The Future of the Advanced Diesel Compression Ignition Engine R.S.G. Baert Towards Clean Diesel Engines 2011 Chester, June 8-9, 2011
some 200.000 horses and around 5000 tonnes of manure had to be removed daily emissions In 1903, London housed fallen down, will create a block which may be felt half a mile away (London, 1897) congestion an accident, such as a horse Source: G. Mom, Geschiedenis van de auto van Morgen, Kluwer, 1997 Sounds familiar? Problems in large cities such as Paris and London: Our past
Our present In 2008, automotive transportation is responsible for 31 % of all final energy consumption in the enlarged EU [1] Sources: International Energy Agency, EU White Paper Approximately 83 % of this energy is for road transport (passenger cars, powered two-wheelers and trucks/buses) Heavy duty transportation is exclusively on diesel and takes up 45 % of all energy used for road transport [1]Final energy consumption is smaller than primary energy supply, because a significant amount of primary energy is used for the production of other forms of energy. By 2050 car numbers worldwide will increase from present 750 million to more than 2.2 billion EU: 220.10 6 vehicles # vehicles % Diesel Many of them in future mega-cities # liter 64 25
Our present 2004 EU-25 road transport contribution to total emissions (%) 100 90 80 70 60 50 40 30 20 10 0 Particulate Forming Precursors NOx CO Total Ozone Forming Precursors # 1 contributor to NOx, # 2 contributor to TOFP (O3, CO, NH3, NMVOC) # 3 contributor to PM10, # 2 contributor to PM2.5 Increases of road transport fleet size and of vehicle weight have off-set improvements in power-train technology and fuel quality Source: EU Environmental Protection Agency
Our future Climate change concerns Concerns about dependency
Similar technology roadmap for Heavy-duty market segment Diesel powertrain efficiency improvement roadmap Light-duty market segment Our future Source: Bosch
Our future Tailpipe pollutant emissions limitation (emissions in g per kg of fuel) NOx+ HC LD-SI-Petrol LD-CI-Diesel HD-CI-Diesel CO PM NOx+H NOx+H NOx CO PM NOx CO PM C C g/kg g/kg mg/kg g/kg g/kg g/kg mg/kg g/kg g/kg g/kg mg/kg Euro3 2000.01 6,7 43,8-13,2 11,7 15,0 1174 2000.10 27,5 23,8 26,0 762 Euro4 2005.01 3,4 19,0-7,0 5,9 11,7 587 2005.10 19,3 16,7 19,0 95 Euro5 2009.09 3,0 19,0 95 5,4 4,2 11,7 117 2008.10 12,1 9,5 19,0 95 Euro6 2014.09 3,0 19,0 86 4,0 1,9 11,7 106 2013.01 3,0 2,2 19,0 48 US-Bin5 2010+ 1,6 0,6 30,6 146 US 2022 0,4 11,8 118 0,4 0,3 14,6 146 2010 2,2 1,3 99,0 64 EU 2030 0,5 48 0,7 0,6 59 2010 1,5 1,1 9,5 24 Based on emission legislation targets (in g/km respectively in g/kwh) Assuming state-of-the art fuel efficiency Long term efficiency improvements will relax the corresponding emission targets with 25 % CO can become an issue, also for diesel engines
CI CI Diesel Diesel engine engine with with EGR EGR and and high high boost boost TC TC system system DPF system system with with active active + SCR SCR aftertreatment aftertreatment + DPF regeneration system regeneration system for for NO NOxx reduction reduction Current cleanest diesel technology in production (Euro 5 / Euro V) A cleaner Diesel CI engine?
Aftertreatment technology performance CI Diesel engine with EGR and high boost TC system + DPF system with active regeneration Wall filter (90 % trapping efficiency) Trap + oxidize Open filter (50 % trapping efficiency) + SCR aftertreatment system for NO x reduction
Aftertreatment technology performance CI Diesel engine with EGR and high boost TC system + DPF system with active regeneration Conversion (%) vs. T ( C) Source: Airflowcatalyst/ Eberspaecher + SCR aftertreatment system for NO x reduction
Aftertreatment technology performance CI Diesel engine with EGR and high boost TC system + DPF system with active regeneration Conversion (%) vs. T ( C) Source: TNO / Eberspaecher + SCR aftertreatment system for NO x reduction
CI Diesel engine with EGR and high boost TC system + DPF system with active regeneration + SCR aftertreatment system for NO x reduction NOx HD Engine-out 0,20 g/kwh 0,67 g/kwh NOx LD Engine-out 0.25 g/kwh 0,83 g/kwh NOx Engine-out 1.0 g/kg 3.33 g/kg ηscr 50% 85% NOx Tailpipe 0.50 g/kg 0.50 g/kg PM HD Engine-out 0.10 g/kwh 0.20 g/kwh PM LD Engine-out 0.125 g/kwh 0.25 g/kwh PM Engine-out 0.50 g/kg 1.00 g/kg ηdpf 90% 90% PM Tailpipe 50 mg/kg 100 mg/kg! These are worst case numbers (i.e. for HD)!! With TNO closed-coupled additional SCR catalyst even higher NO-reduction is achieved!!no 2 negative effect on ozone formation / air quality is over-weighted!
Clean-enough CI combustion through: - O 2 (%v) reduction below 16 towards 15 % (through EGR dilution) for NO-reduction - λ> 1.2-1.3 to supply sufficient oxygen mass for soot oxidation Proven concept from 2 up to 18 bar bmep 20 18 16 14 12 10 10 20 30 40 50 60 EGR (%m) 1 1,2 1,4 1,6 1,8 2 λ O2 (%v) - Sufficiently high injection pressure (200-250 MPa) for fast, low-soot combustion at low λ
CI Diesel engine with EGR and high boost TC system Challenge 1: to realize appropriate EGR/AFR/T IVC conditions across the real-world engine operating range Light-Duty (Source IAV) Heavy-Duty (Source TNO) BUT: Trend with ICE is for strong downsizing; target of 25 bar and30 bar bmepfor LD respectively for HD ICE
CI Diesel engine with EGR and high boost TC system Challenge 1: to realize appropriate cold-egr/afr/t IVC conditions across the real-world engine operating range 4,5 4 2-stage TC 3,5 3 2,5 2 14 15 16 O 2 [%v] Boost pressure [bar] 1,5 Illustr.: 2-stage TC (source: BMW) 1 10 15 20 25 30 Bmep [bar] High boost pressure levels (2 stage turbo-charging) Increased cooling power (in particular for EGR) Air management flexibility (mixed LP and HP EGR circuitry and VNT turbo-equipment)
CI Diesel engine with EGR and high boost TC system Challenge 2: to ensure a similar (or equivalent) turbulent mixing & combustion process up to 30 bar bmep 600,0 500,0 X/dh [-] Illustration: change of spray mixing characteristics with bmepfor constant fuelling rate, in particular increasing interaction between sprays 400,0 Spray tip at EoI D.O.F. to deal with this: - SOI - Fuelling rate (injection pressure) 300,0 200,0 λ=1 HD-impact LD-impact - Multiple injections - More/smaller holes 100,0 Liquid length 0,0 10 15 20 25 30 Bmep [bar]
CI Diesel engine with EGR and high boost TC system Challenge 2: to ensure a similar (or equivalent) turbulent mixing & combustion process Path for extending bmeprange of clean CI combustion: nozzle diameter reduction Reduction below 100 μm is difficult (air utilisation limits) Source: SANDIA Realistic CI combustion range
CI Diesel engine with EGR and high boost TC system Additional challenges: multiple injections / injection rate shaping PILOT PRE MAIN AFTER POST To limit noise To control T (and NO formation) To enhance soot oxidation To ensure acceptable exhaust temperature levels
CI Diesel engine with EGR and high boost TC system Summary:Clean-enoughCI combustion demonstrated up to 18 bar bmep Further BMEP increase NO-increase (higher p max and T f ) PM increase (O 2 -deficit & increased spray/spray interaction) SOI-retard CR-reduction Injection rate control Increase injection pressure Increased boost pressure level Injection rate control Positive effect on BSFC of engine downsizing partly cancelled because of need to meet emission requirements at very high bmep
CI Diesel engine with EGR and high boost TC system Conclusion: Increased BSFC because of need to limit emissions BUT: - Unchallenged at high bmep by other concepts - At lower bmep easy-to-realize other combustion concepts might be equivalent or better; cost-effectiveness of this approach still to be confirmed - CI not as complex and less difficult to control as PCCI/HCCI
Diesel fuel quality changes A source of concern Blending of 1 st gen. biofuelsand of GTL into fossil distilate fuels HC injection DOC cc-scr SCR AMOX 11.00 10.80 10.60 10.40 10.20 10.00 Engine-out NOx WHTC cold AdBlue Combustion control as an enabling technology 1.60 1.50 1.40 1.30 Tailpipe NOx WHTC cold NOx [g/kwh] NOx [g/kwh] 1.20 9.80 1.10 EN590 US Diesel Sasol B20 B100 EN590 US Diesel Sasol B20 B100 Emissions in WHTC (World Harmonized Transient test Cycle) Source: TNO
Diesel fuel quality changes An enabling technology pathway 0.5 0.45 0.4 0.35 0.3 0.25 0.2 SW1-TP-9 SW1- DB-9 EN590 (D) EN590 (D) D-X1-9 D-X1-5 SW1-TP-9 SW1-DB-9 0% EGR 15% EGR 25% EGR 1650 rpm 8.4 bar bmep 13 CA btdcc SOI X1 = cyclohexanone/ 0.35 SW1 = Swedish Class I diesel 0.3 0.25 0.2 0.15 TPGME EN590 (D) DBM SW1-TP-9 SW1-DB-9 D-X1-5 EN590 (D) D-X1-9 D-X1-5 SW1-TP-9 SW1-DB-9 0% EGR 15% EGR 25% EGR 0.15 0.1 0.05 D-X1-5 D-X1-9 0.1 D-X1-9 0.05 0 EURO V EURO IV 0 2 4 6 8 10 NO X [g/kwh] 0 0.2 0.4 0.6 0.8 1 1.2 1.4 τ [ms] d-pm C [g/kwh] d-pm C [g/kwh] Ill.: impact of fuel oxygenation (Cyclox/ TU/e) Requires confirmation @ higher bmep
Conclusions On the chances for the CI Diesel engine The future diesel fueled CI engine will cost more and will have difficulty to meet future LD emission requirements For commercial vehicles the CI combustion concept still looks like the most likely technology path Together with new, dedicated, fuels this combustion concept would deliver an even better (economically more competitive) solution Source: FIAT
Conclusions On needs for combustion research on the CI combustion concept Need for better understanding of high bmep CI combustion Need for technology that will enable such bmep extension Need for better understanding of very late Diesel injection aimed at exhaust T management Need for further study of interaction of multiple consecutive injections Need for increased investigation into new diesel fuels