Mechanical Engineering Commons^™

Derived Cetane Numbers (DCNs) of engine lubricating oil/ 95 Research Octane Number gasoline surrogate mixtures are measured in an Ignition Quality Tester. These measurements separately screen for effects of (1) calcium- and magnesium-based detergent additive, (2) oil degradation, and (3) base oil on mixture ignition propensity at conditions relevant to low speed pre-ignition (LSPI) in gasoline engines. Initial testing of ≤ 25% mass oil in the gasoline surrogate indicates a positive linear relationship between DCN and blend fraction, and also demonstrates the sensitivity of the measurement technique to mixture composition. Despite variation in Ca and Mg concentrations, DCN responses for …

The global chemical characters of complex chemical fuel mixtures are explicitly determined by evaluating the abundances of chemical functional groups present within it rather by applying molecular species composition. Statistical analyses on the relationships of each chemical functional group and the chemical property targets of the fuel are rigorously developed. The results demonstrate that the four CPTs currently used in surrogate formulation - H/C molar ratio, derived cetane number (DCN), average molecular weight (MW), and smoke point (SP) - effectively constrain the chemical function group distribution of the fuel, hence, the global combustion behaviors of pre-vaporized fuel/air mixtures. Emulating the …