WORK-WINDOW BASED ANALYSIS OF IN-USE HEAVY-DUTY VEHICLE EMISSIONS

Transcription

1 WORK-WINDOW BASED ANALYSIS OF IN-USE HEAVY-DUTY VEHICLE EMISSIONS Arvind Thiruvengadam, Daniel K. Carder, Marc C. Besch West Virginia University Benjamin M. Statler College of Engineering and Mineral Resources Department of Mechanical and Aerospace Engineering (MAE)

2 MOTIVATION - In-use activity vs. NTE events In-use compliance program of US- EPA NTE points over segment of onroad vehicle operation Applicability of NTE method for engine compliance evaluation of a wide variety of vocations 2

3 6 4 IN-USE DATA - Drayage Cycles Neardock Cycle 2 Vehicle Speed [mph] Local Cycle Regional Cycle Time [sec] Drayage cycles for chassis dynamometer Simulating typical operation of drayage trucks within the port => Near-dock Cycle between port and local storage/distribution yards => Local Cycle between port and inland, regional distribution centers => Regional Cycle

4 Engine Torque [ft-lb] IN-USE DATA - Regional Cycle, Chassis P 3 T 3 Engine operating points inside NTE zone Engine operating points without AT exclusion (only n 15, T 3, P 3 ) Engine operating points with AT exclusion Actual 3-sec NTE windows 1 single window of 44.2sec Engine Torque [ft-lb] Engine Speed [rpm] P 3 T 3 n 15 Engine operating points inside NTE zone n Engine Speed [rpm] Engine Torque [ft-lb] P 3 T 3 Engine operating points inside NTE zone n Engine Speed [rpm]

5 Engine Torque [ft-lb] IN-USE DATA - Local Cycle, Chassis P 3 T 3 Engine operating points inside NTE zone Engine operating points without AT exclusion (only n 15, T 3, P 3 ) Engine operating points with AT exclusion Actual 3-sec NTE windows No valid 3-sec NTE window Engine Torque [ft-lb] Engine Speed [rpm] P 3 T 3 n 15 Engine operating points inside NTE zone n Engine Speed [rpm] Engine Torque [ft-lb] P 3 T 3 Engine operating points inside NTE zone n Engine Speed [rpm]

6 Engine Torque [ft-lb] IN-USE DATA - Neardock Cycle, Chassis P 3 T 3 Engine operating points inside NTE zone Engine operating points without AT exclusion (only n 15, T 3, P 3 ) Engine operating points with AT exclusion Actual 3-sec NTE windows No valid 3-sec NTE window Engine Torque [ft-lb] Engine Speed [rpm] P 3 T 3 n 15 Engine operating points inside NTE zone n Engine Speed [rpm] Engine Torque [ft-lb] P 3 T 3 Engine operating points inside NTE zone n Engine Speed [rpm]

7 IN-USE DATA - Drayage Cycles NTE Events Cycle Regional Cycle Local Cycle Near-dock Cycle Stats Points inside NTE zone (n 15, T 3, P 3 ) [%] Test Engine: MY 211 HHD, DOC-DPF-ureaSCR Points inside NTE zone (n 15, T 3, P 3 ) with AT exclusion [%] Mean σ.44.6 Mean σ.24 - Mean σ.18 - NTE 3-sec window (n 15, T 3, P 3 ) with AT exclusion [%] 1

8 BACKGROUND Reported data indicates sparse amount of 3sec NTE windows from a shift day (8 hours) Actual amount of total NTE operation is often quite considerable In-use SCR activity data and thermal management strategies Pending NO x and GHG regulations Retain ability to identify off-cycle emissions, but strengthen the relationship between certification (compliance) and real-world emissions Open discussion on current EXISTING practices to assure that emissions reductions demonstrated on certification cycles are also translated into lower off-cycle emissions during real-world vehicle operation Compliance strategies and their impact on emissions inventory reduction plans

9 IN-USE EMISSIONS - Regulations and Compliance Overview PEMS are used to measure emissions while a vehicle is performing it s intended activity. Continuous measurement of gaseous and PM concentrations, exhaust flow rate, ambient conditions, along with broadcast ECU parameters such as engine speed, torque, fuel flow rate, etc. Data must be collected a minimum of one full-shift day (8 hours), with at least 3 hour non-idle operation.

10 NOT-TO-EXCEED ZONE - Definition Speed Lower Bound (n 15 ): 15% ESC Speed n 15 = n lo +.15 x (n hi n lo ) n hi : highest engine speed where 7% of max power line intersect with max. torque curve. n lo : lowest engine speed where 5% of max power line intersects with max. torque curve. Torque Lower Bound: 3% of Peak Torque. Power Lower Bound: 3% of Rated Power. Torque Upper Bound: is the maximum torque curve of the engine (Advertized Engine Map).

11 NOT-TO-EXCEED ZONE - Definition TORQUE (N-m) nlo n15 nhi DD vccliid NTE(5.% LTR) ( ) ( ) 5.% LTR 4 P SPEED (rpm) Advertized_MP8-445C, NTE Region P7 P5 T3

12 VALIDATION OF AN NTE EVENT Engine Speed [rpm]: must be greater than or equal to 15% of European Stationary Cycle (ESC) nn NNNNNN > nn 1111 Engine Torque [ft-lb or Nm]: must be greater than or equal to 3% of the peak torque Tq NTE.3 Tq max/peak Engine Power [bhp or kw]: must be greater than or equal to 3% of the rated power. P NTE.3 P max/rated Test Altitude [ft]: must be less than or equal to 5,5 ft Alt NTE 5,5 Ambient Temperature [F]: must be less than or equal to a maximum ambient temperature, which is a function of altitude. T amb_nte.254 Altitude + 1

13 CONT D Measured Intake Manifold Temperature: for EGR equipped engines must be greater than the calculated temperature as a function of intake manifold pressure. IMT NTE > IMT EGR IMT EGR = IMP abs Measured Engine Coolant Temperature: for EGR equipped engines must be greater than the calculated value, which is a function of intake manifold pressure. ECT NTE > ECT EGR ECT EGR = IMP abs Exhaust Temperature: for engines employing oxidation catalyst or SCR aftertreatment system to reduce NMHC and NOx emissions must be greater than 25 C within 12 of the aftertreatment device. T exh NTE DOC/SCR > 25

14 CONT D Minimum NTE Event Time [s]: must be greater than or equal to 3 s of continuous operation. t NTE 3 Minimum NTE Event Time [s] for DPF Equipped Engine: in the event of regeneration. t NTE(w/regen) t regen1 NTE RF 5.% Time Weighted Limited Testing Region: is an elliptical/rectangular region that shares some boundary with upper limit of NTE zone. The engine should operate less than 5.% of the total NTE event duration in this region. Hence, n 15, Tq NTE, P NTE, T amb_nte, Alt NTE, IMT NTE, ECT NTE, = ff T exh_nte(doc/scr), t NTE, t NTE(w/regen), 5.%TWLTR

15 VEHICLE PASS/FAIL CRITERIA NTE threshold = Cert. Std. NTE multiplier + Acc. margin + Comp. margin = ff NTE threshold NTE event duration weighting, Emissions Pass Ratio Valid NTE events emission 2. NTE threshold If NOx FEL.5g/(bhphr), then valid NTE event NOx 2. NTE threshold, or 2.g/(bhphr)whichever is greater.

16 NTE POINTS & EVENTS - FTP TORQUE (N-m) % of FTP Cycle falls outside the NTE region.3p max n15 26% of the NTE operating points lies in an NTE region 12% of FTP Cycle result in an NTE event with 3 distinct events. Advertized_MP8-445C FTP, NTE Events POWER (kw).3t max n SPEED (rpm) Engine Torque N-m Tmax3 N-m T3(.3Pmax) N-m Engine Torque N-m NTE Region Engine Torque [N-m] NTE Event Engine Torque [N-m] Power kw n15

17 NTE POINTS & EVENTS - WHTC TORQUE (N-m) % of WHTC Cycle falls outside the NTE region.3p max.3t max n15 26% of the NTE operating points lies in an NTE region 7% of Test Cycle result in an NTE event, with a single 131 s event Advertized_MP8-445C WHTC, NTE Events POWER (kw) 5 5 n SPEED (rpm) Engine Torque N-m Tmax3 N-m T3(.3Pmax) N-m Engine Torque N-m NTE Region Engine Torque [N-m] NTE Event Engine Torque [N-m] Power kw n15

18 NTE POINTS & EVENTS - ESC Cycle 9 out of 13 (69.2%) set points in NTE region 35% of weighting factor outside of NTE region Ref: Shade B., 25

19 WORK-BASED WINDOW Moving averaging windows that are integrated against reference value (work or emissions) from representative engine certification cycle Emissions are integrated over a window size equivalent to the reference value Moving averages are incremented by data sampling period Valid windows are those that the average power exceeds 2% of maximum engine power (EU regulation) Same idea as 3% max power lower boundary of NTE zone (US-EPA regulation) Successful test shall comprise of 5% of valid windows, otherwise, power threshold is reduced in steps of 1% to achieve 5% of valid windows Test voided if 5% of valid windows cannot be achieved for a power threshold of 15%.

20 WORK-BASED WINDOW - On-Road Data Highway operation HHD engine equipped vehicle

21 WORK-BASED WINDOW - On-Road Data ~84% Highway operation HHD engine equipped vehicle

22 WORK-BASED WINDOW - On-Road Data DDDDDDDDDDDDDDDDDD RRRRRRRRRR = bbbbbbbbbb iiii uuuuuu bbbbbbbbbb cccccccccccccccccccccccccc Highway operation HHD engine equipped vehicle

23 WORK-BASED WINDOW - Regional Cycle ~66% ~47% Regional Cycle HHD engine equipped vehicle

24 WORK-BASED WINDOW - Regional Cycle DDDDDDDDDDDDDDDDDD RRRRRRRRRR = bbbbbbbbbb iiii uuuuuu bbbbbbbbbb cccccccccccccccccccccccccc Regional Cycle HHD engine equipped vehicle

25 NEW APPROACH EXAMPLE - NOx Use window-based approach (distance, energy, etc.) Consider full operating regime more representative of actual emissions contribution/emissions control strategy performance Integrate windows and compare relevant physical parameter (e.g. SCR outlet temperature exclusion) Validation based upon??? Physical parameter performance during engine certification cycle Weighting of emissions, based on parameter weighting during certification cycle Non-restrictive as to meeting defined number of points or minimum operation during a shift-day Originally considering only altitude exclusion

26 NEW APPROACH EXAMPLE - Exhaust Temperature over FTP 4 (f t < 25 C) = 1/3 (f t > 25 C) = 2/3 Exhaust Temperature [ C] Time [sec] FTP- 211 HHD engine on engine dynamometer

27 NEW APPROACH EXAMPLE - NOx 35 3 Exhaust Temperature [ C] On-road operation of 213 HHD engine equipped vehicle Integrated Nox:.36 g/bhp-hr Actual parameter window split 37%/63% FTP parameter weighting of 71%/29% Resultant weighted NOx:.26 g/bhp-hr Time [sec]

28 ON-GOING WORK Quantification over window sizes defined by the distance, work, or energy-based windows Compare different window-based methods with integration of emissions over the full shift day (comprehensive emissions contribution) Modification of parameter weighting scheme Investigate the impact of different exclusion conditions as functions of selected window method and specific vehicle operating conditions.

29 THANK YOU! Arvind Thiruvengadam Daniel K. Carder - Daniel.Carder@mail.wvu.edu Marc C. Besch Marc.Besch@mail.wvu.edu Center for Alternative Fuels, Engines and Emissions ACKNOWLEDGEMENT