Evaluation of WNTE and Alternative Options. Plenary Meeting of the Off-Cycle Informal Working Group. Zoetermeer, the Netherlands 5-7 April 2006

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1 OCE Informal Document No. 44 Thirteenth Plenary Meeting of the Working Group On Off-Cycle Emissions 5 & 6 April 2006 The Hague, Netherlands Evaluation of WNTE and Alternative Options Plenary Meeting of the Off-Cycle Informal Working Group Zoetermeer, the Netherlands 5-7 April

2 On-going European regulatory developments Heavy-duty EURO V stage In-use conformity checking introduced Elements in 2005/55/EC On-board measurement with PEMS is seen as the main 'route' IUC 'Pass/Fail' options: Oriented towards 'WNTE type' methods (i.e a pass-fail method based on a control area), but other methods are being evaluated. Definition of the test protocol and evaluation work conducted by the EU-PEMS group. 2

3 Future European regulatory developments Heavy-duty EURO VI stage Off-cycle provisions introduced In-use conformity checking kept An issue is to keep a consistency and to prepare a transition between EURO V/IUC and EURO VI/OCE/IUC 3

4 Existing approaches... To evaluate the in-use data, a link to the homologation data must be established. Approaches are sorted in 3 categories: 1. "Control area" (WNTE, US-NTE) 2. Work-based (could also be Fuel-based) 3. Compliance Factor (or BSFC based) 4

5 1. Control Area Approaches 5

6 Principle of the Control Area Approaches Not based on entire engine operation but rather on a control area that can match to a certain extent the control area from homologation cycles. 1. US-NTE 2. WNTE 3. Simplified" to eliminate the operating points that should not be considered (cold start, idling) 6

7 Existing control areas (OICA May 2005) 7

8 Does it fulfill the needs? Questions raised: Are the 'control area approaches' (in particular the WNTE) suitable for any kind of engine/vehicle operation? If not, how far can it be improved? Shall we modify the control area? The minimum sampling rule? What are the rationale behind the definition of the US-NTE and WNTE (Size of the control area and minimum sampling rule in particular)? 8

9 Amount of NTE data collected for 5 Trucks - Highway and extraurban operation: 38% maximum, for a fully loaded vehicle, operated with a cruise-control at maximum speed on the motorway.otherwise below 20% COMPLETE TRIP - WITH 30s RULE FULL LOAD LOW LOAD %TIME IN NTE AREA VM1715 VM5512 VM6740 VM0015 VM2001 VM3542 VM2530 MANUFACTURER 9

10 Is it possible to capture more data? Vehicle 1 Modifying the Low Power Limit (From 30% to 5% of Maximum Power) 5% MP 10 % M P % M P 60 20% MP 25% MP 30% MP % of Points in the Control Area 10 Modifying the Minimum Sampling Rule (From 30s down to 0s) Minimum Sampling Rule [s]

11 Is it possible to capture more data? Vehicle Minimum Sampling Rule [s] 5 5% MP 10 % M P 15 % M P 20% MP 25% MP 30% MP % of Points in the Control Area

12 Are most of the mass emissions captured? Vehicle 1, Highway operation with cruise control (40% of operation in NTE with full load) 5% MP 10 % M P 15 % M P 20% MP 25% MP 30% MP % NOx Mass Emissions in NTE Minimum Sampling Rule [s]

13 Are most of the mass emissions captured? Vehicle 2, Less highway operation with cruise control (20% of operation in NTE with full load) % % MP M P 15 20% MP 25% MP 30% MP % NOx Mass Emissions in NTE Minimum Sampling Rule [s]

14 Effect of the Minimum Sampling Rule (Example) Time [s] VEHICLE SPEED NTE POINTS WITH SAMPLING RULE VEHICLE SPEED NTE POINTS WITH SAMPLING RULE ALL POINTS ALL POINTS ALL POINTS NTE Points WITH SAMPLING NTE Points RULE WITH SAMPLING NTE Points RULE WITH SAMPLING RULE Engine Torque [N Engine Torque [N Engine Torque [N Engine Engine Speed Speed [rpm] [rpm] Engine Speed [rpm] 30s 20s 10s The sampling rule removes a lot of the transient operation 14

15 Control Area Approaches: Preliminary conclusions The Control Area approaches are a very efficient tool to capture random operation of the engines in a definite control area With the current definitions (US-NTE or WNTE) and a 30s minimum sampling rule, it provides a very good tool to capture the operation of long-haul HD vehicles, (in particular if operated with a cruise control), which is typical of the US heavy-duty long haul operation What about the other types of operation? European long-haul operation has a different character from the US and Japanese operations Delivery trucks? City buses? The size of the Control Area and the associated rule could be adjusted to reflect wider regulatory needs 15

16 2. Work-based Approach 16

17 Work (or fuel based) Approach Brake Specific Emissions are calculated for a defined work value. The work window is moved throughout the data set The size of the window depends on the time needed to reach the defined work value. 17

18 Work (or fuel based) Approach Starting from the work W lab [fuel consumption FC lab ] expressed in kw.h [liters] during a laboratory (homologation) test, one calculates for the road PEMS data the brake specific emissions at every data point for the corresponding amount of work W road or fuel FC road Algorithm: At each time t1 of the road PEMS data, one looks for t2 such as W road =W lab (or fuel FC road =FC lab ) 18

19 Work-based window (NOx) BS_NOx [g/kwh] POWER [%] 50 kw.h window No window Time [s] BS_NOx WORK-BASED BS_NOx NTE CUMUL BS_NOx CUMUL BS_NOx_NTE_EVENT POWER [%] 19

20 Work-based window (NOx) BS_NOx [g/kwh] POWER [%] Time [s] BS_NOx WORK-BASED BS_NOx NTE CUMUL BS_NOx CUMUL BS_NOx_NTE_EVENT POWER [%] 20

21 Work-based window (NOx) Effect of window size kw.h window 10 kw.h window BS_NOx [g/kwh] POWER [%] Time [s] BS_NOx WORK-BASED 50 BS_NOx CUMUL BS_NOx WORK-BASED 10 POWER [%] 21

22 3. Compliance Factor Approach 22

23 Approach Type 3: Compliance factor (1) In the test-cell, from the certification data, one calculates the Certification ratio C1: C 1 = BS BS NO CO x 2, lab, lab = M M NO CO x 2, lab, lab W W lab lab = M M NO CO x 2, lab, lab As the work is identical for both species, it can be eliminated from the above ratio and therefore: C 1 M M NO, lab x = BS: Mass emissions CO, lab 2 M: Mass 23

24 Approach Type 3: Compliance factor (2) A similar ratio I1 can be calculated for in-use data: I 1 = BS BS NO x, road CO, road 2 = M M NO x, road CO, road 2 And the "compliance factor" can then be defined as: F = I C Amount of road data to be considered? - Homologation data needed (masses) 24

25 Comparison Of Approaches 25

26 Instantaneous data BS_NOx [g/kwh] POWER [%] Time [s] BS_NOx WORK-BASED BS_NOx NTE CUMUL BS_NOx CUMUL BS_NOx_COMP BS_NOx_COMP_WIN BS_NOx_NTE_EVENT POWER [%] 26

27 Comparison of approaches Vehicle 1 COMPLETE TRIP - MANUFACTURER# BS_NO NO WORK WINDOW 50 kwh WINDOW FUEL WINDOW NTE - WITH 30 SEC 0.00 Test1 - FL Test2 - FL Test3 - FL Test1 - LL Test 2 - LL Test 3 - LL 27

28 Comparison of approaches Vehicle 2 COMPLETE TRIP - MANUFACTURER # BS_NO NO WORK WINDOW 50 kwh WINDOW FUEL WINDOW NTE - WITH 30 SEC Test1 - FL Test2 - FL Test3 - FL Test1 - LL Test 2 - LL Test 3 - LL 28

29 Comparison of approaches (In-use testing) Data needed for the different approaches Approach Engine data Certification On-board Data data 1. Control Area - Maximum - None - All (1) 2. Work (Fuel) Based 3. Compliance Factor / BSFC power curve - None - Work (Fuel) on homologation cycle - All (1) - None - All (2) - All but Engine torque and speed (1) CO, CO2, THC, NOx concentrations, Exhaust Mass Flow, Engine Speed and Torque (2) Homologation CO, CO2 (BSFC), THC, NOx masses 29

30 Advantages and drawbacks Approach Advantages Drawbacks 1. Control Area - Recognised approach, already established as regulatory tool - Clear link with existing control areas from the STATIONARY test cycles - Minimum Sampling rule and other selection rules - Does not account for transient operation - Not Applicable to some operating conditions (City Buses) - No clear link with TRANSIENT test cycles. 2. Work (Fuel) Window - Accounts for all road operation data (TRANSIENT), with the probable exceptions of idling and cold start (to be further investigated) - Provides excellent estimation of scatter of on-road emissions / certification emissions - Cannot easily be linked to a Control Area 3. Compliance Factor / BSFC - No Engine Torque needed on board - Based on BSFC which BSFC? 30