Reciprocating Internal Combustion Engines

Transcription

1 Part 9: Fuels, After-treatment and Controls Reciprocating Internal Combustion Engines Prof. Rolf D. Reitz Engine Research Center University of Wisconsin-Madison 214 Princeton-CEFRC Summer School on Combustion Course Length: 15 hrs (Mon.- Fri., June 23 27, 214) Copyright 214 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 CEFRC5-9, June 29,

2 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,, 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 1: Vehicle Applications, Future of IC Engines 2 CEFRC5-9, 214

3 Engine Base Engine Geometric Compression Ratio Piston Bowl Shape Displacement Bore/Stroke IVC/EVO GM 1.9L Diesel 17.3 RCCI.477 L 82. / 9.4 mm -132 /112 ATDC Swirl Ratio 1.5 Port Fuel Injectors Model Number TFS Inj. Press. Rated Flow Common Rail Injector Model 2.5 to 3.5 bar 25 kg/hr. Bosch CRI2.2 Number of Holes 7 Hole Diameter.14 mm Included Angle 148 Fixed Inj. Press. Part 9: Fuels, After-treatment and Controls Fuels & advanced combustion strategies 5 bar PRF fuels used: n-heptane & iso-octane HCCI: Dual-fuel allows CA5 to be varied with fixed intake temperature. PPC: A gasoline-like reactivity of PRF 94 chosen for both port injection and direct injection i.e., single fuel PPC. RCCI: Port injected neat iso-octane and direct injected n-heptane. DI fuel Tamagna, 27 Dempsey, 214 Fuel Injector HCCI PPC RCCI Port Injector #1 PRF 75 PRF 94 PRF 1 Port Injector #2 PRF 1 PRF 94 PRF 1 DI Injector - PRF 94 PRF 3 CEFRC5-9, 214

4 Pressure [bar] Part 9: Fuels, After-treatment and Controls Dempsey, 214 Controllability of advanced combustion strategies Baseline operating condition (5.5 bar IMEP & 15 rev/min) Inputs HCCI PPC RCCI Pin [bar] Tin [C] Premixed Fuel [%] 1% 79.1% 92.6% Global PRF # DI Timing [ ATDC] Global Phi Results HCCI PPC RCCI CA5 [ ATDC] Gross Ind. Eff. [%] 47.1% 45.6% 47.5% Comb. Eff. [%] 92.8% 93.1% 91.5% NOx [g/kg-fuel] <.5 <.5 <.5 - Single DI injections for PPC & RCCI - Ultra-low NOx emissions and high GIE - RCCI has highest GIE, but lowest η comb, suggesting lower HT losses (lower PPRR) - Fuel stratification with PPC results in higher PPRR compared to HCCI (c.f., Dec et al. 211 low intake pressure (< 2 bar)) HCCI Baseline RCCI Baseline PPC Baseline PPRR [bar/ ] Crank Angle [ATDC] 4 CEFRC5-9, AHRR [J/deg]

5 Pressure [bar] Delta CA5 [degrees] Pressure [bar] Pressure [bar] Sensitivity to intake temperature Each strategy is predominantly controlled by chemical kinetics sensitive to temperature Part 9: Fuels, After-treatment and Controls DT Delta Tin [C] To assess controllability of strategies, try to recover baseline CA5. This demonstrates combustion strategy s ability to be controlled in a real world engine on a cycle-bycycle basis (i.e., transient operation and unpredictable environmental conditions). Dempsey, 214 Intake Temperature Sensitivity DT HCCI RCCI PPC HCCI C 2-1 C Baseline C C PPC 3 Crank Angle [ATDC] C Baseline -1 C Crank Angle [ATDC] 9 RCCI C C PPC +1 C Baseline -1 C +13 C -13 C Crank Angle [ATDC] 5 CEFRC5-9, AHRR [J/deg] AHRR [J/deg] AHRR [J/deg]

6 Pressure [bar] Pressure [bar] Pressure [bar] Part 9: Fuels, After-treatment and Controls Ability to compensate for DT HCCI -1 C Corrected Baseline +1 C Corrected Global PRF # CA5 [ ATDC] NOx [g/kg-fuel] <.5 <.5 <.5 PPC -1 C Corrected Baseline +1 C Corrected Premixed Fuel [%] 72.6% 79.1% 95.2% DI Timing [ ATDC] CA5 [ ATDC] NOx [g/kg-fuel].63 <.5 <.5 RCCI -13 C Corrected Baseline +13 C Corrected Premixed Fuel [%] 89% 92.6% 94% DI Timing [ ATDC] CA5 [ ATDC] NOx [g/kg-fuel] <.5 <.5 < HCCI Correct Tin Sensitivity HCCI Crank Angle [ATDC] Correct PPC Tin Senstivity Baseline C C C RCCI Crank Angle [ATDC] 9 Correct RCCI Tin Sensitvity Crank Angle [ATDC] 6 CEFRC5-9, AHRR [J/deg] AHRR [J/deg] AHRR [J/deg]

7 Combustion Phasing (CA5) [ATDC] Combustion Phasing (CA5) [ATDC] Pressure [bar] Ability to compensate for intake temperature PPC PPC Part 9: Fuels, After-treatment and Controls Dempsey, C Corrected Baseline +1 C Corrected Premixed Fuel [%] 72.6% 79.1% 95.2% DI Timing [ ATDC] CA5 [ ATDC] NOx [g/kg-fuel].63 <.5 <.5 78% Premixed Fuel PPC Correct Tin Senstivity PPC +1 C +1 C Baseline -1 C -1 C Crank Angle [ATDC] -65 deg. ATDC AHRR [J/deg] Direct Injection SOI [deg. ATDC] Premixed Fuel Fraction [-] For PPC with PRF94, advancing SOI timing beyond -65 ATDC or increasing premixed fuel amount has no impact on combustion phasing 7 CEFRC5-9, 214

8 Pressure [bar] Delta CA5 [degrees] Pressure [bar] Pressure [bar] Sensitivity to intake pressure Critical for transient operation of turbocharged or supercharged engines. Dual-Fuel RCCI is not as affected by intake pressure as HCCI or PPC. Reasons for these observations are not well understood and will be subject of future simulation research Part 9: Fuels, After-treatment and Controls DP Delta Pin [kpa] Dempsey, 214 Intake Pressure Sensitivity DP HCCI RCCI PPC HCCI kpa kpa Baseline kpa kpa Crank Angle [ATDC] 9 PPC kpa Baseline -1 kpa Crank Angle [ATDC] 9 RCCI kpa +1 kpa +1 kpa -1 kpa Baseline -1 kpa Crank Angle [ATDC] 8 CEFRC5-9, kpa AHRR [J/deg] AHRR [J/deg] AHRR [J/deg]

9 Pressure [bar] Pressure [bar] Pressure [bar] Part 9: Fuels, After-treatment and Controls Ability to compensate for DP HCCI -1 kpa Corrected Baseline +1 kpa Corrected Global PRF # CA5 [ ATDC] NOx [g/kg-fuel] <.5 <.5 <.5 PPC -1 kpa Corrected Baseline +1 kpa Corrected Premixed Fuel [%] 65% 79.1% 94.7% DI Timing [ ATDC] CA5 [ ATDC] NOx [g/kg-fuel] 6.8 <.5 <.5 PPC - unable to retard combustion with increased boost -1 kpa +1 kpa RCCI Baseline Corrected Corrected Premixed Fuel [%] 91.5% 92.6% 93.5% DI Timing [ ATDC] CA5 [ ATDC] NOx [g/kg-fuel] <.5 <.5 < HCCI Correct Pin Sensitivity Crank Angle [ATDC] 9 Correct PPC Pin 3 Sensitivity kpa Baseline -1 kpa Crank Angle [ATDC] 9 Correct RCCI Pin Sensitivity CEFRC5-9, Crank Angle [ATDC] AHRR [J/deg] AHRR [J/deg] AHRR [J/deg]

10 RCCI - transient operation GM 1.9L Engine Specifications Engine Type Bore Stroke Displacement Cylinder Configuration EURO IV Diesel 82 mm 9.4 mm 1.9 liters Inline 4 4 valves per cylinder Swirl Ratio Variable ( ) Compression Ratio 17.5 EGR System ECU (OEM) ECU (new) Common Rail Injectors Port Fuel Injectors Part 9: Fuels, After-treatment and Controls Hybrid High/Low Pressure, Cooled Bosch EDC16 Drivven Bosch CRIP2-MI 148 Included Angle 7 holes, 44 flow number. Delphi 2.27 g/s steady flow 4 kpa fuel pressure Torque Cell Low rotating inertia -rapid transients (25 rpm/s) Hanson, 214 Hydrostatic dynamometer 1 CEFRC5-9, 214 Dyno

11 Part 9: Fuels, After-treatment and Controls Hanson, 214 Step load change: 1 4 bar BMEP CDC PFI=77% RCCI Pre DOC PFI= 41% RCCI RCCI Post DOC CDC CDC RCCI RCCI provides considerable transient control since ratio of port to directinjected fuel can be changed on a cycle-by-cycle basis 11 CEFRC5-9, 214

12 Part 9: Fuels, After-treatment and Controls Kokjohn, 211 Comparison of single fuel LTC, PPC and dual fuel RCCI Three engines operating with different forms of LTC combustion Case Diesel LTC 1 Ethanol PPC 2 Dual-Fuel RCCI 3 Engine Cummins N14 Scania D12 CAT 341 Displacement (cm3) Stroke (mm) Bore (mm) Con. Rod (mm) CR (-) : Swirl Ratio (-) Number of nozzles Nozzle hole size (μm) Singh, CNF Manente, SAE D. A. Splitter, THIESEL CEFRC5-9, 214

13 Part 9: Fuels, After-treatment and Controls Kokjohn, 211 Comparison with single fuel LTC Diesel LTC Single early injection at 22 BTDC 16 bar injection pressure Diluted intake (~6% EGR) Ethanol PPC Single early injection at 6 BTDC 18 bar injection pressure No EGR Dual-fuel RCCI 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) 8 bar injection pressure Liquid Fuel Vapor Fuel Liquid Fuel Vapor Fuel Liquid Fuel Vapor Fuel 13 CEFRC5-9, 214

14 Mass Fraction [-] AHRR [J/deg] Pressure [MPa] Part 9: Fuels, After-treatment and Controls Kokjohn, 211 Dual-fuel RCCI Comparison of gasoline-diesel and E85- diesel dual-fuel RCCI combustion For fixed combustion phasing, E85-diesel DF RCCI exhibits significantly reduced RoHR (and therefore peak PRR) compared to gasoline-diesel RCCI allows higher load operation E85-diesel RCCI combustion has larger spread between most reactive (lowest RON) and least reactive (highest RON) E85 and Diesel Fuel Gasoline and Diesel Fuel E85 & Diesel - Experiment E85 & Diesel - Simulation Gasoline & Diesel - Experiment Gasoline & Diesel - Simulation E85 & Diesel Gasoline & Diesel RON Distribution at -2 ATDC Gasoline & Diesel Fuel E85 & Diesel Fuel Crank [ ATDC] RON [-] 14 CEFRC5-9, 214

15 Mole Fraction [-] Part 9: Fuels, After-treatment and Controls Kokjohn, 211 Comparison between diesel LTC, ethanol PPC, and RCCI Evolution of key intermediates: Reaction progress fuel CH O OH 2 first stage combustion second stage combustion E85-diesel RCCI combustion shows a staged consumption of more reactive diesel fuel and less reactive E85.1 1E-3 1E-4 1E-5.1 1E-3 Ethanol and gasoline are not consumed 1E-4 until diesel fuel transitions to second stage ignition 1E-5.1 1E-3 Diesel CH2O C2H5OH CH2O C2H5OH ic8h18 OH Diesel LTC Ethanol PPCI OH Dual-Fuel RCCI E85 & Diesel Fuel 1E-4 Diesel CH2O OH 1E Time [ms ATDC] 15 CEFRC5-9, 214

16 AHRR [% Fuel Energy/ms] Part 9: Fuels, After-treatment and Controls Kokjohn, 211 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 significant charge dilution to maintain appropriate combustion phasing (12.7% Inlet O 2 ) Ethanol PPC Low fuel reactivity and charge cooling results in delayed combustion Sequential combustion from leanhigh temperature regions to richcool regions results in extended combustion duration Dual fuel RCCI Combustion begins only slightly later than diesel LTC Combustion duration is broad due to spatial gradient in fuel reactivity Allows highest load operation due to gradual transition from first- to second-stage ignition Diesel LTC Dual-Fuel RCCI Diesel LTC Ethanol PPCI Dual-Fuel RCCI (E85 & Diesel) Ethanol PPCI Time [ms ATDC] RCCI Engine Experiments Hanson SAE Kokjohn IJER 211 Kokjohn SAE CEFRC5-9, 214

17 Estimated CN Part 9: Fuels, After-treatment and Controls Kaddatz, 212 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 ) demonstrated single fuel RCCI in a heavy-duty engine using gasoline + Ditertiary-Butyl Peroxide (DTBP) 2-Ethylhexyl Nitrate (EHN) is another common cetane improver Contains fuel-bound NO and LTC results have shown increased engine-out NOx (Ickes et al. Energy and Fuels 29) SAE EPA 42-B-4-5 Extrapolated 25 2 Concentrations from SAE DTBP EHN Additive Concentration [Vol %] 17 CEFRC5-9, 214

18 Part 9: Fuels, After-treatment and Controls Kaddatz, 212 Comparison of E1-EHN and Diesel Fuel Engine experiments performed on ERC GM 1.9L engine Diesel fuel and splash blended E1-3% EHN mixtures compared under conventional diesel conditions (5.5 bar IMEP, 19 rev/min) Diesel fuel injection parameters adjusted to reproduce combustion characteristics of E1+EHN blend Ignition Differences Diesel fuel SOI must be retarded to match ign. (Consistent with lower CN) Mixing Differences Diesel fuel injection pressure must be increased by 4 bar to reproduce premixed burn Diesel Fuel SOIc = SOIc = SOIc = -7.9 E1+EHN SOIc = Pinj = 5 bar Diesel Fuel Pinj = 5 bar Pinj = 5 bar Pinj = 9 bar SOIc = Pinj = 5 9 bar 18 CEFRC5-9, 214

19 Part 9: Fuels, After-treatment and Controls Kaddatz, 212 Comparison of E1-EHN and Diesel Fuel Diesel fuel and E1-EHN compared under conventional diesel conditions (5.5 bar IMEP, 19 rev/min) Diesel fuel injection parameters adjusted to reproduce combustion characteristics of E1+EHN blend For CDC operation, E1+EHN and diesel fuel show similar NOx and soot CDC operation with matched AHRR EPA CEFRC5-9, 214

20 Pressure [bar] Part 9: Fuels, After-treatment and Controls Kaddatz, 212 Diesel/Gasoline and E1+EHN RCCI PFI E1 and direct-injected E1+3% EHN compared to gasoline diesel RCCI operation Combustion characteristics of gasolinediesel RCCI reproduced with E1 E1+3%EHN Adjustment to PFI percentage required to account for differences in ignitability Operating Conditions DI Fuel E1+EHN Diesel PFI Fuel E1 Gasoline Net IMEP (bar) 5.5 Engine Speed (RPM) Premixed Fuel (% mass) SOIC (degatdc) Gasoline-diesel (84%) E1+EHN/E1 (69%) Heat Release Rate [J/deg] Common Rail SOIc( ATDC) -32 to -52 Injection Pressure (bar) 5 8 Intake Temperature (C) 65 Boost Pressure (bar) 1.3 Swirl Ratio 1.5 EGR (%) CA [degatdc] 2 CEFRC5-9, 214

21 Part 9: Fuels, After-treatment and Controls Kaddatz, 212 Performance of E1 and E1+EHN RCCI Parametric studies performed to optimize efficiency of single-fuel RCCI at 5.5 and 9 bar IMEP E1/E1+EHN E1/Diesel Using a split-injection strategy, performance characteristics of single-fuel + additive RCCI are similar to those of dual-fuel RCCI Peak efficiency data for E1/E1+EHN shows higher NOx emissions, but levels meet EPA mandates Soot is very low for all cases 21 CEFRC5-9, 214

22 IMEP g [bar] Part 9: Fuels, After-treatment and Controls Kaddatz, 212 Additive consumption estimate Light-duty drive cycle average is 55% PFI fuel (i.e., 45% additized fuel) 3% additive level EHN volume is ~1.4% of the total fuel volume Similar to DEF levels Assuming 5 mpg and 1, mile oil 2 1 change intervals, additive tank must be ~2.7 gallons SAE Size shows relative weighting 2 3 Speed [rev/min] 4 Assumes 5 mpg and 1, mile oil change interval 5 22 CEFRC5-9, 214

23 Operating Condition Part 9: Fuels, After-treatment and Controls Nieman, 212 Natural gas/diesel RCCI Low- Load Mid-Load High-Load Gross IMEP [bar] Engine Speed [rpm] Intake Press. [bar abs.] Intake Temp. [ C] Caterpillar 341E SCOTE Displacement [L] 2.44 Bore x Stroke [mm] x Con. Rod Length [mm] Compression Ratio 16.1:1 Swirl Ratio.7 IVC [deg ATDC] -143 EVO [deg ATDC] 13 Common Rail Diesel Fuel Injector Number of Holes 6 Hole Diameter [μm] 25 Included Spray Angle 145 o Design Parameter ERC KIVA PRF kinetics NSGA-II MOGA 32 Citizens per Generation ~95 BDC UW Condor - Convergence after ~4 generations Minimum Maximum Premixed Methane [%] % 1% DI Diesel SOI 1 [deg ATDC] -1-5 DI Diesel SOI 2 [deg ATDC] -4 2 Diesel Fraction in First Inj. [%] % 1% Diesel Injection Pressure [bar] 3 15 EGR [%] % 6% 23 CEFRC5-9, 214

24 Part 9: Fuels, After-treatment and Controls Nieman, 212 GA optimized NOx, Soot, CO, UHC ISFC, PPRR Design Parameter 4 bar 9 bar 11 bar 13.5 bar 16 bar 23 bar Engine Speed [rpm] Total Fuel Mass [mg] Methane [%] 73% 85% 87% 9% 87% 85% Diesel SOI 1 [deg ATDC] Diesel SOI 2 [deg ATDC] Diesel in 1st Inj. [%] 52% 4% 39% 55% 49% 7% Diesel Inj. Press. [bar] EGR [%] 5% % % % 32% 48% * -18 to 18 ATDC Results Soot [g/ikw-hr] NOx [g/ikw-hr] CO [g/ikw-hr] UHC [g/ikw-hr] η gross [%] * 45.1% 5.4% 5.6% 48.9% 49.2% 44.1% PPRR [bar/deg] Ring. Intens. [MW/m 2 ] Extend range to lower/high loads with triple injections - Clean, efficient operation up to 13.5 bar IMEP without needing EGR Meet EPA 21 (except soot at high load) High peak thermal efficiency - Low PPRR 24 CEFRC5-9, 214

25 Part 9: Fuels, After-treatment and Controls Nieman, 212 Comparison with gasoline/diesel RCCI 9 bar IMEP Gasoline/Diesel strategy optimized at 1.75 bar abs. (high boost) Natural Gas/Diesel used 1.45 bar abs. (low boost) Each run at both conditions Design Parameter Nat. Gas/ Diesel Gasoline/ Diesel Intake Temperature [ C] 6 32 Total Fuel Mass [mg] Low-Reactivity Fuel (Premixed) [%] 85% 89% Diesel SOI 1 [deg ATDC] Diesel SOI 2 [deg ATDC] Diesel in 1st Inj. [%] 4% 6% EGR [%] % 43% Quite similar strategies 25 CEFRC5-9, 214

26 Part 9: Fuels, After-treatment and Controls Nieman, 212 Comparison with gasoline/diesel RCCI * -18 to 18 ATDC 9 bar IMEP Nat. Gas Gasoline Results Low High Low High Soot [g/kw-hr] NOx [g/kw-hr] CO [g/kw-hr] UHC [g/kw-hr] η gross [%] * 5.4% 5.4% 52.1% 52.2% PPRR [bar/deg] Design Parameter Nat. Gas/ Diesel Gasoline/ Diesel Intake Temperature [ C] 6 32 Total Fuel Mass [mg] Low-Reactivity Fuel (Premixed) [%] 85% 89% Diesel SOI 1 [deg ATDC] Diesel SOI 2 [deg ATDC] Diesel in 1st Inj. [%] 4% 6% EGR [%] % 43% 2% Efficiency Difference: Higher in-cyl. temps and comb. in squish Greater HT Losses 26 CEFRC5-9, 214

27 % of Fuel Energy In % of Fuel Energy In Part 9: Fuels, After-treatment and Controls Nieman, 212 Double vs. Triple Injection 4 bar IMEP 23 bar IMEP 5% 45% 4% 35% 3% 25% 2% 15% 1% 5% % Results 2 Inj. Optimum 3 Inj. Optimum Soot [g/kw-hr].4.4 NOx [g/kw-hr].24.1 CO [g/kw-hr] UHC [g/kw-hr] η gross [%] 45.1% 47.1% 45.1% 47.1% 31.5% 31.9% 17.1% 18.7% 2 Inj. Optimum 3 Inj. Optimum 6.3% 2.4% Gross Work Exhaust Loss Heat Transfer Combustion Loss 5% 45% 4% 35% 3% 25% 2% 15% 1% 5% % Results 2 Inj. Optimum 3 Inj. Optimum Soot [g/kw-hr] NOx [g/kw-hr].8.17 CO [g/kw-hr] UHC [g/kw-hr] η gross [%] 44.1% 46.5% 46.5% 44.1% 42.4% 43.% 2 Inj. Optimum 3 Inj. Optimum 7.9% 8.5% 5.6% 2.% Gross Work Exhaust Loss Heat Transfer Combustion Loss 27 CEFRC5-9, 214

28 Part 9: Fuels, After-treatment and Controls Nieman, bar IMEP, triple Injection (Isosurface = 16K) ATDC Can achieve low soot, despite late 3 rd injection o o Combustion starts in squish region, so diesel #3 injects into a relatively cool environment Fairly small amount injected 28 CEFRC5-9, 214

29 Part 9: Fuels, After-treatment and Controls Nieman, 212 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 3% Propane.7% Butane.2% Pentane.1% C + 6.1% Nitrogen 3% Carbon Dioxide.6% Ethane enhances combustion Increases reactivity of premix Shortens combustion duration Increases combustion efficiency 29 CEFRC5-9, 214

30 Part 9: Fuels, After-treatment and Controls Nieman, 212 NG/diesel RCCI summary Use of natural gas as the low-reactivity 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 lowload/low-speed to high-load/high-speed. US 21 HD regulations met, in-cylinder (require 3 injections at high load) High NOx/soot & low(er) comb. eff. observed in low- and high-loads Operation controlled by NG/diesel ratio and injection schedule MOGA studies show that utilizing triple injections extends the low- and highload 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 (1-3%) enhanced combustion 3 CEFRC5-9, 214

31 Part 9: Fuels, After-treatment and Controls Prikhodko, 21 RCCI after-treatment 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 H-D engine typically gains 5-1% more load with EGR (CDC - 27 Opel Astra 1.9L, data from ANL) 31 CEFRC5-9, 214

32 Part 9: Fuels, After-treatment and Controls Prikhodko, 21 Exhaust temperature RCCI shows 5-1 C lower turbine inlet temperature than CDC Reduced exhaust availability for turbocharging and after-treatment 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 turbo-machinery exists for this engine, which could improve the performance Low EGTs in the FTP driving area are a challenge for oxidation catalyst performance Need 9+% catalyst efficiency to meet HC and CO targets, challenging with EGTs ~ 2 C CDC RCCI 32 CEFRC5-9, 214

33 ORNL RCCI experiments SAE 21 Part 9: Fuels, After-treatment and Controls Prikhodko, CEFRC5-9, 214

34 Part 9: Fuels, After-treatment and Controls Prikhodko, 21 CDC, PCCI & RCCI NOx and HC emissions 34 CEFRC5-9, 214

35 Part 9: Fuels, After-treatment and Controls Prikhodko, 21 CDC, PCCI & RCCI PM emissions 35 CEFRC5-9, 214

36 Part 9: Fuels, After-treatment and Controls Prikhodko, 21 RCCI - low particle number 2 orders of magnitude 36 CEFRC5-9, 214

37 Part 9: Fuels, After-treatment and Controls Qiu, 214 Modeling organic fraction - Condensed fuel Caterpillar SCOTE 13 rev/min Gross IMEP (bar) Premixed Gasoline (Mass %) 68% 89% Diesel SOI1 ( ATDC) -58 Diesel DOI1 ( CA) Diesel SOI2 ( ATDC) -37 Diesel DOI2 ( CA) Diesel in Injection #1 (Mass %) 62% 64% Intake Tank Temperature ( C) 32 EVO Timing ( ATDC) 13 IVC Timing ( ATDC) -143 Intake Pressure (bar) Exhaust Pressure (bar) EGR Rate (%) 43 Premixed iso-octane as gasoline surrogate, nc 16 H 34 as diesel surrogate 37 CEFRC5-9, 214

38 Part 9: Fuels, After-treatment and Controls Qiu, 214 Modeling fuel condensation Peng-Robinson EOS 38 CEFRC5-9, 214

39 Part 9: Fuels, After-treatment and Controls Qiu, 214 RCCI fuel injection - 9bar IMEP Double injection RCCI fuel condensation predicted within sprays 39 CEFRC5-9, 214

40 Part 9: Fuels, After-treatment and Controls Qiu, CEFRC5-9, 214

41 Part 9: Fuels, After-treatment and Controls Qiu, 214 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 9% of the PM is composed of condensed fuel. At higher load (9. bar IMEP), only about 5% of the engine-out PM is composed of condensed fuel, of which 9% is from the premixed gasoline. 41 CEFRC5-9, 214

42 Part 9: Fuels, After-treatment and Controls VVT to improve LTC catalyst efficiency Case 1 Case 2 Intake Manifold Pressure/Bar Fuel Energy/J Engine Speed/RPM 1,5 Gasoline Quantity (mg/cyl/cyc) Diesel Quantity (mg/cyl/cyc) Gasoline Start of Injection/Deg Diesel Start of Injection/Deg Diesel Fuel Rail Pressure/Bar 4 EGR Fraction (%) Bharath, 214 Case 1 BMEP= 1 bar Case 2 BMEP= 2.5 bar Modeled with KIVA Modeled with GT-Power and Sampara and Bissett DOC model 42 CEFRC5-9, 214

43 Part 9: Fuels, After-treatment and Controls Bharath, 214 VVT to improve LTC catalyst efficiency 43 CEFRC5-9, 214

44 Part 9: Fuels, After-treatment and Controls Bharath, 214 Use of VVT - DOC performance Case 1 Higher exhaust temperatures with early EVO very beneficial in improving after-treatment efficiency at low load, since exhaust temperatures high enough to activate the catalyst. UHC and CO conversion by the DOC Predicted to reach almost 1% Advancing EVO timing increases exhaust temperature, thus reducing EGR needed for same IVC temperature and pressure - improves vol. eff. Case 2 44 CEFRC5-9, 214

45 Part 9: Fuels, After-treatment and Controls Summary and conclusions Due to high cost, complexity, and increased fuel/fluid consumption associated with exhaust after-treatment, 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 auto-ignition 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, ultra-low NOx and soot Challenges: High pressure rise rates and lack of direct cycle-to-cycle control over combustion timing Partially Premixed Combustion (PPC) Advantages: DI injection timing and PFI/DI fuel split mechanism for control Challenges: Lack of Φ-sensitivity for gasoline-like fuels at low pressures Reactivity Controlled Compression Ignition (RCCI) Advantages: In-cylinder 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 CEFRC5-9, 214