Investigation of the Feasibility of Achieving Euro VI Heavy-Duty Diesel Emissions Limits by Advanced Emissions Controls

Transcription

1 Investigation of the Feasibility of Achieving Euro VI Heavy-Duty Diesel Emissions Limits by Advanced Emissions Controls D Bosteels, J May AECC Association for Emissions Control by Catalyst, Belgium A J Nicol, C H Such, J D Andersson, R D Sellers Ricardo UK Ltd

2 Contents Objectives and project details - Test engine and system - Optimisation potential - Protocols ETC & WHTC Results - Regulated emissions - Particle number - Conversion efficiencies - Effect of cold start and soak period - Elemental Carbon and PAH emissions Key results from all cycles Summary 2

3 Objectives of AECC heavy-duty Euro VI test programme Demonstrate the performance of an integrated emissions control system on a modern, low NOx engine. Provide data on regulated and non-regulated emissions. Compare current gravimetric and heavy-duty PMP method for particulate mass (PM). Assess heavy-duty PMP particle number methodology. Provide data on European and World-harmonised transient and steady-state test procedures. 3

4 AECC heavy-duty Euro VI test engine Engine designed for US2007, provided by an engine manufacturer - 6 cylinder 7.5 litre engine - Common rail - Turbocharged (fixed vane) - Max. injection pressure 180Mpa - Cooled lambda-feedback EGR - Original particulate filter replaced by AECC system. No modification to base engine calibration - no changes made to optimise engine-out emissions on the European cycles - engine-out emissions are as received. 4

5 Emissions control system for AECC heavy-duty Euro VI test programme Oxidation catalyst (DOC), catalyst-based wall-flow particulate filter and urea-scr with ammonia slip catalyst (ASC). Engine DOC C-DPF Urea SCR ASC 7,5 l 3,8 l 14 l 14 l 3,5 l Mixer 1m mixing length between injector and SCR face. System oven aged for 200hours at 600 o C. Bosch advanced airless urea dosing system. NOx sensors at engine-out and downstream of the SCR system (upstream as input for dosing control, second as monitor; not for closed loop control). No optimisation was undertaken. 5

6 Testing and Preconditioning procedures Triplicate tests were carried out for tailpipe emissions on each of the test cycles. Average results are presented. Single additional tests were used to measure engine-out PM, particle number and some speciation analyses. For repeatability, each day started with a cold start test. Standard end-of day preconditioning was: - mode 4 warm-up: 15 min rev/min. 560 Nm - followed by: 60 min rev/min. 700 Nm - then: 60 min rev/min. 150 Nm Following each test cycle the engine was run at a Mode 4 standardisation condition for 15 minutes. Pre-test conditioning for hot cycles was: - ETC, ESC: 7.5 min. mode 4 (2130 rev/min, 560 Nm) - WHSC: 10 min. mode 9 (1816 rev/min, 373 Nm) followed by 5 min. soak. 6

7 ETC results for engine-out and tailpipe 2.0 Euro V NOx limit 10 Euro V PM limit 30mg/kWh Engine Out Tailpipe g/kwh Euro V limit (NMHC) Euro V CO limit mg/kwh NOx THC CO/10 PM PM Euro V PM limit 0.03g/kWh 7

8 ETC and WHTC tests CO & HC emissions, engine-out and tailpipe ETC, engine-0ut ETC, tailpipe WHTC, engine-0ut WHTC, tailpipe CO [g/kwh] % conversion Euro V limit 79% conversion Total HC [g/kwh] Euro V NMHC limit 63% conversion 69% conversion ETC WHTC (5 min hot soak, 10% cold weighting) 0.0 ETC WHTC (5 min hot soak, 10% cold weighting) 8

9 ETC and WHTC tests NOx emissions for engine-out and tailpipe ETC, engine-0ut ETC, tailpipe WHTC, engine-0ut WHTC, tailpipe Euro V limit NOx [g/kwh] % conversion 76% conversion ETC WHTC (5 min hot soak, 10% cold weighting) 9

10 ETC and WHTC tests PM emissions for engine-out and tailpipe ETC, engine-0ut ETC, tailpipe WHTC, engine-0ut WHTC, tailpipe Particulate Mass [g/kwh] % conversion 99.7% conversion Particulate Mass [mg/kwh] ETC WHTC (5 min hot soak, 10% cold weighting) 0.0 ETC WHTC (5 min soak, 10% cold weighting) Measurements using partial flow (mini-dilution tunnel) system 10

11 PMP particle number results for ETC & WHTC Particle measurements WERE MADE according to the latest draft of the heavy-duty PMP inter-laboratory correlation exercise guide ETC tailpipe emissions ~ 4 x /kwh DPF Efficiency > 99.9% 1.00E+15 Engine-out Tailpipe WHTC tailpipe emissions < 5 x /kwh DPF Efficiency > 99.8% 1.00E+15 Engine-out Tailpipe 1.00E E+14 particles/kwh 1.00E E+12 particles/kwh 1.00E E E E E+10 ETC 1.00E+10 WHTC (5 min. weighted hot soak, WHTC 10% cold weighting) 11

12 Conversion efficiencies for ETC and WHTC NOx THC CO PM 100% 99.8% 99.7% Conversion Efficiency 80% 60% 40% 20% 86% 63% 90% 76% 69% 79% 0% ETC WHTC (5 min soak,10% cold weighting) WHTC Non-optimised system no thermal management 12

13 Further optimisation potential Thermal Management - a heating strategy is expected to be used in future to further improve cold NOx emissions and particulate filter regeneration. System design - Component volumes and integration would be optimised for a production application. System optimisation - including urea dosing and distribution. Engine calibration. 13

14 SCR temperatures for ETC and cold WHTC WHTC Cold Start Test ETC Test Temperature at SCR inlet 400 ETC is a hot start test Temperarture [ C] EGR valve starts operating after ~570s on cold start tests Time [s] Urea injection for SCR started operating after ~800s on cold start tests The results indicate that there is potential for further improvement of emissions on cold-start cycles through thermal management 14

15 Effect of cold weighting and soak period on composite WHTC results min hot soak, 10% cold weighting 10 min hot soak, 10% cold weighting 20 min hot soak, 10% cold weighting 20 min hot soak, 14% cold weighting Emissions [g/kwh] NOx THC CO/10 PM*100 15

16 Filtration efficiency for elemental carbon Particulate filter efficiency for removal of elemental carbon is > 99%. Efficiencies for particles and elemental carbon are very similar. Filtration Efficiency For Carbon WHTC_C WHTC_H ETC ESC WHSC 16

17 PAH emissions essentially eliminated MDLT MDLT ETC results Split Ratio Split Ratio Engine-out Post-cats System ng/µl ng/µl Efficiency FLUORENE PHENANTHRENE ANTHRACENE FLUORANTHENE PYRENE > >99.95 BENZ(A)ANTHRACENE CHRYSENE BENZO(B)FLUORANTHENE BENZO(K)FLUORANTHENE BENZO(A)PYRENE BENZO(GHI)PERYLENE INDENO(1,2,3CD)PYRENE

18 NOx, PM and particle number comparisons EEV limit value EEV limit value NOx g/kwh PM g/kwh ETC WHTC Bus Cycle ESC WHSC ETC WHTC Bus Cycle ESC WHSC 100% 1.E+16 80% 1.E+15 Engine-out levels NOx conversion % 60% 40% 20% particles/kwh 1.E+14 1.E+13 1.E+12 1.E+11 0% 1.E+10 ETC WHTC Bus Cycle ESC WHSC ETC WHTC Bus cycle ESC WHSC PM result on ESC appears due to desorption of low volatility materials in Mode

19 Summary of findings of the AECC heavy-duty Euro VI test programme A state-of-the-art engine system comprising a low emissions world engine and an emissions control system produced substantial reductions in all regulated pollutants. NOx conversion efficiencies were 86% and 76% over the ETC and EU-composite WHTC respectively, resulting in tailpipe levels of 150 and 300mg/kWh. PM conversion efficiencies were >99.5% over the ETC and EU-composite WHTC, resulting in PM tailpipe levels of 1 to 2mg/kWh when measured with the partial flow method. There is potential for further improvement of emissions through thermal management and optimised system design and engine and urea dosing calibration. 19

20 Summary of findings of the AECC heavy-duty Euro VI test programme The PMP particle number method proved very reliable even at near-ambient particle emissions levels. Engine-out particle emissions of 2.5 to 5 x /kwh were reduced to levels below /kwh at tailpipe and were essentially cycle-independent. The emissions control system reduced elemental carbon emissions by more than 99% and virtually eliminated PAH emissions. The combined engine and emissions control system met the most stringent scenarios from the Commission s Euro VI validation exercise. 20

21 PM vs NOx (ESC test) (Euro V & EEV data) PM g/kwh Euro III limits (<0.75dm 3 & >3000min -1 rated power speed) Euro III limits Euro V limits Euro IV limits AECC Euro VI tailpipe result NOx g/kwh Source: KBA data, June 2002, January 2006, March

22 Acknowledgements the OE engine manufacturer Bosch, urea dosing system supplier Yara International, urea supplier Ricardo UK and the AECC Members Thank you for your attention 22