Predicting Speed of Sound in Fatty Acid Alkyl Esters and Biodiesels at High Pressure
Jean‐Luc Daridon
Abstract
Knowing the thermophysical properties of biodiesels, in particular the speed of sound, over an extended pressure range is essential to optimize injection and combustion processes in diesel engines. The aim of the present work is therefore to propose a predictive method for estimating the speed of sound in biodiesel based on the fatty acid alkyl ester profile. For that purpose, a group contribution method was first developed to predict speed of sound in fatty acid alkyl ester compounds in target p, T ranges (293–423 K and 0.1–150 MPa). Then, using experimental data from the literature supplemented by group contribution predictions, a correlation was established to relate the speed of sound in fatty acid methyl and ethyl ester components to pressure and temperature. Finally, a combination rule was used to extend the pure fatty acid alkyl ester correlations to biodiesel fuels.