Study of an iso-Paraffinic Alcohol-to-Jet Fuel, Kerosene-Based Jet Fuels, and their Mixtures

The HPST Laboratory examines the chemical kinetics of the pyrolysis and oxidation of hydrocarbon propulsion fuels using lower and higher pressure shock tubes. Using both shock tubes, experiments were conducted to determine the pyrolytic and oxidative decomposition products of an alcohol-to-jet fuel (ATJ) composed primarily of about 90% iso-dodecane, the remaining 10% is composed of iso-cetane, iso-nonane, and iso-tridecane. The oxidative decomposition of n-heptane, F-24, Jet A, and mixtures of ATJ/n-heptane and ATJ/F-24 were also studied. Gas chromatography (GC) and GCxGC was used to analyze the products of the chemical reactions and to determine their mole fractions. Experiments were performed over a wide range of conditions, pressure ranging 4 – 50 bar, reaction time 2 – 8.5 ms, initial fuel load 45 – 1400 ppm, and equivalence ratio 0.27 – 1.36 over a determined temperature range. Experiments were performed at such wide range of conditions to analyze the effects of pressure, reaction time, and initial fuel load. ATJ/n-heptane results were compared against pure ATJ and n-heptane to see the effect of mixing an iso-paraffinic synthetic jet fuel with a well-characterized kerosene-based jet fuel surrogate, n-heptane. These comparison between pure fuels and their mixture was repeated for a kerosene-based jet fuel, F-24, instead of a surrogate. Jet A experiments were conducted to analyze the difference between Jet A and F-24, since F-24 is basically Jet A with additives. The experimental results were compared against mole fractions computed using different chemical kinetic models. The ability of each kinetic model to capture the effect of varying the experimental test conditions on the evolution of intermediate species was discussed and kinetic analyses, such as ROP and sensitivity have been conducted to identify the important reaction pathways, and Monte Carlo uncertainty analysis to study the model’s capability of capturing the experimental data within a predetermined pre-exponential factor uncertainty in the model.