Investigations in using higher FAME-blends in DI-CR-Dieselengines

Due to international market’s demand for higher blending rates of biogenic fuels, these fuels came more and more into the focus of development requirements. Currently, the biogenic components in diesel fuel mainly contain fatty acid methyl esters (FAME). By now, in using these biofuels with higher blending rates (up from 7%) various problems have been observed in the field, which are primarily caused by the lower oxidation stability of FAME [1]. For this reason, the problem areas in motor operation caused by highly advanced oxidation of the fatty acid chains in the biodiesel have been systematically evaluated as part of a funded research project at the Institute for Powertrains and Automotive Technology (IFA) of the Vienna University of Technology in cooperation with a partner from the automotive industry. The special focus of this paper lies in the main problematic aspect in using FAME fuels with higher blending rates: the fuel aging. This oxidative ageing causes a possible polymerization of the fatty acid structure which transforms these components in the fuel into a phase characterized as viscous liquid or even solid [2]. As a result, the function of the fuel supply system in the car – from the tank to the injectors – can be severely affected, or at worst a total damage of the internal combustion engine can occur.