Measurements of the Viscosity of n-Hydrogen and (n-Hydrogen + Carbon Dioxide), (n-Hydrogen + Methane), and (n-Hydrogen + Ethane) Mixtures at Temperatures from (253.15 to 473.15) K and at Pressures up to 20 MPa

Viscosity measurements of normal hydrogen (n-hydrogen) and four (n-hydrogen + carbon dioxide), four (n-hydrogen + methane), and two (n-hydrogen + ethane) binary mixtures at temperatures between (253.15 and 473.15) K and at pressures up to 20 MPa are presented. The relative expanded combined uncertainty (k = 2) in terms of viscosity ranges between (0.47 and 0.70) %. The nominal compositions of the gravimetrically prepared mixtures are (10, 20, 40, and 60) mol-% carbon dioxide, (10, 25, 50, and 75) mol-% methane, and (10 and 50) mol-% ethane, respectively. For the measurements, a rotating-body viscometer was used, which is based on the utilization of a magnetic suspension coupling to allow for a contactless and, thus, ideally frictionless suspension of the rotating-body. To provide experimental data with low experimental uncertainty, a relative measurement approach was applied, with helium as reference fluid. The measurement results are compared to experimental data, ab initio-calculated data, and viscosity correlations from the literature. Furthermore, zero-density viscosities are provided, which were obtained from a quadratic expansion in terms of the density fitted to the experimental data. Relative deviations of the pure fluid viscosities for n-hydrogen reported in this work are between (− 0.033 and 0.45) % from the corresponding viscosity correlation and zero-density viscosities for n-hydrogen deviate by (− 0.010 to 0.23) % from the most accurate data found in the literature.