Thermal‐conductivity–reduced‐state correlation for the inert gases

The fragmentary thermal‐conductivity data for argon available in the literature have been correlated by use of a residual thermal conductivity k – k * vs. density ρ relationship. This correlation produced a unique continuous curve which was found to be singularly independent of temperature and pressure for both gaseous‐ and liquid‐state data. From low‐pressure thermal‐conductivity values k * and the relationship given above, it is possible to determine thermal conductivities at any condition of temperature and pressure for which a corresponding density is available. This procedure was used to calculate reliable thermal conductivities k for high‐pressure regions where experimental data were lacking. In a similar manner the critical thermal conductivity k c for argon was established directly from the critical density and the quantity k   T   c*. The k c value permitted the calculation of reduced thermal conductivities k R and made possible the construction of an extensive reduced‐state chart. Although this correlation was developed mainly from data for argon, it was found to apply equally as well to the other inert gases as postulated from the theory of corresponding states. A comparison of thermal conductivities calculated from the reduced‐state plot with over 200 experimental points produced an average deviation of 1.8% for all the inert gases. This chart was also found applicable to the diatomic gases and their mixtures but produced significant deviations for substances having more than two atoms per molecule.