This work aims to provide accurate and wide-ranging experimental new speed of sound data w(p,T) of two binary (CH4 + He) mixtures at a nominal helium content of 5% and 10% at pressures p = (0.5 up to 20) MPa and temperatures T = (273.16, 300, 325, 350 and 375) K. For this purpose, the most accurate technique for determining speed of sound in gas phase has been used: the spherical acoustic resonator. Speed of sound is determined with an overall relative expanded (k = 2) uncertainty of 230 parts in 106 and compared to reference models for multicomponent natural gas-like mixtures: AGA8-DC92 and GERG-2008 equations of state. Relative deviations of experimental data from model estimations are outside the experimental uncertainty limit, although all points are mostly within the AGA uncertainty of 0.2% and GERG uncertainty of 0.5% and worsen as the helium content increases. Absolute average deviations are better than 0.45% for GERG and below 0.14% for AGA models in (0.95 CH4 + 0.05 He) mixture and below 0.83% for GERG and within 0.22% for AGA equations in (0.90 CH4 + 0.10 He) mixture.
Lozano-Martín, D., Rojo, A., Martín, M. C., Vega-Maza, D., & Segovia, J. J. (2019). Speeds of sound for (CH4 + He) mixtures from p = (0.5 to 20) MPa at T = (273.16 to 375) K. Journal of Chemical Thermodynamics, 139. https://doi.org/10.1016/j.jct.2019.07.011