Ignition of H sub 2 /O sub 2 /NH sub 3 , H sub 2 /Air/NH sub 3 and CH sub 4 /O sub 2 /NH sub 3 mixtures by excimer-laser photolysis of HN sub 3

Journal Article · Fri Nov 01 04:00:00 EST 1991 · Combustion and Flame; (United States)

DOI:https://doi.org/10.1016/0010-2180(91)90169-C· OSTI ID:5490820

Chou, M S; Zukowski, T J ^[1]

---

1. TRW Space and Technology Group, Redondo Beach, CA (US)

This paper reports on volumetric ignition of H{sub 2}/O{sub 2}/O{sub 2}, H{sub 2}/air, and Ch{sub 4}/O{sub 2} mixtures (in an open flow system, initially at 1 atm and room temperature) which is achieved via photolysis of a small amount of NH{sub 3} present in the flow mixtures. The photolysis is accomplished by an ArF excimer laser operated at 193 nm. The ignition appears to be homogenous, since the ignition-delay times measured at several locations are approximately identical. The minimum ignition-energy density is measured to be 137 {plus minus} 8, 190 {plus minus} 20, and 380 {plus minus} 30 mJ/cm{sup 3} for stoichiometric mixtures of H{sub 2}/O{sub 2}/NH{sub 3}, H{sub 2}/air/Nh{sub 3}, and Ch{sub 4}/O{sub 2}/NH{sub 3}, respectively, and appears to be insensitive to fuel-equivalence-ratio values between 0.35 and 3.0. The ignition-delay time depends strongly on both the initial NH{sub 3} concentration and the laser-energy-deposition density. However, the ignition-delay time is not sensitive to the fuel equivalence ratio. The measured minimum ignition-energy density appears to be substantially lower than that predicted by a kinetic modeling calculating. This result implies that the hot H atoms produced by the photolysis of NH{sub 3} may play an important role in facilitating the ignition.

• OSTI ID: 5490820
• Journal Information: Combustion and Flame; (United States), Journal Name: Combustion and Flame; (United States) Vol. 87:2; ISSN CBFMA; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
083000* -- Hydrogen-- Combustion-- (1990-)
09 BIOMASS FUELS
092000 -- Biomass Fuels-- Combustion-- (1990-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500 -- Photochemistry
400800 -- Combustion
Pyrolysis
& High-Temperature Chemistry
ALKANES
AMMONIA
CHEMICAL REACTIONS
COMBUSTION
DECOMPOSITION
ELEMENTS
ENERGY DENSITY
EXCIMER LASERS
GAS LASERS
HEATING
HYDRIDES
HYDROCARBONS
HYDROGEN
HYDROGEN COMPOUNDS
LASER-RADIATION HEATING
LASERS
METHANE
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NONMETALS
ORGANIC COMPOUNDS
OXIDATION
OXYGEN
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PLASMA HEATING
THERMOCHEMICAL PROCESSES