The
speed of sound related with the isentropic bulk modulus has a significant
effect on fuel injection and NO
x
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.