Investigations of the Emissions of Fuels with different Compositions and Renewable Fuel Components in a GDI Engine 2020-01-0285

Investigations were performed, in which fuels and fuel components were compared regarding gaseous as well as particulate number (PN) emissions. The focus on the selection of the fuel components was set on the possibility of renewable production, which lead to Ethanol, as the classic bio-fuel, Isopropanol, Isobutanol and methyl tert-butyl ether (MTBE). As fuels, a Euro 6 (EU6) reference fuel, an anti-spark-fouling (ASF) fuel, a European Super Plus (RON 98) in-field fuel and a potentially completely renewable fuel, which was designed by Porsche AG (named POSYN), were chosen. The composition of the fuels differs significantly which results in large differences in the exhaust gas emissions. The fuels, except ASF, are compliant with the European fuel standard EN 228.The experiments chosen were a variation of the start of injection (SOI) at different load points at a constant engine speed of 2000 rpm, amongst others. The influence of the fuel properties like boiling characteristics, fuel composition (e. g. the content of aromatic compounds), viscosity and enthalpy of vaporization were considered for interpreting the gaseous and PN emissions and efficiencies of the fuels. The results show decreased NO emissions, when the oxygen content increases. Based on these observations, a 0D/1D model was calibrated with the engine data of the EU6 fuel. The model was used to calculate the NO emissions using the Zeldovich mechanism. For each fuel, the only difference in the model was the definition of the fuel, which includes the (theoretical) molecular formula, heat of vaporization, heating value, density and the enthalpy. In addition to that, the burn rate was determined by a three-pressure-analysis (TPA) and was put into the full engine model. The results show, that the influence of the fuel on the NO emissions can be described well by calculations performed.