Approaches to Quantifying Heavy-Duty In-Use Vehicles Emissions in California
Shaohua Hu, Ph.D. P.E.Measurement Assessment and Research Section, Monitoring
and Laboratory Division
Current HDE Emissions Standards NOx reduced 97%HC reduced 89 % PM reduced 98%
NOx 6.0 g/bhp-hr
HC 0.14 g/bhp-hrNOx 0.2 g/bhp-hr
PM 0.01 g/bhp-hr
HC 1.3 g/bhp-hr
PM 0.6 g/bhp-hr
1987
present
Heavy-Duty Engine Emissions Standards
1
Ecosystem of Vehicle Testing
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Mobile Sources
Laboratory Dynamometer
TestingEngine and
chassis dynamometer
testing
On-Board Diagnostic Tools Collect ECU and Emissions data
On-Road Emissions
MeasurementsPortable
Emissions Measurement
Systems (PEMS)
Roadside and Remote Sensing Measurements
Plume entrainment or remote imaging
systems
HD On-road PEMS
PEAQS
HD OBD
MTA Engine DynoMTA Chassis Dyno
Depot Park Chassis Dyno
Off-road PEMS
LD On-road PEMS
Instrument Trailer
Updraft Exhaust Intake
Downdraft Exhaust Intake
Heavy-Duty In-Use Vehicle Testing Capabilities
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What is Remote Sensing?• “Remote” emissions measurement
• Emissions measured without touching the vehicle using a Remote Sensing Device (RSD)
• Utilizes emitted radiation to collect emission measurements• Infrared Radiation - Denver University (DU) FEATS• Laser (or LiDAR) – H.E.A.T EDAR, Satellite measurements
• Plume Capture• Similar data, but exhaust plume is physically sampled• DU Tent Measurements, PEAQS, UC Berkeley
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What is PEAQS?
https://www.youtube.com/watch?v=5kdsRR7_VVE
The Portable Emission Acquisition System, or PEAQS, is a roadside emission measurement system that captures a portion of a passing vehicle’s exhaust as it drives through to determine an emission snapshot in real-time.§ Screening tool to help target enforcement activities § Aid in community air quality monitoring
CARB PEAQS
ALPR
Instrument Trailer
Downdraft exhaust intake
Updraft exhaust intake
• Design criteria:üReal-time measurements built-in QA/QCüPortableüCharacterize vehicle speed and accelerationüPlug and play operationüExplore low-cost technologyüAbility to scale up
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PEAQS Components
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Additional Inspection
Species InstrumentCO2 Licor-820/840
BCMagee AE-33
AethLabs AE-51
NOXCAI CLD-64
EcoPhysics CLD-844
OtherGeovision Camera
Doppler Radar, Lidar
PEAQS Front-EndCO
2N
OxBC
Captured Truck Exhaust PlumesNo Measurable BC or NOX
Vehicle ImageMost Recent Valid
EFBCEF g$ kg&'() *+ = ∫.
/ P1 − P. 34∫./ CO7/ − CO7. 34
×9: 7
PEAQS Versions
‘Mid-Grade System’
‘Laboratory Grade System’Instrumentation In Trailer
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PEAQS Field Deployments• PEAQS deployed at 6 locations
across California• >10,000 valid vehicular plumes
measured
• California Department of Food and Agriculture, Truckee
• Port of Oakland• Stockton, CA Intermodal
Railyards• Port of Los Angeles• Cottonwood- California Highway
Patrol Weigh Station• Caldecott Tunnel – Oakland, CA
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PEAQS In the Field
Truckee, CA: California Department of Food & Agriculture (CDFA) Truckee
Wilmington, CA: Port of Los Angeles
PEAQS has measured> 10,000 vehicles
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Roadside
Inside Facility
PEAQS Results
• Above values are for all valid plume captures during all sampling conducted at each location
• POLA includes information from December 2016 and April 2017
All units in g / kg fuelAverage Median
AE-51 BC AE-33 BC NOX AE-51 BC AE-33 BC NOXCDFA Truckee 0.18 0.26 20.2 0.02 0.12 4.51
COTTONWOOD 0.04 0.05 6.6 0.004 0.01 2.20
POLA 0.04 0.03 7.2 0.01 0.01 2.13
Port of Oakland 0.03 0.06 11.3 0.01 0.03 9.47
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Emissions Trend: Black Carbon
2001 2008 2010 2012 2014
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Port of Los Angeles April 2017
Chassis MYBC
EF
(gBC
/kg
fuel
)
• Lower average BC emissions at Port of Los Angeles relative to Cottonwood Weigh Station• Majority of vehicles measured had BC < detection limit (total n >1,000 at each site)• BC emissions driven by ‘high emitters’
1989 1999 2003 2007 2011 2015
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Cottonwood CHP Station April 2017
Chassis MY
BC E
F (g
BC/k
g fu
el)
n = 142
n = 90
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Emissions Trend: Nitrogen Oxides
1985 1998 2002 2006 2010 2014
020
4060
8010
012
0
Cottonwood CHP Station April 2017
Chassis MY
NO
x EF
(gN
Ox/
kg fu
el)
• Broader model year distribution at Cottonwood • NOX emissions decrease with MY 2010+ MY• NOX emission averages driven by ‘high emitters’
2001 2006 2009 2011 2013 2015
020
4060
8010
012
0
Port of Los Angeles April 2017
Chassis MYN
Ox
EF (g
NO
x/kg
fuel
)n = 368
n = 321
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PEAQS Application: “Highest Emitter” Identification
Data collected by PEAQS during 2016-2017 14
Build-in library to dynamically update with emissions data to determine top percentile
BC NOX
High Emitting Vehicle Determinations
• Fuel-based emission factors corresponding to possible exceedances of emission standards as a function of vehicle power.
• A typical HD vehicle (~ 65,000 lbs) will have exceeded the model year (MY) 2010 emission standards (of 0.2 g NOx/bhp-hrand 0.01 g PM/bhp-hr) by three times when fuel-based emission factors are 9.3 g NOx/kg fuel and 0.11 g PM/kg fuel when measured using the roadside plume measurement approach.
Quiros, D., Smith, J., Ham, W., Robertson, W., Huai, T., Ayala A. & Hu, S. (2018) Deriving fuel-based emission factor thresholds to interpret heavy-duty vehicle roadside plume measurements, Journal of the Air & Waste Management Association, 68:9, 969-987, DOI: 10.1080/10962247.2018.1460637
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Please note, those threshold values depend on vehicle driving activities.
A Side Successful Story of PEAQSDuring the November 2016 filed campaign, PEAQS helped to ‘identify’ Glider Kits
a. SAE J1667b. g NOX/ kg fuel on arrival (< 1 mph, decelerating)c. g NOX / kg fuel as vehicle departed
a Snap Idle Driving Through
Opacity BC BC b NOX,i c NOX,f% g/kg fuel g/kg fuel
Glider Kit 1 11.5 0.84 0.025 0.01 1.37
Glider Kit 2 89.3 60 0.21 27.7 39.6
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RSD Data Application: “Hot-Sheets”• Create database of measured ‘high-emitters’
• Top 5-10% of the fleet • “Hot-sheet” created and distributed to Mobile Enforcement as targets for further inspection
• License Plate and vehicle description• Fast screening of vehicles at Ports of Entry – CHP Weigh Stations, Agricultural Inspection Stations,
etc.
Vehicle passes
RSD
Data uploaded
into Statewide Database
BC/NOXEmissions found to be in top
5%
Vehicle added to Monthly
‘Hot-Sheet’
Vehicle found at
weigh station
and pulled for
inspection
Maintenancerelated
emissions failure
Manufacturerrelated
emissions failure
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Summary and Next Steps
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• PEAQS is an important emissions measurement toolo Provide a large quantity of data in a cost-
effective wayo Identify “high emitting” vehicles through roadside
plume captureo Provide emissions trends
• Next step is to expand measurement to multiple locations across CA through small, lower cost applicationso Get PEAQS out on roadways across CA to
10 locationso Create emissions database structure and
procedure for fast data communication
Questions?
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Ecosystem of Vehicle Testing
20
Mobile Sources
Laboratory Dynamometer
TestingEngine and
chassis dynamometer
testing
On-Board Diagnostic Tools Collect ECU and Emissions data
On-Road Emissions
MeasurementsPortable
Emissions Measurement
Systems (PEMS)
Roadside and Remote Sensing Measurements
Plume entrainment or remote imaging
systems
• Sales volume used to select initial MY 2010 and newer engine families for pilot
• Class 4 through 8 vehicles tested at 80% of GVWR (GVWR ranges 14,000-80,000 lbs)
Design of California’s Pioneering Pilot Truck and Bus Surveillance Program
• ‘Randomly’ recruited from state population from small and large fleets with lower (<100,000 mi) to higher (>435,000 mi) odometer readings
• Chassis dynamometer and PEMS testing for 2-3 weeks
• Launched April 2016, will run about two (2) years, 40+ vehicles to date
Key Events for Recruiting, Procuring & Testing
Recruitment & Procurement
Check-In Procedure
• Fuel sample
• Photo documentation
• Oil sample
• DEF check
• Opacity test
• Under-hood inspection
• OBD scan
• Coast-down (for unusual body types)
Check-Out Procedure
• Opacity test
• OBD scan
• Truck wash
• Truck re-fuel
• DEF refill
Return to Fleet
• Transport from Sacramento laboratory back to fleet
• Check issued to fleet by ARB contractor
• Identify vehicle from on-road fleet
• Collect maintenance history
• Sign rental agreement
• Transport from fleet to Sacramento laboratory
Laboratory Testing on Chassis Dynamometer
• Six cycles 20-55 min, 1.8-62 mph avg speed
• 1-hour idling tests under three loads
• 5-15 minute preconditioning specific to each cycle to achieve “hot-start” conditions
• Raw exhaust gas (AVL AMA i60 bench), multi-gas FTIR, partial-flow PM (Sierra Instruments BG-3), and pitot-tube exhaust flow (EFM-HS, Sensors)
• Active OBD monitoring using CANalyzer (Vector Software GmbH)
• As needed, confirmatory on-road testing using PEMS
Program web site: https://www.arb.ca.gov/msprog/onroad/tbsp/tbsp.htm
3 to 5 days 2 to 3 days 4 to 7 days (more if PEMS testing) 1 day 1 day
Test Vehicle Matrix
* 15-L HHD diesel engines manufactured by Cummins with similar performance and NOx certification levels.** This engine family uses an engine shutdown system (ESS) and is not Clean Idle Certified (<30 g/hr).
A 2010 Cummins MHD Diesel 6.7 0.17B* 2010 Cummins HHD Diesel 14.9 0.25 #1C 2010 Detroit Diesel HHD Diesel 14.8 0.15 #1,3D 2011 Ford HDO Gas 6.8 0.05 #1,2,3E 2011 Cummins UB CNG 8.9 0.13 #1,2,3F* 2011 Cummins HHD Diesel 14.9 0.24G 2012 Ford LHD Diesel 6.7 0.12 #1,2,3H 2012 Navistar MHD Diesel 7.6 0.3 #1,2,3I* 2012 Cummins HHD Diesel 14.9 0.24 #1,2J 2013 Isuzu LHD Diesel 5.2 0.16 #2,3K 2013 Paccar HHD Diesel 12.9 0.12L* 2013 Cummins HHD Diesel 14.9 0.18M 2014 Volvo HHD Diesel 12.8 0.06 #3N 2014 Detroit Diesel HHD Diesel 14.8 0.09
O* 2014 Cummins HHD Diesel 14.9 0.18
P 2014 Navistar HHD Diesel 12.4 0.12 #2,3
Fuel Disp (L) Cert NOx (g/bhp-hr) Test NeedMY Manufacturer Weight Class
Six Cycles Represent Average Speeds From 1.8 to 62 mi/hr (3 to 100 km/hr)
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Emissions measured include CO, CO2, THC, NOx, PM, opacity following SAE J1667 (40% limit CA), DEF purity check, fuel and lube oil analysis, and real-time PM metrics
List and statistics of test cycles for TBSP
• A wide range of duty cycles that HD trucks may undergo in the real-world, and• Help better understand the relationship between average vehicle speed and emissions to better
strengthen the current speed-correction curves used in the EMFAC emissions model.
Results to Date Confirm PM Emissions from MY 2010+ Diesel Engines are Low
• Random roadside surveys indicate small percentages of vehicles with MY 2010 engines exceed 5% opacity following SAE J1667:Ø In 2011: 2%Ø In 2014: 2%Ø In 2016: 3%
Measured J1667 opacity ranged from 0.00 to 1.43%, and all vehicles had PM emissions (UDDS) >90% below standard*
UDDS
*Tests with active DPF regeneration excluded from bar chart
UDDS Brake-SpecificNOx (18.9 mph)
• UDDS is used as base emissions rate in EMFAC
• At 65,000 lbs, UDDS and engine FTP power close for many engine platforms
• Engine families already referred to full HD In-Use Compliance (HDIUC) Program
SCR Conversion Efficiency
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• DP-WSAC ART: Arterial driving, combined with highway speeds • DP-WSAC INDEXT with extended industrial: Low speed allows SCR temperature to drop• DP-PLAC: Uphill and heavy loads
TBSP PEMS NTE Events
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Can you use OBD data to calculate NOX emission rates?
• If we have accurate exhaust mass air flow and NOX-out concentrations, we should be able to, right?
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• Large number of adapters• Most function very similarly• Standalone and computer interface options
OBD Data Collection (Hardware)
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• Intake mass air flow (PGN 61450 – SPN 132)• Mass flow rate of fresh air entering the engine air intake, before any EGR mixer, if used.
Flow rate of fresh air conducted to the engine cylinders to support combustion.
• Engine Total Intake Mass Air Flow Rate (PGN 61497 – SPN 6396)• Mass Flow rate of air entering the engine. This also includes the amount of exhaust gas
recirculated, if any.
• Engine Exhaust Flow Rate (PGN 64587 – SPN 6895)• Engine Exhaust Flow Rate shall indicate the measured/calculated exhaust gas mass flow
upstream of the aftertreatment system.
• Aftertreatment 1 gas mass flow (PGN 65247 – SPN 3236)• Measured/calculated exhaust gas mass upstream of the aftertreatment system in
exhaust bank 1 and 2.
Mass Flow – what should we use?
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• DPA5_Aftertreatment 1 Outlet NOx 1_ppm• The amount of combined NO and NO2 in the exhaust exiting the aftertreatment system
measured by a NOx sensor at the aftertreatment outlet, represented in NOx molecule parts per million non-NOx molecules in exhaust bank 1.
• PGN 61455 – SPN 3226
• DPA5_Aftertreatment 1 Outlet NOx 1 Reading Stable_bit• Indicates that the NOx reading of the aftertreatment outlet NOx sensor is stable as
determined by the manufacturer’s control software in exhaust bank 1.• PGN 61455 – SPN 3230
• We only use OBD NOx data when the sensor reading is stable• Handles sleep events and zero/span when sensor comes online
NOX Sensor – what we use
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Exhaust flow – Using Aftertreatment 1 MAF – DD14
• Most slopes have R2 of 0.9 – 1.1• Poor correlation for cycles with low flowrates (eg idle test)• Uncertainty in measurement or calculation?
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Sensor went to sleep
• NOX emission rates look very similar when SCR is hot• Near Dock Drayage cycle has extended periods of low SCR temperatures and
idle flowrates. Very poor correlation because the NOX sensor goes to sleep when the SCR is cold and mass air flow estimates have more uncertainty
Combining OBD MAF and NOX
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• HD chassis dyno• 2 diesel trucks
• same 2014MY engine family
• UDDS & cruise tests• NOx sensor active
time >90%
On-Board NOX Sensor Data vs Lab Bench Measurement
Conclusion• Successes
• 40+ vehicles tested across 20+ engine families• PM emissions lower than standard• In-Use NOx emissions higher than expected• Program provides ‘platform’ for evaluating OBD performance, and tracking other
measures for further program development• OBD NOx data vs Lab NOx data in good agreement for >90% completeness
• Challenges• Vehicle procurement• Vehicle condition• Consistency with OBD collection
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Questions?
PEAQS Information Video:Youtube.com à “PEAQS”
Shaohua Hu, Ph.D. P.E.Manager, Measurement
Assessment and Research SectionCalifornia Air Resources Board
[email protected](916) 229-0911
TBSP Web Site: https://www.arb.ca.gov/msprog/onroad/tbsp/tbsp.htm
Tao Huai, Ph.D. Chief, Freight Emissions
Testing and Research BranchCalifornia Air Resources Board
[email protected](916) 229-0887