Search Results

One political and economic aim in Europe is to increase the use of renewable energy resources. In the transport sector, up to 10 % of fossil diesel fuel should be replaced by biogenic fuels by 2020. This also means a reduction in crude oil dependency. In the area of diesel fuel, fatty acid methyl esters are introduced since over 20 years as biodiesel. However, biodiesel can lead to an increase of engine oil dilution in passenger cars with diesel particulate filters. During the regeneration of the particulate filters, there is an entry of fuel components in the engine oil. While most of the diesel fuel (DF) evaporates from the engine oil, biodiesel remains in the oil and can cause sludge formation in the engine. A promising approach to reduce this problem is the use of a new type of biogenic fuel, called hydrotreated vegetable oil (HVO). This is also produced from vegetable oil or animal fat. Like biodiesel, HVO is free of sulfur and any aromatics.

The European diesel fuel specification limits the biodiesel content to 7 %. It is, however, desirable to increase the amount of renewables in the transport sector; therefore blending with a higher biogenic fuel content is of interest. Blending of fuels can lead to chemical reactions between fuel components and may result in undesired products. In detail, aged biodiesel from unsaturated FAME and fossil diesel fuels can form oligomers and precipitations with a maximum in the range of B10 to B20. Precursors are oligomers that can be separated from the biodiesel or the blends in an amount of up to 20 %. These oligomers are soluble in the fuel, but they seem to have potency for chemical reactions with fuel components or the engine oil. To prevent tentative problems in the fuel filter, the injecting system and the combustion process itself, the formation of oligomers should be disabled in blends. Alcohols have been proven and tested to dissolve precipitations in the fuel.