Biodiesel reduces deposits in common rail injectors
After two years the project "Deposits in common rail injectors – prevention strategies with respect to fuel composition and injection system construction" at the University of Rostock could be completed successfully.
Within the project, constructive strategies for avoiding deposits in the injector system could be identified. Both, laboratory tests with specially developed test specimens and test bench examinations under engine related conditions were carried out. It could be shown that in addition to the reduction of physically dissolved oxygen, the use of fuels free of aromatic compounds such as biodiesel (FAME) and hydrogenated vegetable oils (HVO) in particular reduces the deposit layer thicknesses. The layer thickness decreases with increasing FAME content (B7> B10> B20> B30). The results could also be confirmed at the engine-related test benches (predecessor project) and once again prove the suitability of biodiesel in modern diesel engines. Pure HVO is just as uncritical with respect to oxidative deposits as HVO-FAME blends. The studies also showed that the formation of soaps is particularly critical and should therefore be avoided. The standard-compliant biodiesel used in the project did not produce any soap-like coverings.
In addition, simulations of the flow conditions in critical areas were carried out and evaluated comparatively. These flow simulations were able to show that certain design measures at the guide gap counteract the formation of deposits.
The project was financed by Fachvereinigung Verbrennungskraftmaschinen (FVV e.V.) and the Agency for Renewable Resources (FNR e.V.) and was financially supported and accompanied by AGQM and others.
