Thermal Decomposition Kinetics of RP-1 Rocket Propellant

As part of a thermophysical and transport property measurement project, the global decomposition kinetics of the kerosenebased rocket propellant, RP-1, was investigated. We measured the decomposition of RP-1 at elevated temperatures (that is, under thermal stress) as a function of time and then derived a global pseudo-first-order rate constant that describes the overall mixture decomposition. While not as rigorous as a component-by-component kinetics analysis, this approach is, nevertheless, instructive and can be used to guide the aforementioned property measurements. Decomposition measurements were made at 375, 400, 425, and 500 (degree) C for two separate samples of RP-1. One sample was a typical batch, showing the expected fractions of paraffins, cycloparaffins, olefins, and aromatics. The other was an off-specification batch that had unusually high olefin and aromatic contents. Decomposition rate constants ranged from 6.92 × 10^-5 s^-1 at 375 (degree) C to 1.07 × 10^-3 s^-1 at 500 (degree) C. While the primary purpose of this work was to establish operating ranges for the property measurements, the results clearly have implications in other facets of RP-1 application. These applications include establishing operating ranges for supercritical fluid heat sink regimes, setting residence times in motors, etc. In addition to the decomposition kinetics, we have also done a chemical analysis of the vapor phase that is produced upon thermal stress. The vapor phase for this analysis was extracted using a new gas-liquid separator.