An Investigation of Pyrolytic Cracking of JP-10 in Laminar Flow Reactors with Molecular Beam Mass Spectrometry

The stable operation of hypersonic airbreathing aircraft depends on the implementation of advanced cooling systems. Because the pyrolysis of hydrocarbon fuels is an endothermic process, it has been proposed to use the fuel itself as the active coolant. Exo-tetrahydrodicyclopentadiene (C10H16, known as JP-10) is a jet fuel of interest for hypersonic applications due to its high specific heat, energy density, and potential as an endothermic fuel. An adverse consequence of the endothermic pyrolysis of fuel is the formation of coke in the cooling lines, which clogs the lines to the point of failure. The chemical kinetics of the thermal pyrolysis of fuel which leads to coke formation are not well understood. This study pairs a novel microflow tube reactor featuring a reduced mixing volume to minimize initialization kinetics with molecular beam mass spectrometry, a powerful experimental technique which separates species by mass while preserving radical species for analysis. Accurate measurements of stable and radical species in pyrolytic processes are essential for the development of kinetic models, and speciation data are reported in microflow tube reactor experiments in the temperature range from 1050-1250 K over residence times from 15-100 ms. Reaction pathway analysis reveals the importance of accurate quantification of the cyclopentadienyl radical in predicting important coke precursors. Finally, the reported data are implemented in the construction of a semi-global JP-10 pyrolysis model, which suggests existing literature mechanisms may be further optimized and reduced for incorporation into computational fluid dynamics models.