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Center for Diesel Research
Nanoparticle emissions from an ethanol fueled HCCI engine
David B. Kittelson and Luke FranklinCenter for Diesel
Research
Department of Mechanical EngineeringUniversity of Minnesota
Cambridge Particle Meeting21 May 2010
University Engineering DepartmentTrumpington Street, Cambridge,
UK
Center for Diesel Research
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Center for Diesel Research
Outline
• Introduction
• Experimental apparatus
• Dilution sensitivity
• Results– Engine performance
– Variable intake temperature
– Role of solid particles
– Preliminary hydrogen results
• Conclusions
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Center for Diesel Research
Renewable fuel research
• Ethanol / H2 HCCI
• Ethanol / H2 Diesel
• Synthesis gas HCCI / PCCI / fumigation
• DME Diesel
• FAME, ULSD, and hydro-treated vegetable oil in Caterpillar
ACERT Diesel
• Cold flow filter plugging with FAME
• Butanol Diesel / SI
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Center for Diesel Research
HCCI
• Homogeneous charge compression ignition (HCCI) engines utilize
acombination of high compression ratio and premixed highly dilute
charge to achieve low temperature premixed combustion that avoids
both soot formation and significant NOx formation but CO and
hydrocarbon emissions are high
• It is difficult to utilize this type of combustion at high
engine loads and it is difficult to control the timing of the
combustion process.
• We explored three means of controlling the combustion timing
andmeasured the resulting gaseous and particle emissions– Intake
air heating– Exhaust gas recirculation– Hydrogen injection -
ethanol used was the primary fuel because it can easily be
reformed to make hydrogen
• Number and mass emissions of nanoparticles were of the same
order as those from contemporary Diesel engines without
aftertreatment but the particles were nearly all volatile
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Center for Diesel Research
Typical engine exhaust particle size distribution by mass,
number and surface area
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
1 10 100 1,000 10,000
Diameter (nm)
Nor
mal
ized
Con
cent
ratio
n (
1/C t
otal
)dC
/dlo
gDp
Number Surface Mass
Fine ParticlesDp < 2.5 µm
Ultrafine ParticlesDp < 100 nm
NanoparticlesDp < 50 nm
Nuclei Mode - Usually forms from volatile precursors as exhaust
dilutes and cools
Accumulation Mode - Usually consists of carbonaceous
agglomerates and adsorbed material
Coarse Mode - Usually consists of reentrained accumulation mode
particles, crankcase fumes
PM10Dp < 10 µm
In some cases this mode may consist of very small particles
below the range of conventional instruments, Dp < 10 nm
2pDNS π= 6/
3pDNm ρπ=
Kittelson, D.B. 1998. “Engines and Nanoparticles: A Review,” J.
Aerosol Sci., Vol. 29, No. 5/6, pp. 575-588, 1998
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Center for Diesel Research
Carbonaceous agglomerates comprise most of the mass from Diesel
engines but are largely eliminated by HCCI
metallic ash
semi volatile droplets
Without Exhaust Aftertreatment
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Center for Diesel Research
Outline
• Introduction
• Experimental apparatus
• Dilution sensitivity
• Results– Engine performance
– Variable intake temperature
– Role of solid particles
– Preliminary hydrogen results
• Conclusions
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Center for Diesel Research
Experiment apparatus
PM Emissions Instrumentation
•CPC, SMPS EEPS
Gas Phase Emissions Instrumentation
•NOX, CO, HC, CO2, O2
Dilution System
Engine
Dynamometer
The test engine is a modified 2005 model year Isuzu medium duty
engine. The base engine is a 5.3 liter, 4 cylinder engine,
turbocharged, aftercooled with common rail fuel injection.
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Center for Diesel Research
Engine modifications for HCCI
• Turocharger and aftercooler removed
• Common rail Diesel fuel injection not used
• Primary fuel ethanol preheated to improve atomization
• Independent control of EGR, air temperature, hydrogen,
ethanol
• Closed loop controlled thermal system capable of maintaining
temperatures of 150 °C
• MoTeC engine management system used for fuel injector
control
EGR Manifold
Main EGR Line
EtOH Injectors EtOH Fuel Rail
H2 Fuel Rail
H2 Injectors
Intake Manifold
Thermal Management System
EGR Control
Temperature Feedback
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Center for Diesel Research
Particles were measured with a nano DMA and a 3025 ultrafine CPC
configured to scan from 2 to 64 nm
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Center for Diesel Research
A catalytic stripper was used to differentiate volatile and
solid particles
• Recent stripper design– Stripper consists of a 2 substrate
catalyst* followed by a cooling coil
– The first substrate removes sulfur compounds
– The second substrate is an oxidizing catalyst
– Diffusion and thermophoretic losses present but well
defined*Catalysts were provided by Johnson-Matthey
Kittelson, D. B.; Watts, W. F.; Savstrom, J. C.; Johnson, J. P.
Influence of catalytic stripper on response of PAS and DC. J.
Aerosol Sci. 2005, 36, 1089–1107.
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Center for Diesel Research
Sampling and dilution system
Nano SMPS, other instruments
Primary dilution air temperature, 25 – 45 C
Primary dilution tunnel temperature 25 – 45 C
Secondary dilution air temperature, 25 C
Dilution ratios, primary = 18, secondary = 15Residence time ~
1.5 sec
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Center for Diesel Research
Outline
• Introduction
• Experimental apparatus
• Dilution sensitivity
• Results– Engine performance
– Variable intake temperature
– Role of solid particles
– Preliminary hydrogen results
• Conclusions
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Center for Diesel Research
The first thing we wanted to do was to establish dilution
conditions – dilution sensitivity
0.0E+00
2.0E+08
4.0E+08
6.0E+08
8.0E+08
1.0E+09
1.2E+09
1.4E+09
1 10 100Dp (nm)
dN/d
logD
p (p
artic
les/
cm3 )
S1=25°C, T =25°C S1=35°C, T =25°C S1=45°C, T =25°CS1=25°C, T
=35°C S1=35°C, T =35°C S1=45°C, T =35°C
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Center for Diesel Research
The first thing we wanted to do was to establish dilution
conditions – dilution sensitivity
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E+09
1.0E+10
1 10 100 1000Dp (nm)
dN/d
logD
p (p
artic
les/
cm3 )
S1=25°C, T =25°C S1=35°C, T =25°C S1=45°C, T =25°CS1=25°C, T
=35°C S1=35°C, T =35°C S1=45°C, T =35°C
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Center for Diesel Research
Comparison with earlier Diesel dilution sensitivity
experiments
1.00E+05
1.00E+06
1.00E+07
1.00E+08
1.00E+09
1.00E+10
1 10 100 1000
Dp (nm)
DN
/DLo
g D
p (P
art./
cm³)
Tdil (32 °C) Tdil (48 °C) Tdil (65 °C)
Residence Time ~ 400 ms, Primary DR ~ 12Humidity Ratio ~
0.0016
1600 rpm, 50% load
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E+09
1.0E+10
1 10 100 1000
Dp (nm)dN
/dlo
gDp
(par
ticle
s/cm
3 )S1=25°C, T =25°C S1=35°C, T =25°C S1=45°C, T =25°CS1=25°C, T
=35°C S1=35°C, T =35°C S1=45°C, T =35°C
Abdul-Khalek, I., D.B. Kittelson, and F. Brear. 1999. “The
Influence of Dilution Conditions on Diesel Exhaust Particle Size
Distribution Measurements,” SAE Paper No. 1999-01-1142, 1999.
The sensitivity to dilution conditions is somewhat less than we
have observed with Diesel nanoparticles. We decided to go with
intermediate tunnel and dilution air temperatures, 35 and 35 C,
respectively
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Center for Diesel Research
Outline
• Introduction
• Experimental apparatus
• Dilution sensitivity
• Results– Engine performance
– Variable intake temperature
– Role of solid particles
– Preliminary hydrogen results
• Conclusions
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Center for Diesel Research
Variation of output with intake temperature for 3 fixed fueling
rates, 1500 rpm
0
20
40
60
80
100
120
140
90 100 110 120 130 140 150 160
Intake Temperature (°C)
Bra
ke T
orqu
e (N
m)
λ = 5
λ = 3.75
λ = 3.0
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Center for Diesel Research
Outline
• Introduction
• Experimental apparatus
• Dilution sensitivity
• Results– Engine performance
– Variable intake temperature
– Role of solid particles
– Preliminary hydrogen results
• Conclusions
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Center for Diesel Research
Ethanol HCCI with varying Intake Temperature, λλλλ~4.5, 1500
RPM, No EGR
0.0E+00
2.0E+08
4.0E+08
6.0E+08
8.0E+08
1.0E+09
1.2E+09
1.4E+09
1.6E+09
1.8E+09
2.0E+09
1 10 100
DP (nm)
dN/d
logD
P (
part
icle
s/cm
3 )
T=110
T=120
T=130
T=140
T=150
T=160
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Center for Diesel Research
Ethanol HCCI with varying Intake Temperature, λλλλ~4.5, 1500
RPM, No EGR
0
1000
2000
3000
4000
5000
6000
90 100 110 120 130 140 150 160
Intake Temperature (°C)
CO
and
HC
(pp
m)
0
2
4
6
8
10
12
14
16
18
20
NO
x (p
pm)
CO
HC
NOx
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Center for Diesel Research
Ethanol HCCI with varying Intake Temperature, λλλλ~3.75, 1500
RPM, No EGR
0.0E+00
2.0E+08
4.0E+08
6.0E+08
8.0E+08
1.0E+09
1.2E+09
1.4E+09
1.6E+09
1.8E+09
2.0E+09
1 10 100
DP (nm)
dN/d
logD
P (
part
icle
s/cm
3 )
T=90
T=100
T=110
T=120
T=130
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Center for Diesel Research
Ethanol HCCI with varying Intake Temperature, λλλλ~3.75, 1500
RPM, No EGR
0
1000
2000
3000
4000
5000
6000
90 100 110 120 130 140 150 160
Intake Temperature (°C)
CO
and
HC
(pp
m)
0
2
4
6
8
10
12
14
16
18
20
NO
x (p
pm)
CO
HC
NOx
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Center for Diesel Research
Ethanol HCCI with varying Intake Temperature, λλλλ~3.0, 1500
RPM, No EGR
0.0E+00
5.0E+08
1.0E+09
1.5E+09
2.0E+09
2.5E+09
3.0E+09
3.5E+09
4.0E+09
4.5E+09
1 10 100
DP (nm)
dN/d
logD
P (
part
icle
s/cm
3 )
T=90
T=100
T=108
T=110
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Center for Diesel Research
Ethanol HCCI with varying Intake Temperature, λλλλ~3.0, 1500
RPM, No EGR
0
1000
2000
3000
4000
5000
6000
90 100 110 120 130 140 150 160
Intake Temperature (°C)
CO
and
HC
(pp
m)
0
2
4
6
8
10
12
14
16
18
20
NO
x (p
pm)
CO
HC
NOx
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Center for Diesel Research
Summary total number emissions
0.0E+00
2.0E+08
4.0E+08
6.0E+08
8.0E+08
1.0E+09
1.2E+09
TIn = 90 TIn = 100 TIn = 110 TIn = 120 TIn = 130 TIn = 140 TIn =
150 TIn = 160
Inlet Temperature °C
Tot
al N
umbe
r (p
artic
les/
cm3 )
Low Load Mid Load 1Mid Load 2
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Center for Diesel Research
Summary total estimated mass emissions – these are at Diesel
engine levels
0.0E+00
1.0E+03
2.0E+03
3.0E+03
4.0E+03
5.0E+03
6.0E+03
TIn = 90 TIn = 100 TIn = 110 TIn = 120 TIn = 130 TIn = 140 TIn =
150 TIn = 160
Inlet Temperature °C
Tot
al M
ass
(µµ µµg
/m3 )
Low Load Mid Load 1Mid Load 2
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Center for Diesel Research
Outline
• Introduction
• Experimental apparatus
• Dilution sensitivity
• Results– Engine performance
– Variable intake temperature
– Role of solid particles
– Preliminary hydrogen results
• Conclusions
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Center for Diesel Research
What about solid particles – here are some results with and
without the catalytic stripper at light load
0.0E+00
2.0E+08
4.0E+08
6.0E+08
8.0E+08
1.0E+09
1.2E+09
1 10 100
DP (nm)
dN/d
logD
P (
part
icle
/cm
3 )
Tin=120 Tin=120, CSTin=140 Tin=140, CSTin=160 Tin=160, CS Hot Mo
Hot Mo, CS
Solid particles
Hot Mo refers to hot motoring with no fuel –atomized lube
oil
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Center for Diesel Research
Solid particles from previous slide 10x scale
0.0E+00
2.0E+07
4.0E+07
6.0E+07
8.0E+07
1.0E+08
1.2E+08
1 10 100
DP (nm)
dN/d
logD
P (
part
icle
/cm
3 )
Tin=120, CS
Tin=140, CS
Tin=160, CS
Hot Mo, CS
Hot Mo refers to hot motoring with no fuel –atomized lube oil.
Why are there apparently more lube oil ash particles present during
motoring?
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Center for Diesel Research
Comparison with solid particles from a modern Diesel. HCCI
nucleation mode particles much smaller but in higher
concentration.
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E+09
1.0E+10
1 10 100 1000Dp (nm)
dN/d
logD
p (p
artic
le/c
m3)
Mode 2Mode 2 CSMode 5Mode 5 CS
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E+09
1.0E+10
1 10 100 1000DP (nm)
dN/d
logD
P (
part
icle
/cm
3 )
Tin=120Tin=120, CSTin=140Tin=140, CSTin=160 Tin=160, CS Hot
MoHot Mo, CS
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Center for Diesel Research
Outline
• Introduction
• Experimental apparatus
• Dilution sensitivity
• Results– Engine performance
– Variable intake temperature
– Role of solid particles
– Preliminary hydrogen results
• Conclusions
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Center for Diesel Research
Ethanol HCCI with varying fraction H 2 energy input, λλλλ~4.5,
1500 rpm, T intake = 130° C
0.0E+00
1.0E+08
2.0E+08
3.0E+08
4.0E+08
5.0E+08
6.0E+08
1 10 100DP (nm)
dN/d
logD
P (
part
icle
s/cm
3 )
H2 = 0%
H2 = 5%
H2 = 10%
H2 = 15%
H2 = 20%
H2 = 25%
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Center for Diesel Research
Hydrogen HCCI with varying intake temperature, λλλλ~5, 1500 rpm,
50 N-m
0.00E+00
1.00E+08
2.00E+08
3.00E+08
4.00E+08
5.00E+08
6.00E+08
1 10 100DP (nm)
dN/d
logD
P (
part
icle
s/cm
3 )
H2, Tin = 95
H2, Tin = 100
H2, Tin = 105
Hot motoring
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Center for Diesel Research
Outline
• Introduction
• Experimental apparatus
• Dilution sensitivity
• Results– Engine performance
– Variable intake temperature
– Role of solid particles
– Preliminary hydrogen results
• Conclusions
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Center for Diesel Research
Conclusions
• Significant mass and number emissions observed– Most of
material between 10 and 50 nm– Nearly all volatile– Some solid
particles between 3 and 10 nm– Particle emissions do not correlate
with HC and CO emissions– Significant particle formation even with
pure H2 fuel
• Lube oil must play an important role • Need to consider
detailed in cylinder temperature history and impact on lube
related
particles• Should explore other lube oil formulations and oil
atomization mechanisms
• This is a work in progress – data collection and analysis
continues– In-cylinder pressure measurements for heat release rates
and IMEP– Variable EGR results– Additional hydrogen tests– This
system could be test bed for lube oil generated particles with non
sooting
systems, HCCI, DME, CNG, H2
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Center for Diesel Research
Related work on HCCI particle emissions
-Increased EGR-decreased total PM
-Lack of dilution monitoring/control reported
DMS500
Gasoline
Mixed hot/cold intake streams, variable valve timing
Misztal et al (2009)
-NO2:NOX ≈12-17%
-VOF 75-90% for low load HCCI
-no nucleation mode PM present
-no dilution conditions reported
-HCCI showed more accum. mode PM and less nucl. mode PM than
DISI
-Mid load HCCI yielded more and larger accum. mode PM than DISI
operation
Findings
SMPS 3071A ,with 3022 CPC
DMS500SMPS, 2 stage dilutionInstrumentation
low sulfur(