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

摘要

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 318 K and at pressures from 0.1 MPa to 101 MPa. The densities and heat capacities were measured under atmospheric pressure in the temperature range from 283 to 353 K and 286 to 341 K, 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 80 MPa and 60 MPa for ethyl laurate and ethyl myristate, respectively.