Post on 06-Feb-2018
transcript
Evaluation of the Heavy-Duty In-Use Testing (HDIUT) Program:
Not-to Exceed (NTE) vs. Work-Average Window (WAW) Concepts
In-Use Testing Workgroup Meeting
February 22, 2017
1
Outline
• Rulemaking Timeline• Purpose of the Workgroups• Current Heavy-Duty In-Use Testing (HDIUT) Program
(NTE Method)– Requirements– Program Effectiveness
• NTE Modification Data Analysis• European WAW Method• WAW Modification Data Analysis• Related Research• Open Discussion/Questions• Action Items/Next Steps
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Heavy-Duty Truck Rulemakings
Scheduled Board Dates
Rulemaking Scheduled
Board Hearing Date
Revisions to Periodic Smoke Inspection Program
September 2017
California Phase 2 GHG Standards October 2017
Revisions to the Warranty Period and Recall Authority Requirements
December 2017
New HD Engines: - Low NOx Standard and Test Procedures - Revised HDIUT Program - Revised Durability/Useful Life
2019
Heavy-duty Inspection and Maintenance 2020
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Purpose of Workgroups
• Provide stakeholders the opportunity toprovide suggestions and comments
• Answer questions that CARB has during therulemaking process
• Data and idea exchange between CARB staffand stakeholders during the rulemakingprocess
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Purpose of the In-Use Testing
Workgroup
• Objective: Develop in-use requirements to ensure thecertified NOx reductions are enforced in real-worldoperation
• Considerations:– Update HDIUT program– Analyze/compare NTE and European WAW methods– Potential NTE modifications: event duration, control
area/definition of region, temperature exclusions– Determine recommended method, new agency in-use
compliance method– PEMS measurement accuracy– Alternative emissions metrics– Pass/Fail protocol
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Current HDIUT Program
• HDIUT program adopted in 2005 by U.S. EPA and in2006 by CARB
• In-use testing helps assure that engines meetapplicable emission standards throughout their usefullife
• CARB and U.S. EPA jointly select engine families to betested (25%/year, 4-yr rolling average)
• Manufacturers recruit fleets, conduct testing usingPortable Emissions Measurement Systems (PEMS)
• Test data and results submitted to CARB and U.S. EPA
• Data is analyzed under the NTE requirements
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Number of Vehicles to Test Per Engine
Family under HDIUT Program
• Phase 1 Testing:– 5 vehicles – If all pass, then testing complete– If 1 vehicle fails, then one more tested. If it passes, then
testing complete.– If only 4 of 6 vehicles pass, then test 4 more vehicles, for a
total of 10 vehicles. If 8 of 10 vehicles pass, then testingcomplete.
• Phase 2 Testing:– If fewer than 8 of 10 vehicles pass in Phase 1, Phase 2 may
be required. 10 more vehicles need to be tested.– CARB/U.S. EPA control how vehicles are tested
• Information can be found in 40 CFR 86.1915
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Determining Pass/Fail of a Test
• Under NTE, 1-Hz emission data is gatheredwith PEMS over 1 shift day of driving
• Data points evaluated to determine NTEevents according to set criteria (next slide)
• Emissions evaluated for each NTE event; eventemissions compared to NTE threshold todetermine whether event passes or fails
• Test is considered passing if time in all passingevents over total time in all events is > 0.90
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1. Inside NTE control area• > 30% max power• > 30% max torque• > 15% European Stationary Cycle
speed (rpm)
2. Temperature conditions• > 250oC (for SCR aftertreatment)• Meet minimum intake
manifold/engine coolanttemperatures
3. At least 30 consecutiveseconds meeting abovecriteria
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Current Criteria for Valid NTE Events
Points excluded by reason:
Emissions value: work-specific average of 1 Hz data within each NTE event
HDIUT Program So Far
• Data from 565 tests show:– Average data in NTE events included:
• Mean: 5.4%
• Median: 3.2%
• 105 tests with 0 NTE events
– Average duration of tests (mean): 8.9 hours
– 12 tests failed (6 prompted one more test for itsrespective family, all of which passed)
– Most tests passed with Pass Ratio of 1.0
– Only one manufacture has initiated a recall
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• Potential changes to NTE to reduce dataexclusion and increase data evaluated
– Expand NTE control area
• Reduce minimum torque
• Reduce minimum power
– Lower aftertreatment-out temperature minimum
– Reduce minimum duration of NTE event
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Under Current Program Most Data
Excluded from Emissions Evaluation
• 3 sets of data chosen from HDIUT program– HDIUT data tends to be more over-the-road rather than
vocational
• Data were from passing tests• Data verified to consist of a valid test under the work-
average window method (for next set of analyses)• Data evaluated under 4 variations of NTE:
A. Current (base) B. Min NTE event duration reduced from 30 to 10 sec C. Min torque and power both set to 10% of max, aftertreatment temperature requirement removed D. Both B and C modifications applied
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Data Chosen for Analysis
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
NO
x Em
issi
on
s (g
/bh
p-h
r)
2 Events 28 sec
1 Event 39 sec
13 Events 253 sec
Effect of Modifying NTE Criteria,
Example 1 (HDIUT Data)
Pass Ratio: NTE Time (sec): Events: Med. Event Time:
Test Details: Total Duration: 44774 sec Total Non-idle: 30455 sec Vehicle: Delivery Engine year: 2010 Month of test: FebruaryOverall: 0.18 g/bhp-hr
0.75* g/bhp-hr Threshold
0.20 g/bhp-hr
Base 1.0 4837 (10.8%) 71 53 sec
10 sec 0.99674 8405 (18.8%) 292 18 sec
10%T/P,Temp 0.9967 11972 (26.7%) 167 50 sec
10%T/P,Temp,10sec 0.9843 16101 (40.0%) 411 24 sec
*FEL: 0.33 g/ bhp-hr13
0
0.5
1
1.5
2
2.5
NO
x Em
issi
on
s (g
/bh
p-h
r)
10%P/T,Temp 0.9907 9816 (30.0%) 79 68 sec
10%P/T,Temp,10sec 0.9868 11438 (35.0%) 174 26 sec
Effect of Modifying NTE Criteria,
Example 2 (HDIUT Data)
Pass Ratio: NTE Time (sec): Events: Med. Event Time:
Test Details: Total Duration: 32722 sec Total Non-idle: 17735 sec Vehicle: Tractor Engine year: 2011 Month of test: MayOverall: 0.35 g/bhp-hr
0.65 g/bhp-hr Threshold
0.20 g/bhp-hr
1 Event 87 sec
Base 0.9813 4640 (14.2%) 55 56 sec
10 sec 0.9831 6160 (18.8%) 152 19 sec
2 Events 104 sec
1 Event 87 sec
5 Events 145 sec
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Effect of Modifying NTE Criteria,
Example 3 (HDIUT Data)
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
NO
x Em
issi
on
s (g
/bh
p-h
r)
Base 0.9124 5490 (13.2%) 76 55 sec
10 sec 0.8783 6876 (16.6%) 161 27 sec
10% T/P,Temp 0.8096 8363 (20.2%) 87 63 sec
10% T/P,Temp, 10 sec 0.756 10613 (25.6%) 220 23 sec
8 Events 481 sec
30 Events 837 sec
30 Events 1592 sec
89 Events 2590 sec
Pass Ratio: NTE Time (sec): Events: Med. Event Time:
Test Details: Total Duration: 41444 sec Total Non-idle: 26520 sec Vehicle: Tractor Engine year: 2011 Month of test: JulyOverall: 0.98 g/bhp-hr
0.65 g/bhp-hr Threshold
0.20 g/bhp-hr
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Observations from NTE Cases
• Pass ratio generally lower with modified cases, but notalways
• Amount of additional data varies by test– Certain tests with no NTE events may still not have NTE events
with modified criteria
• Shortening minimum event duration generally resulted inmore, but shorter events
• Reducing the torque and power thresholds and removingthe minimum aftertreatment temperature criteriongenerally resulted in slightly more events, and slightlylonger event durations
• Combining both cases results in more events with longerdurations
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• Adopted in the European Union as part of Euro VI• Emissions evaluated over segments of data (windows)
– Windows consist of consecutive 1 Hz data points that addup to defined quantity of work, windows overlap
– Average power over window meet set percentage of maxpower
– Brake-specific emissions: Total emissions emitted inwindow divided by total work done in window
– Window emissions ranked and emissions at 90th percentileused to determine compliance
– Does not have separate temperature-based exclusions– No measurement margin (conformity = 1.5 x standard)
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Work- Average Window Method
• Work done each second is added until the cycle work isaccumulated (FTP work in this example)
• Average Power = Window work / window duration
• Window is valid if average power > 10% max power
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Determining Valid Windows
Snippet of data from a test conducted on PEMS: A valid window is shown in green and an invalid one in red.
• Same data used as in NTE analysis earlier
• Min window power: 10% of max engine power
• 3 work window sizes, based on:
– World Harmonized Transient Cycle
– Federal Test Procedure
– Custom work window size: 30 seconds at 30% ofmaximum power to approximate work in lowestpossible work NTE event
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Work-Average Window Analysis
0
0.5
1
1.5
2
2.5
3
NO
x Em
issi
on
s (g
/bh
p-h
r)
Effect of Different Work Windows
Sizes, Example 1 (HDIUT Data)
0.5* g/bhp-hr (CF = 1.5)
90th Percentile 0.37 g/bhp-hr (CF = 1.13)
90th Percentile 0.39 g/bhp-hr (CF = 1.20)
90th Percentile 0.54 g/bhp-hr (CF = 1.64)
WHTC
Valid 22.81%
88.1%
Invalid 8.24%
FTP
Valid 24.08%
85.5%
Invalid 7.96%
Custom
Valid 30.68%
68.8%
Invalid 5.15% Med. % Power
% Valid Windows
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> 0.5 g/bhp-hr: 12% Med. HP: 16.2%
> 0.5 g/bhp-hr: 0.1% Med. HP: 31.8%
> 0.5 g/bhp-hr: 2.3% Med. HP: 26.0%
*FEL: 0.33 g/ bhp-hr
0
1
2
3
4
5
6
7
NO
x Em
issi
on
s (g
/bh
p-h
r)
Effect of Different Work Windows
Sizes, Example 2 (HDIUT Data)
0.3 g/bhp-hr (CF = 1.5)
90th Percentile 0.84 g/bhp-hr
90th Percentile 0.76 g/bhp-hr
90th Percentile 0.47g/bhp-hr
WHTC
Valid 26.05%
71.1%
Invalid 5.65%
FTP
Valid 26.83%
65.9%
Invalid 5.00%
Custom
Valid 32.29%
51.3%
Invalid 2.00%
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Med. % Power % Valid Windows
(CF = 4.21) > 0.3 g/bhp-hr: 34.5%Med. HP: 21.4%
(CF = 3.79) > 0.3 g/bhp-hr: 30.5%Med. HP: 18.7%
(CF = 2.35) > 0.3 g/bhp-hr: 18.1%Med. HP: 36.5%
0
2
4
6
8
10
12
14
NO
x Em
issi
on
s (g
/bh
p-h
r)
Effect of Different Work Windows
Sizes, Example 3 (HDIUT Data)
0.3 g/bhp-hr (CF = 1.5)
90th Percentile 1.88 g/bhp-hr
90th Percentile 2.33 g/bhp-hr
90th Percentile 2.80 g/bhp-hr
WHTC
Valid 25.58%
83.6%
Invalid 7.39%
FTP
Valid 28.90%
76.2%
Invalid 6.52%
Custom
Valid 34.93%
65.3%
Invalid 2.03%
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Med. % Power % Valid Windows
(CF = 11.64) > 0.3 g/bhp-hr: 97.5%Med. HP: 28.3%
(CF = 9.41) > 0.3 g/bhp-hr: 99.2%Med. HP: 25.3%
(CF = 14.00) > 0.3 g/bhp-hr: 89.6%Med. HP: 32.9%
Observations from Work-Average
Window Cases
• Generally more challenging than NTE• Impact of different window sizes varied with each
test– WHTC work > FTP work > Custom work– Percentage of windows valid appears to decrease with
window work
WHTC FTP Custom Current NTE
CF %valid CF %valid CF %valid % Time
Example 1 1.13 88.1 1.20 85.5 1.64 68.8 10.8
Example 2 4.21 71.1 3.79 65.9 2.35 51.3 14.2
Example 3 9.41 83.6 11.64 76.2 14.00 65.3 13.2 23
Related Research
• CARB’s contract with Southwest Research Institute will evaluate alternative metrics
– Grams of NOX per unit fuel consumed
– Grams of NOX per unit CO2 emitted
• Will allow for better characterization of emissions at very low loads
• Results expected Summer 2018
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Next Steps
• Continue analysis with vocational data as currently ongoing data collection project with the University of California, Riverside completes
• Consider methods of accounting for emissions from operations below 10% of maximum power, including switching to a separate set of metrics
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Discussion
• Comments or questions about the data analysis or the possible strategies for increasing data inclusion?
• Concerns with NTE modifications approach (e.g. shorter events, lowering requirement to 10% of torque and power, removing or lowering minimum aftertreatment out temperature)?
• Concerns with work-Average window approach (window size based on FTP, WHTC, or another amount, power threshold)?
• Suggestions for other options? Further analyses that you would like to see completed? Other PEMS data that you would wish to contribute, such as data from vocational vehicles?
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