Viscosity and density of mixtures of methane and n-decane from 298 to 393 K and up to 75 MPa

Experimental results of viscosity and density of mixtures of methane and n-decane are reported at temperatures from 303 to 393 K and pressures up to 75 MPa, at five compositions. This binary mixture is considered as a model for gas–condensate fluids since it presents dew-point and bubble point lines extending up to 35 MPa at room temperature. Viscosity and density were measured simultaneously using a vibrating-wire sensor, in an apparatus specifically built to study gas–liquid mixtures. The present results for both properties are compared with values from the literature when possible and present overall uncertainties of ±0.2% for density and ±3% for viscosity. Precisions are of about one third of the uncertainties for both properties. The excess volume of the mixture reaches −20 cm3 mol−1 at 393 K and 40 MPa. Viscosity has a marked non linear behaviour with composition, that is nonetheless well represented by a predictive scheme based on the theory of transport properties of the hard-sphere fluid.