Use of Citric Acid Esters as Alternative Fuel for Diesel Engines

Common fuels for (adapted) diesel engines are fossil diesel fuel, fatty acid methyl ester (FAM E or biodiesel) or vegetable oils. Further potential bio genic substitutes are the citric acid esters tribut ylcitrate (TBC) and triethylcitrate (TEC). Their use as fuel was applied for a patent in Germany in 2010. Proposed advantages are low soot combustion, independence of energy imports due to the possibility of local production and a broad raw material base. Comparison of their properties with relevant f uel standards showed, that only some of the demands are met. However, few rapeseed oil characteristics (e. g. ox idation stability and viscosity) can be improved if the citric acid esters are used as a blend component. The operating and emission behaviour of a vegetable oil compatib le CHP unit fuelled with various rapeseed oil/TBC blends were inv estigated and a trouble free and soot emission redu ced engine operation due to the high molecularly bound oxygen content was observed. Long term test runs are neces sary for an