Hot surface pre-ignition in direct-injection spark-ignition engines: Investigations with Tailor-Made Fuels from Biomass

Abstract

Two promising alternative fuel candidates for spark-ignition engines, 2-butanone and 2-methylfuran, have been identified in the context of the Cluster for Excellence ‘Tailor-Made Fuels from Biomass’. To further explore the potential of these fuels for spark-ignition engine application, experimental and numerical investigations into the occurrence of the abnormal combustion phenomenon of hot surface–induced pre-ignition have been conducted, with pure ethanol, RON97 E10, and pure iso-octane as reference fuels. For the experimental investigations, a single-cylinder engine with a compression ratio of 11, equipped with a glow-plug to create a hot spot in the cylinder, was operated at 1500 r/min and 1500 mbar charge pressure. Each fuel was tested with several glow-plug temperatures until a minimum pre-ignition frequency of 2% was observed. The results show that 2-methylfuran reaches its 2% pre-ignition frequency at a glow-plug temperature of 880 °C, which is 16 °C higher than the 2% pre-ignition frequency of ethanol at 864 °C and 10 °C less than RON97 E10 with 890 °C. Iso-octane showed the lowest pre-ignition resistance with a 2% pre-ignition frequency at a glow-plug temperature of 853 °C, and 2-butanone was most resistant against pre-ignition in this study with a 2% pre-ignition frequency at 932 °C. Further numerical investigations, including zero-dimensional ignition delay time calculations and three-dimensional computational fluid dynamics simulations, revealed a clear connection between the surface ignition frequency of these fuels and their reaction kinetics.