High-precision viscosity measurements on methane

A new vibrating-wire viscometer of very high precision was applied to determine the viscosity coefficient of methane. The relative measurements are characterised by a reproducibility of less than +/-0.1% and by an accuracy of +/-0.3%. The experiments were carried out at nominal temperatures of 260, 280, 300, and 320 K and at pressures up to 20 MPa as well as at temperatures of 340 K and 360 K and at pressures up to 29 MPa. The density dependence of the viscosity can appropriately be represented for all isotherms by a power series expansion restricted to the fourth power. The new experimental values for methane are used together with the most reliable data from the literature to deduce a zero-density correlation and an initial-density dependence correlation as well as a representation of the high density contributions of the residual viscosity. The viscosity surface correlation extends from the triple point to 620 K and 100 MPa.