A simplified theoretical analysis of nonequilibrium effects in bimolecular gas phase reactions

There can be significant differences between the rates of activated chemical reactions calculated as if the reactants and products were in states of mutual thermal equilibrium and the rates associated with concentration and species temperatures obtained from solutions of Boltzmann equations. The theory presented here is based on the assumption that the particle distribution functions can be represented by Boltzmann functions with time-dependent concentrations and species temperatures. This leads from the Boltzmann equations to a set of coupled nonlinear equations of change for the concentrations and temperatures. Solutions of these equations have been obtained and used to calculate the rates of reaction. Numerical results generated by this procedure are found to agree quite well with the outputs of Nanbu–Babovsky Monte Carlo simulations and with predictions based on quasistationary perturbative solutions of the Boltzmann equations.