High pressure thermophysical characteristics of butyl caprate and butyl laurate as fully biorenewable components of biodiesel fuel

•Butyl caprate and butyl laurate were investigated.•Speed of sound was measured at high pressure.•Density-temperature curves of butyl caprate intersect those of butyl laurate.•Different isentropic compressibility of esters can be compensated by temperature.•The isentropic compressibility of butyl laurate and methyl laurate is close to those of diesel fuel. The butyl-based fatty acid esters can be considered as fully biorenewable components of biodiesel fuel due to the possibility of synthesis from biobutanol and vegetable or animal oils. For this reason in this work high pressure thermophysical properties of butyl caprate (butyl decanoate) and butyl laurate (butyl dodecanoate) used for optimization spray characteristics in diesel injection systems are studied. The speed of sound was measured at temperatures from 293 to 318 K and pressures from 0.1 to 101 MPa. The speed of sound, density, isobaric heat capacity, viscosity, surface tension were measured under atmospheric pressure and at the temperatures from the range of 273 to 363 K. The effect of temperature and pressure on density, isentropic and isobaric compressibilities, isobaric heat capacity, and isobaric thermal expansion was determined by the acoustic method. The results obtained show that differences between density and isentropic compressibility of esters can be compensated by temperature and/or pressure. Comparison of thermophysical properties of butyl caprate and butyl laurate with characteristics for diesel, biodiesel composed of fatty acids methyl esters of rapeseed oil, neat methyl and ethyl esters shows that they can be considered as promising fuel additives in this regard.