Alternative Fuels for Commercial Aircraft
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Transcript of Alternative Fuels for Commercial Aircraft
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SEMINAR ON
Alternative fuels for commercialaircrafts
By
Shashishekarayya.R.Hiremath
M.Tech. 1 sem Aeronautical Engg.
M.V.J.C.E Bangalore
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OVERVIEW
yNeed for alternative fuels
y Types of alternatives
yNear term
y Mid term
y Far term
y Conclusion
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NEED FOR ALTERNATIVESy Diminishing discovery of new petroleum sources and
ever increasing demand.
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yNext generation aircrafts will see 15%-20 % fuel efficient,
making air travel one of the most efficient means oftransportion,so aircraft industries will still require an
increasing amount of fuel
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NEAR TERM ALTERNATIVESy Drop in fuels
y Synthetic Jet fuel:
Prepared from Fischer Tropsch process (FT)
Natural gas and coal are main feedstocks
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Positive Attributes:y Cleaner burning fuels with no sulfur
y Higher Thermal Stability
y Lower particulate Engine Emission
y Show excellent low temperature properties
y Maintaining low viscosity at lower temperature
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Negative Attributes:
y Poorer lubrication properties
y Lower volumetric heat content
y Possible contributor to elastomer leakagey Increased CO2 emission during its manufacture
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MID TERM ALTERNATIVES
y 10-25 years from now
y Blending biofuels with synjets
y Some changes in existing engine configuration
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Challenges to be overcome:
y Propensity to freeze at normal operating cruise
temperatures
y Poor high thermal stability characteristics in engine
y Limited excess farm land
One Promising feedstock for bio fuels is Algae.
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FAR TERM ALTERNATIVESyNeed to reduce emissions of greenhouse gases, therefore
low to zero carbon fuels has to be used.
Liquid Methane
Liquid Hydrogen
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Methane Gas
y Huge amounts of methane gas is trapped in the forms of
methane hydrates.
y 0.3 X 1012 m3 in middle east and soviet-union
y 21.1012 m3 in Americas
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Major issues to be considered
y Economics of recovery under unfamiliar & inconvenient
deep under sea conditions.y Environmental and Technical feasibility
y Safety aspects during extraction.
y Extraction in permafrost areas may cause global
warming.
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Liquid Hydrogen
Historical and Technological Evolution of LH2
y The first aircraft that flew with hydrogen was a US Air Force B-57 twin
bomber that in 1956
y In 1988, the Soviets experimented with a modified TU-154 (renamed TU-155), with one engine (out of the two) operated on hydrogen alone.
y Retired Pan American pilot Bill Conrad converted a four seater Grutnnab
Cheetah to run on hydrogen in 1988.
y During the 1989 Paris Air Show, the German partner in the European
Airbus, Messerschmidt-Boelkkov-lBlohm (MBB), showed an interest indeveloping a hydrogen fueled twin of the Airbus A310.
y Samara Trud Project (Samara State Scientific and Production Enterprise
(SSSPE) TRUD),
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y cryoplane design adopted by
Russian-German
Cooperative Venture on the
basis of an existing Airbus
A310
y NASA-Langley Research
Center
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LH2 advantage
y Higher specific energy (119 190 kJ/kg) than conventional fuel (43 60
kJ/kg). Higher fuel efficiency. Wider range of flammability.
y Higher flame speed. Higher combustion temperature.
y Reduced gross weight (26%). Reduced wing area (18%). Smaller engines
and noise reduction. High heat sink capacity. Cruise lift-to-drag ratio
reduced by 10-18%.
y NO missions of CO, CO*, particles, HC, S compounds and odor. Reduced
NO, (33% or less of that produced by todays turbofan engines using
combustion chambers with premixing)
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LH2 disadvantage
y Four times lower energy per unit volume.
y More voluminous fuselage. Necessity of cryogenic fuel
system.y Airport hydrogen plant with following units needed:
Electrolyzer, purification, liquefier, storage and
distribution system About 2.5 times more H2O
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Environmental considerations
y Production of Nox
y Green house effect of water vapor increases enormously.
y Hydrogen is the most advantageous environmental optionover carbon based fuels, since it does not produce CO2CO, SO2, HC, etc., and lowers NOx emission.
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afety and handling
y Hydrogen is an extremely volatile fuel, which has to be
handled with great care. Never the less it is not unsafe.
yplacement of fuel tanks.
y Hydrogen has a wide flammability range.
y Liquid hydrogen, along with other cryogens, has a high
liquid-to-gas volume expansion ratio, so that liquid
hydrogen piping should always include a pressure reliefdevice.
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Economics ofLH 2 aircraft
y LH2 aircraft, the most influential factor is the fuel cost,
representing 50% of the total DOC.
yLH2price will decrease as large scale industrial facilitiesare installed.
yNeed to build industrial facilities for LH2production.
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CONCLUSIONy The short-term option of synthetic fuels processed in the
FT process meets the first target, , it will not reduce CO2
emissions over the entire life cycle.y Algae seem to be a promising future feedstock option
which could provide a much higher oil yield per hectare
than present bio-fuels.
yThe large scale introduction of hydrogen into aviation
presents no unsolvable technical problems, but it does
involve the need for the following work items:
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y A thorough study of the components of a cryogenic fuel
system, mainly as regards the structural materials for
tanks, pipes and insulation systems.y Developing monitoring systems to detect hydrogen leaks
in hydrogen installations.
y Research on reducing NOx emissions.
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QUESTIONSuu
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THANK YOU