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A diesel engine electrical generator set (‘gen-set’) was instrumented with in-cylinder pressure indicating sensors as well as a nearby microphone. Conventional jet fuel plus high (Cetane Number CN55) and low (CN35) secondary reference fuels were operated during which comprehensive engine and acoustic data were collected. Fast Fourier Transforms (FFTs) were analyzed on the acoustic data. FFT peaks were then applied to machine learning neural network analysis with MATLAB based tools. Detection of the low and high cetane fuel operation was audibly determined with correlation coefficients greater than 98% on test data sets. Further, unsupervised machine learning Self Organizing Maps (SOMs) were produced during normal-baseline operation of the engine with jet fuel. Application of the high and low cetane fuel operational acoustic data was then applied to the normal SOM.

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.

A new Alcohol To Jet (ATJ) fuel has been developed using a process which takes biomass feedstock to produce a branched butanol molecule. Further dehydration, reforming and hydro-treating produced principally a highly branched C12 iso-paraffin molecule. This ATJ fuel with a low cetane value (DCN = 18) was blended with Navy jet fuel (JP5) in various quantities and tested in order to determine how much ATJ could be blended before diesel engine operation became problematic (the US Navy and Marine Corps may use jet fuel in their diesel engines). Blends of 20%, 30% and 40% ATJ (by volume) were tested with jet fuel. The Derived Cetane Number (DCN) falls from 45 for the base JP5 to 38 with the 40% ATJ component blended in. Engine start performance was evaluated on two Yanmar engines and a Waukesha CFR diesel engine and showed that engine start times increased steadily with increasing ATJ content.