Chemical and Physical Properties of Sub-Micron Particle Emission from a Diesel Engine
Michael Alexander, Jian Wang, Yong Cai, Alla Zelenyuk, John Storey, Jay
Slowik, Peter DeCarlo, Jose Jimenez, and Douglas Worsnop
PNNL, NTRC, Boston College, University of Colorado, Aerodyne Research
Complimentary Measurement Techniques
Aerodyne AMS* SPLAT-MS**
• ensemble average of particles –size and composition
• real-time, quantitative measurement of certain chemical classes
• large dynamic range (>103 observed at ORNL)• sufficient time response 4 sec to study transients
• Single particle analysis to 50 nm • Classification of particle types • Detection of refractory compounds
**single particle TOF mass spectrometer*aerosol mass spectrometer
Mass Concentrations from AMS Over a Range of Engine Conditions
12x103
10
8
6
4
2
0
Mas
s C
once
ntra
tion
(µg
m-3
)
10:00 AM4/16/2004
11:00 AM 12:00 PM 1:00 PM
Date and Time
500
400
300
200
100
0
Mass C
oncentration of Sulfates
Water Ammonium Nitrate Sulphate Chloride Organics PAH
Engine warm-up
1400 rpm470 ft/lbs torrque
800 rpm4 ft/lbs
Reduce Rail Pressure1000 rpm327 ft/lbs
10
100
1000
Vac
uum
Aer
odyn
amic
Dia
met
e
10:00 AM4/16/2004
11:00 AM 12:00 PM 1:00 PM
Date and Time
12008004000
dM/dlogD
va (µg m-3)
Organics
SPLATSoot Particles are Most Prevalent
The most prevalent particles are composed of almost pure soot as evident by the carbon progression
SPLATPAHs Volatilize from Particles using Laser Heating
PAH Dominated30 NO
152 178-C2H2178 phenanthrene
192 C1 Alkyl phenanthrene
202 Pyrene
216 Alkyl pyrene
234 C4 Alkyl phenanthrene
252 Benzo pyrene
PAH
HCsoot
PAH dominated particles are most common under high RPM and low load conditions
See Poster 6PB7 – Yong Cai for more details on SPLAT
1 0
8
6
4
2
0
Nitr
ate
Equi
vale
nt M
ass
Con
cent
ratio
n (µ
g m
-3)
1 5 01 4 01 3 01 2 01 1 01 0 09 08 07 06 05 04 03 02 01 0m / z
S p e c i e s
O t h e r s 4 . 5 2 ± 0 . 2A i r 1 7 1 ± 0 . 2W a t e r -0 . 2 4 1 ± 0 . 1A m m o n iu m 0 . 4 ± 0 . 0 2N i t r a t e 0 . 1 5 3 ± 0 . 0 0 7S u l p h a t e 0 . 9 6 7 ± 0 . 0 4C h l o r i d e 0 . 0 9 7 6 ± 0 . 0 1P A H 0 . 0 6 6 4 ± 0 . 0 0 8O r g a n i c s 6 7 . 9 ± 0 . 1
Diesel Vehicle Exhaust
Mass Spectrum of AMS organic from heavy duty off road exhaust
NYC, Canagaratna et al, in press
Heavy duty off road MS is virtually identical to that observed in ambient data.
This mass spectrum is very similar to that of lubricating oil (see next slide)
0.01
0.1
1
10
100N
itrat
e Eq
uiva
lent
Mas
s C
once
ntra
tion
(µg
m-3
)
3202802402001601208040m/z
Species
Others 169 ± 0.4Water -1.22 ± 0.1Ammonium 0.456 ± 0.02Nitrate 0.175 ± 0.01Sulphate 1.03 ± 0.05Organics 78.1 ± 0.1
? Oil 78.7 ± 0.2
SPLAT - At Rated Speed, Oil Components and Engine Wear and Tear Appear Products Appear in Particles
Ca Al and Zn indicate lube oil consumption and engine wear and tear
0.0001
0 .001
0.01
0.1
1
10
100
Equ
ival
ent M
ass
Con
c
29 528126 725323 922 52 1119 71 8316 91 5514 11271 13998571574329150M ass / am u
0.0 01
0.01
0.1
1
10
Sig
nal
Inte
nsity
20151050Num ber of Carbons
0.50.40.30.20.10.0
Car
bons
1-4
0.4
0.3
0.2
0.1
0.0
Car
bons
5-6
0.30
0.20
0.10
0.00
Car
bons
7-1
5
-7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6
Delta
1.0
0.8
0.6
0.4
0.2
0.0
rela
tive
Sig
nal
15 16 17 30 46 48 64 80 81 9 8
AM U
45.9%
26.8%
23.4%
0.1 : 1 : 1.42 5.16 : 1 1 : 0.96 : 0.8 : 2.12 : 0.35
Particle Composition (µg/m3)-0.8% Water -1.21960.3% NH4 0.456460.1% NO3 0.174620.7% SO4 1.027449.7% Org 78.07250% Oil 78.651 (NH4)m eas/(NH4)expt =NaN
∆ = 2 29 / 43 ∆ = 0 13 / 55
star t/max
Runs Averaged: 1081 to 1084 (4/9/2004 10:02 to 10:05)
200
150
100
50
0dM
/dlo
gDva
(µg
m-3
)
102 3 4 5 6 7 8 9
1002 3 4 5 6 7 8 9
10002
Diameter (nm)
2500
2000
1500
1000
500
0
dVol/dlogDm
ob (nm3m
-3)15
10
5
0
DMA Volume
1400 nm3/cm3 (?)
AMS mass loading
Organic 70 ug/m3
Sulfate 2Nitrate 0.2
x10
x10
PRELIMINARY (4/11/04, DRW)
Comparison of AMS Massand SMPS Volume
Distributions
Dva < Dmobfractal particles
Effective Density: ρeff ~ Dva/Dmob ~ 0.5 g/cc
This comparison of AMS (mass) and SMPS (volume) distributions isvery similar to what we have observed in ambient urban data, particularly during morning rush hour when primary combustion particles tend to dominate total sub-micron aerosol loading.
FIRST ATTEMPT at MASS BALANCE:
AMS (organic) vs SMPS (total)
DMA volume (1400 nm3/cm3) x ρeff (0.5g/cc) ~ 700 ug/m3 (total)-- AMS Mass (80 ug/m3)) x 1.35 /.9 ~ 120ug/m3 (organic matter)
____________
Black Carbon ~ 580 ug/m3
“BC/OC” ratio ~ 5
cf. ambient (literature) measurements,
typical BC/OC ~ 1-3
Conclusion:
On a mass weighted basis, ~3x less oil from off road engine is ~3x “cleaner” for lube oil emissions compared to typical diesel engines.
ESTIMATE of OC Emission Index for off road engine
~120 ug/m3 / ~7000 ppm ~ 0.017 ug/m3/ppm ~ 0.030 g NRPM / fg Fuel
This engine
OM Emission Indexes for Diesel TrucksComparison of Mexico City and New York City
0.40.30.20.10.0
Frac
tion
9876543210Emission Ratio (g NRPM/ kg Fuel)
0.40.30.20.10.0
Sample Size NYC 19 MC03 24
MC03
NYC
NYC_AMS_Figs4to6_wMexDat.pxp
NYC mean = 0.5
MC03 mean = 1.6
JohnDeere
Manjula R. Canagaratna, et al. “Chase Studies of Particulate Emissions from in-use New York City Vehicles”, Aerosol Science & Technology, submitted March 2003
Particle Density: DMA in front of AMS
2.0
1.5
1.0
0.5
0.0
dM/d
logD
va (µ
g m
-3)
102 3 4 5 6 7 8 9
1002 3 4 5 6 7 8 9
1000Vacuum Aerodynamic Diameter (nm)
200
150
100
50
0
Polydisperse r1080_1085 (DMA bypass)
60 nm r1140_1150 100 1115-1134 200 1096_1115
mass numberug/m3 #/cc
66 >100000 0.05 6300 0.31 5500 0.27 900
4
5
6
7
8
9
1 0 0
2
Vac
uum
Aer
odyn
amic
Dia
met
er (D
va, n
m)
4 5 6 7 8 91 0 0
2 3 4
M o b ili t y D ia m e te r (D m o b , nm )
C o a te d s o o t fr a c ta l d im e n s io n ~ 3
F la m e s o o t f d im e n s i o n ~ 1 .8
"J o h n D e e r e " s o o t f d im e n s io n ~ 2 .5 ? ?
1 0 -1 2
1 0-1 1
1 0-1 0
10-9
10-8
Mas
s pe
r Par
ticle
(ug/
parti
cle)
4 5 6 7 8 910 0
2 3 4
M o b i lity D ia m e te r (D m o b , n m )
T o ta l M a s s p e r P artic le - 2 .5 D F ra c t a l P a tic le s
m a s s _ p e r_ p = C (D m o b )2 .5
p e r m o d e l o f J a y S lo w ik a n d P e te r D e ca rlo D av id o v its ( B C ) a n d J im e n e z (C U ) O C M a ss p e r P a rtic le
fo r O C /B C ra tio ~ 6
M e a su re d O C M a s s p er P a rtic le
= A M S M a s s / C P C N u m b er C o n c
Slowik, et. Al (in press)
Particle Density: DMA in front of AMS
Same Engine Different Day
25
20
15
10
5
0
dM/d
logD
va (µ
g m
-3)
102 3 4 5 6 7 8 9
1002 3 4 5 6 7 8 9
10002
Vacuum Aerodynamic Diameter (nm)
7x106
6
5
4
3
2
1
SM
PS
Cou
nts
800
600
400
200
0
500 nm 300 nm 400nm 200 nm 100 nm SMPS (counts) AMS Polydisperse
Related Talk by Jian Wang 12A3 on Friday
-0.8
-0.6
-0.4
-0.2
0
0.2
1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7
log
(den
sity
)
log (mobility diameter)
Diesel soot density and fractal dimension from SPLAT
Density = Daero/Dm
Density = CDmDf-3
Df = 1.87
Df = 1.96
Off-road John Deer 4045H
1.7L Mercedes A-Class
These values are consistent with fractal dimension predicted for diffusion-limited cluster-cluster agglomeration
The simultaneous measurements of particle size density and composition makes it possible to derive the fractal dimension of the freshly emitted soot
AMS Beam Width Probe Data
1.0
0.9
0.8
0.7
86420Wire Position
6.0x106
5.5
5.0
4.5
4.0
3.5
Airb
eam
10:45 AM 10:50 AM4/16/2004
10:55 AM 11:00 AM 11:05 AM
10
8
6
4
2
0
Organic
AvgWirePositions(161, 3, "org",7) 1400 RPM 352 ft/lbs torque -high load
AMS Organics Signal form On-Road Engine Running in Regen
2500
2000
1500
1000
500
0
4:15 PM4/28/2004
4:30 PM 4:45 PM 5:00 PM 5:15 PM 5:30 PM 5:45 PM
dat
Regen - throttle bodyand injector - 4sec every 30 sec
Regen - throttle bodyand injector - 8 sec every 60 sec
Regen - injector only4sec every 30 sec
Regen - throttle bodyand injector - 8sec every 60 sec
AMS Organic Signal and Laser Induced Incandescence
0.7
0.6
0.5
0.4
0.3
0.2
0.1
LLI S
igna
l Arb
. Uni
ts
4:15 PM4/28/2004
4:30 PM 4:45 PM
Time
3000
2500
2000
1500
1000
500
AMS organic signal ug/M
3
Regen ModeThrottle Body and Injector
4 sec every 30 sec
Regen ModeThrottle Body and Injector
8 sec every 60 sec
LII Org
AMS PAH and Nitrate follow Organics(Negligible Sulfate and Ammonia)
100
80
60
40
20
0
4:30 PM4/28/2004
5:00 PM 5:30 PM 6:00 PM
dat
NO3 PAH
Aerodynamic Size Distribution from AMSOrganics Dominant Species, Small Sulfate, Nitrate
1600
1400
1200
1000
800
600
400
200
0
dM/d
logD
va (µ
g m
-3)
102 3 4 5 6 7 8 9
1002 3 4 5 6 7 8 9
10002
Vacuum Aerodynamic Diameter (nm)
Ammonium Nitrate Sulphate Chloride Organics PAH
AMS Size Distribution and Intensity of Organics vs. Time
Conclusions
• AMS and SPLAT provide complimentary view of Diesel exhaust
• New generations of diesel engines much cleaner
• AMS signal from engine due to fractal carbon particles with adsorbed lube oil
• AMS aerodynamic organic mass vs size distribution is bimodal – larger mode dependent on engine conditions
• Regeneration operation of engine has large effect on organic species
Acknowledgements
• Department of Energy Energy Efficiency Program
•ORNL National Transportation Research Center and Staff
• Aerodyne Research Staff
• Jose Jimenez and group at U. of Colorado
• Davidovitz group at Boston College