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Storage stability of different diesel fuels containing cat-cracked stocks was examined using various aging conditions. The degradation of fuel during storage was monitored through insoluble formation but also through reaction of nitrogen compounds known to be involved in the fuel degradation process. The influence of aging in injector fouling tendency was also investigated on an IDI engine on test bench. Various stabilizer additives (tertiary amines, dispersant…) were tested. Best results were obtained with dispersants which prevent sediment agglomeration making them able to cross the filter mesh. Additives limit indole evolution without inhibiting completely sediment formation, proving that other reactions take place. We showed that fuel oxidability is not modified by additives. None of the tested formulations is effective on fuel darkening. After aging, surfactants remain effective on injector fouling. Another way of improving the storage stability of Diesel fuel is hydrotreatment.

To ensure overall optimisation of heavy duty engine performance (with the respect of NOx&PM future European and US emissions standards), the use of a high efficiency NOx after-treatment system such as a NOx trap appears to be necessary. But running in rich conditions, even for a short time, leads to a large increase of particulate emissions so that a particulate filter is required. A first investigation with a NOx-trap only has been carried out to evaluate and optimise the storage, destorage and reduction phases from the NOx conversion efficiency and fuel penalty trade-off. The equivalence ratio level, the fuel penalty and the temperature level of the NOx-trap have been shown as a key parameter. Respective DPF and LNA locations have been studied. The configuration with the NOx-trap upstream provides the best NOx / fuel penalty trade-off since it allows NOx slip reduction and does not disturb the rich pulses.

This paper presents the main properties of a SiC diesel particulate filter bonded with specific ceramic oxides at a markedly lower sintering temperature than normal pure SiC DPF. The elasticity of the bond has been studied to have a good behavior to thermal shock permitting a larger cross section element and a reduction of the number of cement joints in the final monolith. That new product, manufactured at present is composed of seven square elements. Endurance tests have been carried out by laboratory bench testing in two commercial automobile diesel engines. The DPF pore size has been adjusted so that it may be catalyzed or impregnated.