The thermal conductivity of binary mixtures of helium and methane at 27.5 °C and pressures up to 13 MPa

Abstract

AbstractThe paper reports new, accurate measurements of the thermal conductivity of mixtures of helium and methane in the pressure range 1–13 MPa at 27.5 °C. The measurements have been carried out in a transient hot‐wire instrument and have an estimated uncertainty of ± 0.2%. — The experimental data as a function of density have been extrapolated to yield reliable values of the zero‐density thermal conductivity of the mixtures. It is found that these experimental data cannot be satisfactorily represented by the existing first‐order kinetic theory formulae using independently determined collision numbers for rotational energy relaxation, unless empirical adjustments are made to certain collision integral ratios occurring in the equations. A recently proposed scheme for the prediction of the density dependence of the thermal conductivity of the mixtures is found to correlate the observed density dependence satisfactorily.