Internal combustion engine fuel efficiency

internal combustion engines performance fuel economy and emissions and internal combustion engine specific fuel consumption
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Part 9: Fuels, After-treatment and Controls Reciprocating Internal Combustion Engines Prof. Rolf D. Reitz Engine Research Center University of Wisconsin-Madison 2014 Princeton-CEFRC 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, After-treatment and Controls Short course outine: Engine fundamentals and performance metrics, computer modeling supported by in-depth understanding of fundamental engine processes and detailed experiments in engine design optimization. Day 1 (Engine fundamentals) Part 1: IC Engine Review, 0, 1 and 3-D 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, After-treatment and Controls Part 10: Vehicle Applications, Future of IC Engines 2 CEFRC5-9, 2014 Part 9: Fuels, After-treatment and Controls Tamagna, 2007 Dempsey, 2014 Fuels & advanced combustion strategies Engine PRF fuels used: n-heptane & iso-octane Base Engine GM 1.9L Diesel HCCI: Dual-fuel allows CA50 to be varied with fixed Geometric 17.3 intake temperature. Compression Ratio Piston Bowl Shape RCCI PPC: A gasoline-like 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 iso-octane and direct IVC/EVO -132°/112° ATDC injected n-heptane. Swirl Ratio 1.5 Port Fuel Injectors Model Number TFS-89055-1 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 CEFRC5-9, 2014 AHRR J/deg Part 9: Fuels, After-treatment 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 - Ultra-low 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/kg-fuel 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 CEFRC5-9, 2014 Pressure barAHRR J/deg AHRR J/deg AHRR J/deg 100 300 HCCI Part 9: Fuels, After-treatment 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 cycle-by- 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 CEFRC5-9, 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, After-treatment 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/kg-fuel 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/kg-fuel 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/kg-fuel 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 CEFRC5-9, 2014 Pressure bar Pressure bar Pressure barAHRR J/deg Part 9: Fuels, After-treatment 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/kg-fuel 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 CEFRC5-9, 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, After-treatment 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 • Dual-Fuel 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 CEFRC5-9, 2014 Delta CA50 degrees Pressure bar Pressure bar Pressure barAHRR J/deg AHRR J/deg AHRR J/deg 300 Part 9: Fuels, After-treatment 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/kg-fuel 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/kg-fuel 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/kg-fuel 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 CEFRC5-9, 2014 Pressure bar Pressure bar Pressure barPart 9: Fuels, After-treatment 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 (2.2-5.6) Compression 17.5 Ratio Hybrid High/Low EGR System Pressure, Cooled Hydrostatic dynamometer ECU (OEM) Bosch EDC16 ECU (new) Drivven Bosch CRIP2-MI 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 CEFRC5-9, 2014 Part 9: Fuels, After-treatment 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 cycle-by-cycle basis RCCI 11 CEFRC5-9, 2014 Part 9: Fuels, After-treatment 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 Dual-Fuel 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 2010-01-0871 3. D. A. Splitter, THIESEL 2010 12 CEFRC5-9, 2014 Part 9: Fuels, After-treatment 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 Dual-fuel RCCI Vapor Fuel Port-fuel-injection of low reactivity fuel (gasoline or E85) Direct-injection of diesel fuel Split early injections (SOI1 = 58° BTDC and SOI2 = 37° BTDC) 800 bar injection pressure Liquid Fuel Vapor Fuel 13 CEFRC5-9, 2014 Part 9: Fuels, After-treatment and Controls Kokjohn, 2011 Dual-fuel RCCI Comparison of gasoline-diesel and E85- diesel dual-fuel RCCI combustion 12 E85 and Diesel Fuel For fixed combustion phasing, E85-diesel 10 DF RCCI exhibits significantly reduced Gasoline 8 RoHR (and therefore peak PRR) and Diesel Fuel 6 compared to gasoline-diesel RCCI E85 & Diesel - Experiment allows higher load operation 4 E85 & Diesel - Simulation E85-diesel 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 CEFRC5-9, 2014 Mass Fraction - AHRR J/deg Pressure MPaPart 9: Fuels, After-treatment and Controls Kokjohn, 2011 Comparison between diesel LTC, ethanol PPC, and RCCI Evolution of key intermediates: Diesel LTC Diesel 0.01 Reaction progress CH2O 1E-3 fuel CH O OH 2 1E-4 second stage OH first stage combustion combustion 1E-5 E85-diesel RCCI combustion shows a Ethanol PPCI C2H5OH 0.01 staged consumption of more reactive diesel fuel and less reactive E85 1E-3 OH Ethanol and gasoline are not consumed 1E-4 CH2O until diesel fuel transitions to second 1E-5 stage ignition Dual-Fuel RCCI 0.01 C2H5OH E85 & Diesel iC8H18 Fuel 1E-3 Diesel 1E-4 OH CH2O 1E-5 -3 -2 -1 0 1 2 3 Time ms ATDC 15 CEFRC5-9, 2014 Mole Fraction -Part 9: Fuels, After-treatment 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 Dual-Fuel 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- Dual-Fuel 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 2010-01-0864 Kokjohn IJER 2011 Allows highest load operation due to Kokjohn SAE 2011-01-0357 gradual transition from first- to second-stage ignition 16 CEFRC5-9, 2014 AHRR % Fuel Energy/msPart 9: Fuels, After-treatment 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 2010-01-2167) demonstrated single fuel RCCI in a heavy-duty engine using gasoline + Di- SAE 2010-01-2167 tertiary-Butyl Peroxide (DTBP) 2-Ethylhexyl Nitrate (EHN) is another 40 common cetane improver EPA 420-B-04-005 ◦ Contains fuel-bound NO and LTC results Extrapolated 35 have shown increased engine-out NOx (Ickes et al. Energy and Fuels 2009) 30 25 Concentrations from SAE 2010-01-2167 20 DTBP EHN 0 2 4 6 8 10 Additive Concentration Vol % 17 CEFRC5-9, 2014 Estimated CNPart 9: Fuels, After-treatment and Controls Kaddatz, 2012 Comparison of E10-EHN and Diesel Fuel Engine experiments performed on ERC GM 1.9L engine E10+EHN Diesel fuel and splash blended E10-3% 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 CEFRC5-9, 2014 Part 9: Fuels, After-treatment and Controls Kaddatz, 2012 Comparison of E10-EHN and Diesel Fuel CDC operation with matched Diesel fuel and E10-EHN 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 CEFRC5-9, 2014 Heat Release Rate J/deg Part 9: Fuels, After-treatment and Controls Kaddatz, 2012 Diesel/Gasoline and E10+EHN RCCI PFI E10 and direct-injected 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+3%EHN 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 Gasoline-diesel (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 CEFRC5-9, 2014 Pressure bar