Pressure Effects
Few experimental data are available on the thermal conductivity of high-pressure gas mixtures. Keyes studied the nitrogen-carbon dioxide system. Comings and his coworkers reported on ethylene-nitrogen and carbon dioxide-ethylene mixtures, rare-gas, and ethane. Rosenbaum and Thodos studied methane-carbon dioxide and methane-carbon tetrafluoride binaries.
Although the Lindsay-Bromley method has been suggested as a technique for estimating high-pressure gas thermal conductivities. The mixture is treated as a hypothetical pure component with pseudocritical properties. By the use of Prausnitz and Gunn’s modified rules, Table 10-7 has been prepared. With a few exceptions, this simple technique is reliable. The use of other pseudocritical rules has been considered, but the results are not significantly affected. In the CH4 – CF4 case, however, the Stiel and Thodos method yielded the poorest results to make (λ-λ^º)Zc5 = f(ρr,T,M).
More data are necessary to comfier the applicability of the Stiel-Thodos relations for dense-gas-mixture thermal conductivities, but, at present, it is the most reliable general method available.