Viscosity of the CO₂ + CH₄ Binary Systems from 238 to 423 K at Pressures up to 80 MPa

A capillary tube viscometer was used to measure the viscosity of the carbon dioxide + methane binary systems (with the mole fraction of CO2 = 0, 0.25 0.50, 0.74, 0.90, and 1) at temperatures between 238.15 and 423.15 K and pressures up to 80 MPa. The new viscosity data were compared against predictions of four types of viscosity models: a corresponding state (CS2) model using two reference fluids, an extended corresponding states (ECS) model, a corresponding states model derived from molecular dynamics simulations of Lennard-Jones fluids, and a residual entropy scaling approach. The required density for viscosity predictions was calculated using Multi-Fluid Helmholtz Energy Approximation (MFHEA) equations of state (EoS). It is found that the deviations of the predicted results and the experimental viscosity data are generally within 2.5% for the SRES model to 4.5% for the CS2 model.