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Fuels, After-treatment and Controls

Fuels, After-treatment and Controls 21
Part 9: Fuels, Aftertreatment and Controls Reciprocating Internal Combustion Engines Prof. Rolf D. Reitz Engine Research Center University of WisconsinMadison 2014 PrincetonCEFRC Summer School on Combustion Course Length: 15 hrs (Mon. Fri., June 23 – 27, 2014) Copyright ©2014 by Rolf D. Reitz. This material is not to be sold, reproduced or distributed without prior written permission of the owner, Rolf D. Reitz. 1 1 CEFRC9 J CEFRC5 une 29, 9, 2014 2012 Part 9: Fuels, Aftertreatment and Controls Short course outine: Engine fundamentals and performance metrics, computer modeling supported by indepth understanding of fundamental engine processes and detailed experiments in engine design optimization. Day 1 (Engine fundamentals) Part 1: IC Engine Review, 0, 1 and 3D modeling Part 2: Turbochargers, Engine Performance Metrics Day 2 (Combustion Modeling) Part 3: Chemical Kinetics, HCCI SI Combustion Part 4: Heat transfer, NOx and Soot Emissions Day 3 (Spray Modeling) Part 5: Atomization, Drop Breakup/Coalescence Part 6: Drop Drag/Wall Impinge/Vaporization/Sprays Day 4 (Engine Optimization) Part 7: Diesel combustion and SI knock modeling Part 8: Optimization and Low Temperature Combustion Day 5 (Applications and the Future) Part 9: Fuels, Aftertreatment and Controls Part 10: Vehicle Applications, Future of IC Engines 2 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Tamagna, 2007 Dempsey, 2014 Fuels advanced combustion strategies Engine PRF fuels used: nheptane isooctane Base Engine GM 1.9L Diesel HCCI: Dualfuel allows CA50 to be varied with fixed Geometric 17.3 intake temperature. Compression Ratio Piston Bowl Shape RCCI PPC: A gasolinelike reactivity of PRF 94 chosen for both port injection and direct injection – i.e., single Displacement 0.477 L fuel PPC. Bore/Stroke 82.0 / 90.4 mm RCCI: Port injected neat isooctane and direct IVC/EVO 132°/112° ATDC injected nheptane. Swirl Ratio 1.5 Port Fuel Injectors Model Number TFS890551 DI fuel Inj. Press. 2.5 to 3.5 bar Rated Flow 25 kg/hr. Common Rail Injector Fuel Injector HCCI PPC RCCI Model Bosch CRI2.2 Port Injector 1 PRF 75 PRF 94 PRF 100 Number of Holes 7 Hole Diameter 0.14 mm Port Injector 2 PRF 100 PRF 94 PRF 100 Included Angle 148° DI Injector PRF 94 PRF 0 Fixed Inj. Press. 500 bar 3 CEFRC59, 2014 AHRR J/deg Part 9: Fuels, Aftertreatment and Controls Dempsey, 2014 Controllability of advanced combustion strategies Baseline operating condition (5.5 bar IMEP 1500 rev/min) Single DI injections for PPC RCCI Ultralow NOx emissions and high GIE Inputs HCCI PPC RCCI RCCI has highest GIE, but lowest η , comb Pin bar 1.3 1.3 1.3 suggesting lower HT losses (lower PPRR) Tin C 50 70 50 Fuel stratification with PPC results in higher PPRR compared to HCCI Premixed Fuel 100 79.1 92.6 (c.f., Dec et al. 2011 low intake pressure ( 2 bar)) Global PRF 93 94 92.6 250 HCCI Baseline DI Timing °ATDC 65° 45° 90 225 RCCI Baseline 80 PPC Baseline Global Phi 0.33 0.34 0.33 200 70 175 Results HCCI PPC RCCI 60 150 CA50 °ATDC 3.5 2.5 2.2 50 125 40 100 Gross Ind. Eff. 47.1 45.6 47.5 30 75 Comb. Eff. 92.8 93.1 91.5 20 50 NOx g/kgfuel 0.05 0.05 0.05 10 25 0 0 PPRR bar/° 14 16 5.8 20 15 10 5 0 5 10 15 20 Crank Angle ATDC 4 CEFRC59, 2014 Pressure barAHRR J/deg AHRR J/deg AHRR J/deg 100 300 HCCI Part 9: Fuels, Aftertreatment and Controls 275 90 HCCI 250 80 225 +10 C Sensitivity to intake temperature 70 200 10 C 60 175 • Each strategy is predominantly controlled by 50 150 chemical kinetics  sensitive to temperature 125 40 Baseline 100 30 75 +10 C 5 20 50 Intake HCCI 10 C 10 4 Temperature RCCI 25 Sensitivity PPC 0 0 3 100 10 7.5 5 2.5 0 2.5 5 7.5 10 12.5 15 300 PPC Crank Angle ATDC 90 PPC 2 250 80 DT 1 +10 C 10 C 70 200 0 60 50 150 1 Baseline 40 DT 2 100 30 +10 C 20 3 50 10 C 15 10 5 0 5 10 15 10 Delta Tin C 0 0 100 160 10 7.5 5 2.5 0 2.5 5 7.5 10 12.5 15 • To assess controllability of strategies, try to RCCI Crank Angle ATDC 90 RCCI 140 recover baseline CA50. 80 120 +13 C • This demonstrates combustion strategy’s ability to 70 13 C 100 60 be controlled in a real world engine on a cycleby 50 80 cycle basis (i.e., transient operation and Baseline 40 60 unpredictable environmental conditions). 30 40 20 +13 C 13 C 20 10 Dempsey, 2014 0 0 10 7.5 5 2.5 0 2.5 5 7.5 10 12.5 15 5 CEFRC59, 2014 Crank Angle ATDC Delta CA50 degrees Pressure bar Pressure bar Pressure barAHRR J/deg AHRR J/deg AHRR J/deg 100 250 HCCI 90 225 Part 9: Fuels, Aftertreatment and Controls HCCI Correct Tin Sensitivity 80 200 70 175 Ability to compensate for DT 60 150 10 C +10 C 50 125 Baseline HCCI Corrected Corrected 40 100 30 75 Global PRF 91 93 94 20 50 10 25 CA50 °ATDC 3.0 3.5 3.5 0 0 100 300 10 7.5 5 2.5 0 2.5 5 7.5 10 12.5 15 NOx g/kgfuel 0.05 0.05 0.05 Crank Angle ATDC PPC 275 90 Correct Tin Senstivity PPC 250 80 10 C +10 C 225 Baseline PPC 70 200 Corrected Corrected 60 175 Baseline Premixed Fuel 72.6 79.1 95.2 50 150 125 40 DI Timing °ATDC 36° 65° 65° 100 30 +10 C 75 +10 C 20 50 CA50 °ATDC 3.0 2.5 1.2 10 C 10 C 10 25 0 0 NOx g/kgfuel 0.63 0.05 0.05 100 10 7.5 5 2.5 0 2.5 5 7.5 10 12.5 15 120 Crank Angle ATDC RCCI 90 Correct Tin Sensitvity RCCI 13 C +13 C 100 80 Baseline RCCI Corrected Corrected 70 80 Premixed Fuel 89 92.6 94 60 50 60 DI Timing °ATDC 45° 45° 45° 40 40 30 CA50 °ATDC 1.7 2.2 2.7 20 20 10 NOx g/kgfuel 0.05 0.05 0.05 0 0 10 7.5 5 2.5 0 2.5 5 7.5 10 12.5 15 Crank Angle ATDC 6 CEFRC59, 2014 Pressure bar Pressure bar Pressure barAHRR J/deg Part 9: Fuels, Aftertreatment and Controls Dempsey, 2014 Ability to compensate for intake temperature – PPC 100 300 PPC 275 90 10 C +10 C Correct Tin Senstivity PPC Baseline PPC 250 80 Corrected Corrected 225 70 200 Premixed Fuel 72.6 79.1 95.2 60 175 Baseline 50 150 DI Timing °ATDC 36° 65° 65° 125 40 100 30 CA50 °ATDC 3.0 2.5 1.2 +10 C 75 +10 C 20 50 10 C 10 C NOx g/kgfuel 0.63 0.05 0.05 10 25 0 0 10 7.5 5 2.5 0 2.5 5 7.5 10 12.5 15 3.0 Crank Angle ATDC 3.0 78 Premixed Fuel 2.0 65 deg. ATDC 2.0 1.0 1.0 0.0 0.0 1.0 1.0 2.0 2.0 3.0 3.0 65 60 55 50 45 40 35 30 25 0.45 0.55 0.65 0.75 0.85 Premixed Fuel Fraction Direct Injection SOI deg. ATDC For PPC with PRF94, advancing SOI timing beyond 65°ATDC or increasing premixed fuel amount has no impact on combustion phasing 7 CEFRC59, 2014 Combustion Phasing (CA50) ATDC Combustion Phasing (CA50) ATDC Pressure barAHRR J/deg AHRR J/deg AHRR J/deg 300 100 HCCI Part 9: Fuels, Aftertreatment and Controls 275 HCCI 90 250 80 225 Sensitivity to intake pressure +10 kPa 70 200 10 kPa 175 60 • Critical for transient operation of turbocharged 150 50 or supercharged engines. 125 Baseline 40 100 30 • DualFuel RCCI is not as affected by intake 75 +10 kPa 20 50 pressure as HCCI or PPC. 10 kPa 10 25 0 0 • Reasons for these observations are not well 350 10 7.5 5 2.5 0 2.5 5 7.5 10 12.5 15 100 PPC Crank Angle ATDC understood and will be subject of future PPC 90 300 simulation research. 80 250 +10 kPa 6 70 HCCI 10 kPa Intake 60 200 5 RCCI Pressure 50 150 Sensitivity PPC 4 40 Baseline 30 100 10 kPa 3 20 +10 kPa 50 10 2 0 0 DP 100 120 10 7.5 5 2.5 0 2.5 5 7.5 10 12.5 15 1 RCCI Crank Angle ATDC 90 RCCI 0 100 80 +10 kPa 70 1 80 10 kPa 60 DP 2 Baseline 50 60 40 3 40 12 9 6 3 0 3 6 9 12 30 +10 kPa Delta Pin kPa 20 20 10 kPa 10 Dempsey, 2014 0 0 10 7.5 5 2.5 0 2.5 5 7.5 10 12.5 15 Crank Angle ATDC 8 CEFRC59, 2014 Delta CA50 degrees Pressure bar Pressure bar Pressure barAHRR J/deg AHRR J/deg AHRR J/deg 300 Part 9: Fuels, Aftertreatment and Controls 100 HCCI 275 HCCI 90 Correct Pin Sensitivity 250 80 225 Ability to compensate for DP 70 200 10 kPa +10 kPa 175 60 Baseline HCCI 150 Corrected Corrected 50 125 40 Global PRF 90.6 93 94.6 100 30 75 20 50 CA50 °ATDC 3.0 3.5 3.5 10 25 0 0 NOx g/kgfuel 0.05 0.05 0.05 350 10 7.5 5 2.5 0 2.5 5 7.5 10 12.5 15 100 PPC Crank Angle ATDC Correct P PPC in 90 300 10 kPa +10 kPa Sensitivity Baseline PPC 80 250 Corrected Corrected 70 60 200 Premixed Fuel 65 79.1 94.7 50 150 Baseline DI Timing °ATDC 35° 65° 65° 40 +10 kPa 30 100 CA50 °ATDC 3.2 2.5 0.5 20 50 10 kPa 10 NOx g/kgfuel 6.8 0.05 0.05 0 0 100 120 10 7.5 5 2.5 0 2.5 5 7.5 10 12.5 15 PPC unable to retard combustion with increased boost Crank Angle ATDC RCCI 90 RCCI Correct Pin Sensitivity 100 10 kPa +10 kPa 80 Baseline RCCI Corrected Corrected 70 80 60 Premixed Fuel 91.5 92.6 93.5 50 60 40 DI Timing °ATDC 45° 45° 45° 40 30 CA50 °ATDC 2.2 2.2 2.5 20 20 10 NOx g/kgfuel 0.05 0.05 0.05 0 0 10 7.5 5 2.5 0 2.5 5 7.5 10 12.5 15 Crank Angle ATDC 9 CEFRC59, 2014 Pressure bar Pressure bar Pressure barPart 9: Fuels, Aftertreatment and Controls Hanson, 2014 RCCI transient operation GM 1.9L Engine Specifications Engine Type EURO IV Diesel Bore 82 mm Stroke 90.4 mm Displacement 1.9 liters Cylinder Inline 4 Configuration 4 valves per cylinder Swirl Ratio Variable (2.25.6) Compression 17.5 Ratio Hybrid High/Low EGR System Pressure, Cooled Hydrostatic dynamometer ECU (OEM) Bosch EDC16 ECU (new) Drivven Bosch CRIP2MI Torque Dyno Common Rail 148° Included Angle Cell Injectors 7 holes, 440 flow number. Low rotating Delphi inertia Port Fuel 2.27 g/s steady flow rapid transients Injectors 400 kPa fuel pressure (2500 rpm/s) 10 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Hanson, 2014 Step load change: 1  4 bar BMEP CDC RCCI – Pre DOC PFI=77 PFI= RCCI – Post DOC 41 RCCI CDC CDC RCCI provides considerable transient control since ratio of port to direct injected fuel can be changed on a cyclebycycle basis RCCI 11 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Kokjohn, 2011 Comparison of single fuel LTC, PPC and dual fuel RCCI Three engines operating with different forms of LTC combustion 1 2 3 Case Diesel LTC Ethanol PPC DualFuel RCCI Engine Cummins N14 Scania D12 CAT 3401 Displacement (cm3) 2340 1966 2440 Stroke (mm) 152.4 154 165.1 Bore (mm) 139.7 127.5 137.2 Con. Rod (mm) 304.8 255 261 CR () 11.2 14.3:1 16.1 Swirl Ratio () 0.5 2.9 0.7 Number of nozzles 8 8 6 Nozzle hole size (μm) 196 180 250 1. Singh, CNF 2009 2. Manente, SAE 2010010871 3. D. A. Splitter, THIESEL 2010 12 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Kokjohn, 2011 Comparison with single fuel LTC Diesel LTC Single early injection at 22° BTDC 1600 bar injection pressure Liquid Fuel Diluted intake (60 EGR) Vapor Fuel Ethanol PPC Single early injection at 60° BTDC 1800 bar injection pressure No EGR Liquid Fuel Dualfuel RCCI Vapor Fuel Portfuelinjection of low reactivity fuel (gasoline or E85) Directinjection of diesel fuel Split early injections (SOI1 = 58° BTDC and SOI2 = 37° BTDC) 800 bar injection pressure Liquid Fuel Vapor Fuel 13 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Kokjohn, 2011 Dualfuel RCCI Comparison of gasolinediesel and E85 diesel dualfuel RCCI combustion 12 E85 and Diesel Fuel For fixed combustion phasing, E85diesel 10 DF RCCI exhibits significantly reduced Gasoline 8 RoHR (and therefore peak PRR) and Diesel Fuel 6 compared to gasolinediesel RCCI E85 Diesel Experiment allows higher load operation 4 E85 Diesel Simulation E85diesel RCCI combustion has larger Gasoline Diesel Experiment 2 Gasoline Diesel Simulation spread between most reactive (lowest 0 RON) and least reactive (highest RON) 700 600 0.30 E85 Diesel Gasoline Diesel 500 0.25 RON Distribution at 400 20 ATDC 0.20 300 Gasoline 0.15 200 Diesel Fuel 0.10 100 E85 0.05 0 Diesel Fuel 20 15 10 5 0 5 10 15 20 0.00 85 90 95 100 105 Crank ATDC RON 14 CEFRC59, 2014 Mass Fraction AHRR J/deg Pressure MPaPart 9: Fuels, Aftertreatment and Controls Kokjohn, 2011 Comparison between diesel LTC, ethanol PPC, and RCCI Evolution of key intermediates: Diesel LTC Diesel 0.01 Reaction progress CH2O 1E3 fuel CH O OH 2 1E4 second stage OH first stage combustion combustion 1E5 E85diesel RCCI combustion shows a Ethanol PPCI C2H5OH 0.01 staged consumption of more reactive diesel fuel and less reactive E85 1E3 OH Ethanol and gasoline are not consumed 1E4 CH2O until diesel fuel transitions to second 1E5 stage ignition DualFuel RCCI 0.01 C2H5OH E85 Diesel iC8H18 Fuel 1E3 Diesel 1E4 OH CH2O 1E5 3 2 1 0 1 2 3 Time ms ATDC 15 CEFRC59, 2014 Mole Fraction Part 9: Fuels, Aftertreatment and Controls Kokjohn, 2011 Comparison between diesel LTC, ethanol PPC, and RCCI Diesel LTC Earliest combustion phasing and most rapid energy release rate High reactivity of diesel fuel requires Diesel LTC significant charge dilution to 350 Ethanol PPCI maintain appropriate combustion 300 DualFuel RCCI phasing (12.7 Inlet O ) 2 (E85 Diesel) Ethanol PPC 250 Diesel LTC Low fuel reactivity and charge 200 cooling results in delayed combustion 150 Sequential combustion from lean DualFuel 100 Ethanol high temperature regions to rich RCCI PPCI cool regions results in extended 50 combustion duration 0 Dual fuel RCCI 3 2 1 0 1 2 3 Combustion begins only slightly Time ms ATDC later than diesel LTC Combustion duration is broad due to RCCI Engine Experiments spatial gradient in fuel reactivity Hanson SAE 2010010864 Kokjohn IJER 2011 Allows highest load operation due to Kokjohn SAE 2011010357 gradual transition from first to secondstage ignition 16 CEFRC59, 2014 AHRR Fuel Energy/msPart 9: Fuels, Aftertreatment and Controls Kaddatz, 2012 ‘Single fuel’ RCCI RCCI is inherently fuel flexible and is promising to control PCI combustion. Can similar results be achieved with a single fuel and an additive Splitter et al. (SAE 2010012167) demonstrated single fuel RCCI in a heavyduty engine using gasoline + Di SAE 2010012167 tertiaryButyl Peroxide (DTBP) 2Ethylhexyl Nitrate (EHN) is another 40 common cetane improver EPA 420B04005 ◦ Contains fuelbound NO and LTC results Extrapolated 35 have shown increased engineout NOx (Ickes et al. Energy and Fuels 2009) 30 25 Concentrations from SAE 2010012167 20 DTBP EHN 0 2 4 6 8 10 Additive Concentration Vol 17 CEFRC59, 2014 Estimated CNPart 9: Fuels, Aftertreatment and Controls Kaddatz, 2012 Comparison of E10EHN and Diesel Fuel Engine experiments performed on ERC GM 1.9L engine E10+EHN Diesel fuel and splash blended E103 SOIc = 11.25° EHN mixtures compared under Pinj = 500 bar conventional diesel conditions (5.5 bar IMEP, 1900 rev/min) Diesel Fuel – Diesel fuel injection parameters SOIc SOIc SOIc = = = 9.25 7.9 11.25 ° ° ° adjusted to reproduce combustion Pinj Pinj = = 500 bar 900 bar characteristics of E10+EHN blend Ignition Differences – Diesel fuel SOI must be retarded to match ign. (Consistent with lower CN) Mixing Differences Diesel Fuel – Diesel fuel injection pressure must be increased by 400 bar to reproduce SOIc = 11.5 Pinj = 500 bar premixed burn SOIc = 9.25 Pinj = 500 bar SOIc = 7.9 Pinj = 900 bar 18 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Kaddatz, 2012 Comparison of E10EHN and Diesel Fuel CDC operation with matched Diesel fuel and E10EHN compared under AHRR conventional diesel conditions (5.5 bar IMEP, 1900 rev/min) – Diesel fuel injection parameters adjusted to reproduce combustion characteristics of E10+EHN blend For CDC operation, E10+EHN and diesel fuel show similar NOx and soot EPA 2010 19 CEFRC59, 2014 Heat Release Rate J/deg Part 9: Fuels, Aftertreatment and Controls Kaddatz, 2012 Diesel/Gasoline and E10+EHN RCCI PFI E10 and directinjected E10+3 EHN compared to gasoline – diesel RCCI operation Operating Conditions Combustion characteristics of gasoline DI Fuel E10+EHN Diesel diesel RCCI reproduced with E10 – E10+3EHN PFI Fuel E10 Gasoline – Adjustment to PFI percentage required Net IMEP (bar) 5.5 to account for differences in ignitability Engine Speed (RPM) 1900 120 240 Premixed Fuel ( mass) 69 84 42 SOIC (degATDC) Common Rail 100 200 Gasolinediesel (84) 32 to 52 SOIc(°ATDC) E10+EHN/E10 (69) 80 160 Injection Pressure (bar) 500 800 60 120 Intake Temperature (C) 65 40 80 Boost Pressure (bar) 1.3 Swirl Ratio 1.5 20 40 EGR () 0 0 0 30 20 10 0 10 20 30 CA degATDC 20 CEFRC59, 2014 Pressure bar Part 9: Fuels, Aftertreatment and Controls Kaddatz, 2012 Performance of E10 and E10+EHN RCCI Parametric studies performed to E10/E10+EHN optimize efficiency of singlefuel E10/Diesel RCCI at 5.5 and 9 bar IMEP Using a splitinjection strategy, performance characteristics of singlefuel + additive RCCI are similar to those of dualfuel RCCI Peak efficiency data for E10/E10+EHN shows higher NOx emissions, but levels meet EPA mandates Soot is very low for all cases 21 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Kaddatz, 2012 12 Additive consumption estimate SAE 2001010151 5 10 Lightduty drive cycle average is 55 PFI Size shows relative fuel (i.e., 45 additized fuel) weighting 8 3 additive level  EHN volume is 1.4 6 4 of the total fuel volume 4 2 Similar to DEF levels 3 2 Assuming 50 mpg and 10,000 mile oil 1 change intervals, additive tank must be 0 1000 1500 2000 2500 3000 2.7 gallons Speed rev/min Assumes 50 mpg and 10,000 mile oil change interval 22 CEFRC59, 2014 IMEP bar gPart 9: Fuels, Aftertreatment and Controls Nieman, 2012 Natural gas/diesel RCCI Operating Condition Low MidLoad HighLoad Load Gross IMEP bar 4 9 11 13.5 16 23 Engine Speed rpm 800 1300 1370 1460 1550 1800 ERC KIVA PRF kinetics Intake Press. bar abs. 1.00 1.45 1.94 2.16 2.37 3.00 NSGAII MOGA 32 Citizens per Intake Temp. °C 60 60 60 60 60 60 Generation 9500 Cells BDC Caterpillar 3401E SCOTE UW Condor Displacement L 2.44 Convergence after Bore x Stroke mm 137.2 x 165.1 40 generations Con. Rod Length mm 261.6 Compression Ratio 16.1:1 Design Parameter Minimum Maximum Swirl Ratio 0.7 Premixed Methane 0 100 IVC deg ATDC 143 DI Diesel SOI 1 deg ATDC 100 50 EVO deg ATDC 130 DI Diesel SOI 2 deg ATDC 40 20 Common Rail Diesel Fuel Injector Diesel Fraction in First Inj. 0 100 Number of Holes 6 Diesel Injection Pressure bar 300 1500 Hole Diameter μm 250 o EGR 0 60 Included Spray Angle 145 23 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Nieman, 2012 GA optimized NOx, Soot, CO, UHC ISFC, PPRR 4 bar 9 bar 11 bar 13.5 bar 16 bar 23 bar Design Parameter Clean, Engine Speed rpm 800 1300 1370 1460 1550 1800 efficient Total Fuel Mass mg 40 89 109 133 158 228 Methane 73 85 87 90 87 85 operation up Diesel SOI 1 deg ATDC 52.9 87.3 87.2 79.5 81.1 92.7 to 13.5 bar Diesel SOI 2 deg ATDC 22.5 38.3 39.4 39.6 39.7 20.4 IMEP without Diesel in 1st Inj. 52 40 39 55 49 70 needing EGR Diesel Inj. Press. bar 1300 954 465 822 594 742 EGR 5 0 0 0 32 48 180° to 180° ATDC Results Soot g/ikWhr 0.004 0.002 0.002 0.002 0.003 0.079 Meet EPA 2010 NOx g/ikWhr 0.24 0.25 0.08 0.07 0.15 0.08 (except soot at CO g/ikWhr 10.8 0.2 0.9 0.8 0.5 6.0 high load) UHC g/ikWhr 10.5 0.5 2.2 2.4 1.5 9.4 η 45.1 50.4 50.6 48.9 49.2 44.1 gross High peak PPRR bar/deg 2.7 5.1 8.1 4.4 5.7 5.0 thermal 2 Ring. Intens. MW/m 0.2 1.5 2.8 1.0 1.8 1.5 efficiency Extend range to lower/high loads with triple injections Low PPRR 24 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Nieman, 2012 Comparison with gasoline/diesel RCCI Gasoline/Diesel strategy optimized at 1.75 bar abs. 9 bar IMEP (high boost) Natural Gas/Diesel used 1.45 bar abs. (low boost) Each run at both conditions Quite similar strategies Nat. Gas/ Gasoline/ Design Parameter Diesel Diesel Intake Temperature °C 60 32 Total Fuel Mass mg 89 94 LowReactivity Fuel (Premixed) 85 89 Diesel SOI 1 deg ATDC 87.3 58.0 Diesel SOI 2 deg ATDC 38.3 37.0 Diesel in 1st Inj. 40 60 EGR 0 43 25 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Nieman, 2012 Comparison with gasoline/diesel RCCI 180° to 180° ATDC N Nat. at. Gas Gas Gas Gaso olliin ne e 9 bar IMEP R Resu esullts ts Low Low H Hiig gh h Low Low H Hiig gh h Soot Soot g/ g/k kW W hr hr 0. 0.002 002 0. 0.003 003 0. 0.007 007 0. 0.014 014 N NOx Ox g/ g/k kW W hr hr 0. 0.25 25 0. 0.02 02 0. 0.02 02 0. 0.01 01 C CO O g/ g/k kW W hr hr 0. 0.2 2 1. 1.8 8 1. 1.2 2 3. 3.6 6 U UH HC C g/ g/k kW W hr hr 0. 0.5 5 2. 2.5 5 2. 2.7 7 4. 4.0 0 η η 50. 50.4 4 50. 50.4 4 52. 52.1 1 52. 52.2 2 g gro ross ss PPR PPRR R bar/ bar/deg deg 5. 5.1 1 4. 4.8 8 10. 10.6 6 9. 9.9 9 • 2 Efficiency Difference: Nat. Gas/ Gasoline/ Design Parameter Diesel Diesel Higher incyl. temps and Intake Temperature °C 60 32 comb. in squish Total Fuel Mass mg 89 94 LowReactivity Fuel (Premixed) 85 89 Diesel SOI 1 deg ATDC 87.3 58.0 Diesel SOI 2 deg ATDC 38.3 37.0 Diesel in 1st Inj. 40 60 Greater HT Losses EGR 0 43 26 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Nieman, 2012 Double vs. Triple Injection 4 bar IMEP 23 bar IMEP Results 2 Inj. Optimum 3 Inj. Optimum Results 2 Inj. Optimum 3 Inj. Optimum Soot g/kWhr 0.004 0.004 Soot g/kWhr 0.079 0.014 NOx g/kWhr 0.24 0.10 NOx g/kWhr 0.08 0.17 CO g/kWhr 10.8 7.3 CO g/kWhr 6.0 1.7 UHC g/kWhr 10.5 3.8 UHC g/kWhr 9.4 3.3 η 45.1 47.1 η 44.1 46.5 gross gross 50 50 2 Inj. Optimum 2 Inj. Optimum 45 45 3 Inj. Optimum 3 Inj. Optimum 47.1 46.5 45.1 40 40 44.1 43.0 42.4 35 35 30 30 31.9 31.5 25 25 20 20 15 15 18.7 17.1 10 10 5 5 6.3 7.9 8.5 5.6 2.4 2.0 0 0 Gross Work Exhaust Loss Heat Transfer Combustion Loss Gross Work Exhaust Loss Heat Transfer Combustion Loss 27 CEFRC59, 2014 of Fuel Energy In of Fuel Energy In Part 9: Fuels, Aftertreatment and Controls Nieman, 2012 23 bar IMEP, triple Injection Isosurface (Isosurface = 1600K) 10 12 14 16 18 2 6 4 8 0° ° ° ° ° ° ° ° ° ° A A A A A A A A A AT T T T T T T T T TDC DC DC DC DC DC DC DC DC DC rd • Can achieve low soot, despite late 3 injection o Combustion starts in squish region, so diesel 3 injects into a relatively cool environment o Fairly small amount injected 28 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Nieman, 2012 Natural gas composition effects • Optimization studies assumed nat. gas = pure methane • Ethane can also be in substantial concentration • 23 bar IMEP triple injection strategy – Replace some methane with ethane Species Name Content Methane 92 Ethane enhances combustion Ethane 3 • Increases reactivity of premix Propane 0.7 • Shortens combustion duration Butane 0.02 • Increases combustion efficiency Pentane 0.1 + C 0.1 6 Nitrogen 3 Carbon Dioxide 0.6 29 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Nieman, 2012 NG/diesel RCCI summary • Use of natural gas as the lowreactivity fuel in conjunction with diesel fuel in RCCI combustion investigated. • Modeling of NG/diesel RCCI showed good combustion phasing could be achieved over a wide range of intake temperatures. Changes in intake T can be accounted for by varying NG/diesel ratio. • MOGA has been used to develop strategies for RCCI operation from low load/lowspeed to highload/highspeed. – US 2010 HD regulations met, incylinder (require 3 injections at high load) – High NOx/soot low(er) comb. eff. observed in low and highloads – Operation controlled by NG/diesel ratio and injection schedule • MOGA studies show that utilizing triple injections extends the low and high load operating ranges – Added flexibility = decreased NOx/soot, increased combustion efficiency • Study of nat. gas composition effects shows that ethane/propane/etc. concentrations have substantial effect on reactivity of NG (i.e., comb. phasing, duration, and completeness). – Small amounts (13) enhanced combustion 30 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Prikhodko, 2010 RCCI aftertreatment requirements CDC RCCI Additional load requires EGR Experiments in collaboration with Oak Ridge National Laboratory RCCI operating range covers most of EPA FTP drive area Cooled and/or LP EGR can be used to extend max load with RCCI • UW HD engine typically gains 50100 more load with EGR (CDC 2007 Opel Astra 1.9L, data from ANL) 31 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Prikhodko, 2010 Exhaust temperature RCCI shows 50100 °C lower turbine inlet temperature than CDC Reduced exhaust availability for turbocharging and aftertreatment systems Low load operation with RCCI is a challenge with the OEM turbocharger Lower temperatures drop exhaust enthalpy, increasing pumping work and limiting thermal efficiency Improved turbomachinery exists for this engine, which could improve the performance Low EGTs in the FTP driving area are a challenge for oxidation catalyst performance Need 90+ catalyst efficiency to meet HC and CO targets, challenging with EGTs 200 ° C CDC RCCI 32 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Prikhodko, 2010 ORNL RCCI experiments SAE 2010 33 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Prikhodko, 2010 CDC, PCCI RCCI NOx and HC emissions 34 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Prikhodko, 2010 CDC, PCCI RCCI PM emissions 35 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Prikhodko, 2010 RCCI low particle number 2 orders of magnitude 36 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Qiu, 2014 Modeling organic fraction Condensed fuel Caterpillar SCOTE – 1300 rev/min Gross IMEP (bar) 5.2 9.0 Premixed Gasoline (Mass ) 68 89 Diesel SOI1 (°ATDC) 58 Diesel DOI1 (°CA) 5.07 3.9 Diesel SOI2 (°ATDC) 37 Diesel DOI2 (°CA) 2.34 1.95 Diesel in Injection 1 (Mass ) 62 64 Intake Tank Temperature (°C) 32 EVO Timing (°ATDC) 130 IVC Timing (°ATDC) 143 Intake Pressure (bar) 1.38 1.75 Exhaust Pressure (bar) 1.45 1.84 EGR Rate () 0 43 Premixed isooctane as gasoline surrogate, nC H as diesel surrogate 16 34 37 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Qiu, 2014 Modeling fuel condensation PengRobinson EOS 38 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Qiu, 2014 RCCI fuel injection 9bar IMEP Double injection RCCI – fuel condensation predicted within sprays 39 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Qiu, 2014 40 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Qiu, 2014 RCCI particulate – predicted condensed fuel and soot at EVO Fuel condensation in RCCI is predicted to play an important role in PM formation. At low load (5.2 bar IMEP), about 90 of the PM is composed of condensed fuel. At higher load (9.0 bar IMEP), only about 50 of the engineout PM is composed of condensed fuel, of which 90 is from the premixed gasoline. 41 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Bharath, 2014 VVT to improve LTC catalyst efficiency Case 1 Case 2 Case 1 Intake Manifold Pressure/Bar 1.006 1.02 BMEP= Fuel Energy/J 275.1 393 1 bar Engine Speed/RPM 1,500 Gasoline Quantity (mg/cyl/cyc) 3.525 6.321 Diesel Quantity (mg/cyl/cyc) 2.619 2.482 Gasoline Start of Injection/Deg. 227.36 Diesel Start of Injection/Deg. 40 42 Diesel Fuel Rail Pressure/Bar 400 EGR Fraction () 49.9 44.9 Case 2 BMEP= 2.5 bar Modeled with GTPower and Modeled with KIVA Sampara and Bissett DOC model 42 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Bharath, 2014 VVT to improve LTC catalyst efficiency 43 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Bharath, 2014 Use of VVT DOC performance Higher exhaust temperatures with early EVO very beneficial in improving aftertreatment efficiency at low load, since exhaust temperatures high enough to activate the catalyst. Case 1 UHC and CO conversion by the DOC Predicted to reach almost 100 Case 2 Advancing EVO timing increases exhaust temperature, thus reducing EGR needed for same IVC temperature and pressure improves vol. eff. 44 CEFRC59, 2014 Part 9: Fuels, Aftertreatment and Controls Summary and conclusions • Due to high cost, complexity, and increased fuel/fluid consumption associated with exhaust aftertreatment, there is a growing need for advanced combustion development • Desire for alternatives to petroleum for transportation that have potential for large scale production is growing • Modify fuel’s reactivity to allow sufficient premixing of fuel air prior to autoignition  High octane fuels like gasoline, natural gas or alcohols • Challenges with stability, controllability, combustion efficiency, and pressure rise rates • Homogeneous Charge Compression Ignition (HCCI) – Advantages: Simple/inexpensive, ultralow NOx and soot – Challenges: High pressure rise rates and lack of direct cycletocycle control over combustion timing • Partially Premixed Combustion (PPC) – Advantages: DI injection timing and PFI/DI fuel split  mechanism for control – Challenges: Lack of Φsensitivity for gasolinelike fuels at low pressures • Reactivity Controlled Compression Ignition (RCCI) – Advantages: Incylinder blending of fuel reactivity broadens HR duration and allows global fuel reactivity to be changed. DI injection timing global fuel reactivity  mechanism for control – Challenges: Consumer acceptance of requiring two fuel tanks 45 CEFRC59, 2014
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