A calorimeter was set up to determine the heat sink and to investigate the mechanism of thermal cracking of endothermic hydrocarbon fuels under supercritical conditions. The thermal cracking of n-heptane or JP-10 was studied under different temperatures and pressures, and the corresponding data of heat sinks were obtained. Incorporating with the analyses from gas chromatography, the effects of the temperature or pressure on the heat sink and distribution of gaseous products were elucidated. The heat sink was 3.14 MJ•kg－1 for the thermal cracking of n-heptane at 873 K and 3.4 MPa, and 3.08 MJ•kg－1 for that of JP-10 at 903 K and 3.2 MPa with the conversions of 32% and 4.7%, respectively, which could meet the cooling requirement of aircrafts at 5～6 Mach number.

Key words: endothermic hydrocarbon fuel, supercritical, thermal cracking, heat sink, n-heptane, JP-10