Direct Sugar to Hydrocarbon (DSH) Fuel Performance Evaluation in Multiple Diesel Engines

A new alternative fuel has been tested in a number of engines and compared to conventional Navy diesel fuel performance using in-cylinder based diagnostics and brake performance comparisons. This new fuel is derived from a Direct Sugar to Hydrocarbon (DSH) process in which sugar and yeast produce a farnesene type hydrocarbon molecule (branched hydrocarbon with multiple double bonds) which is then processed into a moderately branched single alkane molecule (> 98% purity) with a moderately higher cetane number than conventional diesel fuels. This new fuel was extensively characterized and has a lower density, viscosity and bulk modulus as compared to conventional diesel fuel. These physical property differences lead to later Start of Injection times in three diesel engines (AM General GEP, Waukesha CFR and Yanmar). However, due to the increased reactivity of DSH, ignition delay is reduced - faster across most of the speeds and loads tested. While engine operation on the neat form of DSH falls just inside the proposed Navy alternative fuel acceptance criteria at all operating points, it is expected that a 50% DSH and 50% diesel fuel blend will be tested for broader application due to acceptable combustion characteristics in this compression-ignition study.