The Role of Intermediate-Temperature Heat Release in Octane Sensitivity of Fuels with Matching Research Octane Number

Improving the efficiency of internal combustion engines is important for reducing global greenhouse gas emissions; spark ignition (SI) limited by knock phenomenon. As opposed to naturally aspirated engines, turbocharged operate at beyond research octane number (RON) conditions, and fuel sensitivity (OS = RON – motor (MON)) becomes under such conditions. Previous work this group [ Energy Fuels 2017, 31, 1945−1960, DOI: 10.1021/acs.energyfuels.6b02659] elucidated chemical kinetic origins OS; study extended provide a qualitative, as well quantitative, definition OS, based on fundamental markers. A varying amount toluene blended with various primary reference fuels match delay targeted fuels, allowing range sensitivities each number. This establishes correlation between OS heat release rates low, intermediate, high temperatures. The significance intermediate-temperature in defining mixture iso-octane n-heptane also clarified. For toluene–iso-octane–n-heptane mixtures considered here, low-temperature reactivity was not found be key marker OS. results show areas improved operating where high-sensitivity could beneficial.