The US Navy is in the process of evaluating Catalytic Hydrothermal Conversion Jet fuel (CHCJ-5) for inclusion in the JP-5 specification, MIL-DTL-5624, and evaluating Catalytic Hydrothermal Conversion Diesel fuel (CHCD-76) for inclusion in the F-76 specification, MILDTL-16884. CHC fuels are produced from renewable feedstocks such as triglycerides, plant oils, and fatty acids. A Catalytic Hydrothermolysis process chemically converts these feedstocks into a mixture of paraffins, cycloparaffins, aromatics, olefins, and organic acids. The resulting mixture is then hydroprocessed and fractionated to produce a kerosene (or diesel) product having a distillation profile comparable to traditional petroleum derived fuels. The end product is a fuel that is able to meet the jet (or diesel) chemical and physical MIL-SPEC requirements without blending with conventional petroleum fuels. Detailed physical and chemical characterizations are presented showing these new renewable fuels in neat form have similar properties as compared to their natural petroleum counterparts (JP-5 and F-76).
Engine testing was performed using three highly instrumented engines (Waukesha, Yanmar and AM General). CHCJ-5 was compared to the combustion performance of JP-5, while CHCD-76 was compared to conventional diesel NATO F-76. Engine data from this testing was processed to compare the fuels on the basis of relative combustion metric changes. The results of this testing and analysis show that, in general, ignition delay is similar to or slightly shorter than the base fuel. Combustion phasing shifts are quite small, with the maximum rate of heat release showing a modest decrease with the CHC fuels due to their moderately higher cetane values. Overall, both CHC fuels have combustion changes that fall within Navy acceptance standards. Engine operation (including cold starting) with these new renewable neat fuels was similar to the base natural petroleum fuels with no concerns noted.