Enhancing the lubricity of an environmentally friendly Swedish diesel fuel MK1

The lubricity of diesel fuel has a direct effect on the service life of the fuel injection equipment, and when alternative fuels are specified, is of vital importance. One such fuel is the Swedish diesel fuel, MK1 which contains low levels of sulphur and low lubricity. This paper investigated the use of ultra low sulphur diesel (ULSD) and fatty acid methyl esters derived from rapeseed (RME) blends to improve MK1 lubricity. Fuel lubricity was assessed using a high frequency reciprocating rig. The wear scar diameter of the ball specimen was measured using optical microscopy while the wear profile and surface roughness of the disc were analysed using a profilometer. Scanning electron microscopy with an energy dispersive spectrometer was used to evaluate the microscopic topography and chemical compositions of the surfaces. Results confirm that MK1 has poor lubricity when compared to other base fuels. Of the blended fuels, ULSD showed little improvement. However, a small percentage of RME improved the lubricity of both the pure MK1 and the blends. Analysis of the worn surfaces indicated that chemical compositions of MK1 did not adsorb and react as well when compared with those of ULSD, RME and selected blended fuels.