Speed of Sound Measurements and Thermophysical Modeling of Binary Mixtures of Methyl Laurate and n-Dodecane

The speed of sound in binary mixtures of methyl laurate and n-dodecane can directly characterize fuel injection and NOx emissions from diesel engines. Currently, experimental data on the speed of sound of binary mixtures have not yet been reported. In this study, the speeds of sound of the binary system were measured by using Brillouin light scattering. The speeds of sound were measured in the range of 298.15–568.15 K and 0.1–9 MPa. The relative combined expanded uncertainty for the reported speed of sound is estimated to be 1.6% with the level of confidence is 0.95 (k = 2). The experimental data were correlated as a function of temperature and pressure resulting with absolute average percentage deviations of 0.19, 0.16, 0.20, 0.24, and 0.22% for the mole fractions of n-dodecane being 0.100, 0.300, 0.500, 0.700, and 0.900, respectively. Considering the effect of temperature on the binary interaction parameter k_ij, k_ij of the PC-SAFT equation of state (EoS) was fitted using experimental data for methyl laurate and n-dodecane. The speeds of sound of binary system were calculated using the PC-SAFT EoS, and the average absolute relative deviation is 2.7%.