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Office of Research and DevelopmentNational Risk Management Research Laboratory
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COLD TEMPERATURE EFFECTS ON SPECIATED VOC EMISSIONS FROM
MODERN GDI LIGHT-DUTY VEHICLES:Preliminary Results
Ingrid George, Michael Hays, Richard Snow, James Faircloth, Thomas Long and Richard Baldauf
Office of Research and Development,
U. S. Environmental Protection Agency
Emissions Inventory Conference
Baltimore, MD
Aug. 18, 2017
Office of Research and DevelopmentNational Risk Management Research Laboratory
2
Mobile Source VOC Emissions
VOC emissions have
been steadily decreasing
Transportation sector
contributes ~20% of all
(non-biogenic) U.S. VOC
emissions in 2016
Detailed speciated VOC
emissions data is needed
to accurately predict the
air quality impacts of
mobile sources
https://www.epa.gov/air-emissions-inventories/air-pollutant-emissions-trends-data
Office of Research and DevelopmentNational Risk Management Research Laboratory
3
ORD’s Vehicle Emissions Research
Overall objective: to characterize speciated gas- and particle-phase emissions in
vehicle exhaust with focus on high priority data gaps in emissions
inventories/models
• Biofuels: ethanol/gasoline blends, biodiesel/diesel blends
• Ambient temperatures: “winter” effect (-7 C vs 22 C)
• Modern engine and emission control technologies: diesel emission control
aftertreatments, GDI technologies
• Driving conditions: trailer towing
Recent Studies: 1) Biodiesel/HD diesel vehicles, 2) Ethanol/LD gasoline vehicles,
3) GDI gasoline vehicles (current)
Office of Research and DevelopmentNational Risk Management Research Laboratory
4
Light-duty Dynamometer:
48 in. roll
Capacity: 12,000 lbs
Temp: -30 to 43 °C
Heavy-duty Dynamometer:
72 in. roll
Capacity: 30,000 lbs
Temp: 22 °C
ORD’s Vehicle Emissions Facilities
Office of Research and DevelopmentNational Risk Management Research Laboratory
EEPS
5
Dilution Tunnel and Sampling
TO-15
(GC-MS)
TO-11A
(HPLC)
113C
113C
CEMs
Speciated
SVOCs/PM by
TO-13A/TO-17
(GC/MS)
Online Particle
Instrumentation
Dilution factor ~20-30
CEM = Continuous Emission Monitor
EEPS=Engine Exhaust Particle Sizer
VOCs
Office of Research and DevelopmentNational Risk Management Research Laboratory
68/22/2017
Carbonyls represent most of cold start
VOC emissions
Cold Start/Cold Temp effects significantly
increase emissions
Biodiesel HD Vehicle Study Highlights
Test Conditions: Three LHDD trucks (MY2011), T= -7, 22 C, Fuels: ULSD, soy
B20 Driving Cycle: MHDTLO, HD-UDDS Ref: George et al. 2014
Office of Research and DevelopmentNational Risk Management Research Laboratory
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Biodiesel HD Vehicle Study Highlights
One previous study reported
major mobile source air toxics
(MSATs) VOC emissions from
modern HD diesel vehicle
MSAT ERs in literature
Office of Research and DevelopmentNational Risk Management Research Laboratory
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8/22/2017 8
Cold temp VOC emissions enhancements
vary with compound class and fuel
VOCs contribute to ozone formation
potentials variably by fuel
Ethanol LD Vehicle Study Highlights
Test Conditions: Three LD gasoline vehicles (MY2008), T= -7, 24 C, Fuels:
E0,E10,E85, Driving Cycle: LA92. Ref.: George et al. 2015.
Office of Research and DevelopmentNational Risk Management Research Laboratory
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Ethanol LD Vehicle Study Highlights
No previous cold temp
emissions data for
several major MSAT
VOCs
Office of Research and DevelopmentNational Risk Management Research Laboratory
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GDI Study - Motivation
• Gasoline direct injection (GDI) engines were introduced into the
market in 2007 and their market share has rapidly increased to
46% of MY2015 LD cars/trucks1
• Emissions studies of GDI vehicles have mostly focused on
PM/PN; few studies have measured MSATs/speciated VOCs
• The effect of different GDI technologies and ambient
temperature on LD vehicle emissions are not well known
Objective: To characterize speciated volatile organic
emissions from three LD GDI vehicle exhaust at warm
and cold temps (20 and 72 °F)
1https://www.epa.gov/fuel-economy/trends-report
Office of Research and DevelopmentNational Risk Management Research Laboratory
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GDI Study - Test Conditions
Fuel: E10 gasoline from pump (summer and winter
grades)
Temperature: 72 F (22 °C), 20 F (-7 °C)
Vehicles: Three GDI gasoline vehicles (V1, V2, V3)
Driving Cycles: FTP, SFTP (US06)
Dynamometer: Light-duty dyno (48 in. roll)
Office of Research and DevelopmentNational Risk Management Research Laboratory
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Test Vehicles:
V1) MY 2014 (Tier 2, Bin 5)
ODO=12,700 miles, 2.4 liter,
Naturally aspirated, wall-guided GDI engine
V2) MY 2015 (Tier 2, Bin 5)
ODO=10,500 miles, 1.5 liter,
Spray-guided, turbocharged GDI engine
V3) MY 2014 (Tier 2, Bin 5)
ODO=9,200 miles, 1.8 liter
Wall and air guided, turbocharged GDI engine
Office of Research and DevelopmentNational Risk Management Research Laboratory
Time / s
0 500 1000 1500
NM
HC
/ p
pm
C1
0
20
40
60
80
100
120
140
Spe
ed
/ mph
0
20
40
60
80
V2 NMHCFTP Driving Trace
13
NMHC Traces - FTP
FTP1 FTP2 FTP3
427
Office of Research and DevelopmentNational Risk Management Research Laboratory
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NMHC Traces – US06
Time / s
0 100 200 300 400 500 600
NM
HC
/ p
pm
C1
0
20
40
60
80
100
120
140
Sp
ee
d / m
ph
0
20
40
60
80
100
V2 NMHC US06 driving trace
Office of Research and DevelopmentNational Risk Management Research Laboratory
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Total VOC Emissions
Cold start emissions were
substantially higher (4-400x)
than warm start (intensified at
20F)
Cold temp. effect was most
prominent during cold start and
varied by vehicle
V2 emissions were mostly
higher than V1, V3
N≥3
22x6x
33x
Office of Research and DevelopmentNational Risk Management Research Laboratory
Toluene
Benzene
iso-P
entane
Butane
Propyle
ne
n-Penta
ne
Ethanol
m-X
ylene
2-Meth
ylpenta
ne
1-Bute
ne
Isoocta
ne
1,2,4
-Trim
ethylb
enzene
p-Xyle
ne
Aceto
ne
n-Hexa
ne
o-Xyle
ne
3-Meth
ylpenta
ne
3-meth
ylhexa
ne
2-Meth
ylhexa
ne
Heptane
Naphthalene
Ethylb
enzene
Aceta
ldehyde
m-E
thylt
oluene
Meth
ylcyc
lopentane
Em
issio
n R
ate
/ m
g m
ile-1
0
2
4
6
8
10
16
VOC Profiles: Cold start FTP1 (72F)
TOP 25 VOCs
V1
V2
V3
VOC ERs from V2
were higher than V1,
V3 for all VOCs
Office of Research and DevelopmentNational Risk Management Research Laboratory
Toluene
Benzene
iso-P
entane
Ethanol
Propyle
ne
m-X
ylene
n-Penta
ne
Butane
1,2,4
-Trim
ethylb
enzene
2-Meth
ylpenta
ne
p-Xyle
ne
1-Bute
ne
o-Xyle
ne
n-Hexa
ne
Isoocta
ne
m-E
thylt
oluene
Naphthalene
Ethylb
enzene
3-Meth
ylpenta
ne
3-Meth
ylhexa
ne
2-Meth
ylhexa
ne
Aceto
ne
Heptane
Meth
ylcyc
lopentane
3-Meth
ylhepta
ne
Em
issio
n R
ate
/ m
g m
ile-1
0
20
40
60
80
100
120
17
VOC Profiles: Cold start FTP1 (20F)
V1
V2
V3
TOP 25 VOCs
VOC ERs from V3
were higher than V1,
V2 for most VOCs
Office of Research and DevelopmentNational Risk Management Research Laboratory
18
Literature comparison
Benze
ne
Tolue
ne
Ethylbe
nzen
e
m,p
-xylen
e
o-Xylen
e
Form
alde
hyde
Aceta
ldeh
yde
MS
AT
ER
/ m
g m
iles-1
0
5
10
15
20
25
30
V1
V2
V3
Louis et al.
Cold Start Emissions
Louis et al. 2016:
Euro 5, Artemis
urban CS
Office of Research and DevelopmentNational Risk Management Research Laboratory
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Conclusions
• Cold start and cold temp. effects have the most dramatic impact on
VOC emissions of conditions studied
• Fuel effects are more subtle for ethanol and biodiesel blends
• Cold temperature enhancements can vary by fuel, vehicle and VOC
compound
• Speciated VOC emissions data for modern LD & HD vehicles remains
sparse; this work has started to fill some of the data gaps
Office of Research and DevelopmentNational Risk Management Research Laboratory
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Questions?