Post on 29-Jul-2020
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
Presented at ECMA's 11th International Conference & Exhibition-2018
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
Presented at ECMA's 11th International Conference & Exhibition-2018
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
Presented at ECMA's 11th International Conference & Exhibition-2018
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
Presented at ECMA's 11th International Conference & Exhibition-2018
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
Presented at ECMA's 11th International Conference & Exhibition-2018
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
Presented at ECMA's 11th International Conference & Exhibition-2018
Page 13
Impact of Catalyst Location / Pre Cat Temp and HC emission
Presented at ECMA's 11th International Conference & Exhibition-2018
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
Presented at ECMA's 11th International Conference & Exhibition-2018
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
Presented at ECMA's 11th International Conference & Exhibition-2018
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.
Presented at ECMA's 11th International Conference & Exhibition-2018
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
Presented at ECMA's 11th International Conference & Exhibition-2018
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
Presented at ECMA's 11th International Conference & Exhibition-2018
Page 19
OBD-II Strategy
Presented at ECMA's 11th International Conference & Exhibition-2018
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
Presented at ECMA's 11th International Conference & Exhibition-2018
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
Presented at ECMA's 11th International Conference & Exhibition-2018
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
Presented at ECMA's 11th International Conference & Exhibition-2018
• 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
Presented at ECMA's 11th International Conference & Exhibition-2018
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
Presented at ECMA's 11th International Conference & Exhibition-2018
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
Presented at ECMA's 11th International Conference & Exhibition-2018
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
Presented at ECMA's 11th International Conference & Exhibition-2018
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
Presented at ECMA's 11th International Conference & Exhibition-2018
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
Presented at ECMA's 11th International Conference & Exhibition-2018
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
Presented at ECMA's 11th International Conference & Exhibition-2018