Supercritical pyrolysis of a jet propulsion JP-7-type fuel with chemical initiators: Heat sink, product, and coke analysis

Abstract

Improving cooling performance while mitigating coke formation remains a critical challenge in the development of thermal management and propulsion systems for supersonic aerospace vehicles. This study looked at the supercritical pyrolysis characteristics of a JP-7-type jet fuel using different chemical initiators. The five different initiators we tested were di-tert-butyl peroxide (DTBP), 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO), triethylamine (TEA), diphenyl selenide (DPS), n-cumene hydroperoxide (CHP), and we pyrolyzed the JP-7-type fuel under inert, supercritical conditions at a temperature of 665°C and a pressure of 40 bar. This study evaluated the effect of the chemical initiators on heat sink performance, the primary distribution of cracking products, and coke formation. The oxygen-based DTBP initiator (H/C ratio=2.25) exhibited the highest heat sink capacity (1432 Btu/lb, 3331 kJ/kg) but generated substantial coke deposits (40 mg), while a selenium-based type like DPS (H/C ratio=0.83) effectively suppressed coke formation (14 mg) at the expense of heat sink potential (1293 Btu/lb, 3007 kJ/kg). A correlation was identified between total heat sink, initiator H/C ratio, and coke formation behavior during supercritical pyrolysis. These results offer new insights into the connection between chemical initiator structure, radical production ways, and thermal cracking behavior under extreme conditions at high temperature and in an inert atmosphere. The obtained results, in turn, have consequences for the optimization of endothermic cooling and coke management strategies in advanced air-breathing propulsion systems.