The role played by self-inhibition in combustion processes

The absence of correlations between the heat of combustion of substances and substance combustion characteristics is shown to be caused by the special features of competition between reaction chain branching and termination, including partial participation of fuels in the inhibition of their oxidation. By way of example, differences in the characteristics of combustion of hydrocarbons and hydrogen at atmospheric pressure and the mechanisms of the development of chain avalanches in these processes are considered.     

The relative contributions of self-heating and chain branching to the kinetics of hydrogen oxidation outside the ignition region close to the third limit

It is shown that, in hydrogen-oxygen mixtures, under the conditions when the rate of reaction chain termination is higher than the rate of chain branching, the characteristic reaction time is hundreds of seconds even in the immediate vicinity of the third ignition limit. The self-heating of the mixtures therefore does not exceed several degrees and, contrary to the accepted views, cannot result in thermal combustion. Ignition observed in the third limit region is caused by a higher rate of chain branching compared with chain termination; that is, it is a chain reaction. Self-heating only becomes substantial during the development of chain combustion.     

Features of the temperature dependence for the rates of gas-phase reactions of combustion

The specific character of the dependence for the rate of most gas-phase reactions of combustion on temperature and reagent concentrations is found to be determined by the ratio of the rates of the multiplication and death of active intermediate particles. It is shown that the stepwise acceleration of the process and the transition to the combustion mode upon raising the initial temperature by 1–2 K and crossing over a critical value is due to a change in the character of the rate’s temperature dependence as a result of the sign changing from negative to positive to reflect the difference between the rates of chain branching and termination. It is concluded that this difference’s change in sign upon varying the content of reagents imposes limits on concentration.     

Mechanism of silane oxidation

The polymerization of acrylonitrile has been studied in dimethylformamide in the presence of the complex catalyst tris-(-allyl/chromium and pyridine. The structure of the active sites of polymerization is discussed on the basis of experimental data.

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The Contribution from Quadratic Reactions to the Thermal Regime of Branched Chain Combustion

A mathematical model was developed for the dependence of maximal self-heating in the course of the combustion of a hydrogen–oxygen mixture inside the ignition peninsula. The specific features of the thermal regime, which are related to a dual role of quadratic termination reaction, are discussed.