Volumetric Properties of Pentane + Carbon Dioxide at High Pressures

The volumetric behavior of carbon dioxide + pentane has been investigated at 323, 348, 373, 398, and 423 K at pressures up to 70 MPa using a variable-volume view cell. Densities for pure components and fluid mixtures containing 10, 20, 35, 50, 62, 72, 80, and 88% by weight carbon dioxide are presented as a function of pressure at each temperature. With increasing pressure (above 20 MPa) the density of carbon dioxide becomes greater than that of pentane, and mixture densities show a crossover with composition. At a given temperature and pressure, under a majority of the conditions evaluated, the excess volume for the mixtures shows a sigmoidal variation with composition, being negative at low carbon dioxide content and becoming positive with increasing carbon dioxide content. With increasing pressure, excess volumes become less negative.