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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

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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)

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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

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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

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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

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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)

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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

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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

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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

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Questions?