Formulation of 7-Component Surrogate Mixtures for Military Jet Fuel and Testing in Diesel Engine

Abstract

In this work, military jet fuel JP-5 surrogates were formulated and tested in comparison to a nominal JP-5 fuel. Combustion experiments were conducted in an advanced engine technology (AET) ignition quality tester (IQT) and a Yanmar L100W Tier 4 diesel engine due to the potential use of jet fuel in diesel engines in military situations. The surrogate development process began with determining the fuel chemical composition based on analyses of 256 JP-5 fuel samples. The physical and chemical properties of density, viscosity, flash point, surface tension, speed of sound, and distillation behavior guided the selection of the surrogate components and their composition. JP-5 differs from other aviation fuels in its properties, but most importantly in flash point, which is higher for safety purposes. Surrogates were prepared from n-dodecane, n-butylbenzene, 1-methylnaphthalene, tetralin, trans-decalin, iso-cetane, and n-butylcyclohexane as representatives of seven of the nine major chemical categories found in jet fuel. The mass fraction of each compound in the surrogates that fell within the range for that chemical class was found in real JP-5 fuels. After optimizing the surrogates for physical and chemical properties, six surrogates were selected for combustion testing in the Yanmar diesel engine, one of which was specifically selected for a low-derived cetane number (DCN). This surrogate performed poorly in the Yanmar engine. Four of the remaining five surrogates performed similarly to the baseline JP-5 in the diesel engine in terms of values and variability of ignition delay, rate of heat release, peak pressure, and the crank angle at which 50% of the fuel is burned. Of the six surrogates tested, the best one in terms of physical properties, chemical properties, and combustion behavior was the one that contained 0.2421, 0.1503, 0.0500, 0.0141, 0.0121, 0.2532, and 0.2782 mass percentages of n-dodecane, n-butylbenzene, 1-methylnaphthalene, tetralin, trans-decalin, iso-cetane, and n-butylcyclohexane, respectively.