VAPOR-LIQUID-EQUILIBRIUM PREDICTIONS OF REFRIGERANT MIXTURES FROM A CUBIC EQUATION OF STATE WITH A G(E)-EOS MIXING RULE

A modified excess Gibbs energy model which is based on the local compo sition concept and assigns a single energy parameter per pair of compo nents, is incorporated into the G(E)-EoS thermodynamic formalism for v apor-liquid equilibrium (VLE) calculations of simple and complex refri gerant mixtures. One temperature set of data close to 273 K is used to obtain the model's parameters, which are used to extrapolate the VLE at other temperatures and pressures. A one-parameter form of the model based on the Wong-Sandler mixing rule is presented for several simple systems. The physical significance of the model's energy parameter is connected to the preference of the mixture for like to unlike interac tions. The model is applied for VLE predictions of the ternary system R14-R23-R13, and the results are compared to calculations using the 3P WS model [H. Orbey, S.I. Sandler, Ind. Eng. Chem. Res. 34 (1995) 2520- 2525] and the van der Waals mixing rule. Modelling of a few complex sy stems with only three data points given at each temperature is shown w ith a two parameter version of our model on the basis of the Huron-Vid al mixing rule. Published by Elsevier Science B.V.