Thermal conductivity of argon, nitrogen and carbon dioxide at elevated temperatures and pressures

Abstract

The transient hot-wire technique has been used to measure the thermal conductivity of argon at 427 and 470 K, nitrogen at 430 K and carbon dioxide at 380, 430 and 470 K at various pressures, the maximum being 30 MPa. The argon results served to test the apparatus, which has been adapted to operate at these higher temperatures. The low-density limits for the argon thermal conductivities were found to be consistent with published viscosity values. The density dependence of the thermal conductivity of argon was found at both temperatures to be equal, within experimental uncertainties, to that observed at lower temperatures. The results for nitrogen were compared with earlier results and the low-density limit gave an Eucken factor consistent with previous trends. The results for carbon dioxide are compared with previous measurements made at low densities by other techniques and with a theoretically predicted surface for the thermal conductivity of carbon dioxide in the region of the critical point.