Kinetic Model and Experiment for Self-Ignition of Triethylaluminum and Triethylborane Droplets in Air

Triethylaluminum Al(C2H5)3, TEA, and triethylborane, B(C2H5)3, TEB, are transparent, colorless, pyrophoric liquids with boiling points of approximately 190 °C and 95 °C, respectively. Upon contact with ambient air, TEA, TEB, as well as their mixtures and solutions, in hydrocarbon solvents, ignite. T...

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Published in:Micromachines (Basel) 2022-11, Vol.13 (11), p.2033
Main Authors: Frolov, Sergey M., Basevich, Valentin Y., Belyaev, Andrey A., Shamshin, Igor O., Aksenov, Viktor S., Frolov, Fedor S., Storozhenko, Pavel A., Guseinov, Shirin L.
Format: Article
Language:English
Subjects:
Activation energy
Aluminum
Autoxidation
Boiling points
Constraining
droplet
Droplets
Gases
Heat
Homogeneous mixtures
Hydrocarbons
Hypergolic rocket propellants
Ignition
Oxygen
oxygen intrusion reaction
rate constant
Rocket propellants
Temperature
triethylaluminum
triethylborane
Vapor phases
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Summary:Triethylaluminum Al(C2H5)3, TEA, and triethylborane, B(C2H5)3, TEB, are transparent, colorless, pyrophoric liquids with boiling points of approximately 190 °C and 95 °C, respectively. Upon contact with ambient air, TEA, TEB, as well as their mixtures and solutions, in hydrocarbon solvents, ignite. They can also violently react with water. TEA and TEB can be used as hypergolic rocket propellants and incendiary compositions. In this manuscript, a novel scheme of the heterogeneous interaction of gaseous oxygen with liquid TEA/TEB microdroplets accompanied by the release of light hydrocarbon radicals into the gas phase is used for calculating the self-ignition of a spatially homogeneous mixture of fuel microdroplets in ambient air at normal pressure and temperature (NPT) conditions. In the primary initiation step, TEA and TEB react with oxygen, producing an ethyl radical, which can initiate an autoxidation chain. The ignition delay is shown to decrease with the decrease in the droplet size. Preliminary experiments on the self-ignition of pulsed and continuous TEA–TEB sprays in ambient air at NPT conditions are used for estimating the Arrhenius parameters of the rate-limiting reaction. Experiments confirm that the self-ignition delay of TEA–TEB sprays decreases with the injection pressure and provide the data for estimating the activation energy of the rate-limiting reaction, which appears to be close to 2 kcal/mol.
ISSN:2072-666X
2072-666X
DOI:10.3390/mi13112033