Speed of sound measurements and derived thermodynamic properties of bio-jet fuel components at saturation: N-butylcyclohexane

The composition of bio-jet fuels, i.e., the total content of hydrocarbons such as n-alkanes, iso-alkanes, cycloalkanes and aromatics, reached 85 % to 95 %, are mainly defining the thermophysical properties of bio-jet fuels. Short-chain cycloalkanes, such as n-butylcyclohexane, are one of the main components of bio-jet fuel. N-butylcyclohexane is included as one of the components of diesel fuel surrogate mixture. Therefore, more information on n-butylcyclohexane thermophysical properties in surrogate mixtures is required. In the present work the speed of sound in n-butylcyclohexane at saturation in the temperature range from (276 to 456) K has been measured using the pulse method with a constant (acoustic) sounding base. The combined expanded absolute and relative uncertainties (0.95 level of confidence, k = 2) of the temperature and speed of sound measurements are estimated to be 20 mK and 0.2 %, respectively. The measured speed of sound data together with reported density data were used to calculate the derived thermodynamic properties (kS,kT, and CP/CV) of n-butylcyclohexane at saturation.