environmentally neutral propulsion
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Environmentally-Neutral AircraftPropulsion Using Low
Temperature Plasma
John Leylegian, Jason Tyll, and Wallace Chinitz
GASL, Inc.
Ronkonkoma, NY 11779
NIAC Annual Meeting - June 6, 2000
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Motivation
• NO x formation is a consequence of thecombustion of various fuels.
• Nitric oxide (NO):
• Quickly forms nitrogen dioxide (NO2), a
respiratory irritant.
• Active participant in photochemical smog
formation.
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Motivation (2)
• Current methods of NO x reduction involvecatalysts used either alone (e.g. Rh), or in an
atmosphere containing hydrocarbons (e.g.
Cu or Fe).
• Rhodium is too expensive for widespread
use, and extra hydrocarbons in fuel exhaustare undesirable.
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Objective
• To reduce NO x in turbojet emissions by anorder of magnitude using a low-temperature
plasma.
• “Low-temperature plasma” implies plasma
excitation temperatures in the range of 3000
to 5500 K.
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Previous Work
• Luo et al. ( J. Phys. Chem. A 102:7954,1998) decomposed NO in He using a low-
temperature plasma at atmospheric pressure.
• The degree of NO destruction is a function
of initial NO concentration, residence time,
input voltage, and additives.
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Additive Effects on NO
Reduction from Previous Work
• CO2 and H2O inhibited the destruction of
NO.
• CO, O2, C2H6, and other carbon species
accelerated the destruction of NO.
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Extending This Concept to the
Turbojet Engine
(Could it still work?)
• Higher temperatures (up to 1700 K)
• Higher pressures (up to 40 atm)
• Shorter residence times (~0.1 s)
• Presence of different species (O2, N2, CO2,
H2O)
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Turbojet Engine1. Air is compressed and heated in diffuser/compressor
2. Fuel mixed in and burned in combustor 3. Partially expanded in turbine to provide power for
compressor
4. Expansion continues through nozzle, generating thrust
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Proposed Work
• Perform experiments similar to those of Luoet al., using the products of hydrocarbon
combustion, at conditions similar to those
encountered in a turbojet engine.
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Program Outline
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Rig Schematic
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Estimation of NO Levels
in Jet Exhaust
• Equilibrium temperatures of ethylene/air mixtures:
1000
1200
1400
1600
1800
0.3 0.4 0.5 0.6
Equivalence Ratio
A
d i a b a t i c F l a m
e
T
e m p e r a t u r e ( K
)
1 atm5 atm
10 atm
20 atm
40 atm
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Estimation of NO Levels
in Jet Exhaust
• Variation of NO in ethylene/air products withtemperature:
0.000
0.001
0.002
0.003
0.004
1000 1200 1400 1600 1800
Flame Temperature (K)
M o l e
F r a c t i o n N O 1 atm
5 atm
10 atm
20 atm
40 atm
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Determination of Power
Requirements (1)
Rate constant for overall reaction:
NO→ ½N2 + ½O2
converted to Arrhenius form: k = A T 0.75
where A is a function of the input power.
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Determination of Power
Requirements (2)
Using the power-rate constant data of Luo et
al. and the LSENS code, the power required
for an order-of-magnitude reduction in NOmole fraction can be determined:
P (W) = 4.868 X NO –1.0196
For X NO = 0.002, P = 2.75 kW
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Power Sources
• Fuel Cells: Automotive PEM fuel cellsavailable up to 20 kW (if DC is required)
• Fuel Cell + Inverter (if AC is required)
• Turbine
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Summary
• Oxides of nitrogen, produced by fossil fuelcombustion, are environmental and health
hazards.
• Use of plasmas to reduce NO levels is a
clean and inexpensive method.
• A plasma generator is being designed to testthis method on hydrocarbon-air combustion
products at high temperature and pressure.