Surface tensions of petro-diesel, canola, jatropha and soapnut biodiesel fuels at elevated temperatures and pressures

► Surface tensions of three biodiesel fuels and diesel were measured at elevated temperatures and pressures. ► Surface tensions were measured up to 473K and 7MPa for all biodiesel samples. ► Surface tensions of three biodiesel were measured at elevated temperatures and pressures. ► The surface tension of diesel and biodiesel fuels showed a linear relationship with temperatures and pressures. This study presents the experimental results of surface tension measurements of diesel as well as canola, jatropha and soapnut biodiesel fuels. A high pressure pendant drop equipment (PD-E 1700) and drop shape analysis (DSA 100 V1.9) were used to measure the equilibrium surface tension of diesel and biodiesel fuels at elevated temperatures and pressures. Surface tension tests were carried out in a nitrogen environment. The surface tension of diesel and biodiesel fuels showed a linear relationship with temperatures and pressures. A regression model was also developed using the measured data from the tests for each fuel.