In this study, the chemical composition and physical properties of an alcohol-to-jet (ATJ) fuel were used to develop a surrogate mixture containing commercially available hydrocarbons. Analysis of the chemical composition of the ATJ showed a high quantity of two specific branched alkanes (2,2,4,4,6,8,8-heptamethylnonane and 2,2,4,6,6-pentamethylheptane) and a small quantity of other branched alkanes that are isomers of these two alkanes. Surrogate mixtures containing 2,2,4,4,6,8,8-heptamethylnonane and a mixture of isododecane isomers were prepared to determine what composition would match the density, viscosity, speed of sound, bulk modulus, surface tension, and flash point of ATJ. The optimal surrogate contained a 0.25 mass fraction of 2,2,4,4,6,8,8-heptamethylnonane in isododecane isomers. Combustion experiments were then conducted in a Yanmar diesel engine with fuel mixtures containing 70% (by volume) petroleum jet fuel with 30% ATJ, 2,2,4,4,6,8,8-heptamethylnonane, the optimal surrogate mixtures based on physical properties, or the isododecane isomers. The startup performances of the three 30% surrogate mixtures were very similar to that of the 70% JP-5 with 30% ATJ fuel. No significant differences were seen in the engine combustion characteristics of the three 70/30 surrogates, as compared to the base 70% JP-5/ 30% ATJ fuel mixture. These results show that a surrogate mixture has been successfully prepared that matches the physical and chemical properties and combustion behavior of an ATJ fuel.

In this work, the physical properties of binary mixtures of n-hexadecane with toluene or ethylbenzene were measured. Density and viscosity were measured at temperatures ranging from (293.15 to 373.15) K, and the speed of sound was measured at temperatures ranging from (293.15 to 333.15) K. Density mole fraction and temperature data were fit to a fourthorder polynomial. Viscosity mole fraction data were fit using the three-body McAllister model, while the viscosity deviations were fit to a Redlich−Kister type equation. For both two-component mixtures, the speed of sound at 293.15 K decreased as the mole fraction of the aromatic compound increased until a minimum was reached after which the speed of sound increased slightly to the value of the pure aromatic compound. The bulk modulus was calculated from density and speed of sound data. For both 2-component mixtures, the bulk modulus at 293.15 K decreased slightly as the mole fraction of the aromatic compound increased until a minimum was reached after which the bulk modulus increased to its highest value, which is the value for the aromatic compound. Flash points for the mixtures ranged from (278.5 to 408) K, and surface tension values ranged from (27.3 to 29.2) mN•m −1 .

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