1 Alternative Fuels for DI-Diesel Engines Meeting Future Emission Standards ERC - 2007 Symposium Madison, June 6, 2007 Erik Koehler and Dean Tomazic FEV Engine Technology, Inc. Auburn Hills, MI, USA
2 Overview 1. Introduction 2. Current Market Situation 3. GTL 4. Biodiesel 5. Alcohols 6. Potential Approaches and Technologies 7. Summary
Influence of Fuel Properties 3 Fuel Availability Fuel Cost Performance Fuel Properties CO2 Emissions Emissions NVH Behavior
4 Overview 1. Introduction 2. Current Market Situation 3. GTL 4. Biodiesel 5. Alcohols 6. Potential Approaches and Technologies 7. Summary
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6 Overview 1. Introduction 2. Current Market Situation 3. GTL 4. Biodiesel 5. Alcohols 6. Potential Approaches and Technologies 7. Summary
GTL (Gas-to-Liquid) 7 Pros No Sulfur No Aromatics High CN# Cons Investment Infrastructure Cost
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44 i [%] 42 40 38 36 34 10 8 6 4 2 0 EU Diesel Fuel GTL Fuel COPI ISCO [g/kwh] 0 1 2 3 4 5 ISNO x [g/kwh] 2.5 ISHC [g/kwh] 2.0 1.5 1.0 0.5 0.0 PARPI ISPM [g/kwh] 0.10 0.08 0.06 0.04 0.02 0.00 2000 rpm, IMEP=2.8 bar 0 1 2 3 4 5 ISNO x [g/kwh] 9
10 60 50 40 30 20 10 0 1.0 EU Diesel Fuel GTL-Fuel Cylinder Pressure [bar] 0.20 0.16 0.12 0.08 0.04 2000 rpm, IMEP=2.8 bar XEGR=45%, ISNOx=0.5g/kWh Burning Rate [1/ CA] 0.00 2 dp/d [bar/ CA] 0.8 1 0.6 0 0.4 Burned Mass 0.2-1 Fraction [-] 0.0-2 140 160 180 200 220 240 140 160 180 200 220 240 Crank Angle [ ] Crank Angle [ ]
11 44 42 40 38 36 2.0 1.5 1.0 0.5 0.0 88 86 84 82 80 Indicated Effiency [%] ETAI ISHC [g/kwh] CSL [db(a)] 0 1 2 3 4 5 6 ISNOx [g/kwh] 0.20 0.15 0.10 0.05 0.00 8 6 4 2 0 Diesel Fuel GTL-Fuel ISPM [g/kwh] ISCO [g/kwh] 0 1 2 3 4 5 6 ISNO x [g/kwh] 2000 rpm, IMEP=7.8 bar
12 100 80 EU Diesel Fuel GTL Fuel Cylinder Pressure [bar] 1.0 0.8 2000 rpm, IMEP=7.8 bar X EGR =30%, ISNOx=0.8g/kWh 60 0.6 40 20 0 0.16 0.12 Burning Rate [1/ CA] 0.4 0.2 0.0 1600 1400 Burned Mass Fraction [-] 0.08 0.04 0.00 160 170 180 190 200 210 220 230 240 Crank Angle [ ] 1200 1000 Mean Cylinder Temperature [K] 800 160 170 180 190 200 210 220 230 240 Crank Angle [ ]
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ERC Research Symposium GTL diesel fuel shows significant potential to improve the NOx-PM trade-off, particularly at low engine loads. HC and CO emissions, which might become very challenging with reduced compression ratios and/or higher degrees of combustion homogenization, can be reduced significantly. The ignition delay is substantially shortened with GTL fuels, resulting in a more advanced and rapid combustion of the pilot quantity, which allows a lower compression ratio and better cold start behavior. To use the full potential of such fuels, the application of an optimized pilot injection strategy is necessary. Combustion stability is considerably improved, thus allowing stable engine operation at higher EGR rates compared to conventional diesel fuel. GTL diesel fuel allows similar full load performance compared to fossil diesel fuel. However, due to the lower volumetric heating value of GTL, injection system hardware and injection strategy require reconfiguration. The hydraulic investigations revealed a similar behavior of the piezoelectric common-rail system for both GTL and fossil diesel fuel. 14
15 Overview 1. Introduction 2. Current Market Situation 3. GTL 4. Biodiesel 5. Alcohols 6. Potential Approaches and Technologies 7. Summary
Impact of Biodiesel on Emissions 16 Source: EPA Biodiesel Report October 2002
Impact of Biodiesel on NOx Emissions 17 Source: EPA Biodiesel Report October 2002
Impact of Biodiesel on Aftertreatment Controlled Regeneration @ Lambda = 1.15 18
Impact of Biodiesel on Aftertreatment 19
20 Overview 1. Introduction 2. Current Market Situation 3. GTL 4. Biodiesel 5. Alcohols 6. Potential Approaches and Technologies 7. Summary
26 21 Compression Ratio [-] 24 22 20 18 16 14 12 Alcohols Premium Regular Gasoline Kerosene Self-Ignition Bad Good Diesel Fuel 0 10 20 30 40 50 60 Cetane Number [-]
22 Property Ethanol Methanol Diesel Net Heat [kj/kg] 26,800 19,700 42,500 Heat of Evap. [kj/kg] 904 1,119 250-300 Cetane Number [-] - 3 40-50 Carbon Content [wt%] 52.0 37.5 86.3 Hydrogen Content [wt%] 13.0 12.5 13.7 Oxygen Content [wt%] 35.0 50.0 0 Intake Valve Direction of Swirl Nozzle Glow Plug Ignition Jet Exhaust Valve
23 Overview 1. Introduction 2. Current Market Situation 3. GTL 4. Biodiesel 5. Alcohols 6. Potential Approaches and Technologies 7. Summary
Influence of Fuel Properties on Combustion System Benefits 24 Conventional Combustion System Short ignition delay Short pre-mix combustion Low dp/d good NVH Lower NOx Cetane # Alternative Combustion System Long ignition delay Long pre-mix combustion High dp/d bad NVH Very low NOx and PM Ignition Delay
Cylinder Pressure Controlled Combustion 25 Siemens Beru Bosch Optrand
26 Overview 1. Introduction 2. Current Market Situation 3. GTL 4. Biodiesel 5. Alcohols 6. Potential Approaches and Technologies 7. Summary
27 Summary Fuels have evolved to important factors defining noise, performance, and emissions Designer fuels and corresponding blends increase in value GTL and biodiesel offer many advantages but are not available in desired quantities yet GTL- or Biodiesel-Diesel blends will be targeted Alcohols due to low cetane number and net heat do not represent meaningful alternatives for diesel engines Technologies to maintain high efficiencies and low emissions need to be adapted (engine & aftertreatment) working independently of the fuel type/quality level
28 Back-Up Slides
Fuel Types 29 Most common fuel property variations: Cetane Number ( CN > 10 units) Sulfur Content ( S > 250 ppm for 500 ppm fuel; misfueling: S > 2500 ppm ) Possible Fuel Types for Tier 4: ULSD Biodiesel (neat or blended) GTL, BTL Impact on aftertreatment (durability, regeneration behavior/corrections, etc.) Closed-loop feedback for emissions and performance optimization Influence on NVH behavior Influence on engine components (acidity, corrosivity, etc.) Remedies: Smart engine control system (adaptive learning) w/ closed-loop feedback References: Biodiesel Fuel Blend Effects, 17 th CRC Vehicle Emissions Workshop 2007; SAE 2006-01-0232 Potential of Synthetic Fuels
2007 Certification Fuel Specifications 30 Specific gravity: Sulfur content: Flash point: Viscosity (@40ºC): 0.84-0.865 kg/l 8-12 ppm 130ºF (min.) 2.0 cst (min.) Cetane number: 40-48 Cetane index: 40-48 Aromatics: 27-32 % by vol. Distillation Curve (ASTM D86): 10% 50% 90% 400-460ºF 470-540ºF 560-630ºF
Impact of Fuel Sulfur Content on SO2 Emissions 31