Due to potential beneficial environmental impacts and increased supply availability, alternative fuels derived from renewable resources are evolving on the forefront as unconventional substitutes for fossil fuel. Focus is being given to the evaluation and certification of Hydroprocessed Renewable Jet (HRJ), a fuel produced from animal fat and/or plant oils (triglycerides) by hydroprocessing, as the next potential synthetic aviation fuel. Extensive efforts have recently been performed at the Air Force Research Laboratory (AFRL) at Wright Patterson Air Force Base (WPAFB) to evaluate the potential of two HRJ fuels produced from camelina and tallow feedstocks. These have included characterization of the fuel chemical and physical fuel characteristics, and Fit-for-Purpose properties (FFP). The present effort describes general combustion performance and emission propensity of a T63-A-700 Allison turbine engine operated on the HRJs and 50/50 (by volume) HRJ/JP-8 fuel blends relative to a specification JP-8. In addition, engine and emission testing with a blend of the tallow-derived HRJ and 16% bio-derived aromatic components was completed. Fundamental engine performance characterization allows for determination of the suitability of potential synthetic fuels while quantitation of gaseous and particulate matter emissions provides an assessment of the potential environmental impact compared to current petroleum-derived fuels. In addition, an extended 150 hour endurance test was performed using a 50/50 blend of tallow-derived HRJ with JP-8 to evaluate the long-term operation of the engine with the synthetic fuel blend. This paper discusses the laboratory testing performed to characterize HRJs and results from the basic engine operability and emissions studies of the alternative fuel blends.

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