A Generalized Model for the Transport Properties of Air Components and Mixtures

Abstract

A generalized correlation for the transport properties (viscosity and thermal conductivity) of pure fluids is presented. The new formulation, which is applicable to the whole fluid region, is based on Eyring’s significant liquid structure theory. We have incorporated a modification of Eyring’s reaction rate theory for liquid viscosity and gas kinetic theory for the dilute gas viscosity and thermal conductivity. An empirical hyperbolic secant function is used for the critical region transport property enhancements. In addition to transport properties for the pure cryogenic fluids, the formulation has been applied to the viscosity and thermal conductivity for mixtures of nitrogen, oxygen and argon, including air, in both gas and liquid phases. The accuracy of the formulation is assessed based upon comparisons to experimental data for both pure fluids and mixtures. The wide-range formulation is explicit in viscosity and thermal conductivity as functions of temperature and density. Wide-range equations of state developed earlier for each pure fluid and for air were used to calculate the densities of the fluids at specific temperatures and pressures in the development of the generalized correlation.