On Iso-Paraffinic Kerosene Oxidation

The increasing development of synthetic aviation fuels from alternative feedstocks requires fuels that not only meet stringent combustion performance standards but are also compatible with existing infrastructure. Combustion properties, such as ignition delay, and combustor operating regimes, such as gas turbine lean blowout, are strongly influenced by parameters including cetane number (CN), viscosity, and volatility. Because jet fuels do not have a specification for CN, synthetic fuels often exhibit lower CN values, leading to longer ignition delays. They also exhibit reduced lubricity relative to conventional petroleum-based jet fuels, as hydrocracking removes oxygen-, sulfur-, and nitrogen-containing compounds from the fuels. These limitations can be addressed through additive use or strategic blending. To streamline certification processes and reduce associated costs, reliable prescreening tools capable of predicting fuel properties are essential for compliance with ASTM fast-track certification protocols. In this work, we present a generalized low-volume screening and kinetic modeling strategy, demonstrated using isoparaffinic kerosene (IPK) produced by Sasol, to enable efficient combustion characterization of synthetic and conventional fuels. Single-pulse shock tube experiments were conducted at 50 atm pressure, 13 ms reaction time, and temperatures ranging from 800 to 1400 K under equivalence ratios of 1.0 and 0.5. Post-shock species were quantified using gas chromatography (GC). Comprehensive compositional analysis via GC × GC-TOFMS/FID revealed that IPK is composed predominantly of C9–C14 isoparaffins. A chemical functional group optimization (CFGO) approach was applied to formulate surrogate mixtures by matching functional group distributions and the experimentally measured derived cetane number (DCN = 31.52, determined via IQT). The surrogate mechanism, based on the CRECK kinetic model, demonstrated good agreement with experimental speciation data. Rate-of-production, sensitivity, and reaction pathway analyses identified the dominant reaction channels governing fuel oxidation. The results demonstrate the capability of surrogate-based models to accurately capture the combustion characteristics of complex synthetic fuels. Moreover, it is desirable that such surrogates, composed of commercially available components, can also enable experimental evaluation of other key combustion metrics, such as atomization, droplet size, and spray behavior, which typically require large quantities of fuel. This capability facilitates efficient, low-volume screening of novel synthetic fuels prior to large-scale production.