Thermophysical properties of fatty acid methyl and ethyl esters

Abstract

In present study, surface light scattering (SLS) was used for the simultaneous determination of liquid surface tension and kinematic viscosity of twelve fatty acid esters, including six methyl esters (FAMEs) and six ethyl esters (FAEEs). The SLS apparatus was firstly checked with a reference fluid n-dodecane, and a good agreement of our data from SLS with those from literatures could be found. By utilizing this apparatus, both properties were investigated in the temperature ranges between (298 and 448) K for all substances with an exception of methyl myristate and ethyl myristate covering the temperatures between (323 and 448) K due to their high melting points. Additionally, the liquid density and refractive index were determined by an Anton Paar U-tube densimeter between (293 and 453) K and a refractometer from (278 to 358) K, respectively. The surface tension and viscosity data obtained from the SLS experiment were fitted to the van der Waals type and the reciprocal temperature-dependent polynomial equations, respectively. The quadric and linear functions were adopted to correlate the density and refractive index data, respectively. This work improves the data situation for these fatty acid esters especially at elevated temperatures and provides necessary data and models for the crucial thermophysical properties in connection with the design and optimization of the injection system of an internal combustion engine (ICE).