THE KINETIC CHEMICAL-EQUILIBRIUM REGIME

We investigate reactive gas mixtures in the kinetic chemical equilibri um regime. Our starting point is a generalized Boltzmann equation with a chemical source term valid for arbitrary reaction mechanisms and yi elding a positive entropy production. We first study the Enskog expans ion in the kinetic chemical equilibrium regime. We derive a new set of macroscopic equations in the zeroth- and first-order regimes, express ing conservation of element densities, momentum and energy. The transp ort fluxes arising in the Navier-Stokes equilibrium regime are the ele ment diffusion velocities, the heat flux vector and the pressure tenso r and are written in terms of transport coefficients. Upon introducing species diffusion velocities, the kinetic equilibrium regime appears to be formally equivalent to the one obtained for gas mixtures in chem ical nonequilibrium and then letting the chemical reactions approach e quilibrium. The actual values of the transport coefficients are, howev er, different. Finally, we derive the entropy conservation equation in the Navier-Stokes equilibrium regime and show that the source term is positive and that it is compatible with Onsager's reciprocal relation s. (C) 1998 Elsevier Science B.V. All rights reserved.