Combustion Chemistry. Self-Ignition of Fuel Components

Controlling the oxidation and auto-ignition of organic compounds is essential to the smooth operation of many energy and chemical processes. Diesel engine operation is based on spontaneous self-ignition of the fuel when injected into hot, compressed air. In the case of gasoline engines, auto-ignition of the air/fuel mixture upstream of the propagation of the flame front initiated by ignition can lead to knocking.

The direct oxidation of hydrocarbons in the gas phase is a common initial step in many industrial chemical processes. Self-ignition phenomena in this context can lead to explosions with sometimes catastrophic consequences.

In all combustion processes, a good understanding of the oxidation chemistry of organic compounds can help to model and, if necessary, minimize the formation of gaseous pollutants that are harmful to the environment or toxic to mankind.

Understanding and controlling oxidation and auto-ignition phenomena in many cases requires the determination of a detailed kinetic model, made up of a set of elementary reactions called the reaction mechanism, together with the corresponding rate constants and thermodynamic data.

After recalling some of the basics of chemical kinetics in this article, we describe the exothermic and chemical phenomena associated with the oxidation of organic compounds, and detail the content of the various chemical mechanisms that help explain the appearance of these phenomena and write the detailed kinetic models needed to model them.