Measurement and prediction of speeds of sound of fatty acid ethyl esters and ethylic biodiesels

Speed of sound of fatty esters provides important information about biodiesel injection characteristics and enables the estimation of many other important properties of biodiesels. Nevertheless, the experimental speeds of sound of fatty esters are very scant. This work provides new data on speed of sound for nine fatty acid ethyl esters and four ethylic biodiesels, measured at atmospheric pressure and temperatures ranging from 293.15 to 343.15 K. These new data is used to evaluate the ability of the Wada’s group contribution method to predict the biodiesel speed of sound. It is here shown that this model provides excellent description of the experimental data, with overall average relative deviations (OARDs) of 0.25% for the ethyl esters and between 0.45% and 0.59% for the biodiesels.