n-Pentadecane and n-Alkylcyclohexane Mixtures: Viscosity Deviations and Excess Molar Volumes, Speeds of Sound, and Isentropic Compressibilities at 0.1 MPa

Thisstudy measured the densities, viscosities, and speeds of soundof mixtures of n-pentadecane with n-alkylcyclohexanes (methyl-, ethyl-, propyl-, butyl-, pentyl-, hexyl-heptyl-, octyl-, decyl-, and dodecylcyclohexane) and determined excessmolar volumes (V (m) (E)'s),excess speeds of sound (c (E)'s),excess isentropic compressibilities (K (s) (E)'s), and viscosity deviations (& UDelta;& eta;'s).For each n-alkylcyclohexane, mixture V (m) (E), c (E)'s, K (s) (E)'s, and & UDelta;& eta;'sfor n-pentadecane fell between previously reportedvalues for n-tetradecane and n-hexadecane.In general, mixture V (m) (E)'sincreased with decreases in n-alkylcyclohexane'smolar mass. Mixture c (E)'s and & UDelta;& eta;'sdecreased with increasing n-alkylcyclohexane molarmass until a minimum was reached after which the c (E)'s and & UDelta;& eta;'s increased. Themixture K (s) (E)'s increasedwith increasing n-alkylcyclohexane molar mass untila maximum was reached after which the K (s) (E)'s decreased. For many of the mixtures, the V (m) (E)'s and K (s) (E)'s had the same sign, thereby suggestingthat the deviations in mixture compressibility were impacted by deviationsin the volume occupied by the molecules. A notable exception was methylcyclohexane,which had the largest positive V (m) (E) but a negative K (s) (E). Its greater volume was less compressible. The n-pentadecane could be used in surrogate mixtures to replace n-hexadecane when a smaller density, viscosity, and speedsof sound are needed to properly model a fuel of interest.