Influence of DMC percentage in fuel on deposit formation and emission behaviour

•The engine tests with DMC fuel blends showed a clear dependence of the CCD layer thickness on the DMC content. The film thickness was calculated in-situ using a mathematical model by Hopwood et al., (1998) and then calibrated with an optical profiler. The results showed a decreasing film thickness with increasing DMC content. This could be explained by the decreasing proportion of high boiling components with increasing DMC content in the fuel. This leads to a reduction in condensation on the combustion chamber surfaces, and thus to lower precursors of deposits.•DMC additionally influenced the emission behaviour. It resulted in reduced NOx emissions due to lower combustion temperature caused by lower stoichiometric air demand and lower heating value.•HC emissions also decreased proportionally to the DMC content due to the decreasing boiling curves of the fuel used.•The increase in CO2 emissions is explained by the higher CO2 energy ratio of DMC compared to RON95.•Fuel diluted with 50% and 75% DMC showed a significant increase in particle emissions at early SOI compared to RON95. High speed imaging showed poolfire flames as the main cause. Due to the higher penetration depth of a DMC spray Plaß et al., (2021) and the low energy density of DMC, increasing piston wetting dominated soot formation. The chemical advantages of DMC with respect to soot formation, such as higher oxygen content and the strongly reduced carbon-carbon bonds and the lower boiling temperature compared to RON95, only predominate when pure DMC is operated and then lead to an almost complete reduction of particles. E-Fuels are gaining in importance in the development of internal combustion engines. Their properties can differ from currently used fuels and affect the combustion behaviour. Here, the influence of the potential e-Fuel dimethylcarbonate (DMC) on the combustion process is investigated with the focus on combustion chamber deposit (CCD) formation. The effect of DMC on the CCD formation was observed. A one-cylinder research engine was equipped with changeable samples to investigate the deposit with a confocal microscope in addition to an in-situ measurement. The deposits on the top of the piston were compared to the deposits on the cylinder head. Furthermore, the dependency of the emissions on the DMC content in the fuel was characterized. The emphasis is on the gaseous emissions HC, NOx and CO2 and the emitted particle number. For a detailed analysis, an optical access was used t