Idle Emissions from Heavy-Duty Diesel Vehicles€¦ · Idle Emissions from Heavy-Duty Diesel...

Idle Emissions from Heavy-Duty Diesel Vehicles

Nigel N. Clark, ABM S. Khan, Gregory J. Thompson, W. Scott Wayne, Mridul Gautam, and Donald W. Lyons

Center for Alternative Fuels, Engines, and Emissions (CAFEE) Department of Mechanical and Aerospace Engineering

West Virginia University (WVU)

CAFEE

Idle Emissions from Heavy-Duty DieselVehicles have Environmental, Economic,

and Health Effects

• Idling periods may be necessary for driver comfort• Idling produces particulate matter, regulated gaseous

emissions, and carbon dioxide• Fuel consumption and maintenance cost increases

due to idling• Health risks are posed for drivers and transportation

workers

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Economic Impact of Idling

• A typical truck consumes 1800 gallons diesel fuel per year in idling

• At today’s market price idle fuel consumption costs $4300 per year

• American Trucking Association (ATA) estimated a $2000 annual increase in maintenance cost per truck due to idling(Reference: www.epa.gov/ne/eco/diesel/)

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Objectives of this Research

• Study idle emissions from sixty four Heavy-Duty Diesel Trucks (HDDT), and two transit buses*

• Compare idle emissions rates from heavy-duty trucks of Model Year (MY) 1975 to 2004

• Quantify idle fuel consumption• Compare WVU idle emissions and fuel consumption data

with data from other research projects• Help the market to avoid ambiguity in quantifying idle

emissions and fuel consumption

(* Data from the E-55/59 Study and the DOE’s Gasoline-Diesel PM Split Study)

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Vehicle Statistics

0

2

4

619

7519

7819

7919

8219

8319

8419

8519

8619

8719

8919

9019

9119

9219

9319

9419

9519

9619

9719

9819

9920

0020

0120

0320

04

Model Year

No.

of V

ehic

les

48 vehicles from E-55/59 18 vehicles from PM Split Study

Average Engine Displacement: 12.25 L

Vehicle Data Collection with WVU Transportable Laboratory

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Data Collection: Regulated Emissions Bench

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Test-to-Test Variation

0

10

20

30

40

50

60

70

80

90

CO NOx HC PM *10 CO2 /100

Em

issi

ons

(g/h

r)

CRC 7 CRC 19 CRC 28

• Each truck above has been tested for six different idle tests

• Error bars show ±1 standard deviations

• Variations between test runs could be due to changes in injection timing, accessory loading, and measurement errors

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0

0.005

0.01

0.015

0.02

0.025

0.03

0 100 200 300 400 500 600 700 800 900 1000

Time (s)

Con

tinuo

us N

Ox

(g/s)

3674-01-A/C and All Lights Off

3675-01-A/C and All Lights On

Variation in Idle NOx Concentration with Different Engine Accessories Operating

(Source: SAE Paper 2004-01-2904)

Model Year Split

All trucks are broadly divided into two groups –

MY 1975 to 1990 and MY 1991 to 2004 as a surrogate for engine technology:

• The majority of the MY 1975-1990 heavy-duty trucks had mechanically managed engines

• A high proportion of heavy-duty trucks after 1990 had electronically managed engines

• Electronically managed engines may have advanced timing at low loads or low temperature to avoid ‘white smoking’

• Advanced timing increases NOx• Superior fuel atomization, air management, and

charge motion decreases PM for later MY vehicles• The data will be reprocessed in the future for an exact

mechanical vs. electronic control splitCAFEE

Available Data

• Regulated gases, CO2, fuel consumption, and PM emissions from idle tests

• NOx/CO2 ratio from the idle mode and the transient mode of the ‘HHDDT Schedule’ for comparative purposes

• Accessory (Fan) loading may differ between idle tests and transient mode

• Engine speed at idle was not elevated, except for two runs on truck CRC-38 (MY 2003)

• Air conditioning was not used except for two idle runs on truck CRC-38 (MY 2003)

• CRC-16 and CRC-45 had high PM and HC levels and were excluded as malfunctioning vehicles

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Idle NOx/CO2 Ratio

0.0180.015PM Split Study0.01820.0104E-55/59

MY 1991-2004MY 1975-1990NOx/CO2 Ratio

0

0.01

0.02

0.03

0.04

1975 1980 1985 1990 1995 2000 2005

Engine Model Year

NO

x/C

O 2 R

atio

E-55/59 data PM Split Study

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NOx/CO2 Ratio from Idle and Transient Mode

2.01.2Idle/Transient Ratio

0.00890.0087Transient (E-55/59)

0.01820.0104Idle (E-55/59)

1991-20041975-1990NOx/CO2 Ratio

0

0.01

0.02

0.03

0.04

1975 1980 1985 1990 1995 2000 2005

Engine Model Year

NO

x/C

O 2

Rat

io

E-55/59 PM Split Study Transient Mode

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Idle Speed and Air Conditioning Effects(Tests were performed on CRC-38 truck (MY 2003) on 1/7/2004)

Note: Air conditioning load depends on temperature, humidity, and heat load, and may not be repeatable.

0

50

100

150

200

250

600 rpm, no A/C 600 rpm, with A/C 1100 rpm, no A/C 1100 rpm, with A/C

Emis

sion

s (g

/hr)

CO2/100 NOx PM*50

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Effect of Injection Timing Repair: CRC-3 Truck

0

15

30

45

60

75

90

105

120

135

CO NOx HC PM*10 CO2/100

Emis

sion

s (g

/hr)

Before Repair After Repair

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Idle CO Emissions

0

10

20

30

40

50

60

70

80

90

1975 1980 1985 1990 1995 2000 2005Engine Model Year

CO

em

issi

ons

(g/h

r)

E-55/59 PM Split Study

MY 1991-2004Average: 23.32 g/hrStd. deviation: 13.07


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Idle NOx Emissions

0

20

40

60

80

100

120

140

160

180

200

1975 1980 1985 1990 1995 2000 2005

Engine Model Year

NOx

emis

sion

s (g

/hr)




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Idle HC Emissions

0

10

20

30

40

50

60

70

80

90

100

1975 1980 1985 1990 1995 2000 2005

Engine Model Year

HC e

mis

sion

s (g

/hr)



MY 1991-2004Average: 9.50 g/hr

Std. deviation: 11.91

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Idle PM Emissions

0

5

10

15

20

1975 1980 1985 1990 1995 2000 2005

Engine Model Year

PM e

mis

sion

s (g

/hr)




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Idle CO2 Emissions

0

2000

4000

6000

8000

10000

12000

1975 1980 1985 1990 1995 2000 2005

Engine Model Year

CO2 e

mis

sion

s (g

/hr)


MY 1975-1990Average: 4504 g/hrStd. deviation: 1143

MY 1991-2004Average: 4614 g/hrStd. deviation: 930

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Idle Fuel Consumption

0

0.2

0.4

0.6

0.8

1

1.2

1975 1980 1985 1990 1995 2000 2005

Engine Model Year

Fuel

Con

sum

ptio

n (g

al/h

r)


MY 1975-1990Average: 0.46 gal/hrStd. deviation: 0.12

MY 1991-2004Average: 0.47 gal/hrStd. deviation: 0.09

Engine Data Collection with WVU Engine Dynamometer

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Engine Idle Emissions (Set 1)

Engine 1: 12.7 L DDC Series 60, MY 1992 (Hot Start)

Engine 2: Engine 1 with rebuilt head and new Injectors (Hot Start)



Engine 5: 12.7 L DDC Series 60, MY 2000 (Warm Start)

Engine 6: 12.7 L DDC Series 60, MY 1995 (Warm Start)

0

20

40

60

80

100

120

140

Engine 1 Engine 2 Engine 3 Engine 4 Engine 5 Engine 6

Emis

sion

s (g

/hr)

CO NOx THC CO2/100

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Engine Idle Emissions(Engine 2 with PM Data included)

0

20

40

60

80

100

Run 1 Run 2 Run 3

Em

issi

ons

(g/h

r)

CO NOx HC*10 PM*100 CO2/100

* MY1994+40981.004*80.73.4826.3EMFAC 2002 (version 2.2)

CNG bus average0.1816.0286.167.14McCormick et al.

Diesel bus average2.8120.98.2279.56McCormick et al.@

600 RPM, 65ºF, MY 2001 Freightliner0.447200.8578.625.229.8Storey et al.@

600 RPM, 65ºF0.46517097n/an/aPekula et al.@

1995 International0.424256n/a84.54n/an/aHan Lim, EPA@

Idling after transient0.394472n/a1052.915.9Brodrick et al.@

Idling after cruise0.364034n/a1031.814.6Brodrick et al.@

* With heating/ air-conditioning,1000 rpm1.0*103972.5756.712.694.6Stodolsky et al. @

MY 1991,92, 95, and 2000 MY DDC0.3633000.8474.884.8429.46WVU Engine Idle data

MY 1975-1990 0.4645043.8047.7621.0631.31WVU Vehicle Idle data

MY 1991-2004 0.4746141.4183.319.5023.32WVU Vehicle Idle data

Winter (30ºF)2.5756.712.694.6EMFAC 2000 Model

Summer (75ºF)2.575512.594EMFAC 2000 Model

CommentsFuel

(gal/hr) CO2

(g/hr)PM

(g/hr)NOx (g/hr)

HC (g/hr)

CO (g/hr)Source

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Comparison of Idle Emissions (Class 8 Vehicles)

@ See Reference

Total Daily Idle Emissions in California[Based on WVU data and EMFAC 2000 and EMFAC 2002 Model]

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Note: Data considered 1,500,000 class 8 trucks, each truck idling for 6 hours per day

13923PM (tpd)

8631112HC (tpd)

750726500NOx (tpd)

210237846CO (tpd*)

WVU Vehicle Idle Data (Post 1990 MY)

EMFAC 2002 ModelEMFAC 2000 Model(Summer Condition)

* tpd: tons per day

Conclusions• Idle emissions in the literature may include cooling fan, air

compressor, air conditioner, and alternator loads, which can cause substantial variability in data collection

• Average idle NOx/CO2 for post 1990 MY was found to be higher (approximately 67%) than NOx/CO2 during transient mode indicating that many of these vehicles had advanced timing at low load to avoid ‘white smoking’

• Average idle NOx from post 1990 MY was 83.31 g/hr while from 1975-1990 MY it was 47.76 g/hr

• Average idle PM from post 1990 MY was 1.41 g/hr while from 1975-1990 it was 3.80 g/hr

• Data in the literature are highly variable for all species• Variability in CO2/fuel ratios in studies may be partly due

to correction for engine intake CO2 mass.• Data in this study showed that idle fuel consumption did

not change with MYCAFEE

References1. Stodolsky, F., Gaines, L., and Vyas A., “Analysis of Technology Options to Reduce

the Fuel Consumption of Idling Trucks”, ANL/ESD-43; Argonne National Laboratory: Argonne, IL, June 2000.

2. Brodrick, C.J., Dwyer, H.A., Farshchi, M., Harris, D.B., and King, F.G. Jr., “Effects of Engine Speed and Accessory Load on Idling Emissions from Heavy-Duty Diesel Truck Engines”, Journal of the Air & Waste Management Association, September 2002, 52:1026-1031.

3. Lim, Han, “Study of Exhaust Emissions from Idling Heavy Duty Diesel Trucks and Commercially Available Idle Reducing Devices”, SAE Paper 2003-01-0288.

4. Pekula, N., Kuritz, B., Hearne, J., Marchese, A.J., and Hesketh, R.P., “The Effect of Ambient Temperature, Humidity and Engine Speed on Idling Emissions from Heavy-Duty Diesel Trucks”, SAE Paper 2003-01-0290.

5. Storey, J.M.E., Thomas, J.F., Lewis, S.A. Sr., Dam, T.Q., Edwards, K.D., DeVault, G.L., and Retrossa, D.J., “Particulate Matter and Aldehyde Emissions from Idling Heavy-Duty Diesel Trucks”, SAE Paper 2003-01-0289.

6. McCormick, R.L., Graboski, M.S., Alleman, T.L., and Yanowitz, J., “Idling Emissions from Heavy-Duty Diesel and Natural Gas Vehicles at High Altitude”, Journal of the Air & Waste Management Association, November 2000, 50:1992-1998.

7. Clark, N.N., Gautam, M., Wayne, W.S., Riddle, W., Nine, R.D., Lyons, D.W., and Xu, S., “Examination of a Heavy Heavy-Duty Diesel Truck Chassis Dynamometer Schedule”, SAE Paper 2004-02-2904.

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Acknowledgement of the Study Sponsors

• Gasoline-Diesel PM Split Study. Sponsored by the U.S.Department of Energy (DOE) Office of FreedomCAR and Vehicle Technologies through the National Renewable Energy Laboratory (NREL).

• E-55/59 Study. Sponsored by the Coordinating Research Council (CRC), California Air Resources Board (CARB), U.S. EnvironmentalProtection Agency (USEPA), U.S. Department of Energy (DOE) Office of FreedomCAR and Vehicle Technologies through the National Renewable Energy Laboratory (NREL), South Coast Air Quality Management District and the Engine Manufacturers Association.

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