Dual-Fuel Homogeneous Charge Compression Ignition Engine with Ethanol and 1-Octanol

Abstract

Due to stricter regulations on exhaust gas emissions in the upcoming Euro 7 emission norms, a deeper onus is put upon developing alternative combustion concepts with renewable fuels, thus increasing the overall internal combustion engine (ICE) efficiency and reducing exhaust emissions. As a part of the Munich Mobility Research Campus (MORE) Project, a serial hybrid vehicle is being developed based on a dual-fuel homogeneous charge compression ignition (HCCI) engine concept operating on a less reactive portinjected fuel of ethanol with a more reactive direct-injected fuel of 1-octanol. The current concept involves injecting 1-octanol early at the end of the intake stroke, so that the mixture formed is highly homogeneous, resulting in extremely low soot emissions, as opposed to a reactivity-controlled compression ignition (RCCI) concept, where the high reactivity fuel is injected shortly before ignition. This paper deals with developing a methodology to simulate the combustion concept for optimizing the boundary operation conditions, such as intake temperature, valve timing, injected amount, etc. Simulation models in 0-D, 1-D and 3-D with computational fluid dynamics (CFD) are developed using ANSYS Chemkin, GT Power, and AVL Fire M software, respectively, integrating a reduced chemical kinetic mechanism. The cylinder pressure curves and heat release characteristics from the simulation model will be validated against testbench measurements for a stable operating point. These validated models will form a baseline for the simulations, which would be further used in optimizing the parameters, such as valve timing, injection quantity, and timing, intake temperature, pressure, etc., for the other application operation points on the serial hybrid powertrain.