© Ricardo plc 2017
Aftertreatment and Emissions Control for Improved GHG and Air Quality
Mark Christie , Andy WardRicardo plc15 June 2017
215 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
• Introduction
• Light-duty applications
– Drivers and requirements
– Diesel technology
– Gasoline technology
• Heavy Duty
– Drivers and requirements
– Diesel technology
• Summary and Conclusions
Contents
315 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Future Propulsion Systems
Propulsion systems must meet competing needs for a wide variety of applications. Aftertreatment and emissions control technology is key to meeting these needs for thermal propulsion syste ms
FUTUREPROPULSION
SYSTEMS
* WTW - Well to wheels
Future aftertreatment andemissions control technologyshould be• High efficiency over the
widest range of feedgasproperties
• Cost effective• Enable high powertrain
efficiency• Maintain performance over
product life
415 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
WHO estimates 7 million or ~1 in 8 global deaths linked to impacts of poor air quality
Air pollution now world’s largest single environmental health risk.
515 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Air Quality – Why It Matters
Contribution of transport emissions to overall burd en of emissions
• NOx emissions in Europe are predominantly from the transport sector
• Not the case for some other pollutants where other sources dominate
Non-transport,
73%
Road transport exhaust, 10%
Road transport non-exhaust, 5%
Domestic shipping, 2%
International shipping, 10%
Transport, 27%
PM2.5
Non-transport,
42%
Road transport exhaust, 33%
Railways, 1%Domestic shipping, 4%
International shipping, 15%
Domestic aviation, 1%International aviation,
4%
Transport, 58%
NOx
Non-transport,
79%
Domestic shipping, 2%
International shipping, 19%
Transport, 21%
SOx
615 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
NOx emissions in cities and human exposure at roads ide are dominated by road transport
At the roadside transport emissions completely dominate human exposure
Legal Limit
Areas exceeding NO2 limit
• Close to roads, the contribution from road vehicles easily dominates concentrations and exposure – across the EU, road transport emissions account for 64% of NO2 concentrations
• Emissions are released at ground level where they have maximum impact
Air Quality – Why It Matters
715 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Evidence exists that roadside NO 2 has been falling, but levels are still higher than those permitted by Air Qualit y legislation
• Roadside NO2 falling but too slowly
• Not all NO2 derives from light-duty diesel vehicles, but they are seen as substantial contributors
• All diesel vehicles fitted with particulate traps since Euro 5 or earlier
– Diesel Pm emissions now lower than gasoline vehicles
Trends in raw and meteorology-adjusted NO2data – 15 London Roadside Sites
Annual mean limit value 40µg/m 3
Air Quality – Why It Matters
815 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
• Introduction
• Light-duty applications
– Drivers and requirements
– Diesel technology
– Gasoline technology
• Heavy Duty
– Drivers and requirements
– Diesel technology
• Summary and Conclusions
Contents
915 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Passenger car & LCV legislation is led by Europe an d US, with other regions currently following Planned/Implemented
Predicted Unknown
Source: Ricardo EMLEG Emissions Legislation database www.emleg.com
2005 20152010 20302020 2025
Emissions Euro 4
EPA Tier 3
Post-Euro 6Euro 5a Euro 5b Euro 6b Euro6dTEMP Euro 6d
NEDC WLTP + RDE
EPA Tier 2
2005 2010 2015 2020 2025 2030
2012-2016 CO2 limits 2017-2025 CO2 limits
EPA Tier 4
US FTP 75, SFTP (US06 cycle, SC03 cycle), HWFET
CARB LEV III (Harmonised with EPA Tier 3)
US FTP 75, SFTP (US06 cycle, SC03 cycle), HWFET
CARB LEV II
LEV II standards (2009-2016) LEV III (consistent with EPA standards, 2017-2025)
130 g(CO2)/km target (LCV-2017: 175 g(CO 2)/km) 68 – 78 g(CO2)/km 95 g(CO2)/km(LCV: 147 g(CO 2)/km )
2017 target 2022 target
Phase 1 Phase 2 Phase 3 Phase 4 (LCV: new standard from 2018)
Phase 5
Bharat Stage III Bharat Stage IV Bharat Stage VI
Indian Drive Cycle (NEDC with max speed reduced t o 90 km/h)
WLTP + RDENEDC
Indian Drive Cycle + RDE
China III China 6a China 6bChina IV China 5
Overview: Light-Duty and LCV Markets
Test cycles
CO2 / CAFC
Emissions
Test cycles
CO2 / CAFC
Emissions
Test cycles
CO2 / CAFC
Emissions
Test cycles
CO2 / CAFC
Emissions
Test cycles
CO2 / CAFC
Emissions
Test cycles
CO2 / CAFC
2020 targets
New long term
10-15 mode+11 mode
China
India
Japan
California
US-Federal
EU
RDE effective Sept 17 –WLTP proposed introduction Sept 17
Post new long term standards WLTP based standards
JC08 test cycle (with 10-15 mode until Oct 2011) WLTP + on-road testing
2015 targets2005 targets (diesel) 2010 targets (gasoline)
1015 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
• Introduction
• Light-duty applications
– Drivers and requirements
– Diesel technology
– Gasoline technology
• Heavy Duty
– Drivers and requirements
– Diesel technology
• Summary and Conclusions
Contents
1115 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Diesel Passenger Car
Post Euro 6 2020 Diesel Passenger Car Solutions
• Objective: improve the efficiency of current diesel powertrains and after-treatment technologies for multiple passenger car classifications
−Emissions capability beyond Euro 6d limits under real driving conditions
• ReWArD collaborative program initiated multiple OEMs, research institutes and suppliers involved under Ricardo leadership
• The work reported here received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 636380
Legislation CO [g/km] HC + NO X [g/km] NO X [g/km] PM [g/km] Pn [#/km]
Euro 6 0.50 0.170 0.08 0.005 6.0x1011
ReWArD 0.25 0.085 0.04 0.0025 3.0x10 11
REWARD Project Targets: RDE cycles conformity factor = 1.5
1215 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Diesel Passenger Car
Wide temperature and space velocity range of RDE cy cles limits effectiveness of current after-treatment / NO X control solutions
Low temperature during urban driving:• Limited opportunity for LNT deNOX,
PNA desorption or Adblue injection• Likely requirement for active exhaust
thermal management
High speed content of highway phase:• high temperature and space
velocities (>100 kh-1) limiting effectiveness of NOX control
systems
Urban Rural Highway
1315 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Diesel Passenger Car
The Ricardo Integrated Model Based Development allo ws a system level approach to evaluate potential solutions
A-T = after-treatment
Note: includes fuel consumption penalty
1415 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Diesel Passenger Car
A number of cycles have to be considered to capture the range of real world conditions
• Delivery and RUK City contain only urban content • RA1-140+ designed to be at the limit
• RS115 considered standard driving
• RTS95 is above the limit
Urban Rural Highway
Urban Rural Highway
1515 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Diesel Passenger Car
RDE Simulation Results: A comparison of LNT based s ystems with LNT + aSCRF
Note: NOx CFs on basis of
0.04g/km target
NOX CF results for 1.6L C-Segment
over RS115
UU
RRHH
Urban phaseUrban phase
Highway phase
Rural phase
UU
RR
HH
UU
RR HH
LNT-only based systems cannot achieve RDE conformity due to wide temperature range – aSCR required to extend range of NOX control
1615 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Diesel Passenger Car
RDE Simulation Results: Evaluation of aSCR based sys tems with exhaust thermal management
Note: NOx CFs on basis of 0.04g/km target
aSCRF NOX CF results for 1.6L C-Segment
Exhaust thermal management required during RDE urban phase and RUK Delivery for PNA
and DOC systems (management of SCRF NH3loading also beneficial)
LNT reduces low temperature NOX slip risk
and suffers lower CO2penalty (deNOX + ETM)
PNAs are suitable for fixed short cycles when
paired with HT NOXcontrol, long urban
cycles result in saturation and highly transient events risk
tailpipe NOX slip
LNT+aSCRF PNA+aSCRF DOC+aSCRF
LNT offers NOx control advantage over PNA or DOC due to improved low temperature conversion
1715 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Diesel Passenger Car
RDE Simulation Results - Summary
Clear oncost-CO2 trade-off
Note: larger area is a more favourable results
Addition of LNT to active SCR offers best fuel consumption at higher cost
1815 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Diesel Passenger Car
Cost Benefit Trade Off
CO2/oncost 1.6L C-Segment
over WLTC
CONCLUSION: LNT coupled with aSCRF offers the best emissions/cost/CO2improvement trade off
1915 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
• Introduction
• Light-duty applications
– Drivers and requirements
– Diesel technology
– Gasoline technology
• Heavy Duty
– Drivers and requirements
– Diesel technology
• Summary and Conclusions
Contents
2015 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Post Euro 6/Tier 3 Gasoline Passenger Car Solutions
Parallel paths of lean and stoichiometric now being combined with Miller Cycle
λ = 1
λ > 1
Ricardo HyBoost & Adept
� Aggressively downsize gasoline engine (50%)
Ricardo Volcano
� Stratified charge engine
� Up to 40% brake thermal efficiency
The ultimate solution will be a combination of both approaches with ‘deep’ powertrain integration
Currently in development2015�2020
Next generation engines2025�
Ricardo Research2019�
Ricardo Magma λ = 1
� Advanced valvetraintrue ‘Miller’ engine
Ricardo Magma λ > 1
� As stoichiometric but with Lean operation
Integrated Electrified Thermal
Propulsion Systems
Real World Driving NOx Perspective λ = 1• Detailed development
challenges for high power operation and low speed scavenging
Real World Driving NOx Perspective λ > 1• Significant challenges but
significant additional CO2opportunity
Gasoline Passenger Car
2115 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Gasoline Passenger Car
Comparison of Lean Combustion Strategies
Lean stratified
• Lean boosted direct injection– Lambda up to 1.5
– Conventional ignition system
• Stratified gasoline direct injection– Lambda up to 4
– Piezo-electronic injectors required
• Ultra-lean homogeneous (λ = 2)– Lambda up to 2
– Advanced ignition system
Moderate lean homogeneous Ultra-lean homogeneous
• High FC benefit
• Low engine-out NOx
• Low to medium FC benefit
• Low engine-out NOx
• High FC benefit
• Medium engine-out NOx
The challenge is emission control under lean condition
2215 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
• Project targets for WLTP NOx = 0.04 g/km [~30% engineering margin]
• The RDE the emissions limit via conformity factor (CF) of 1.5
• Project NOx CF for the aggressive RDE cycle of 1.0 [~30% engineering margin]
• N2O emissions limits outside of Euro 6d for the US and China legislation
Euro 6d and RDE Simulation Results – Lean Gasoline A ftertreatment
LegislationCO
[g/km]THC (NMHC)
[g/km]NOx
[g/km] N2O *
Euro 6d (WLTP)
1.0 0.1 (0.068) 0.06US
EPA 201210 mg/mile
Euro6d (RDE) 1.5 0.15 (0.102) 0.09China 6
202020 – 30 mg/km
* Not part of Euro 6 legislation
Gasoline Passenger Car
2315 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Gasoline Passenger Car
Advanced NOx control is required for lean operation – LNT and SCR systems provide NOx conversion capability under lean conditions, TWC is still required for stoichiometric operation
Euro 6d and RDE Simulation Results – Potential After treatment Layouts
2415 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Gasoline Passenger Car
λ = 1Warm-up
λ = lean (1.2 – 4.1)Possible lean operation
λ = 1High temperature NO x control
rich
lean
Stoichiometric exhaust temperature
Homogeneous leanexhaust temperature
Stratified leanexhaust temperature
Engine speed/load� Lean operational area
Exhaust temperature profile� Lean operational area
Engine lambda
LNT & SCRtemperature
operatingwindow
Euro 6d and RDE Simulation Results – Lambda Operatin g Regimes
2515 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Gasoline Passenger Car
Lean/stoichiometric ratio targets tailpipe NOx and defines the achievable CO2 benefit for the lean combustion strategy with aftertreatment system
λ = 1Warm-up
λ = lean (1.2 – 4.1)Possible lean operation
λ = 1High temperature NO x control
rich
lean
Engine lambda
Engine-out NOx
Close-coupled TWLNT out NOx
u/f LNT - Tailpipe NOx
lean
rich
Euro 6d and RDE Simulation Results – Lean/Stoichiome tric Ratio
2615 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Lean / stoichiometric (L/S) ratio can increases when the lean aftertreatment system NOx conversion capability increases
Lean stratifiedTwin LNT systems
Lean stratifiedSCR systems
Ultra-lean homogeneous
Twin LNT system
Lean homogeneousTwin LNT systems
Lean homogeneousSCR systems
Lean stratifiedSingle LNT systems
Lean homogeneousSingle LNT systems
Stratified
Homogeneous
Gasoline Passenger Car
Euro 6d and RDE Simulation Results – Lean/Stoichiome tric Ratio
2715 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
LEAN-S – Engine add-on costs €90 (piezo injectors)LEAN-H (λ = 2) – Engine add-on costs €150 (Advanced ignition system)aSCR w/o AdBlue consumption incl. to FC benefit
C-Segment Baseline TWC
Stratified
Homogeneous
Lean stratifiedSingle LNT systems
Lean stratifiedTwin LNT systems
Lean stratifiedSCR systems
Lean homogeneousTwin LNT systems
Lean homogeneousSCR systems
Lean homogeneousSingle LNT systems
Ultra-lean homogeneous
Twin LNT system
Euro 6d and RDE Simulation Results – Cost Benefit Su mmary
Gasoline Passenger Car
2815 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
• LNT and SCR systems produce N2O depending on amount of converted NOx and catalyst temperatures
• US and China legislations are have tight N2O emissions
– US EPA: 10 mg/mile and China 6: 20 -30 mg/km
• Simulated N2O tailpipe results need further hardware and calibration optimization
• China 6 looks feasible, unclear as yet if US limits can be met
LNT N2O emissions SCR N2O emissionsLNT CO2 benefits SCR CO2 benefits
Stratified HomogeneousStratified Homogeneous
Stratified HomogeneousStratified Homogeneous
Euro 6d and RDE Simulation Results – GHG N 2O Emissions WIP
Gasoline Passenger Car
2915 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
• Every system was able to meet Euro 6d NO x emissions limits , utilising the ability of these engines to switch to stoichiometric operation and rely on TWC operation when needed
• Lean-to-stoichiometric (L/S) time ratio , defines the fuel consumption benefit available
• Lean stratified operation has a fuel consumption benefit over moderate lean homogeneous operation, but the ultra-lean homogeneous concept has competitive fuel consumption with stratified combustion
• LNT-based aftertreatment systems offer the cost-effective approach
• Active SCR systems delivered marginally higher fuel consumption/CO 2 benefits compared to twin LNT, but also have significantly increased costs resulting in a reduced cost to benefit ratio
• LNT & SCR aftertreatment systems create N2O during NOx conversion; further hardware and calibration optimisation are required to reduce N2O emissions, but 20 mg/km limits appear to be feasible
Euro 6d and RDE Simulation Results – Summary
Gasoline Passenger Car
3015 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
• Introduction
• Light-duty applications
– Drivers and requirements
– Diesel technology
– Gasoline technology
• Heavy Duty
– Drivers and requirements
– Diesel technology
• Summary and Conclusions
Contents
3115 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Global Emissions and CO 2 legislation continue to be key drivers influencing the development of Commercial Vehicles
Emissions legislation for heavy duty vehiclesPlanned/Implemented Delayed
Predicted Unknown
Source: EMLEG, Ricardo analysis 2005 20152010 20302020 2025
Emissions
CO2 / FC
Emissions
CO2 / FC
Emissions
CO2 / FC
Emissions
CO2 / FC
EmissionsMajor cities
Nationwide
CO2 / FC
EmissionsMajor cities
Nationwide
CO2 / FC
China III Beijing VI
Phase 1
Euro V (2008)Euro IV (2005)
CO2 Monitoring
EPA 04 EPA 2007
GHG Phase 1
JP05 (2005) PLT (2009) Future regulation (2016)
PROCONVE P-5 (2006) P-7 (2012) P-8?
BS III (2005) BS IV (2010) BS VI
BS II BS IV BS VI
GHG Phase 2
CO2 Limits
P-6 (2009 – skipped)
CO2 Limits
Phase 2 Phase 3
China II
Euro VII
CO2 Phase 2
EPA 2010
China IV China V
China VChina IV (2013)China III (2008)
CO2 Limits
BS III (2007)
Euro VI (2013)
EPA 2010 Ultra-low NOx
China VI
CO2 Limits
BSV (2020 – skipped)
ULTRA LOW NOx Voluntary
Diesel Commercial Vehicle
3215 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
• Introduction
• Light-duty applications
– Drivers and requirements
– Diesel technology
– Gasoline technology
• Heavy Duty
– Drivers and requirements
– Diesel technology
• Summary and Conclusions
Contents
3315 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Ultra Low NOx (ULN) – Focus Areas and Potential Solu tions
There Are Several Key Attention Areas And
Enablers To Help Reduce NOx
Diesel Commercial Vehicle
3415 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
ULN Simulation Results – Concept Down SelectDiesel Commercial Vehicle
NOX
EMISSIONS RISK (non
NOX)
FUEL PENALTY
N2O
ROBUST/ DURAB
COST
FUTURE PROOF
LNT cDPF SCR
LNT SCRF SCR
PNA cDPF SCR
PNA SCRF SCR
SCR cDPF
SCRF SCR
AdvancedAdvancedAdvancedAdvanced High Potential
LayoutsLayoutsLayoutsLayouts For Detailed
Simulation Efforts
AdvancedAdvancedAdvancedAdvanced TechnologiesTechnologiesTechnologiesTechnologies
For Detailed Simulation
Efforts
3515 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Diesel Commercial Vehicle
Effect of Advanced Technologies on Base AT Layout: Composite Tailpipe NOx
NonNonNonNon---- Fuel PenaltyFuel PenaltyFuel PenaltyFuel Penalty
• Short mixer
• Gaseous ammonia
• Larger SCR
Fuel PenaltyFuel PenaltyFuel PenaltyFuel Penalty
• Close coupled EHC
• Smart EHC control and
optimized dosing control
Targeting ≈ 1-1.3 g/bhp-h
on HOT FTP
• X-Axis: NOx conversion during Cold FTP
• Y-Axis: NOx conversion during Hot FTP
• Z-Axis: Composite Cold-Hot FTP Tailpipe NOx in mg/bhp-h (1/7th Cold, 6/7th
Hot)
3615 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Diesel Commercial Vehicle
Advanced After-treatment Configurations with and wi thout Fuel Penalty: Composite Tailpipe NOx
TAKEAWAYSTAKEAWAYSTAKEAWAYSTAKEAWAYS
• Basic Advanced AT layouts have the potential to meet
optional NOx levels of 100 and 50mg without fuel penalty
• With fuel penalty, the advanced layouts have the
potential to meet 20mg with development margin.
• X-Axis: NOx conversion during Cold FTP
• Y-Axis: NOx conversion during Hot FTP
• Z-Axis: Composite Cold-Hot FTP Tailpipe NOx in mg/bhp-h (1/7th Cold, 6/7th
Hot)
3715 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Diesel Commercial Vehicle
Advanced After-treatment Configurations with and wi thout Fuel Penalty: Fuel Penalty
Base Layout with new Technology [no Fuel penalty]
Base Layout
Base with new Technology [Fuel Penalty ]
Advanced Layout
Advanced Layout with new Technology [no Fuel penalty]
Advanced Layout with new Technology [Fuel penalty]
0
20
40
60
80
100
120
140
160
180
200
220
240
-1 0 1 2 3 4 5 6 7 8
CO
MP
OS
ITE
FT
P [
mg/
bhp-
h]
COMPOSITE FUEL PENALTY[%]
TAKEAWAYSTAKEAWAYSTAKEAWAYSTAKEAWAYS
• Advanced technology layouts have the potential to
provide a development margin below 20mg as well
as reduce the fuel penalty
3815 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
Target TPO NOx [mg/bhp-h]
Actual TPO NOx [mg/bhp-h]
Target Fuel Penalty [%]
Fuel Penalty [%]
N2O [mg/bhp-h]
Baseline 200 159 0 0 10
Soln. A 12 12 < 3 4.2 94
Soln. B 12 11 < 3 1.7 42
Diesel Commercial Vehicle
Final Layouts: Based on the simulation results and analysis, following two concepts are recommended
SOLUTION B:Cheap, Simple, High Risk
((((optional or virtual sensor using storage model ))))
PNAPNAPNAPNA
SC
RS
CR
SC
RS
CR
NONONONOxxxx
Urea InjectorUrea InjectorUrea InjectorUrea Injector
Urea mixerUrea mixerUrea mixerUrea mixer
SCRFSCRFSCRFSCRF
TTTTTTTT
AS
CA
SC
AS
CA
SC
NHNHNHNH3333
NONONONOxxxx
EH
CE
HC
EH
CE
HC
HC DoserHC DoserHC DoserHC Doser NONONONOxxxx
TTTT
∆∆∆∆P
NHNHNHNH3333
((((optional or virtual sensor dosing volume and
NOx sensor reading))))NONONONOxxxx
Urea InjectorUrea InjectorUrea InjectorUrea Injector NONONONOxxxx
EH
CE
HC
EH
CE
HC
SC
RS
CR
SC
RS
CR
NHNHNHNH3333
cDPFcDPFcDPFcDPF
TTTT
TURBOTURBOTURBOTURBO
HC DoserHC DoserHC DoserHC Doser
TTTT
∆∆∆∆P
SOLUTION A:Low risk, Complex
3915 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
• Introduction
• Light-duty applications
– Drivers and requirements
– Diesel technology
– Gasoline technology
• Heavy Duty
– Drivers and requirements
– Diesel technology
• Summary and Conclusions
Contents
4015 June 2017For Wisconsin ERC Symposium © Ricardo plc 2017
• Aftertreatment systems continue to evolve to support the reduction of GHG and emissions that support high efficiency powertrain yet operate effectively over a wide range of feed gas conditions
• Predictive methods, capable of simulating RDE scenarios are key in developing compliant systems whilst simultaneously understanding CO2 trade-offs
• Light Duty Diesel aftertreatment configurations have been identified that can meet future conformation factors of 1.5.
• Lean gasoline aftertreatment systems show good potential to meet constituent emissions and initial work has suggests N2O emissions can be reduced to meet China 6 standards however more work is required before conclusions can be drawn for US standards
• The heavy duty on highway market faces 90% reduction in NOx emissions, work to date suggest that this can be met with advanced configurations but not without a CO2penalty
Summary and Conclusions
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