After Treatment System to meet BS-6 Emission Norms for Two Wheelers

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1 After Treatment System to meet BS-6 Emission Norms for Two Wheelers Dinesh K Gogia Air Purification-Automotive Page 1

2 BS-6 Norms for 2W Vehicle Class CO mg/k m THC mg/ km NOx mg/ km NMHC mg/ km All Classes DF V1 Limit with DF PM mg/ km 4.5* * OBD-II EVAP g/test Durabi lity (km) K **For GDI engines only BS-4 THC+NOx : 790 mg/km NOx : 390 mg/km Page 2

3 WMTC-Class 1 & 2.1 Carburetor % 24% BS-IV 300 BS-IV cat Nox, mg/km % % % BS-VI 50 92% BS-VI, DF-V , CO mg/km HC mg/km 100 NMHC : 96% Page 3

4 WMTC-Class 2.2, 200 CC EFI 96% % NOx, mg/km BS-IV % BS-4/ Euro-III Cat 78% BS-VI ' CO mg/km HC, mg/km BS-VI,DF-V1 74% 86% NMHC:94% 0.39 Page 4

5 WMTC-Class 3.2, Euro-IV 97% % 350 Raw Emission, g/km NOx, mg/km Euro IV Cat % % BS-VI ' CO mg/km HC, mg/km BS-VI,DF-V1 89% 88% 0.44 NMHC:95% Page 5

6 BS-6 Norms for 2W mg/km Pollutant BS-6 Norms Eng. Target 70% of Norms with DF Typical Conversion Efficiency Requirement CC 200 CC 300 CC WMTC 2.1 WMTC 2.2 WMTC 3.2 CO NMHC NOx Most Stringent Target is for NMHC Page 6

7 Difference Between 2W & 4W Emission control Same BS-6 emission Norms for 2 & 4 wheeler, driving cycles are different Weightage Factor Vehicle Cold Phase Hot Phase Two Wheelers WMTC Class 1, 2.1 & 2.2 Four Wheeler (Estimated) 50% 50% 38% 62% Pre cat temperature plays a major role in HC conversion. In case of 4W, catalyst is close to exhaust manifold compared to 2W in most of cases. Two wheelers being a single cylinder engine, effective SV are higher Hence the ratio of cat/engine volume is higher compared to 4W. Page 7

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9 Catalyst / Engine Parameters influencing HC Emissions Page 9

10 Effect of Cell Density on Emission cpsi 600 cpsi 900 cpsi Mass emission, g/km CO/10 THC NOx PGM Loading in all the catalyst is same HC conversion increases with cpsi Page 10

11 Impact of PGM content on HC emissions- Two wheeler Mass Emissions, mg/km BS-6 Engg Target 0.23 g PGM 0.36 g PGM PGM, g 0.48 g/pgm 0.57 g PGM Higher PGM helps to meet NMHC emission Meeting NMHC require higher volume of substrate, higher PGM & Optimized WC Chemistry Page 11

12 Oxygen Storage capacity (+3) (+4) Lean Ce 2 O 3 + ½ O 2 2 CeO 2 (+4) (+3) Rich 2 CeO 2 + CO CO 2 + Ce 2 O 3 Ce 2 O 3 captures excess O 2, that would have escape to tail pipe and saves it when in short supply. O 2 storage enhances the CO NO reduction Page 12

13 Impact of Catalyst Location / Pre Cat Temp and HC emission Close Loop EFI WMTC Class 2.1 Catalyst Std Location : mm Catalyst Close Location: ~ 200 mm Page 13

14 Effect of Secondary Air Secondary air benefit depends on ; Engine design and operating parameters engine out emissions Exhaust Gas temperature Mixing process of reactants with Secondary Air Mixture residence time inside the exhaust port and manifold The system operates during the warm-up of catalyst Duration of operation depends on engine temperature After the A/F system is active, SAS is deactivated by engine controller Typical Secondary Air System Ref: Tech. for zero Ems veh. By F. Zhao Page 14

Location of Air Injection HC g/km 0.20 0.15 0.10 0.05 0.00 0.

15 Location of Air Injection HC g/km Without Air injection Location of Air Injection Page 15

16 TYPICAL EVENT AND TIME HISTORY OF TEMP AND HC CONCENTRATION WITH SAS Normalized HC Concentration Catalyst temperature Exhaust temperature Secondary Air On Secondary Air Off HC concentration Time (Sec) Temperature ( o C) Engine starts at 5 s HC spike associated with fuel enrichment for good startability Around 8 s thermal oxidation begins after SAS is ON, HC concentration drops considerably Exhaust temp and catalyst temp. increases as Secondary air continues. This trend continues during idling. Page 16

17 Strategy to Meet BS 6 Norms : Engine Electronic Fuel Injection with close loop lambda control Catalyst Configuration Pre cat and main body cat in most of the cases. Pre cat temp. to exceed 300 C temperature in first 150 Main body TWC catalyst will be targeted to reduce NOx. Optimised secondary air introduction during cold start may help to reduce HC emission Page 17

18 BS-6 : Strategies to control cold-start HC - Catalyst Thermally stable oxidation catalyst close to the engine Lower light-off Higher catalyst size Higher cpsi,& Structured substrates OSC & OBD-II Compliance To reduce overall PGM content, - Layering/Zone catalyst coating architecture Page 18

19 OBD-II Strategy Page 19

20 OBD OBD systems for emission control shall have the capability of identifying the likely area of malfunction by means of fault codes stored in the computer memory Monitoring Items OBD-2 Circuit continuity for all emission related powertrain component (if equipped Distance Travelled since MIL (malfunction indicator lamp) ON Electrical disconnection of Electronic Evaporative purge control device ( if equipped & if active) Catalytic Converter Monitoring EGR system Monitoring Misfire Detection Oxygen Sensor Deterioration Page 20

21 OBD-2 Emission thresholds for BS-VI Vehicle Class OBD-2 Stage Gasoline Type CO g/km NMHC g/km NOx g/km Class -1 & 2-1 (BS-VI Norm) Class- 2-2 (BS-VI Norm) Class & 3-2 (BS-VI Norm) 1.90 (1.00) 1.90 (1.00) 1.90 (1.00) (0.100) (0.100) (0.100) 0.30 (0.060) 0.30 (0.060) 0.30 (0.060) PM g/km Page 21

22 Downstream Oxygen Sensor Signal Upstream O2 Signal Downstream O2 Signal Remarks Limit Good Limit Bad Catalyst Monitoring by Downstream O2 sensor differentiate good and bad catalyst With aged (bad) catalyst, downstream O2 signal indicates deterioration of OSC Page 22

OSC measurement on synthetic Gas Rig L L L L Space

5 cycles; 120sec settling time R R R Time R R Pre

23 OSC measurement on synthetic Gas Rig L L L L Space Velocity (hr -1 ) per catalyst: 60k Temperature Setting 475 C Cycle Timing 120 sec/120 sec R/L/R/L/R/L/R/L/R/.. Duration: 4.5 cycles; 120sec settling time R R R Time R R Pre cat heated O 2 sensor Post cat heated O 2 sensor Monolithic Catalysts To FTIR

24 OSC on Catalyst CO2 formation i.e. O2 utilization Delay due to O 2 sorption CO2 formation i.e. O2 utilization Delay due to O 2 sorption O cat O cat

25 Methodology for OSC Estimation OSC has been estimated by measuring the area between the pre_cat lambda signal to post cat lambda signal. Pre Cat signal Fresh catalyst area is considered as 100 and aged catalyst area has been reported % to the fresh catalyst Fresh Catalyst Area = F Aged Catalyst Area =A OSC %= A / F*100 Page 25

of Cylinder : 4 Rated power : 87 @ 6000 rpm Magic Box : to change A/F Air

26 Engine Test Bed for Catalyst aging and OSC measurement O2 Sensor Engine Specifications Capacity : 1300 CC No. of Cylinder : 4 Rated power : 6000 rpm Magic Box : to change A/F Air Injection Intake Temperature No. of catalyst : One Close Coupled Catalyst Catalyst Bed Temp. Out Let Temperature Page 26

Qualitative OSC Studies on Engine Test Bed @ SCIL HC: 0.

078 g/km Post Fresh Cat Dummy-cat Post 100K HC: 0.

27 Qualitative OSC Studies on Engine Test SCIL HC: 0.90 g/km HC: g/km Post Fresh Cat Dummy-cat Post 100K HC: g/km Post BAD HC: 0.33 g/km Illustrates dependence of HC Emissions on Post Cat Lambda Signal Page 27

28 Hydrothermal Aging Set up Gas Mass Flow Controller Temperature Controller Gas / N2 / Water Inlet Water Flow Controller Maximum Oven Temp. : 1300 C Page 28

29 Relationship between HC and OSC Two wheeler Relative OSC % Fresh EE125T EE250T EE350T FE600T FE850T Aging Severity >>>>>> HC, mg/km With increase in Aging severity, OSC drops, resulting in increase in HC emission Page 29

30 THANK YOU Page 30

Indian Emission Norms and Leapfrogging from BS IV to BS VI and Challenges for Two Wheeler

Indian Emission Norms and Leapfrogging from BS IV to BS VI and Challenges for Two Wheeler ECT 2018 Conference by ECMA @ Hyatt Regency Pune By Mr. Harjeet Singh, (Executive Advisor Tech) Hero Motocorp Ltd