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Vapor-phase (p, , T, x) behavior and virial coefficients for the (methane + propane) system



Mark O. McLinden, Markus Richter


The (p, ρ, T, x) behavior of three (methane + propane) mixtures was measured with a two-sinker magnetic suspension densimeter over the temperature range of (248.15 to 373.15) K with pressures up to the lesser of the dew point pressure or 6 MPa. The compositions of the gravimetrically prepared mixtures were (0.74977, 0.50688, and 0.26579) mole fraction methane. A detailed uncertainty analysis is presented, and the expanded (k = 2) state-point uncertainty in density considering all effects, including the uncertainty in composition, was 0.05 %, except it was larger at densities less than 5 kg⋅m–3. Comparisons to the GERG-2008 equation of state for natural gas mixtures showed significant deviations in density (as large as –1.3 %) that increased with decreasing temperature and with increasing pressure and increasing propane fraction in the mixture. The data were also used to calculate interaction virial coefficients B12(T) for this system. The B12(T) agreed well with literature values. They were constant (within experimental uncertainty) with composition, as expected from theory. In contrast, the B12(T) calculated with the GERG-2008 equation of state varied with composition.
Journal of Chemical and Engineering Data


density, measurements, experimental uncertainty, mixture models, virial coefficient


McLinden, M. and Richter, M. (2014), Vapor-phase (p, <rho>, T, x) behavior and virial coefficients for the (methane + propane) system, Journal of Chemical and Engineering Data, [online], (Accessed June 22, 2024)


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Created November 12, 2014, Updated June 2, 2021