Endothermic heat sink capacity of fuels is important for the thermal management of hypersonic vehicles. Chemical kinetic models of multi-component hydrocarbon fuels can be used to estimate the endothermic heat sink capacity, but require knowledge of the chemical kinetic behavior of these complex fuels during cracking. The heat sink capacity of these fuels is largely controlled by the ratio of olefins to n-paraffins produced during the thermal/catalytic cracking. Therefore, it is important to validate the model for product selectivity for accurate prediction of endothermic heat sink capacity. A detailed chemical kinetic model for the thermal and catalytic cracking of n-paraffins was developed and validated over a range of experimental conditions including hypersonic relevant conditions. The model includes a detailed gas-phase pyrolysis kinetic model for C_1 to C_(16) n-paraffins along with a surface kinetic model for n-octane on H-ZSM-5 zeolite catalyst. It was demonstrated that gas-phase kinetic model coupled with the surface kinetic model was able to predict the endothermic heat sink capacity correctly during the thermal and catalytic cracking of «-octane. The model also predicts the product selectivity of thermal and catalytic cracking reasonably well.
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