Calculation of the thermal conductivities of hydrogen, nitrogen, oxygen and carbon dioxide at high temperatures

Abstract

The thermal conductivities of a number of gases have been calculated at high temperatures as follows: hydrogen, nitrogen and oxygen to 2100 K and carbon dioxide to 1500 K. The hard-spherocylinder model of Curtiss and Muckenfuss has been used in which the cylinder lengths were obtained from the known internuclear distances and the common cap and cylinder radii obtained from viscosity measurements at the same temperature. Thus the model was used to convert available and accurate viscosity data into thermal conductivity values, for which the equivalent experimental data are sparse and less accurate. An attempt was made to evaluate this procedure by comparison with available experimental data and also by observing the effect of varying the cylinder length used. It was concluded that the method probably gave predictions that were within a few percent for nitrogen, oxygen and carbon dioxide. For hydrogen, however, the wide spacing of the rotational levels means that the predictions, which assume classical rotational behaviour, are too low over the whole temperature range and can be obtained more reliably by other methods.