Thermal Cracking and Heat Sink Capacity of Aviation Kerosene Under Supercritical Conditions

Thermal cracking and endothermicity of China No. 3 aviation kerosene were studied experimentally under supercritical conditions relevant to regenerative cooling systems for scramjet applications. A multiple-stage heating system with reaction products collection was used that can achieve a fuel temperature range of 780-1050 K, a pressure range of 3-4.5 MPa, and a residence time range of 0.6-3 s. The chemical heat sink was determined through a control volume analysis of the fuel flow. Compositions of I he cracked gaseous and liquid products were analyzed via gas chromatography. Based on the results of fuel conversion, the temperature range for the active cracking was observed to be approximately 800-1000 K, beyond which the cracking approaches completion. It was also found that the variation of the chemical heat sink with temperature can be nonmonotonic and a maximum endothermicity was seen to occur in the temperature range of 900-960 K, depending on the residence time. For the current operation conditions, the maximum chemical heat sink reached 0.5 MJ/k g at a fuel conversion of 45%. Composition analysis of the gaseous product indicated that the saturated hydrocarbons such as methane became dominant as temperature was increased. On the other hand, the major compositions of the liquid product were benzene-based and naphthalene-based hydrocarbons.