Path to High Efficiency Gasoline Engine
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Path to High Efficiency Gasoline Engine SI HCCI PPC Prof. Bengt Johansson Division of Combustion Engines Department of Energy Sciences Lund University 1 Scania diesel engine running on gasoline Group 3, 1300 [rpm] 60 ! 55 50 FR47333CVX 45 FR47334CVX FR47336CVX 40 35 30 Gross Indicated Efficiency [%] Efficiency Indicated Gross 25 20 0 2 4 6 8 10 12 14 Gross IMEP [bar] ηi=57% = Isfc =147 g/kWh (@43 MJ/kg heating value) 2 Outline • HCCI and fuel efficiency – 50% thermal efficiency • Partially premixed combustion, PPC – Background – Why gasoline is the best diesel engine fuel – 56% thermal efficiency in car size engine – 57% thermal efficiency in truck size engine – Why 55% thermal efficiency is better than 57% – How to reach 26 bar IMEP with US10 NOx, PM, HC and CO engine out 3 Outline • HCCI and fuel efficiency – 50% thermal efficiency • Partially premixed combustion, PPC – Background – Why gasoline is the best diesel engine fuel – 56% thermal efficiency in car size engine – 57% thermal efficiency in truck size engine – Why 55% thermal efficiency is better than 57% – How to reach 26 bar IMEP with US10 NOx, PM, HC and CO engine out 4 Efficiencies? 5 Energy flow in an IC engine FuelMEP Combustion efficiency QemisMEP QhrMEP QhtMEP Thermodynamic efficiency QlossMEP QexhMEP Gross Indicated efficiency IMEPgross Gas exchange efficiency PMEP Net Indicated efficiency lMEPnet Mechanical efficiency FMEP Brake efficiency BMEP = * * * η Brake η Combustion ηThermodynamic η GasExchange η Mechanical Thermodynamic efficiency Saab SVC variable compression ratio, VCR, HCCI, Rc=10:1-30:1; General Motors L850 “World engine”, HCCI, Rc=18:1, SI, Rc=18:1, SI, Rc=9.5:1 (std) Scania D12 Heavy duty diesel engine, HCCI, Rc=18:1; Fuel: US regular Gasoline 7 SAE2006-01-0205 All four efficiencies 8 Problem with HCCI: Too fast combustion 9 Phasing HCCI combustion late helps burn rate but reduce ηC 10 Magnus Christensen Ph.D. thesis 2002 Outline • HCCI and fuel efficiency – 50% thermal efficiency • Partially premixed combustion, PPC – Background – Why gasoline is the best diesel engine fuel – 56% thermal efficiency in car size engine – 57% thermal efficiency in truck size engine – Why 55% thermal efficiency is better than 57% – How to reach 26 bar IMEP with US10 NOx, PM, HC and CO engine out 11 + Clean with 3-way Background + High efficiency Catalyst Combustion concepts - Emissions of NO and - Poor low & part load x soot efficiency Spark Ignition (SI) Compression Ignition engine (Gasoline, (CI) engine (Diesel) Otto) + High efficiency Homogeneous Charge -Combustion control Compression Ignition + Ultra low NOx -Power density (HCCI) Spark Assisted Partially premixed Compression Ignition combustion (PPC) (SACI) Diesel HCCI Gasoline HCCI + Injection controlled - Less emissions advantage Partially Premixed Combustion, PPC p y 6000 1200 CI HCCI PCCI 5000 PPC 1000 4000 800 3000 600 HC [ppm] NOx [ppm] 2000 400 1000 200 -180 -160 -140 -120 -100 -80 -60 -40 -20 SOI [ATDC] Def: region between truly homogeneous combustion, HCCI, and diffusion controlled combustion, diesel 13 PPC: Effect of EGR with diesel fuel Load 8 bar IMEP Abs. Inlet Pressure 2.5 bar Engine Speed 1090 rpm Swirl Ratio 1.7 Compression Ratio 12.4:1 (Low) Scania D12 single cylinder 14 DEER2005 1 2 3 4 Lund/Delphi/Volvo PPC Project Volvo D13 Multi-cylinder engine NOx <0.3 g/kWh PM < 2 FSN using Swedish MK1 diesel fuel Adapted from 16 SAE paper 2009-01-1127 Outline • HCCI and fuel efficiency – 50% thermal efficiency • Partially premixed combustion, PPC – Background – Why gasoline is the best diesel engine fuel – 56% thermal efficiency in car size engine – 57% thermal efficiency in truck size engine – Why 55% thermal efficiency is better than 57% – How to reach 26 bar IMEP with US10 NOx, PM, HC and CO engine out 17 PPC with low cetane diesel Lic. Thesis by Henrik Nordgren 2005 and 18 presented at DEER2005 Outline • HCCI and fuel efficiency – 50% thermal efficiency • Partially premixed combustion, PPC – Background – Why gasoline is the best diesel engine fuel – 56% thermal efficiency in car size engine – 57% thermal efficiency in truck size engine – Why 55% thermal efficiency is better than 57% – How to reach 26 bar IMEP with US10 NOx, PM, HC and CO engine out 19 VOLVO D5 with Gasoline Injection SOI [TDC] Fuel MEP [bar] Percentage [%] 1 -64.00 10.88 41.28 2 -29.20 7.74 29.36 3 0.80 7.74 29.36 150 Cyl Pressure [bar] Inj Signal [a.u.] RoHR [J/CAD] 100 Load & CA50 N 2000 [rpm] Noise Load IMEPg 13.38 [bar] 50 Pin 2.57 [bar] Tin 354 [K] EGR 39 [%] 0 lambda 1.75 [-] -8020 -60 -40 -20 0 20 40 CAD [TDC] Efficiencies & Emissions ! D60 project goal 60 40 0.46 % 58 35 56 30 54 52 25 4598 ppm 50 20 48 Emissions 13 ppm Efficiency [%] 91 % 15 46 10 44 Below 42 5 Detectable Level 40 0 Indicated Gross Thermal Combustion/2 NOx*100 [g/kWh] CO [g/kWh] HC [g/kWh] Soot [FSN] dPmax 7.20 [bar/CAD] CA5 3.40 [TDC] ID -1.00 [CAD] CA50 11.35 [TDC] CA90-10 13.00 [CAD] 21 Burn rate and ηT Optimum Thermodynamic efficiency 150 Cyl Pressure [bar] Inj Signal [a.u.] Low effective RoHR [J/CAD] High heat expansion 100 losses ratio 50 0 -80 -60 -40 -20 0 20 40 CAD [TDC] Premixedness 22 Outline • HCCI and fuel efficiency – 50% thermal efficiency • Partially premixed combustion, PPC – Background – Why gasoline is the best diesel engine fuel – 56% thermal efficiency in car size engine – 57% thermal efficiency in truck size engine – Why 55% thermal efficiency is better than 57% – How to reach 26 bar IMEP with US10 NOx, PM, HC and CO engine out 23 Experimental setup, Scania D12 Bosch Common Rail Prailmax 1600 [bar] Orifices 8 [-] Orifice Diameter 0.18 [mm] Umbrella Angle 120 [deg] Engine / Dyno Spec BMEPmax 15 [bar] Vd 1951 [cm3] Swirl ratio 2.9 [-] Fuel: Gasoline or Ethanol 24 Two Test Series: High & Low Compression Ratio rc: 14.3:1 rc: 17.1:1 Low Compression Ratio PPC High Compression Ratio PPC 25 Injection Strategy It consists of two injections. The first Const. Load & CA50 one is placed @ -60 TDC to create a 1 homogeneous mixture while the second 0.8 around TDC. The stratification created 0.6 by the second injection triggers the [a.u.] combustion. The first injection must not 0.4 It must not react during the compression stroke, react during 0.2 this is achieved by using EGR. compression 0 -60 -50 -40 -30 -20 -10 0 10 CAD [TDC] Fuel amount in the pilot is a function of: 1.rc 2.RON/MON 3.EGR 26 SAE 2009-01-0944 High Compression Ratio PPC IMEP sweep @ 1300 [rpm] EGR ~ const throughout the sweep, 40-50 [%] λ~ const throughout the sweep, 1.5-1.6 [-] Tin = 308 [K] Standard piston bowl, rc: 17:1 27 SAE 2009-01-2668 Running Conditions 2.5 350 2 60 Inlet Temperature 300 1.9 Exhaust Temperature 55 2.25 1.8 250 50 1.7 200 Inlet Pressure 2 [-] 1.6 45 [C] Exhaust Pressure λ [bar] 150 EGR [%] 1.5 40 100 1.75 1.4 35 50 1.3 1.5 0 1.2 30 4 5 6 7 8 9 10 11 12 13 4 5 6 7 8 9 10 11 12 13 Gross IMEP [bar] Gross IMEP [bar] 28 Efficiencies 100 95 90 85 80 Combustion Efficiency 75 [%] Thermal Efficiency 70 Gas Exchange Efficiency Mechanical Efficiency 65 60 55 50 4 5 6 7 8 9 10 11 12 13 Gross IMEP [bar] 29 Efficiency 57% 60 Too much rate Too much heat transfer controlled combustion 55 50 45 [%] Gross Ind. Efficiency 40 Net Ind. Efficiency Brake Efficiency 35 30 2 4 6 8 10 12 14 Gross IMEP [bar] 30 Emissions 0.5 5 Obsolete injection 0.45 Gross 4.5 Net system 0.4 Brake 4 EU VI Not well tuned EGR-λ 0.35 3.5 US 10 combination 0.3 3 0.25 2.5 NOx [g/kWh] 0.2 2 Smoke [FSN] Smoke 0.15 1.5 0.1 1 0.05 0.5 0 0 2 4 6 8 10 12 14 2 4 6 8 10 12 14 Gross IMEP [bar] Gross IMEP [bar] 5 18 4.5 16 Gross 4 Gross 14 Net 3.5 Net Brake Brake 12 EU VI 3 EU VI US 10 US 10 10 2.5 8 HC [g/kWh] 2 CO [g/kWh] 6 1.5 1 4 0.5 2 0 31 0 2 4 6 8 10 12 14 2 4 6 8 10 12 14 Gross IMEP [bar] Gross IMEP [bar] Outline • HCCI and fuel efficiency – 50% thermal efficiency • Partially premixed combustion, PPC – Background – Why gasoline is the best diesel engine fuel – 56% thermal efficiency in car size engine – 57% thermal efficiency in truck size engine – Why 55% thermal efficiency is better than 57% – How to reach 26 bar IMEP with US10 NOx, PM, HC and CO engine out 32 Low Compression Ratio PPC IMEP sweep @ 1300 [rpm] EGR ~ const throughout the sweep, 40-50 [%] λ~ const throughout the sweep, 1.5-1.6 [-] Tin = 308 [K] Custom piston bowl, rc: 14.3:1 33 SAE 2010-01-0871 Efficiencies 100 95 90 85 80 Combustion Efficiency [%] 75 Thermal Efficiency 70 Gas Exchange Efficiency Mechanical Efficiency 65 60 55 50 4 6 8 10 12 14 16 18 Gross IMEP [bar] 34 Emissions 0.6 2 1.8 λ Gross Better tuned EGR- 0.5 Net 1.6 combination Brake 1.4 0.4 EU VI US 10 1.2 0.3 1 NOx [g/kWh] 0.8 Smoke [FSN] Smoke 0.2 0.6 0.4 0.1 0.2 0 0 2 4 6 8 10 12 14 16 18 4 6 8 10 12 14 16 18 Gross IMEP [bar] Gross IMEP [bar] 1.5 10 Gross 9 Gross Net Net 1.2 Brake 8 Brake EU VI EU VI US 10 7 US 10 0.9 6 5 HC [g/kWh] 0.6 CO [g/kWh] 4 3 0.3 2 1 0 35 0 2 4 6 8 10 12 14 16 18 2 4 6 8 10 12 14 16 18 Gross IMEP [bar] Gross IMEP [bar] Emissions – different fuels Ethanol 2.5 0.5 FR47330CVX 0.45 FR47331CVX Ethanol FR47333CVX FR47330CVX 0.4 FR47334CVX 2 FR47331CVX FR47335CVX FR47333CVX 0.35 FR47336CVX FR47334CVX 0.3 FR47338CVX 1.5 FR47335CVX FR47336CVX 0.25 FR47338CVX Soot [FSN] NOx [g/kWh] 0.2 1 0.15 0.1 0.5 0.05 0 0 2 4 6 8 10 12 14 16 18 20 2 4 6 8 10 12 14 16 18 20 Gross IMEP [bar] Gross IMEP [bar] 12 10 Ethanol Ethanol FR47330CVX 9 FR47330CVX 10 FR47331CVX 8 FR47331CVX FR47333CVX FR47333CVX FR47334CVX 7 FR47334CVX 8 FR47335CVX FR47335CVX FR47336CVX 6 FR47336CVX 6 FR47338CVX 5 FR47338CVX CO [g/kWh] HC [g/kWh] 4 4 3 2 2 1 0 36 0 2 4 6 8 10 12 14 16 18 20 2 4 6