The Thermal Conductivity of Methane and Tetrafluoromethane in the Limit of Zero Density

The paper presents accurate representation of the thermal conductivity of methane and tetrafluoromethane in the limit of zero density. The theoretically‐based correlations provided are valid for the temperature range 120–1000 K and 280–750 K for methane and tetrafluoromethane respectively. The methane correlations has associated uncertainties of ±2% between 300 and 500 K, rising to ±2.5% at the low, and ±4% at the high, temperature extremes. The tetrafluoromethane correlation has uncertainties of 1% between 280 K and 450 K, rising to ±5% at the highest temperature. A comparison with some earlier correlations is given. The paper also includes an improved correlation for the temperature dependence of the zero‐density viscosity of tetrafluoromethane.