Emissions of Size- Segregated Aerosols from On-Road Vehicles in the Caldecott Tunnel Jonathan O. Allen SCOS97 -- NARSTO Data Analysis Conference 15 February 2001 Environmental Engineering Science Department, California Institute of Technology School of Earth and Atmospheric Science, Georgia Institute of Technology Glen R. Cass Civil and Environmental Engineering Department, Arizona State University Chemistry Department, University of California, Riverside Paul R. Mayo, Lynn G. Salmon Lara S. Hughes
Transcript
Emissions of Size-Segregated Aerosols from On-Road Vehicles in
the Caldecott TunnelJonathan O. Allen
SCOS97 -- NARSTO Data Analysis Conference 15 February 2001
Environmental Engineering Science Department,California Institute of Technology
School of Earth and Atmospheric Science, Georgia Institute of Technology
Glen R. Cass
Civil and Environmental Engineering Department,Arizona State University
Chemistry Department,University of California, Riverside
Paul R. Mayo, Lynn G. Salmon
Lara S. Hughes
Motivation• Vehicle emissions are large contributors to ambient aerosol
concentrations• Los Angeles aerosol in September 1996 study was
composed of – 9-11% primary particles emitted by vehicles
Electronic Particle Counters Particle Size Distribution
PM1.9 Concentrations
0
20
40
60
80
100
Con
cent
ratio
n (
g m
-3)
Bore 1(HDV and LDV)
Bore 2("LDV Only")
Unidentified Cl - Na+ SO
4=
NH4+
NO3-
Organic Compounds Elemental Carbon
Metals and Metal Oxides
• Carbonaceous emissions are most important• Higher emissions in HDV than LDV Tunnel Bore
Emissions Calculations• Gas phase carbonaceous species (CO2, CO, CH4, NMHC)
measured
• Calculate aerosol emissions based on fuel consumption as
EC,i = Ci
CC,j
Ci Concentration increase in species i
EC,i Emission of species i on carbon consumption basis
CC,j Sum of carbon emissions in tunnel
PM1.9 Emissions
0
100
200
300
400
500
Em
issi
on R
ate
(mg
kgC
-1)
Bore 1(HDV and LDV)
Bore 2("LDV Only")
Unidentified Cl - Na+ SO
4=
NH4+
NO3-
Organic Compounds Elemental Carbon
Metals and Metal Oxides
0.02 0.05 0.1 0.2 0.5 10
100
200
300
400
E
/
log
Da (
mg
kg
C-1
)
Aerodynamic Diameter, Da (m)
Size-Segregated Emissions in Bore 1 (HDV and LDV)
Unidentified Cl - Na+ SO
4=
NH4+
NO3-
Organic Compounds Elemental Carbon
Metals and Metal Oxides
Size-Segregated Emissions in Bore 2 (“LDV Only”)
0.02 0.05 0.1 0.2 0.5 10
20
40
60
80
100
E
/
log
Da (
mg
kg
C-1
)
Aerodynamic Diameter, Da (m)
Unidentified Cl - Na+ SO
4=
NH4+
NO3-
Organic Compounds Elemental Carbon
Metals and Metal Oxides
LDV and HDV Fleet Emissions
Estimate emission rates of LDV and HDV fleets by linearregression
EC,ik = k EC,i(HDV) + (1-k) EC,i(LDV) + ik
k Fraction of carbon emitted by HDV fleet in experiment k
k calculated from • vehicle counts• fuel consumption estimates• fuel properties
Linear Fit of Mass Emissions
0 0.2 0.4 0.6 0.8 10
500
1000
1500
2000
2500
Fraction Carbon Emitted by HDVs,
Mas
s E
mis
sion
s (m
g kg
C-1
)
PM1.9 Emissions by HDV and LDV Fleets
0
500
1000
1500
Em
issi
on
Ra
te (
mg
kg
C-1)
HDV Fleet
LDV Fleet(x 10)
HDV emissions 25 times greater than LDV emissions
Unidentified Cl - Na+ SO
4=
NH4+
NO3-
Organic Compounds Elemental Carbon
Metals and Metal Oxides
Size-Segregated HDV Emissions
0.02 0.05 0.1 0.2 0.5 10
500
1000
1500
E
/
log
Da (
mg
kg
C-1
)
Aerodynamic Diameter, Da (m)
Size-segregated LDV emissions are indistinguishable from zeroMaximum LDV emissions are those for Bore 2
Unidentified Cl - Na+ SO
4=
NH4+
NO3-
Organic Compounds Elemental Carbon
Metals and Metal Oxides
Emission Source Measurements
• Kleeman, Schauer, and Cass (Environ. Sci. Technol., 34:1578–1587, 2000) measured the emissions of – Catalyst-Equipped Gasoline Vehicles– Noncatalyst-Equipped Gasoline Vehicles– Medium Duty Diesel Trucks
• Size-segregated emission profiles agree with tunnel measurements
• Note: no afterfilter analyses on these source samples
Medium Duty Diesel Emissions
0.1 1.00
0.5
1
1.5
2
Da (m)
M /
lo
g D
a M
tot
Unidentified Cl - Na+ SO
4=
NH4+
NO3-
Organic Compounds Elemental Carbon
Metals and Metal Oxides
Catalyst-Equipped Gasoline Vehicle Emissions
0.1 1.00
0.2
0.4
0.6
0.8
1
1.2
1.4
Da (m)
M /
lo
g D
a M
tot Unidentified
Cl - Na+ SO
4=
NH4+
NO3-
Organic Compounds Elemental Carbon
Metals and Metal Oxides
Noncatalyst-Equipped Gasoline Vehicle Emissions
0.1 1.00
0.5
1
1.5
2
Da (m)
M /
lo
g D
a M
tot
Unidentified Cl - Na+ SO
4=
NH4+
NO3-
Organic Compounds Elemental Carbon
Metals and Metal Oxides
Comparison of Laboratory and Tunnel Emissions Measurements
• Medium duty diesel truck emissions profile similar to HDV emissions profile
• Relatively more HDV emissions of particles larger than 0.2 m — due to – heavy duty trucks (source sample was medium duty) – non-tailpipe emissions
• Organic compounds emissions in Bore 2 similar to profiles for gasoline powered vehicles
• Elemental carbon emissions in Bore 2 due to– few trucks– non-tailpipe emissions
Conclusions• Emission rates measured were comparable with
other tunnel studies• Size-segregated emission profiles are comparable to
those from source tests possible additional emissions from untested sources– heavy duty trucks– gasoline powered trucks– non-tailpipe emissions
• Ammonia emissions were 194 and 267 mg l-1 fuel consumed
Acknowledgement
This work was supported by the Coordinating Research Council, Inc., and the U.S. DOE Office of Heavy Vehicle Technologies through the National Renewable Energy Laboratory under CRC Project No. A-22.
