Aftertreatment and Emissions Control for Improved GHG and Air Quality. Mark Christie, Andy Ward Ricardo plc 15 June 2017

Transcription

1 Aftertreatment and Emissions Control for Improved GHG and Air Quality Mark Christie, Andy Ward Ricardo plc

2 Contents Introduction Light-duty applications Drivers and requirements Diesel technology Gasoline technology Heavy Duty Drivers and requirements Diesel technology Summary and Conclusions 2

3 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 systems * WTW - Well to wheels FUTURE PROPULSION SYSTEMS Future aftertreatment and emissions control technology should be High efficiency over the widest range of feedgas properties Cost effective Enable high powertrain efficiency Maintain performance over product life 3

4 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. 4

5 Air Quality Why It Matters Contribution of transport emissions to overall burden of emissions NOx PM 2.5 Nontransport, 42% Transport, 58% Road transport exhaust, 33% Railways, 1% Domestic shipping, 4% International shipping, 15% Domestic aviation, 1% International aviation, 4% Nontransport, 73% Transport, 27% Road transport exhaust, 10% Road transport nonexhaust, 5% Domestic shipping, 2% International shipping, 10% SOx Nontransport, 79% Transport, 21% Domestic shipping, 2% International shipping, 19% NOx emissions in Europe are predominantly from the transport sector Not the case for some other pollutants where other sources dominate 5

6 Air Quality Why It Matters NOx emissions in cities and human exposure at roadside are dominated by road transport Legal Limit Areas exceeding NO 2 limit Close to roads, the contribution from road vehicles easily dominates concentrations and exposure across the EU, road transport emissions account for 64% of NO 2 concentrations Emissions are released at ground level where they have maximum impact At the roadside transport emissions completely dominate human exposure 6

7 Air Quality Why It Matters Evidence exists that roadside NO 2 has been falling, but levels are still higher than those permitted by Air Quality legislation Trends in raw and meteorology-adjusted NO 2 data 15 London Roadside Sites Roadside NO 2 falling but too slowly Not all NO 2 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 Annual mean limit value 40µg/m 3 Diesel Pm emissions now lower than gasoline vehicles 7

8 Contents Introduction Light-duty applications Drivers and requirements Diesel technology Gasoline technology Heavy Duty Drivers and requirements Diesel technology Summary and Conclusions 8

9 Overview: Light-Duty and LCV Markets Passenger car & LCV legislation is led by Europe and US, with other regions currently following Planned/Implemented Predicted Unknown EU Emissions Euro 4 Test cycles CO 2 / CAFC Euro 5a Euro 5b Euro 6b Euro6dTEMP Euro 6d NEDC Post-Euro 6 RDE effective Sept 17 WLTP + RDE WLTP proposed introduction Sept g(co 2 )/km 130 g(co 2 )/km target (LCV-2017: 175 g(co 2 )/km) (LCV: 147 g(co 2 )/km ) g(co 2 )/km Emissions EPA Tier 2 EPA Tier 3 EPA Tier 4 US-Federal Test cycles CO 2 / CAFC US FTP 75, SFTP (US06 cycle, SC03 cycle), HWFET CO 2 limits CO 2 limits Emissions CARB LEV II CARB LEV III (Harmonised with EPA Tier 3) California Test cycles CO 2 / CAFC US FTP 75, SFTP (US06 cycle, SC03 cycle), HWFET LEV II standards ( ) LEV III (consistent with EPA standards, ) Emissions New long term Post new long term standards WLTP based standards Test cycles mode+11 mode JC08 test cycle (with mode until Oct 2011) WLTP + on-road testing Japan CO 2 / CAFC 2005 targets (diesel) 2010 targets (gasoline) 2015 targets 2020 targets Emissions Bharat Stage III Bharat Stage IV Bharat Stage VI India Test cycles CO 2 / CAFC Indian Drive Cycle (NEDC with max speed reduced to 90 km/h) Indian Drive Cycle + RDE 2017 target 2022 target Emissions China III China IV China 5 China 6a China 6b China Source: Ricardo EMLEG Emissions Legislation database Test cycles CO 2 / CAFC Phase 1 Phase 2 Phase 3 Phase 4 (LCV: new standard from 2018) NEDC Phase 5 WLTP + RDE 9

10 Contents Introduction Light-duty applications Drivers and requirements Diesel technology Gasoline technology Heavy Duty Drivers and requirements Diesel technology Summary and Conclusions 10

11 Diesel Passenger Car Post Euro Diesel Passenger Car Solutions Objective: improve the efficiency of current diesel powertrains and aftertreatment 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 Legislation CO [g/km] HC + NO X [g/km] NO X [g/km] PM [g/km] Pn [#/km] Euro x10 11 ReWArD x10 11 REWARD Project Targets: RDE cycles conformity factor =

12 Diesel Passenger Car Wide temperature and space velocity range of RDE cycles limits effectiveness of current after-treatment / NO X control solutions Low temperature during urban driving: Limited opportunity for LNT deno X, PNA desorption or Adblue injection Likely requirement for active exhaust thermal management Urban Rural Highway High speed content of highway phase: high temperature and space velocities (>100 kh -1 ) limiting effectiveness of NO X control systems 12

13 Diesel Passenger Car The Ricardo Integrated Model Based Development allows a system level approach to evaluate potential solutions Note: includes fuel consumption penalty A-T = after-treatment 13

14 Diesel Passenger Car A number of cycles have to be considered to capture the range of real world conditions Urban Rural Highwa y Urban Rural Highwa y Delivery and RUK City contain only urban content RA designed to be at the limit RS115 considered standard driving RTS95 is above the limit 14

15 Diesel Passenger Car RDE Simulation Results: A comparison of LNT based systems with LNT + ascrf NO X CF results for 1.6L C-Segment over RS115 U Highway phase Urban phase R H Rural phase U H R U H R Note: NOx CFs on basis of 0.04g/km target LNT-only based systems cannot achieve RDE conformity due to wide temperature range ascr required to extend range of NOX control 15

16 Diesel Passenger Car RDE Simulation Results: Evaluation of ascr based systems with exhaust thermal management ascrf NO X 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 NH 3 loading also beneficial) LNT reduces low temperature NO X slip risk and suffers lower CO 2 penalty (deno X + ETM) PNAs are suitable for fixed short cycles when paired with HT NO X control, long urban cycles result in saturation and highly transient events risk tailpipe NO X slip Note: NOx CFs on basis of 0.04g/km target LNT+aSCRF PNA+aSCRF DOC+aSCRF LNT offers NOx control advantage over PNA or DOC due to improved low temperature conversion 16

17 Diesel Passenger Car RDE Simulation Results - Summary Clear oncost-co2 trade-off Addition of LNT to active SCR offers best fuel consumption at higher cost Note: larger area is a more favourable results 17

18 Diesel Passenger Car Cost Benefit Trade Off CO 2 /oncost 1.6L C-Segment over WLTC CONCLUSION: LNT coupled with ascrf offers the best emissions/cost/co 2 improvement trade off 18

19 Contents Introduction Light-duty applications Drivers and requirements Diesel technology Gasoline technology Heavy Duty Drivers and requirements Diesel technology Summary and Conclusions 19

20 Gasoline Passenger Car Post Euro 6/Tier 3 Gasoline Passenger Car Solutions Parallel paths of lean and stoichiometric now being combined with Miller Cycle Real World Driving NOx Perspective λ = 1 Detailed development challenges for high power operation and low speed scavenging λ = 1 Currently in development Ricardo Research 2019 Ricardo Magma λ = 1 Advanced valvetrain true Miller engine Next generation engines 2025 Integrated Electrified Thermal Propulsion Systems Ricardo HyBoost & Adept Aggressively downsize gasoline engine (50%) Ricardo Volcano Stratified charge engine λ > 1 Up to 40% brake thermal efficiency Real World Driving NOx Perspective λ > 1 Significant challenges but significant additional CO 2 opportunity Ricardo Magma λ > 1 As stoichiometric but with Lean operation The ultimate solution will be a combination of both approaches with deep powertrain integration 20

21 Gasoline Passenger Car Comparison of Lean Combustion Strategies Lean stratified Stratified gasoline direct injection Lambda up to 4 Piezo-electronic injectors required Moderate lean homogeneous Lean boosted direct injection Lambda up to 1.5 Conventional ignition system Ultra-lean homogeneous Ultra-lean homogeneous (λ = 2) Lambda up to 2 Advanced ignition system High FC benefit Medium engine-out NO x Low to medium FC benefit Low engine-out NO x High FC benefit Low engine-out NO x The challenge is emission control under lean condition 21

22 Gasoline Passenger Car Euro 6d and RDE Simulation Results Lean Gasoline Aftertreatment Project targets for WLTP NO x = 0.04 g/km [~30% engineering margin] The RDE the emissions limit via conformity factor (CF) of 1.5 Project NO x CF for the aggressive RDE cycle of 1.0 [~30% engineering margin] N 2 O emissions limits outside of Euro 6d for the US and China legislation Legislation Euro 6d (WLTP) CO [g/km] THC (NMHC) [g/km] NO x [g/km] (0.068) 0.06 Euro6d (RDE) (0.102) 0.09 US EPA 2012 China N 2 O * 10 mg/mile mg/km * Not part of Euro 6 legislation 22

23 Gasoline Passenger Car Euro 6d and RDE Simulation Results Potential Aftertreatment Layouts Advanced NOx control is required for lean operation LNT and SCR systems provide NO x conversion capability under lean conditions, TWC is still required for stoichiometric operation 23

24 Gasoline Passenger Car Euro 6d and RDE Simulation Results Lambda Operating Regimes Exhaust temperature profile Lean operational area λ = 1 Warm-up Engine lambda λ = lean ( ) Possible lean operation Stoichiometric exhaust temperature λ = 1 High temperature NO x control lean Homogeneous lean exhaust temperature Stratified lean exhaust temperature LNT & SCR temperature operating window rich Engine speed/load Lean operational area 24

25 Gasoline Passenger Car Euro 6d and RDE Simulation Results Lean/Stoichiometric Ratio λ = 1 Warm-up λ = lean ( ) Possible lean operation Engine lambda λ = 1 High temperature NO x control lean Engine-out NO x Close-coupled TWLNT out NO x u/f LNT - Tailpipe NO x rich Lean/stoichiometric ratio targets tailpipe NO x and defines the achievable CO 2 benefit for the lean combustion strategy with aftertreatment system 25

26 Gasoline Passenger Car Euro 6d and RDE Simulation Results Lean/Stoichiometric Ratio Lean stratified Single LNT systems Lean homogeneous Single LNT systems Lean stratified Twin LNT systems Lean stratified SCR systems Stratified Homogeneous Ultra-lean homogeneous Twin LNT system Lean homogeneous SCR systems Lean homogeneous Twin LNT systems Lean / stoichiometric (L/S) ratio can increases when the lean aftertreatment system NO x conversion capability increases 26

27 Gasoline Passenger Car Euro 6d and RDE Simulation Results Cost Benefit Summary Lean stratified Twin LNT systems Lean stratified Single LNT systems Lean stratified SCR systems Lean homogeneous Single LNT systems Ultra-lean homogeneous Twin LNT system Stratified Homogeneous Lean homogeneous SCR systems Lean homogeneous Twin LNT systems C-Segment Baseline TWC 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 27

28 Gasoline Passenger Car Euro 6d and RDE Simulation Results GHG N 2 O Emissions WIP LNT and SCR systems produce N 2 O depending on amount of converted NO x and catalyst temperatures US and China legislations are have tight N 2 O emissions US EPA: 10 mg/mile and China 6: mg/km Simulated N 2 O tailpipe results need further hardware and calibration optimization China 6 looks feasible, unclear as yet if US limits can be met LNT CO 2 benefits Stratified Homogeneous SCR CO 2 benefits Stratified Homogeneous LNT N 2 O emissions Stratified Homogeneous SCR N 2 O emissions Stratified Homogeneous 28

29 Gasoline Passenger Car Euro 6d and RDE Simulation Results Summary 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 N 2 O during NO x conversion; further hardware and calibration optimisation are required to reduce N 2 O emissions, but 20 mg/km limits appear to be feasible 29

30 Contents Introduction Light-duty applications Drivers and requirements Diesel technology Gasoline technology Heavy Duty Drivers and requirements Diesel technology Summary and Conclusions 30

31 Diesel Commercial Vehicle Global Emissions and CO 2 legislation continue to be key drivers influencing the development of Commercial Vehicles Emissions legislation for heavy duty vehicles Planned/Implemented Predicted Delayed Unknown Emissions Euro IV (2005) Euro V (2008) Euro VI (2013) Euro VII CO 2 / FC CO 2 Monitoring CO 2 Limits Emissions EPA 04 EPA 2007 EPA 2010 EPA 2010 Ultra-low NOx CO 2 / FC ULTRA LOW NOx Voluntary GHG Phase 1 GHG Phase 2 Emissions JP05 (2005) PLT (2009) Future regulation (2016) CO 2 / FC CO 2 Limits CO 2 Phase 2 Emissions CO 2 / FC PROCONVE P-5 (2006) P-7 (2012) P-8? P-6 (2009 skipped) CO 2 Limits Emissions Major cities Nationwide CO 2 / FC BS III (2005) BS IV (2010) BS VI BS II BS III (2007) BS IV BS VI BSV (2020 skipped) CO 2 Limits Emissions Major cities China III China IV China V Beijing VI Nationwide China II China III (2008) China IV (2013) China V China VI CO 2 / FC Phase 1 Phase 2 Phase Source: EMLEG, Ricardo analysis 31

32 Contents Introduction Light-duty applications Drivers and requirements Diesel technology Gasoline technology Heavy Duty Drivers and requirements Diesel technology Summary and Conclusions 32

33 Diesel Commercial Vehicle Ultra Low NOx (ULN) Focus Areas and Potential Solutions There Are Several Key Attention Areas And Enablers To Help Reduce NOx 33

34 Diesel Commercial Vehicle ULN Simulation Results Concept Down Select FUTURE PROOF NOX EMISSIONS RISK (non NOX) COST ROBUST/ DURAB FUEL PENALTY N2O LNT LNT PNA PNA Advanced Technologies For Detailed Simulation Efforts cdpf SCRF cdpf SCRF SCR SCRF SCR SCR SCR SCR cdpf SCR Advanced High Potential Layouts For Detailed Simulation Efforts 34

35 Diesel Commercial Vehicle Effect of Advanced Technologies on Base AT Layout: Composite Tailpipe NOx Non- Fuel Penalty Short mixer Gaseous ammonia Larger SCR Fuel Penalty Close coupled EHC Smart EHC control and optimized dosing control Targeting 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 (1/7 th Cold, 6/7 th Hot) 35

36 Diesel Commercial Vehicle Advanced After-treatment Configurations with and without Fuel Penalty: Composite Tailpipe NOx TAKEAWAYS 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 (1/7 th Cold, 6/7 th Hot) 36

37 Diesel Commercial Vehicle Advanced After-treatment Configurations with and without Fuel Penalty: Fuel Penalty 240 COMPOSITE FTP [mg/bhp-h] Base Layout Base Layout with new Technology [no Fuel penalty] Advanced Layout Advanced Layout with new Technology [no Fuel penalty] TAKEAWAYS Advanced technology layouts have the potential to provide a development margin below 20mg as well as reduce the fuel penalty Advanced Layout with new Technology [Fuel penalty] 20 0 Base with new Technology [Fuel Penalty ] COMPOSITE FUEL PENALTY[%] 37

38 Diesel Commercial Vehicle Final Layouts: Based on the simulation results and analysis, following two concepts are recommended T Urea mixer T P NH 3 T NO x PNA SCRF EHC SCR ASC HC Doser NO x NO x Urea Injector (optional or virtual sensor using storage model ) SOLUTION A: Low risk, Complex Target TPO NOx [mg/bhp-h] Actual TPO NOx [mg/bhp-h] Target Fuel Penalty [%] Fuel Penalty [%] N 2 O [mg/bhp-h] Baseline Soln. A < Soln. B < SOLUTION B: Cheap, Simple, High Risk (optional or virtual sensor dosing volume and NOx sensor reading) NH 3 T NH 3 T P NO x TURBO EHC SCR cdpf Urea Injector NO x HC Doser 38

39 Contents Introduction Light-duty applications Drivers and requirements Diesel technology Gasoline technology Heavy Duty Drivers and requirements Diesel technology Summary and Conclusions 39

40 Summary and Conclusions 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 CO 2 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 N 2 O 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 CO 2 penalty 40