Measurement and prediction of the speed of sound of biodiesel fuels
Résumé
Speed of sound is an important fuel thermophysical property that directly characterizes the fuel injection and the NOx emissions in diesel engines especially for injectors activated with pressure. Nevertheless, the experimental data of speed of sound for biodiesel fuels are very scarce in the literature. Thereby, this work aims at measuring the speed of sound for biodiesels fuels and evaluating some predictive models to estimate the speed of sound from the composition of fatty acid methyl esters in the biodiesel. For that purpose the measurement of speeds of sound for three fatty acid methyl esters and ten biodiesel fuels at atmospheric pressure and temperatures from 288.15 to 343.15 K was done. The ability of two versions of Auerbach's relation, and the ideal mixture mixing rule to describe the speed of sound of biodiesels was evaluated. The results evinced that, with the exception to the original version of Auerbach's relation, the other models studied provide a good estimate of the experimental data. The modified Auerbach's relation displays an overall average relative deviation of 1.64%, and the ideal mixture mixing rules predict the biodiesel speed of sound with only 0.37% of overall deviation. Moreover, the dependency of speed of sound on pressure was also correlated with a linear equation, presenting only an overall deviation of 0.56%. These models can thus be a good tool to estimate the speeds of sound using only information about the biodiesel composition.
Mots clés
Model
Speed of sound
Thermophysical properties Bio-diesel fuel
Fatty acid methyl ester
Mixing rules
Predictive models
Pressure and temperature
Relative deviations
Speeds of sound Engineering controlled terms: Atmospheric pressure
Biodiesel
Diesel engines
Esterification
Esters
Estimation
Fuels
Mixing
Models
Thermodynamic properties Engineering main heading: Acoustic wave velocity