The Autoignition Chemistry of Paraffinic Fuels and Pro-Knock and Anti-Knock Additives: A Detailed Chemical Kinetic Study

A numerical model is used to examine the chemical kinetic processes leadING to knocking in spark-ignition internal combustion engines. The construction and validation of the model is described in detail, including low temperature reaction paths involving alkylperoxy radical isomerization. The numerical model is applied to C₁ to C₇ paraffinic hydrocarbon fuels, and a correlation is developed between the Research Octane Number (RON) and the computed time of ignition for each fuel. Octane number is shown to depend on the rates of OH radical production through isomerization reactions, and factors influencing the rate of isomerization such as fuel molecule size and structure are interpreted in terms of the kinetic model, knock behavior of fuel mixtures is examined, and the manner in which pro-knock and anti-knock additives influence ignition is studied numerically. The kinetics of methyl tert-butyl ether (MTBE) is discussed in particular detail.