After Treatment System to meet BS-6 Emission Norms for Two ... Dinesh Kumar (Sud-Chemie).pdf · Dinesh K Gogia Air Purification-Automotive After Treatment System to meet BS-6 Emission

Page 1

Dinesh K Gogia

Air Purification-Automotive

After Treatment System to meet BS-6 Emission Norms

for Two Wheelers

Page 2

BS-6 Norms for 2W

Vehicle Class

COmg/k

m

THC mg/km

NOx mg/km

NMHC mg/km

PMmg/km

EVAP g/test

Durability

(km)

All Classes 1000 100 60 68 4.5** 1.50 35K

DF 1.3 1.3 1.3 1.3V1 Limit with DF 538 54 37 32

OBD-II 1.9 -- 0.3 0.25 0.05

**For GDI engines only

Presented at ECMA's 11th International Conference & Exhibition-2018

BS-4 THC+NOx : 790 mg/km NOx : 390 mg/km

Page 3

WMTC-Class 1 & 2.1 Carburetor

0

50

100

150

200

250

300

350

400

450

-1600 -1400 -1200 -1000 -800 -600 -400 -200 0 200 400 600

Nox

, mg/

km

, CO mg/km HC mg/km

73%

80%

72%

92%

BS-IV cat

BS-VI

24%92%

BS-IV

BS-VI, DF-V1

0.41

2.65 0.64

NMHC : 96%Presented at ECMA's 11th International Conference & Exhibition-2018

Page 4

WMTC-Class 2.2 , 200 CC EFI

0

50

100

150

200

250

300

350

400

-2200 -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 200 400 600

NO

x, m

g/km

' CO mg/km HC, mg/km

89%96% 0.92

BS-IV

BS-VI,DF-V1BS-VI

BS-4/ Euro-III Cat

2.300.39

74%

86%77%

78%

NMHC:94%Presented at ECMA's 11th International Conference & Exhibition-2018

Page 5

WMTC-Class 3.2 , Euro-IV

0

50

100

150

200

250

300

350

400

-2200 -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 200 400 600

NO

x, m

g/km

' CO mg/km HC, mg/km

96%97% 1.07

Euro –IV Cat.

BS-VI,DF-V1

2.930.44

89%

88%82%

79%

Raw Emission, g/km

BS-VI

NMHC:95%Presented at ECMA's 11th International Conference & Exhibition-2018

Page 6

Pollutant BS-6 Norms

Eng. Target 70% of Norms with DF

Typical Conversion Efficiency Requirement

100 -110 CC 200 CC 300 CC

WMTC 2.1 WMTC 2.2 WMTC 3.2

CO 1000 538 80 77 82

NMHC 68 37 96 94 95NOx 60 32 92 96 97

BS-6 Norms for 2Wmg/km

Most Stringent Target is for NMHC


Page 7

Same BS-6 emission Norms for 2 & 4 wheeler, driving cycles are different

Weightage Factor

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.

Difference Between 2W & 4W Emission control


Vehicle Cold Phase Hot PhaseTwo Wheelers WMTC

Class 1, 2.1 & 2.2 50% 50%

Four Wheeler (Estimated) 38% 62%

Page 8Presented at ECMA's 11th International Conference & Exhibition-2018

Page 9

Catalyst / Engine Parameters influencing HC Emissions


Page 10

Effect of Cell Density on Emission

• PGM Loading in all the catalyst is same• HC conversion increases with cpsi

0.08

28 0.08

9

0.06

10.07

27

0.07

3

0.05

4

0.06

49

0.06

2

0.04

2

0

0.02

0.04

0.06

0.08

0.1

CO/10 THC NOx

Mas

s em

issi

on, g

/km

400 cpsi 600 cpsi 900 cpsi


Page 11

01020304050607080

BS-6 EnggTarget

0.23 gPGM

0.36 gPGM

0.48g/PGM

0.57 gPGM

Mas

s Em

issio

ns, m

g/km

PGM, g

Impact of PGM content on HC emissions- Two wheeler

Higher PGM helps to meet NMHC emissionMeeting NMHC require higher volume of substrate,

higher PGM & Optimized WC Chemistry


Page 12

Oxygen Storage capacity

Lean Ce2O3 + ½ O2 2 CeO2

Rich 2 CeO2 + CO CO2 + Ce2O3

(+3)

(+3)

(+4)

(+4)

Ce2O3 captures excess O2, that would have escape to tail pipe and saves it when in short supply. O2 storage enhances the CO NO reduction


Page 13

Impact of Catalyst Location / Pre Cat Temp and HC emission


Close Loop EFIWMTC Class 2.1Catalyst Std Location : 400- 500 mmCatalyst Close Location: ~ 200 mm

Page 14

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

Effect of Secondary Air


Typical Secondary Air System

• 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 Ref: Tech. for zero Ems veh. By F. Zhao

Page 15

Location of Air Injection


0.19 0.15 0.140.10 0.09

0.000.050.100.150.20

WithoutAir

injection

HC g

/km

Location of Air Injection

Page 16

TYPICAL EVENT AND TIME – HISTORY OF TEMP AND HC CONCENTRATION WITH SAS

5 10 15 20 25 30 35 40 450.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Secondary Air On

Nor

mal

ized

HC

Con

cent

ratio

n

Time (Sec)

Exhaust temperatureCatalyst temperature

HC concentration

Secondary Air Off

0

200

400

600

800

Tem

pera

ture

(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 17

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

Strategy to Meet BS – 6 Norms : Engine


Page 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 19

OBD-II Strategy


Page 20

OBD

Monitoring Items OBD-2

Circuit continuity for all emission related powertrain component (if equippedDistance Travelled since MIL (malfunction indicator lamp) ONElectrical disconnection of Electronic Evaporative purge

control device ( if equipped & if active)Catalytic Converter MonitoringEGR system Monitoring

Misfire Detection

Oxygen Sensor Deterioration

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


Page 21

Vehicle Class OBD-2 Stage Gasoline

Type CO g/km NMHC g/km NOx g/km

PM g/km

Class -1 & 2-1(BS-VI Norm)

1.90(1.00)

0.250(0.100)

0.30(0.060)

0.050

Class- 2-2(BS-VI Norm)

1.90(1.00)

0.250(0.100)

0.30(0.060)

0.050

Class - 3-1 & 3-2(BS-VI Norm)

1.90(1.00)

0.250(0.100)

0.30(0.060)

0.050

OBD-2 Emission thresholds for BS-VI


Page 22

Downstream Oxygen Sensor Signal

Limit Good

Limit Bad

Upstream O2 Signal Downstream O2 Signal Remarks

Catalyst Monitoring by Downstream O2 sensor – differentiate good and bad catalyst

With aged (bad) catalyst, downstream O2 signal indicates deterioration of OSC


• 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

Time

L

R

L

R

L

R

L

R R

Space Velocity (hr-1) per catalyst: 60k

OSC measurement on synthetic Gas Rig

Monolithic Catalysts

Post cat heated O2 sensorPre cat heated O2 sensor

To FTIR


CO2 formation i.e. O2 utilization

CO2 formation i.e. O2 utilizationDelay due to

O2 sorption

Delay due to O2 sorption

Oca

t

Oca

t

OSC on Catalyst


Page 25

Methodology for OSC Estimation

• OSC has been estimated by measuring the area between the pre_cat lambda signal to post cat lambda signal.

• Fresh catalyst area is considered as 100 and aged catalyst area has been reported % to the fresh catalyst


Pre Cat signal

Fresh Catalyst Area = FAged Catalyst Area =A

OSC %= A / F*100

Page 26

Engine Test Bed for Catalyst aging and OSC measurement

Engine Specifications

Capacity : 1300 CCNo. of Cylinder : 4Rated power : 87 @ 6000 rpmMagic Box : to change A/F

No. of catalyst : One

Close Coupled Catalyst

Catalyst Bed Temp.Out Let Temperature

Air Injection

O2 Sensor

Intake Temperature


Page 27

Qualitative OSC Studies on Engine Test Bed @ SCIL Du

mm

y-ca

t

Post

BA

D

Post

Fre

sh C

at

Post

100

K

HC: 0.33 g/km

HC: 0.078 g/km

HC: 0.068 g/km

HC: 0.90 g/km

Illustrates dependence of HC Emissions on Post Cat Lambda SignalPresented at ECMA's 11th International Conference & Exhibition-2018

Page 28

Hydrothermal Aging Set up


Gas Mass Flow ControllerTemperature Controller

Water Flow Controller

Gas / N2 /

Water Inlet

Maximum Oven Temp. : 1300 C

Page 29

Relationship between HC and OSC – Two wheeler


0102030405060708090

100

Fresh EE125T EE250T EE350T FE600T FE850T

HC, m

g/km

Rela

tive

OSC

%

Aging Severity >>>>>>

With increase in Aging severity, OSC drops, resulting in increase in HC emission

Page 30

THANK YOU


Documents

After Treatment System to meet BS-6 Emission Norms for Two ... Dinesh Kumar (Sud-Chemie).pdf · Dinesh K Gogia Air Purification-Automotive After Treatment System to meet BS-6 Emission