Measurement of the ([formula omitted], [formula omitted], [formula omitted]) behavior of Helium, Neon, and their mixtures at temperatures from (100 to 283.15) K and pressures up to 10.0 MPa

Abstract

Densities of three binary mixtures of helium and neon were measured along six isotherms in the supercritical temperature range of (100 to 233.15) K at pressures of up to 10.0 MPa using a low-temperature single-sinker magnetic-suspension densimeter. The three mixtures were prepared gravimetrically with molar helium fractions of approximately 0.75, 0.50, and 0.25. In addition, densities of pure helium and neon were measured at temperatures from (100 to 283.15) K. In total, results for 108 and 64 (p, ρ, T) state points are presented for the binary mixtures and pure fluids, respectively. The relative expanded combined uncertainty (k = 2) of the experimental densities was estimated to be between (0.024 and 0.157) % for the binary mixtures and within (0.015 and 0.305) % for the pure fluids. The main uncertainty contributions are the weighings of the sinker and the composition of the gas mixtures for most state points. The new experimental results for the binary mixtures were compared with a new mixture model of Tkaczuk et al. for binary mixtures composed of helium, neon, and argon, as well as with a preliminary equation of state by Lemmon for mixtures of helium and neon. The relative deviations to the model of Tkaczuk et al. range from (−2.71 to −0.06) % while the deviations to the model of Lemmon are between (−0.68 and 0.78) %. The relative deviations of the pure substances to the respective reference equations are less than ±0.03 % for helium and within (−0.12 to 0.01) % for neon.