Decane and n-Alkylbenzene Binary Mixtures: Densities and Speeds of Sound within the Range of 288.15 and 333.15 K and Viscosities within the Range of 288.15 and 323.15 K at 0.1 MPa

Abstract

Fuel combustion in an engine is affected by the fuel’s physical properties, and measuring these properties can help researchers better model the combustion process. In this work, densities, viscosities, and speeds of sound are reported for binary mixtures of decane with n-alkylbenzenes. Increasing alkylbenzene mole fractions increase densities, speeds of sound, and viscosities, except for the viscosities of propylbenzene(1)/decane(2) mixtures where viscosity is lowest at x₁ = 0.7. Some of these mixtures comply with commercial aviation and military fuel density specifications. Excess speeds of sound (c^E’s) increase, while excess molar volumes (V_m^E’s) and excess isentropic compressibilities (K_s^E’s) decrease with increasing alkylbenzene size (up to decylbenzene). Viscosity deviations (Δη’s) are the lowest for n-pentylbenzene mixtures. Positive V_m^E’s are likely caused by interactional contributions in these nonpolar molecules, while negative V_m^E’s may be caused by changes in molecular arrangement. Some systems have V_m^E’s and K_s^E’s with the same sign, suggesting that the volume changes are affecting mixture compressibility. Other systems have V_m^E’s and K_s^E’s with the differing signs, which suggests that more complicated mixture processes are occurring. Comparisons with alkylcyclohexane/decane mixtures reveal similar trends in derived properties. These data can be used by developers of surrogate fuel mixtures and modelers of engine combustion processes.