Transient RDE NOx emissions from gasoline and diesel vehicles

Transcription

1 Transient RDE NOx emissions from gasoline and diesel vehicles Mark Peckham, Harry Bradley, Matthew Duckhouse, Martin Irwin Note: many videos were included in this presentation; please ask Mark Peckham for these separately if required

2 Fast gas analyzers for alignment of emissions with engine conditions

3 HFR500 fast FID

4 PFI gasoline cold start Maximum HC occurs during Cold-Start. Fast FID accurately resolves magnitude of initial transients in real time Transient HC measurement seconds of FTP 75 drive-cycle Fast FID Engine Out [HC] as ppm propane Individual cylinder exhaust events visible in engine out HC Fast FID Tailpipe Conventional bench Slow FID Engine Out analyzer Desired Speed (mph) Vehicle speed (mph) Time since start (seconds) -10

5 Fast RDE configuration 12V battery Easily changeable by customer between lab and RDE configuration One or two channels (on short conduits) Integration with other vehicle/engine parameters (lambda, speed, load) so that transient emissions can be correlated. Real-time calculation of cumulative gram emissions Cope with climatic conditions Durable and vibration insensitive T 10-90% response time <10ms Minimal changes to vehicle

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7 Sampling and data collection Fast [NO] sampling point: 40mm before silencer/muffler Engine Control Unit data recorded from vehicle s own OBD port and logged alongside fast [NO] Software was developed to combine the vehicle s exhaust mass flow rate with the fast [NO] to provide fast cumulative gram emissions, providing insight in to the causes of short-duration emissions spikes which may not be visible with slower equipment.

8 User-interface

9 RDE - Lab - RDE 1. RDE on-road cycle logging emissions and ECU data 2. Auto-identify problems and associated engine conditions 4. Adjust vehicle s emissions calibration 3. Translate problem transients on to dyno for repeatability 9

10 Comparison of fast RDE CLD500 with PEMS

11 Candidate Vehicle Information

12 PEMS vs fast RDE comparison Testing performed at MAHLE Powertrain s EU6 emissions test facility - VCA certified facility Simulated RDE Testing performed on MAHLE Emissions Development Centre - RDE Limit cycle for trip dynamics and cumulative positive gradient MAHLE supplementing the current RDE capability in Q with the Real Driving Emissions Centre - Fully climatic -40 C to +50 C - Full hypobaric chamber m - 4WD facility MAHLE 12

13 Decel. fuel shut-off - Engine Operation

14 Decel. fuel shut-off with restart of combustion

15 Prolonged Acceleration (Engine Operation) High engine torque Low engine speed Scavenging employed

16 Prolonged Acceleration (Fast NO) 0% conversion when no reductants are present. Fresh air from scavenging event skews Lambda lean Scavenged oxygen strips reductants from catalyst Oxygen storage limit reached. Breakthrough occurs.

17 Prolonged Acceleration (Tailpipe Emissions) Enhanced clarity of emissions transients.

18 Speed bump Euro 4 gasoline

19 Euro 5 diesel 19

20 TfL West London route emissions overview

21 Piccadilly NOx

22 Piccadilly

23 Joining M1

24 Joining M1 24

25 Euro 6 diesel 25

26 Sampling point post-scr 26

27 Cambridge RDE route 27

28 General overview test 1 - Urban 28

29 RDE cumulative NO and NOx test 1 - Urban NO 2 was about 1/2 of total cumulative NOx High levels at start and end of urban Cumulative NOx Cumulative NO Distance Total: g Total: g Total: km g/km g/km LIMIT: 0.08 g/km Conformity: 2.48x limit 29

30 SCR system activating from cold Large spike on vehicle s NOx sensor at wake-up 30

31 SCR NOx sensor settling time Vehicle s NOx sensor continues to over-read for a further ~700s note aftertreatment working well despite transient urban conditions 31

32 NOx breakthrough begins later on urban section

33 Aggressively-negotiated speed bumps During these harsh transients, most of NOx is NO2! (NOx-NO = NO2)

34 Effect of each urea injection pulse motorway phase

35 2017 Euro 6 gasoline plug-in hybrid (vehicle available courtesy of Byron Mason, Loughborough University) 35

36 Cambridge Air quality route 36

37 Focus on 2 major transients sections 37

38 Comparison of two transients 38

39 Cumulative mass calculated from OBD exh mass flow 39

40 Comparison of two transients in detail Engine firing frequency Lean excursion causes catalyst breakthrough 40

41 NOx breakthrough in a single street 41

42 Are vehicle comparisons valid? Variations in climate, congestion, battery state of charge etc etc will greatly affect the above treat comparisons with great care! 42

43 TfL West London Route with PHEV vehicle [NO] tailpipe (ppm) Generally very good for NOx emissions, but Trouble at Swiss Cottage and in West London over speed bumps 43

44 What to watch for in videos During accelerations, engine start delayed first by electric traction Engine switch-on causes PHEV cough Lambda shows PFI lean excursion causing NOx breakthrough Engine off/on frequently (especially over consecutive speed bumps) Best viewed with audio on (poor quality but helps perception of electric vs engine split) 44

45 Swiss Cottage 45

46 West London residential speed bumps 46

47 In conclusion RDE presents unpredictable transients Fast response analyzers can measure transient emissions and correlate these with other engine parameters Observed emissions issues are solvable using conventional means 47

48 Contact details Dr. Mark Peckham Cambustion Ltd J6 The Paddocks 347 Cherry Hinton Road Cambridge CB1 8DH United Kingdom 48