In this article we present results for the viscosity and the mass transfer rates of hydrogen/ air, hydrogen/oxygen, methane/air and methane/oxygen mixtures in the temperature range from 1000 to 7000 K and a pressure range from lo3 to lo6 Pa. In addition, the combustion ratio is varied from 0 to 03. The transport properties are calculated from the first order solution of the Chapman Enskog approach to the Boltzmann equation, assuming chemical equilibrium composition. An extensive literature study was performed to derive experimental and/or theoretically based data for the respective binary interaction potentials. The values of the collision integrals, as derived from a complex numerical integration procedure, are correlated to an approximation formula. In addition, the exact solutions of the kinetic theory are compared to frequently used empirical mixture rules. For the mixture viscosity an easy approximation formula is deduced from the gas-kinetic theory.

The determination of the composition of multi-component mixtures is the basis by which a number of technical and physical problems in the field of power and process engineering are modelled. In order to calculate chemical states of equilibrium in the gas phase, a calculation method will be presented which is founded on a minimization of the Gibbs enthalpy. This method is characterized by a high reliability in convergency, considerable independence of starting vectors and by a moderate requirement for programming. These characteristics are achieved by a transformation of variables which results in numerically more favourable solutions to the non-linear equation system. Calculated equilibrium compositions (including dissociation and ionisation) for a stochiometric mixture of hydrogen and oxygen in a temperature range of 300-12000 K and a pressure of lo5 Pa as well as the application of the method will be demonstrated.

This article presents gas kinetic calculation methods for the energy transport in hydrogen/ air and methane/air mixtures. The total molecular heat conductivity as well as its various shares are calculated and discussed for a temperature range of 400 to 3500 K and for a pressure of lo5 Pa. The variation of the air/fuel ratio under the conditions of chemical equilibrium is also investigated. As opposed to our previous article, an extension of the ChapmanEnskog method which goes beyond the classical 1st approximation for elastic collisions is applied for the evaluation of suitable calculation methods. This is carried out following the method for strong relaxing thermal nonequilibrium according to Brun. The equations applied in this work are simplified formulations for the proximity to equilibrium. The method for the evaluation of the parameters of the inelastic collision and some chosen results are presented. A discussion of the various shares of the molecular heat conductivity emphasizes the considerable influence of the diffusion and the thermal diffusion processes in fuel/air mixtures compared to the Fourier heat conductivity.