Abstract
Initiators can accelerate the pyrolysis of hydrocarbon fuels, thereby reducing the required reaction temperature in the hypersonic vehicle heat exchanger/reactor. Nitro-alkanes are considered as efficient initiators due to their lower energy barrier of the C-N bond cleavage reaction. To research the mechanism of the initiation effect of nitro-alkanes on the decomposition of hydrocarbon fuel, synchrotron radiation vacuum ultraviolet photoionization-mass spectrometry (SVUV-PIMS) was employed to experimentally study the pyrolysis of n-C(10)H(22), 1-C(3)H(7)NO(2), and their binary mixtures in a flow tube under pressures of 30 and 760 Torr. The species identified and measured in the experiments included alkanes, alkenes, dialkenes, alkynes, nitrogen oxides, benzene, and free radicals, which revealed the mechanism of n-decane and 1-C(3)H(7)NO(2) pyrolysis, as well as the interactions of the two fuels. Experiments show that the presence of 1-C(3)H(7)NO(2) reduces the initial decomposition temperature of n-C(10)H(22), and the increased pressures could achieve a stronger promoting effect on the conversion of n-C(10)H(22). A detailed kinetic model containing 1769 reactions and 278 species was established and validated based on the mole fraction distributions of n-C(10)H(22), major pyrolysis species, and important intermediates measured in pure fuel and initiated pyrolysis. The kinetic model can accurately predict the experimental data, and the mechanism of 1-C(3)H(7)NO(2)-initiated pyrolysis of n-C(10)H(22) is analyzed with the model. The effect of 1-C(3)H(7)NO(2) on the consumption of n-C(10)H(22) and selectivity of cracked products is highlighted.