OnUse, On--Road Emissions Testing of Road Emissions ... · PDF fileRoad Emissions Testing of...

InIn--Use, OnUse, On--Road Emissions Testing of Road Emissions Testing of HeavyHeavy--Duty Diesel Vehicles : Challenges Duty Diesel Vehicles : Challenges

and Opportunitiesand Opportunities

Mridul GautamProfessor

Department of Mechanical and Aerospace EngineeringWest Virginia University

NATIONAL RESEARCH CENTER FOR ALTERNATIVE TRANSPORTATION FUELS, ENGINES AND EMISSIONS

MOBILE EMISSIONS MEASUREMENT SYSTEMMOBILE EMISSIONS MEASUREMENT SYSTEM

Mack TruckMack Truck

Purpose Of InPurpose Of In--use Emissions Measurementsuse Emissions Measurements

•COMPLIANCE

•I/M

•SCREENING

•INVENTORY

•TECHNOLOGY DEVELOPMENT AND/OR ASSESSMENT

West Virginia University, Morgantown,WV 26506

Available ToolsAvailable Tools

• Engine Test Cells (Engine Recalls)

• Chassis Dynamometers

•Fixed and Transportable Chassis Dynamometers

• On-road, On-board Emission Measurement Systems

Testing An Urban Transit Bus(WVU Transportable Heavy-duty Vehicle Emissions Testing Laboratory)

Need For On-board Emissions Measurement Systems

• Real-world, on-road emissions are very different from in-laboratory emissions

• Engine certification cycles are not representative of in-use, on-road operation• Federal Test Procedure (FTP)• Urban Dynamometer Driving Schedule (UDDS)

• FTP and UDDS were developed by studying traffic patterns in New York and Los Angeles during the 1970s

• Traffic patterns have changed over the years.• Different chassis dynamometer cycles yield

very different emissions results

Challenges to Measurement of Challenges to Measurement of OnOn--board, Onboard, On--road Diesel Emissionsroad Diesel Emissions

• Torque (or percent load) broadcast• Instrumentation

–Portability; Bulk • Obsession with brake-specific emissions

–It is recognized that the FTP (brake-specific emissions) is essential

–However, In-use fuel-specific emissions would eliminate majority of challenges associated with brake-specific emissions measurements

Prior Art in Portable InPrior Art in Portable In--field field MeasurementsMeasurements

• Caterpillar (Englund, 1982)• SwRI (Human and Ullman, 1992)• General Motors (Kelly and Groblicki,

1993)• Ford Motor Company, 1994• U.S. Coast Guard, 1997• Flemish Institute for Technology Research,

VITO, (Since 1991; de Vlieger, 1997)West Virginia University,Morgantown,WV 26506


InIn--Use Emissions Work at WVUUse Emissions Work at WVURelated to Consent DecreesRelated to Consent Decrees

• PHASE I: DEVELOPMENT OF A STATE-OF-THE-ART MOBILE EMISSIONS MEASUREMENT SYSTEM FOR ON-BOARD, IN-USE HEAVY-DUTY VEHICLE APPLICATIONS

• PHASE II: DEVELOPMENT OF IN-USE EMISSIONS TESTING PROCEDURES, AND TEST ROUTES

• PHASE III: CONDUCT EMISSIONS TESTING ON A VARIETY OF IN-SERVICE DIESEL ENGINES USING THE WVU MOBILE EMISSIONS MEASUREMENT SYSTEM (MEMS) TO CHARACTERIZE REAL-WORLD EMISSIONS FROM SUCH ENGINES


InIn--Use Emissions Work at WVUUse Emissions Work at WVURelated to Consent Decrees (…Cont’d)Related to Consent Decrees (…Cont’d)

• PHASE IV: CONDUCT ON-ROAD COMPLIANCE MONITORING OF HEAVY-DUTY DIESEL VEHICLES USING THE MONITORING TECHNOLOGY, AND PREVIOUSLY DEFINED TESTING PROCEDURES (AND DRIVING ROUTES) DEVELOPED BY WVU, AND APPROVED BY THE US EPA.

Mobile Emissions Measurement System(MEMS)

Exhaust Samplingand Conditioning

FlowMeter

EngineInterface

AmbientSensors

ExhaustConstituentsNOx & CO2

Differential Pressure,Absolute Pressure,and Temperature

Engine Speed,Vehicle Speed,

& TorqueAmbient

Temperature,Pressure,

& Humidity

GPS

Vehicle Speed & Location

MEMS Sampling and Emissions Analysis System

Mobile Emissions Measurement SystemFlow

AnnubarDifferential Pressure TransducerAbsolute Pressure TransducerThermocouples

EmissionsSolid State NDIR for CO2Zirconium Oxide Sensor for NOxNO2 ConverterThermoelectric ChillerHeated Sampling System

Engine PowerECU Protocol AdaptorSerial Interface to DAS

Mobile Emissions Measurement SystemGPS

DifferentialSerial or Analog Interface to DAS

Ambient SensorsAbsolute Pressure TransducerRelative HumidityThermocouple

System IntegrationNational Instruments PXI-1025 Chassis; PC-104Serial Interface Card64 Analog ChannelsExpandable to 256+ Analog ChannelsVisual Basic Interface Environment

V-Cone®

No straight pipe runs

“Pre-conditions”the flow

Accuracy to +/-0.5%

Repeatability to 0.1%

Low headloss

Low maintenance

No recalibration

V-Cone®

CO2 Mass Emission Rates UsingV-Cone® and Annubar®

(DDC Series 60, MY2000)

0

5

10

15

20

25

30

35

-50 50 150 250 350 450 550 650

Time (sec)

CO

2 (g

/sec

)

CO2-AnnubarCO2 VCone

0.6

0.7

0.8

0.9

1.0

5400 7200 9000 10800 12600

time (s)

norm

aliz

ed r

espo

nse

R12 - 9.1 umref - 9.8 umR12 - 10.8 umSF6 - 10.6 um

(offset for clarity)

30 ppm60ppm

100 ppm120 ppm

pressure transient when SF6 valve opens

~3 ppm

Solid State NDIR Sensor - Response to SF6

The signal to noise ratio for these deflections indicates a sensitivity limit of ~3 ppm for SF6 when the system response time is 1 second. Averaging over 5-10 seconds should improve sensitivity to better than 1 ppm.

0102030405060708090

100

8.5 9.0 9.5 10.0 10.5 11.0 11.5

wavelength (um)

Tran

smis

sion

(%)

T1 - 9.1 umT2 - 9.8 umT3 - 10.8 umT4 - 10.6 um

SF6

R12

GB

GD

GA

Source: Ion-Optics, Inc.

Percentage of NO2 Reported by Zirconia Sensor

NO2 Concentration (ppm) before NOx

Converter

Percent of NO2 after Converter Reported

by MEXA-120

62 - 124 70 186 78 248 82 310 78 372 74 434 70 496 65 558 62 620 58

Effect of Sampling Lines on NOx Measurements

DD60SeriesEngine

FourierTransformInfraredSpectrometerAnalyzer

A

B

C

D

Heated Stainless Steel Line

Cold Teflon Line

Heated Filter

NOx Converter

Dryer

0

50

100

150

200

250

300

0 200 400 600 800 1000 1200 1400 1600 1800

Time (Seconds)

NO

2 (p

pm)

NO2 emissions-450F (ppm) NO2 emissions-400F (ppm) NO2 emissions-300F (ppm)NO2 measured with dryer (ppm) NO2 measured without dryer (ppm) NO2 baseline (250F)-dry (ppm)

A. Heated line

C. Heated line + Converter + Dryer + Teflon line

B. Heated line + Converter + Dryer + Heated line

D. Heated line + Converter + Teflon line

Effect of Sampling Lines on NOx Measurements

Comparison of Concentrations Reported by the 955 NOx Analyzer with Wet and Dry

Exhaust Samples from a Mack E7-400 Engine

-200

0

200

400

600

800

1000

1200

1400

1600

0 200 400 600 800 1000 1200

Time (s)

Con

cent

ratio

n (p

pm)

Lab NOx - no chillerLab NOx - with chiller

Cycle Integrated Percent Difference with Chiller: =8.5%

NOX Index

(Concentration of NOx) x (Exhaust flow rate) x MWNOx

(Concentration of CO2) x (Exhaust flow rate) x (12.011+1.008*(H:C))

grams of NOx / kg of Fuel

•NOx concentration•CO2 concentration•Fuel H:C ratio

NH3Oxidation

NOX Sensor

NH3 Sensor

NH3 deNOx

Exhaust gas

NOX= (A+B)/2

NH3= (A-B)/2

Output: B (ppm)

B=a –b

(Here, a>b)

Output: A (ppm)

A=a + b

NOx= a (ppm)

NH3=b (ppm)

NOx/ NH3 Zirconia Sensor

Kobayashi et al. (2001), Mitsubishi Heavy Industries, Ltd., Technical Review Vol. 38, No. 3, Oct. 2001

t (msec)

I (m

A)

t (msec)

T (K

)

λλλλ (µµµµm)

Flux

(a.u

.)


Flux

(a.u

.)


Flux

(a.u

.)

t (msec)

T (K

)Source driver

Source temperature

Source emission

Optical efficiencyGas attenuation

Dual wavelength source/detector

Detector response

Sensor-on-a-Chip

Source: Ion-Optics, Inc.

Real-Time Particulate Mass MonitorMARI Model RPM 100®

Sample Conditioning System and a Microbalance

Model RPM 100

Model RPM 100

Model RPM 100

Model RPM 100

MARIMARIMARIMARI

Dilution Ratios – 1:12 to 1:2000

Crystal Surfaces

Continuous TPM Measured with MARI MODEL RPM 100®

TPM Trace vs. Power: FTP Cycle

-1000

-500

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 200 400 600 800 1000 1200 1400

Time(s)

Con

cent

ratio

n (u

g/m

3)

-100

-50

0

50

100

150

200

Pow

er(h

p)

TPM Trace over the Transient Portion (Sinusoidally Varying) of a Customized Engine Cycle

1000

1100

1200

1300

1400

1500

1600

1700

1800

1900

2000

700.00 710.00 720.00 730.00 740.00 750.00 760.00 770.00 780.00 790.00 800.000

50

100

150

200

250

conc 10 sec

conc 2 secs

Speed

Torque

Pow er

ECU Derived Engine Torque

WVU Approach:

Measure the no-load percent load through the speed domain at the curb and employ the lug curve obtained through laboratory testing or from manufacturer-supplied data. .

.

( ) rpmrpmnoload

rpm

rpmnoload

rpmrpm T

ECUECUECUECUtT max

max%

% ∗

−−=

Function of: Lug CurveFriction Torque (Zero Fueling Curve or Zero

Flywheel (Zero Output Shaft Load) Percent Load Curve

Shaft Torque and ECU Percent Load Variation for a Modern Electronically

Controlled Engine

0

100

200

300

400

500

600

500 1000 1500 2000 2500 3000Engine Speed (rpm)

Shaft

Tor

que (

ft-lb)

0

20

40

60

80

100

120

ECU

Perce

nt Lo

ad (%

)

T2

P2

T3

T1

P3

P1

Error in the Inferred Torque Due to an Error in Measured Percent Load

-10

-8

-6

-4

-2

0

2

4

6

8

10

0 20 40 60 80 100

Percent Load (%)

Erro

r in T

orqu

e Valu

e (%

)

14% Idle Point-2% Deviation-1% Deviation0% Deviation1% Deviation2% Deviation

Error in the Inferred Torque Due to an Error in No-Load ECU Load Reading

-10

-8

-6

-4

-2

0

2

4

6

8

10

0 20 40 60 80 100

Percent Load (%)

Erro

r in T

orqu

e Valu

e (%

)

14% Idle Point-3% Deviation-2% Deviation-1% Deviation0% Deviation1% Deviation2% Deviation3% Deviation

Integrated 30 Second Brake Power Windows Between Laboratory and ECU Inferred Data for a

Modern Diesel Engine Exercised Through the FTP Cycle (600 to 1000 Seconds)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

600 650 700 750 800 850 900 950 1000Time (s)

Integ

rated

Pow

er (b

hp-h

r)

Manufacturer SuppliedLaboratory SuppliedLaboratory Measured

Integrated 30 Second Brake Power Windows Percent Difference Between Laboratory and ECU

Inferred Data for a Modern Diesel Engine Exercised through the FTP Cycle

-100

-75

-50

-25

0

25

50

0 200 400 600 800 1000 1200

Time (s)

Powe

r Diffe

renc

e (%

)

Manufacturer SuppliedLaboratory Supplied


TEST ENGINES

• Mack E7-400• 12 L, 400 hp, 1460 ft-lb torque

• Cummins ISM-370• 10.8 L, 370 hp, 1350 ft-lb torque

• Navistar T444E• 7.3 L, 210 hp, 520 ft-lb torque

West Virginia University,Morgantown, WV 26506

NOX MASS EMISSION RATES ON FTP – REAL WORLD AND LABORATORY:

CUMMINS ISM 370

0.0

0.1

0.2

0.3

0.4

0.5

0 200 400 600 800 1000 1200

Time (s)

NO

x (g

/s)

Dilute LaboratoryRaw MEMS

COMPARISON OF BRAKE SPECIFIC EMISSIONS

RESULTS FROM THE FTP TEST CELL AND MEMS

-4.39%

524.0

548.0

CO2(g/bhp-hr)

-0.18%Percent Difference

4.389MEMS

4.397Laboratory

NOx(g/bhp-hr)FTP Cycle


CHASSIS DYNAMOMETER TESTING

• Steady state testing was performed

• Vehicle speeds of 35, 45, and 55 mph

• Errors• MEMS CO2 = -2.17%• MEMS MEXA-120 =

-2.14%0

10

20

30

40

50

60

0 200 400 600 800 1000 1200Time (s)

CO

2 (g/

s)

Lab Dilute CO2MEMS CO2

Cycle Integrated Percent DifferenceMEMS = -2.18


ON-ROAD ROUTE DEVELOPMENT• Four routes were developed to operate a heavy-

duty Class 8 tractor throughout representative ranges of speed and load• Morgantown Route

• Urban and highway operation

• Saltwell Route• Highway operation

• Bruceton Mills Route• Highway operation (mountainous terrain)

• Pittsburgh Route• Urban and highway operation

CONCLUSIONS• An on-board emissions measurement system is needed to

measure brake specific emissions from vehicles during their in-use operation, since engine and chassis dynamometer cycles are not representative of real-world driving conditions.

• MEMS utilizes state-of-the-art technology to report emissions measurements. • Horiba BE-140 NDIR HC, CO, CO2 analyzer; Horiba MEXA-120 NOx

analyzer.• Horiba NOx converter, M&C Products thermoelectric chiller.

• MEMS is capable of reporting brake-specific emissions of CO2to within 3% and NOx to within 5% over an FTP cycle.

• WVU has developed routes have been developed to operate the engine of a heavy-duty vehicle through a wide range of speed and load combinations.

• It is anticipated that over the next couple of years in-use emissions measurement tools will be more compact, accurate, precise, rugged, and easy to use.

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