Fachausschuss Kraftstoffe

Investigations on the Additive of FAME to Diesel Fuels – Part I: Laboratory test programme – Part II: Coking test runs with four B10 fuels and a reference fuel with the analysis of deposits formed at the nozzles of diesel fuel injectors – Part III: B10 Vehicle Road Testing

With the Biofuels Quota Act, which came into effect in January 2007, a growing share of biofuels related to the total fuel sales is legally stipulated. An increase of the permissible share of biofuels in the required specifications for fuels is necessary, in order to reach the demanded proportion by the addition.

Within the scope of this project, a laboratory test programme (part I) was carried out with the focal points oxidation and storage stability as well as fuel influence on the quality of engine oils, in order to broaden the data basis for B10 fuels. In part II, deposit formation at diesel injection nozzles was investigated in coking test runs with four B10 fuels and one fossil reference fuel. Tests with two vehicles, driven by B10 fuel, were an element of project part III.

Diesel/FAME blends can exhibit a very sophisticated ageing behaviour. Basically, the oxidation stability of B10 fuels depends on the oxidation stabilities of the starting components. By the addition of FAME, the oxidation stability of a blend tends to decrease in comparison to the fossil reference diesel fuel.

Tests run within the framework of this project for the evaluation of the risk of coking with Euro 4 engines show, that the tendency for deposit formation of fuels with 10 % (v/v) FAME is slightly raised in comparison to straight fossil diesel fuel, when investigated under the selected test conditions of engine test benches. However, the influence on deposit formation is comparingly small, especially when the variably strong tendency for coking of diesel fuels of different quality or the influence of different engine concepts is taken into account.

Vehicle tests with two cars, running on B10, showed a significant increase of oil dilution with B10 compared to B0. As for all other properties and parameters, respectively, no negative influence of B10 could be observed.