Supercritical pyrolysis of in-house developed endothermic fuel and estimation of coke and endothermicity

Abstract

The present investigation includes the development of potential endothermic fuels for regenerative cooling in air-breathing supersonic engines. The endothermic characteristics of two multi-component fuels, namely AF-1 (a boiling range of157–234 °C) and AF-2 (a boiling range of155–207 °C), were studied by performing pyrolysis experiments using a flow reactor under supercritical conditions, and the results are compared with a single component n-dodecane hydrocarbon Various techniques, such as ASTM D86 distillation, aniline temperature, calorific value, GC, GC-MS, thermogravimetric, and non-dispersive infrared radiation spectroscopy, were used to characterize the feed and product properties. At 700 °C and 55 bar pressure, the cracking conversion of AF-1, AF-2, and n-dodecane feed were 13.2, 15.6, and 25.1 %, respectively. The coke deposition rate was in the order of AF-2 > AF-1 > n-dodecane. In the work, a composition-based enthalpy estimation approach was adopted in estimating the endothermicity of the multi-component fuels. The endothermic heat sink capacity of the in-house developed AF-2 fuel (475 kJ/kg) was marginally higher than the AF-1 (456 kJ/kg) and about 15 % lower than n-dodecane (560 kJ/kg) at 700 °C.