The tribology of fructose derived biofuels for DISI gasoline engines

2-Methylfuran (MF) and 2,5-dimethylfuran's (DMF) combustion characteristics have confirmed their validity as appropriate gasoline replacement and enhancement fuels. However, the performance of fuel injection equipment is dependant on the tribological performance of these fuels lubricity testing of MF, DMF and their blends with gasoline was undertaken using the high frequency reciprocating rig method, based on ASTM D6079. Results showed that both MF and DMF possessed greater lubricity and wear resistance characteristics than those of gasoline when tested as pure substances. Their blends with gasoline at 2, 4, 6, 8, 10, 20 and 50 percent volume (%vol) showed improved tribological performance also. DMF was found to possess greater lubricating properties than that of MF. As little as 2%vol reduced the wear scar diameter by 46% and 47% for MF and DMF respectively showing even a small addition of these biofuels could greatly improve the tribological performance of the fuel within the engine. This was mainly due to the polar functional groups of MF and DMF bonding to the bearing surfaces during testing, creating a tribo-film that protected the surface, reducing both wear and friction. These effects were greatest for the DMF blends, with two methyl groups leading to stronger polarity and a resulting higher bonding strength to the metal surfaces. The reduction in friction coefficients with the addition of the biofuels showed that utilisation of these blends would reduce frictional losses along the fuel line, improving the overall engine efficiency.