High pressure physicochemical properties of biodiesel components used for spray characteristics in diesel injection systems

Abstract

The two components of biodiesel derived from coconut oil or babassu oil such as ethyl laurate and ethyl myristate are studied. The speeds of sound were measured within the temperatures from 293 to 318K and at pressures from 0.1MPa to 101MPa. The densities and heat capacities were measured under atmospheric pressure in the temperature range from 283 to 353K and 286 to 341K, respectively. The densities, isobaric heat capacities, isentropic and isothermal compressibilities, and isobaric thermal expansions as functions of temperature and pressure have been calculated using the experimental results. The results obtained show that the densities of ethyl myristate are lower than that of ethyl laurate below intersection temperature while at higher temperatures the densities ethyl myristate are higher than that of ethyl laurate. Moreover, analysis of the temperature dependence of density of esters under test using the Tait equation shows that the intersection temperature probably moves toward higher temperatures with increasing pressure. Additionally, for a given temperature, the differences between densities of the ethyl esters under test increases with increasing pressure. The isobaric thermal expansivity is approximately independent on temperature at pressures higher than 80MPa and 60MPa for ethyl laurate and ethyl myristate, respectively.