A Primer: Aircraft Emissions & Environmental Impact Alan Epstein Vice President Technology & Environment Aviation and the Environment Washington, DC, March 2008
Impact of Aviation on The Environment ~40,000 ft (12-17 km) Stratosphere: NO x Ozone Layer Change Halogens Troposphere: ~3,000 ft (1000m) CO 2 NO x H 2 O Particulates Ground Level: NO x O 3 Particulates Climate Change Local Air Quality Noise
Engine Efficiency Vs. Combustor Technology Fuel Air Combustor
Engine Efficiency Vs. Combustor Technology Fuel Set By Engine Efficiency Carbon Dioxide - CO 2 Water Vapor - H 2 O Air Combustor
Engine Efficiency Vs. Combustor Technology Fuel Set By Engine Efficiency Carbon Dioxide - CO 2 Water Vapor - H 2 O Air Combustor Combustion Products Set By Combustor Technology Nitrogen Oxides NO x Carbon Monoxide CO Unburned Hydrocarbons UHC Smoke
Engine Efficiency Vs. Combustor Technology Fuel Set By Engine Efficiency Carbon Dioxide - CO 2 Water Vapor - H 2 O Air Combustor Two Paths to Emission Reduction Reduce emissions per kg of fuel Reduce absolute amount of fuel Combustion Products Set By Combustor Technology Nitrogen Oxides NO x Carbon Monoxide CO Unburned Hydrocarbons UHC Smoke
Improving Combustors to Reduce Emissions Combustor Requirements Local Air Quality & Global Warming Emissions Stability SAFETY Endurance Altitude Re-light and Starting
Science Behind Low NO x Technology NO x Up With Temperature and Time Mixing & Lean Fuel Rich Combustion Combustion 200 Lean Rich NO x (EI) 100 Time 4 ms 1 ms Rich Quick Quench Lean (RQL) Combustor Design EI Emission Index, grams NO x per kg of fuel 0 0.3 ms 0.2 0.6 1 1.4 1.8 Equivalence Ratio ~ Fuel/Air
Science Behind Low NO x Technology NO x Up With Temperature and Time Mixing & Lean Fuel Rich Combustion Combustion 200 Lean Rich NO x (EI) 100 Time 4 ms 1 ms Rich Quick Quench Lean (RQL) Combustor Design EI Emission Index, grams NO x per kg of fuel 0 Max Allowed 0.3 ms 0.2 0.6 1 1.4 1.8 Equivalence Ratio ~ Fuel/Air
Science Behind Low NO x Technology NO x Up With Temperature and Time Mixing & Lean Fuel Rich Combustion Combustion 200 Lean Rich NO x (EI) 100 Too Lean to Burn Time 4 ms 1 ms Rich Quick Quench Lean (RQL) Combustor Design EI Emission Index, grams NO x per kg of fuel 0 Max Allowed 0.3 ms 0.2 0.6 1 1.4 1.8 Equivalence Ratio ~ Fuel/Air
Science Behind Low NO x Technology NO x Up With Temperature and Time Mixing & Lean Fuel Rich Combustion Combustion 200 Lean Rich Rich Quick Quench Lean (RQL) Combustor Design NO x (EI) EI Emission Index, grams NO x per kg of fuel 100 0 Too Lean to Burn Engine Average Time 4 ms 1 ms Max Allowed 0.3 ms 0.2 0.6 1 1.4 1.8 Equivalence Ratio ~ Fuel/Air
History of Regulated Emissions Reduction 600 % of CAEP2 limit 500 400 300 200 HC CO NOx 100 0 pre 76 76-80 81-85 86-90 91-95 Year of Engine Certification
NO x Reductions Continue to be Mandated Cannot compromise CO, UHC, and Smoke % ICAO CAEP/2 NO x Standard 140 120 100 80 60 40 20 Original Standard Conventional TALON I TALON II PW4090 CAEP/2 PW4098 PW4168 TALON X CAEP/4 PW6000 CAEP/6 CAEP: Committee on Aviation Environmental Protection 0 1988 1992 1996 2000 2004 2008 2012
Reducing Fuel Burn to Reduce Emissions Thermal and Propulsive Efficiency Set Fuel Burn (SFC)
NO x -CO 2 Engine Design Trade Improving Thermal Efficiency Can Increase NO x Specific Fuel Consumption SFC (lb/lb-hr) SFC Improving Engine performance Improving Combustor Technology NO X Emissions Index EI (grams NOx/kg fuel) 0 10 20 30 40 50 60 Overall Compressor Pressure Ratio (Thermal Efficiency)
NO x -CO 2 Engine Design Trade Improving Thermal Efficiency Can Increase NO x Specific Fuel Consumption SFC (lb/lb-hr) SFC Improving Engine performance Improving Combustor Technology NO X Emissions Index EI (grams NOx/kg fuel) 0 10 20 30 40 50 60 Overall Compressor Pressure Ratio (Thermal Efficiency)
NO x -CO 2 Engine Design Trade Improving Thermal Efficiency Can Increase NO x Specific Fuel Consumption SFC (lb/lb-hr) SFC Improving Engine performance Improving Combustor Technology NO X Emissions Index EI (grams NOx/kg fuel) 0 10 20 30 40 50 60 Overall Compressor Pressure Ratio (Thermal Efficiency)
Evolution in By-Pass Ratio & Efficiency TURBOJET B707 (JT3C) TURBOFAN Low by-pass B707-320 (JT3D), B727 (JT8D) Lower fuel consumption so - Lower CO 2 - Lower NO x TURBOFAN High by-pass - B747 (JT9D) B777 (PW4084) Ultra high by-pass 1960 1970 1980 1990 2000 2010
History of 70-100 PAX Class Air Transport DC-3 Boeing 377 Stratocruiser Electra ATR 72 CRJ1000 Entry into Service 1936 1948 1958 1998 2009 MTOGW (lbs) 25,200 145,800 116,000 49,600 91,800 Fuel Capacity (gals) Passengers Wing Span (ft) Cruise Altitude (ft) Cruise/Max Speed (KCAS) Range (NM) 720 28 95 6,000 150 cruise 1450 6900 89 141 20,000 260/325 3700 6535 85 99 20,000 325/352 3500 1645 68 89 17,000 250/275 890 2900 100 86 41,000 447 / 470 816 Fuel Efficiency (seat-st.mi / US gal) 20 23 38 83 70 Engine Pratt & Whitney Twin Wasps Pratt & Whitney Wasp Major Allison 501-D13 Turboprop PW127 Turboprop CF-34 Turbofan Diameter (in.) Takeoff Power 138 prop 1200 HP 199 prop 3500 HP 162 prop 3750 HP 155 prop 2475 HP 46 fan 13,600 lbf
Summary of Aircraft Emissions Primer Aircraft engines have unique requirements Safety, weight, life in addition to low emissions Regulated emissions Smoke, HC, CO are well in hand NOX will stay a challenge as rules tighten & efficiency up Climate change concerns may add new constraints CO 2 is a concern H 2 0 may be a player if contrails important
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