A re-evaluation of the means used to calculate transport properties of reacting flows

Simulations of laminar combustion and other reactive flow processes (like chemical vapor deposition, plasma etching, etc.) are presently carried out in most cases using the transport code TRANFIT attached to the CHEMKIN package. The approach used is based on experimental data from 1975 and is now outdated, especially in view of recent work presented in the literature.

The new approach described here seeks to remove the deficiencies of former transport models by using the following features: (1) representation of transport data of light species at high temperature by switching to an exponential repulsive potential, (2) use of effective potential parameters to handle the intermolecular forces in an easy and elegant way, if polar molecules are considered, and (3) use of a simplified formula for binary thermal diffusion factors, based on an expansion for large values of the mass ratio of the species included.

This paper presents the new transport model in terms of a complete set of equations. The molecular parameters provided allow a complete treatment of the oxidation of H₂ and H₂/CO mixtures (data for species taking place in the oxidation of hydrocarbons and in other reaction systems are not yet available). To demonstrate the consequences of the new transport model for combustion processes, results have been generated by implementing the model in a code for the simulation of premixed laminar flames.