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
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
West Virginia University, Morgantown,WV 26506
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
.)
λλλλ (µµµµm)
Flux
(a.u
.)
λλλλ (µµµµm)
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
West Virginia University, Morgantown,WV 26506
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
West Virginia University, Morgantown,WV 26506
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
West Virginia University, Morgantown,WV 26506
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.