Characteristics of the Development of a Chain Thermal Explosion when Burning Gas Mixtures under Atmospheric Pressure

Abstract

An experimental study of the features of the critical transition between two kinetic combustion regimes of gas-air mixtures reacting by a chain mechanism is carried out. The presence of two radically different combustion modes is experimentally confirmed by the example of the combustion of propane–air mixtures, both containing an inhibitor (trifluoromethane) and without it, and in complete agreement with the predictions of the theory of A chain thermal explosion (CTE). It is shown that the pattern observed in this work is characteristic not only for slow-burning but also for fast-burning gas mixtures of various compositions. The two distinct and radically different regions observed on the pressure–time variation curve during the combustion of gas mixtures are a manifestation of the general laws which combustible gas mixtures reacting by the chain mechanism follow in a wide range of pressures. It is found that fluorine-containing hydrocarbon is capable of induced oxidation in rich combustible gas mixtures. Trifluoroethane CF₃H has an inhibitory effect on the chain combustion process of the propane–air mixture before it enters the CTE and promotes combustion in the CTE mode. If the transition to the CTE is not possible during the propane–air mixture combustion, the fluorinated agent has only an inhibitory effect on combustion.