Analysis of the impact of Diesel-Ethanol fuel blends on CI engine performance and emissions via multi-zone combustion modelling

Nowadays the high competition reached in the automotive market forces original equipment manufacturers (OEMs) towards the implementation of more and more innovative solutions. Strict emission standards and fuel economy targets make the work hard to be accomplished. Therefore modern engines feature complex architecture and embed new devices for exhaust gas recirculation (LP-HP EGR), turbocharging (e.g. multi-stage compressors), gas after-treatment (e.g. DPF, SCR, LNT) and fuel injection. This results in increased costs for engine and components as well as great complexity for the overall powertrain management. An alternative solution to comply with emissions and CO2standards is to supply the engine with alternative fuel blends that allow reducing significantly engine pollutants thus lowering the complexity of the after-treatment path. The paper deals with the analysis of the impact of different fuel blends Diesel-Ethanol on the performance and NOx / Particulate emissions in a common-rail CI engine. The simulation analyses are performed by a multi-zone phenomenological model of fuel spray, combustion and emissions mechanisms, that takes into account the influence of the specific fuel blend on the fuel-air mixture formation and the in-cylinder gas mixture evolution. Model validation is carried out vs. experimental data collected on an automotive common-rail CI engine, fuelled by a E20 blend and operating at different working conditions. Afterwards simulations are performed by spanning the fuel blends and the combustion control parameters (i.e. injection pattern and EGR) with the aim of optimizing combustion tuning vs. fuel blend.