Composition dependence of the thermal conductivity of dense gas mixtures

In this paper we present a method for predicting the composition dependence of the thermal conductivity of dense gas mixtures. The method requires the knowledge of the thermal conductivities of the pure component gases at high density, of the zero-density values of the thermal conductivities both of the pure components and of one binary mixture, and of the virial coefficients B_ij and their derivatives dB_ij dT. The Thorne-Enskog hard-sphere theory, after a minor correction for consistency with the Onsager reciprocal relations, is then used as an interpolating formula between the end points. An extension of the method to mixtures of dense polyatomic gases is also provided. For these gases, the transport of internal energy is assumed to be entirely kinetic (diffusion mechanism). The method has been applied to the three binary monatomic systems He-Ne, Ne-Ar and He-Ar at 30°C and up to a pressure of 20 MPa. The calculated values of the thermal conductivity of these systems agree with the best available experimental data to within the uncertainty of the latter (about 2%). No comparison was performed for the polyatomic species owing to the unavailability of reliable experimental data.