Octane Index Applicability over the Pressure-Temperature Domain

Modern boosted spark-ignition (SI) engines and emerging advanced compression ignition (ACI) operate under conditions that deviate substantially from the of conventional autoignition metrics, namely research motor octane numbers (RON MON). The index (OI) is an metric based on RON MON which was developed to better describe fuel knock resistance over a broader range engine conditions. Prior at Oak Ridge National Laboratory (ORNL) identified OI performs reasonably well stoichiometric conditions, but inconsistencies exist in ability predict behavior ACI strategies. Instead, operation found correlate more closely composition, suggesting chemistry differences are insensitive tests may become dominant factor these high efficiency operating This investigation builds earlier work study six pressure-temperature (PT) trajectories correspond wide including SI operation, partial stratification (PFS), spark-assisted (SACI). A total 12 different fuels were investigated, Co-Optima core five represent refinery-relevant blending streams. It that, for modes investigated here, low temperature reactions dominate reactivity, similar because their PT lay close trajectory. Additionally, adequately domain, chemical families. finding contrast with prior using type thermodynamic specifically significantly higher start compression, illustrating response depends highly strategy being used.