A thermokinetic foundation for oscillatory phenomena in gaseous organic oxidations under well stirred flowing conditions

Abstract

An experimental and theoretical attack on the fundamentals of thermokinetic phenomena associated with the gaseous, non-isothermal oxidation of hydrocarbons and other organic substrates is described. Quantitative comparisons are made between numerical modelling and experimental measurements under well stirred flowing conditions.

Two chemical systems are considered, involving reactions of methyl radicals. These are: (i) di-t-butyl peroxide decomposition in nitrogen and (ii) di-t-butyl peroxide decomposition in an excess of oxygen. Simplified kinetic mechanisms for each of these systems are described and numerical computations for non-isothermal reactions are discussed. Stationary states and two different types of oscillatory modes are predicted to exist within limited ranges of p, T_a and composition, and these match experimental measurements quite satisfactorily. The integral role played by self-heating in thermokinetic oscillations is demonstrated and relationships to cool-flame phenomena are outlined.