Speed of Sound in Methyl Caprate, Methyl Laurate, and Methyl Myristate: Measurement by Brillouin Light Scattering and Prediction by Wada's Group Contribution Method

摘要

The speed of sound related with the isentropic bulk modulus has a significant effect on fuel injection and NOx emissions in diesel engines. Nevertheless, the speed of sound in pure fatty acid (methyl and ethyl) esters, which were widely used and investigated as the main components of biodiesel, is scarce in the literature. Most of the experimental data are available only at atmospheric pressure or in a narrow range of temperatures. In this work, the speed of sound in three fatty acid methyl esters [FAMEs = caprate (MeC10:0), laurate (MeC12:0), myristate (MeC14:0)] was measured by the Brillouin light scattering method. The measurements were carried out at temperatures ranging from 288 to 498 K along four isobaric lines of 0.1, 4.0, 7.0, and 10.0 MPa. The relative expanded uncertainty in the speed of sound was estimated to be less than 1.0%. A rational function that correlates 1/c(2) as a function of the pressure and temperature was used to correlate the experimental speed of sound in liquid MeC10:0, MeC12:0, and MeC14:0, respectively. In comparison of the experimental speed of sound to the correlation results in the measured range, the absolute average deviations (AADs) are 0.15% for MeC10:0, 0.10% for MeC12:0, and 0.17% for Mec14:0. Moreover, the data were also used to assess the predicted ability of Wada's model.