ADVANCED DIAGNOSTICS FOR DIESELINE COMBUSTION IN A RESEARCH ENGINE

Compression ignition engines are widely used for transport and energy generation thanks to their high efficiency and low fuel consumption. Conversely, they are source of pollutant emissions at the exhaust that are strictly regulated. To face this issue, alternative strategies as low-temperature combustion (LTC) concepts are born, recently. The reactivity controlled compression ignition (RCCI) uses two fuels (direct- and port fuel- injected) with different reactivity to control the reactivity of the charge by adjusting the proportion of both fuels. Besides this, the characteristics of the direct-injected fuel play a main role on the combustion process. Use of gasoline for direct injection is attractive to retard the start of combustion and to improve the air-fuel mixing process. In this work, RCCI combustion mode is performed in an optical compression ignition engine. Gasoline is injected in the intake manifold while a high reactivity fuel is directly injected in the cylinder. To investigate the effect of the direct-injected fuel properties on combustion, the engine is fed alternately with pure diesel and with a blend in volume of gasoline and diesel (a.k.a. Dieseline). Optical diagnostics of the combustion process is applied to investigate with high spatial resolution the phenomena involved in the combustion chamber. In particular, non-conventional optical diagnostics in the visible and infrared spectra is applied for the investigation of the injection and combustion processes