temperature too low to oxidize soot
• OC higher for lean burn
• Survives the catalyst
• OC/EC ratios 0.2 – 0.7
• Diesel OC/EC > 5 typically
30 mph
Stoichiometric Lean
EC
Con
cent
ratio
n (u
g/m
3 )
0
200
400
600
800
1000 E0E10E20
30 mph
Stoichiometric Lean
OC
Con
cent
ratio
n (u
g/m
3 )
0
200
400
600
800
1000 E0E10E20
7 Managed by UT-Battelle for the Department of Energy 7
Results – Particle size and number
• Used scanning mobility particle sizer (SMPS ) ~ 1 -2 minutes for size distributions – steady state only
• Particle counter (CPC3025) can be used independently – particle concentration too high! Required 1000:1 dilution
• Investigated three separate sizes for accels: 10, 50, 100 nm
SAE 2010-01-2129
Size distributions consistent at both steady-state points (stoich GDI)
Ethanol content does not change general shape. E20 reduces total number concentration by about 50% at 30 mph and 70% at 80 mph
Geometric mean diameter for all distributions ~ 50 nm Distribution broader than diesel exhaust particles
30 mphPost-catalystDilution Ratio ~21
dp (nm)1 10 100 1000
dN/d
logd
p (#
/cm
3 )
0
2e+5
4e+5
6e+5
8e+5
1e+6E0E10 E20
dp (nm)1 10 100 100
dN/d
logd
p (#
/cm
3 )
0
1e+6
2e+6
3e+6E0E10 E20
80 mphPost-catalystDilution Ratio ~21
10 100
dN/d
logd
p (#
/cm
3 )
0
1e+6
2e+6
3e+6StoichLean GDI Vehicle
Particle Size Distribution for 80 mph (E0 fuel)
Stoich GDI particles biased larger but less abundant than lean particles
Geometric mean ~ 50 nm
dp (nm)10 100
dN/d
logd
p (#
/cm
3 )
0
2e+7
4e+7
6e+7
8e+7LeanStoich
Geometric Mean ~ 40 nm
23 nm European PMP (Particulate Measurement Protocol) counts particles above 23 nm
10 Managed by UT-Battelle for the Department of Energy
Lean GDI total number emissions also higher than stoich GDI – comparable to potential regulation
Cold LA04 Hot LA04 US06Tota
l Par
ticle
Num
ber E
mis
sion
s (#
/mi)
1e+12
1e+13
1e+14Lean DISIStoich DISI
Proposed
CARB
Regulation
E0, Catalyst OutTotal Particle
11 Managed by UT-Battelle for the Department of Energy
Particles per mile decrease with ethanol content and hot cycles
E0 E2050 n
m P
artic
le N
umbe
r Em
issi
ons
(#/m
i)
0
2e+10
4e+10
6e+10
8e+10Stoich DISICold LA04Engine Out
50 nm
Cold LA04 Hot LA04
0.0
5.0e+9
1.0e+10
1.5e+10
2.0e+10
2.5e+10Stoich DISIEngine Out
E2050 nm
• All fuels show majority of particles from cold start • Ethanol reduces overall particle count
12 Managed by UT-Battelle for the Department of Energy
Reduction by E-blends E10 & E20 Similar for lean DI vehicle
Cold LA04 Hot LA04 US06
Par
ticle
Num
ber E
mis
sion
s (#
/mi)
3.0e+12
6.0e+12
9.0e+12
1.2e+13
1.5e+13
1.8e+13E0E10E20
ProposedCARBRegulation
EuropeanRegulation
8.1 e+11
Lean DISICatalyst OutTotal Particle
< 23 nm particles included in our measurements
13 Managed by UT-Battelle for the Department of Energy
Time (sec)0 100 200 300 400 500 600
Num
ber C
once
ntra
tion
(par
t./cm
3 )
0.0
2.0e+4
4.0e+4
6.0e+4
8.0e+4
1.0e+510 nm50 nm100 nm
Stoich GDI Wide Open
Throttle 0 – 80 mph
Time (sec)0 200 400 600
Num
ber C
once
ntra
tion
(par
t./cm
3 )
0
2e+4
4e+4
6e+4
8e+4
1e+510 nm50 nm100 nm
E0 Post-catalyst
E20 Post-catalyst
0
20
40
60
80
100
Spe
ed
MP
H
Speed Trace
14 Managed by UT-Battelle for the Department of Energy
Time (sec)0 100 200 300 400 500 600Pa
rtic
le N
umbe
r Con
cent
ratio
n (#
/cm
3 )
0
10000
20000
30000
40000
5000010 nm50 nm100 nm
Time (sec)0 100 200 300 400 500 600Pa
rtic
le N
umbe
r Con
cent
ratio
n (#
/cm
3 )
0
10000
20000
30000
40000
5000010 nm50 nm100 nm
E20
E0 Lean GDI vehicle
Wide Open Throttle
0 – 80 mph
0
20
40
60
80
100
Spe
ed
MP
H
Speed Trace
Distinct spikes disappear for E20; not much reduction in 100 nm particles
Conclusions: Fuel Effects for the stoich GDI Vehicle • Use of E20 resulted in a 40 to 60% reduction in PM mass emissions
• >50% reduction in total particle number concentration for 30 and 80 mph; no change in size distribution
• Reduction of 50 and 100 nm particle emissions during acceleration
• Cold start significant contributor to overall PM number
Fuel Effects for the lean GDI Vehicle • E20 resulted in 30-40% drop in cycle-based PM mass emissions
• Lean vehicle had smaller mean size, larger number of particles
• Ethanol slightly reduced number based emissions
• Implies fewer larger particles
• Less difference between cold start and warm cycles.
Implications for GDI PM control
• Need for exhaust particulate filter (GPF) depends on success of in-cylinder control – Cold start worse for wall-guided injectors – Oil entrainment? – Avoidance of sooting conditions
• Particulate filter issues for GDI – High EC content implies refractory particles – High temperatures will help – Ash content would have to be addressed
17 Managed by UT-Battelle for the Department of Energy
Extra slides
Contact Information
John Storey [email protected] 865-946-1232 Teresa Barone [email protected] 865-946-1338
19 Managed by UT-Battelle for the Department of Energy
Stoich Wide Open Throttle 0 – 80 mph (E20 detail)
Time (sec)0 200 400 600
Num
ber C
once
ntra
tion
(par
t./cm
3 )
0
2000
4000
6000
8000
10000
12000
14000 10 nm50 nm100 nm
E20 Post-catalyst
Stoich vehicle moderate acceleration - 0 to 50 mph
E0 Post-catalyst
E20 Post-catalyst
• Particles may be generated in in-cylinder fuel rich zones
• Ethanol may reduces amount of carbon available for soot formation through CO formation pathway (Wu et. al, 2006)
Time (sec)0 100 200 300 400 500 600
Num
ber C
once
ntra
tion
(par
t./cm
3 )
0
2e+4
4e+4
6e+4
8e+4
1e+510 nm50 nm100 nm
Time (sec)0 100 200 300 400 500 600
Num
ber C
once
ntra
tion
(par
t./cm
3 )
0
2e+4
4e+4
6e+4
8e+4
1e+510 nm50 nm100 nm
E0 Post-catalyst
E20 Post-catalyst
0
20
40
60
80
100
Sp
ee
d (
MP
H)
Speed Trace As for the WOT accelerations, 50 and 100 nm particle emissions reduced by E20
(FTP acceleration)
21 Managed by UT-Battelle for the Department of Energy
The cycling behavior of the lean GDI vehicle results in a variety of PM size distributions
dp (nm)10 100
dN/d
logd
p (#
/cm
3 )
0.0
2.0e+6
4.0e+6
6.0e+6
8.0e+6
1.0e+7
1.2e+7
1.4e+7LeanSlightly RichStoich
30 mph