Viscosity measurements of CO2-rich; CO2 + N2 and CO2 + H2 mixtures in gas or supercritical phase at temperatures between 273 and 473 K and pressures up to 8.7 MPa

New experimental viscosity data of three binary CO₂-rich mixtures with approximate mole fractions of 0.93 CO₂ + 0.07 H₂, 0.80 CO₂ + 0.20 H₂, and 0.90 CO₂ + 0.10 N2 are reported. The measurements were performed at four different isotherms between 273 K and 473 K. Two independent rotating body viscometers with different pressure range were utilized, suitable for measurement of pressures up to 2 MPa and 20 MPa, respectively. The maximum expanded combined relative uncertainty (k = 2) in viscosity was 0.25% for the data obtained from the low-pressure viscometer and 0.6% for the data measured by the high-pressure viscometer. The experimental data were compared to the data estimated by the extended corresponding states (ECS) model implemented in the NIST REFPROP 10.0 database. The maximum deviation between the model and the new data is 1.86%. The data measured with the two apparatuses agree within the estimated uncertainty.