OP-II-3

PP-I-6PHENOMENA OF SUPERADIABATIC TEMPERATURE IN FLAMESAND SPONTANEOUS IGNITION PROCESSESBabkin V.S. and Bunev V.A.Institute of Chemical Kinetics and Combustion, Novosibirsk, Russiae-mail: babkin@kinetics.nsc.ruThe term “superadiabatic temperature” (SAT) implies the phenomena occurringupon combustion with which the temperatures evolve that are superequilibrium forthe given system and conditions in the zone of chemical transformations. Althoughthese phenomena have long been observed, they did not fix much attention ofresearchers. On the other hand, the phenomena are of interest in terms of thechemical physics of the mechanisms of interaction of elementary processes leadingto SAT and are rather promising regarding the present-day technologies. It appearedthat the SAT effects in which tens and hundreds of degrees of superequilibriumtemperature are attained, can be used to solve the problems of energetics, ecology,fire-and-explosion safety, chemical technology, etc.Usually, the SAT phenomena result from a competition of the processes ofmolecular diffusion and heat conductivity, the selective diffusion of fuel and oxidizer,heat transfer in multiphase systems, the interaction between parallel and cross-fieldthermal conductivities, the appearance of the effects of compressibility, etc. Theexistence of a great variety of the mechanisms of SAT formation has become evident[1]. Thus, of interest is the formation of SAT in flames and the processes ofspontaneous ignition.This report is a review of the recent results from works devoted to the origin ofSAT in flames and upon spontaneous ignition of gaseous systems. The studies inthis area have produced intriguing results [2-10]. The SAT effect is observed in ,e.g.,the flames of rich hydrocarbon mixtures[2]. In [2], attention was given to the formationof superequilibrium water concentration upon combustion. Therefore, the conclusionwas drawn on the origin of SAT due to molecular hydrogen diffusion from a hightemperaturezone to the low-temperature one. It was further demonstrated that Н 2 isof no importance in SAT formation because of its lower reactivity as compared withhydrocarbon molecules in reactions of water formation in the low-temperature zone[7]. A decisive role in the formation of superequilibrium water concentration belongsto the Н atom diffusing from the high-temperature zone to the heating one [7-8]. The229