VAPOR-LIQUID-EQUILIBRIUM IN THE TERNARY-SYSTEM METHANE-N-HEXANE-N-TETRADECANE

The paper presents the results of new measurements of the phase behavi or of the ternary system methane-n-hexane-n-tetradecane. The measureme nts have extended over the range of compositions at 348.15 K and 383.1 5 K for pressures from 2 MPa up to the vicinity of the critical pressu re of around 25 MPa. As well as the phase envelope itself, measurement s of the density of both phases have been carried out simultaneously. The experimental data provide the opportunity to examine the effective ness of three different thermodynamic models for the prediction of the properties of ternary mixtures from prescribed information on the con stituent binary systems. The models employed for the tests include the cubic equation of Peng-Robinson, the one-fluid corresponding-states m odel and the more flexible, multiple-reference fluid corresponding-sta tes model. It will be shown that only the multiple-reference fluid mod el provides a satisfactory description of the fluid density. The same model also represents the phase compositions moderately well, but not quite as well as the Peng-Robinson equation. (C) 1998 Elsevier Science B.V. All rights reserved.