Reaction Rates and Reaction Rate Constant Conception. One-Temperature Case

摘要

The new method of getting a normal solution for the generalized Boltzmann equation for reacting gas mixtures was proposed. It is based on the following items: (i) slow variables are introduced via approximate summational invariants, defined within the method, (ii) kinetic equations are presented in the form of a singularly perturbed system for gas-dynamic (slow) variables and for the "fast" part of the distribution function, (iii) collisional integral is not expanded into the series over the Knudsen number (no assumption is made that the part of the collisional integral, responsible for the chemical reactions, can be treated as the perturbation of its "elastic" part). While deriving the gas-dynamic equations it is shown that the role of non-equilibrium effects is much more essential in our approach, than is generally accepted. By non-equilibrium effects we mean all kind of effects caused by deviation of the distribution function from its quasi-equilibrium value. From several examples it was shown that non-equilibrium corrections and the traditional equilibrium rate constants could be of the same order of magnitude. In this paper we derive expressions for corrections to equilibrium rate constants for arbitrary mixtures and corresponding integral equations for corrections to the quasi-equilibrium distributions. In situations where corrections to the reaction rates are not small non-equilibrium effects dramatically impacts the chemical kinetics of the reacting gas mixture. This leads to the necessity of the revision of the concept of getting information on the reaction rates from the experiments.