EQUATION OF STATE MIXING RULE FOR NONIDEAL MIXTURES USING AVAILABLE ACTIVITY-COEFFICIENT MODEL PARAMETERS AND THAT ALLOWS EXTRAPOLATION OVER LARGE RANGES OF TEMPERATURE AND PRESSURE

We demonstrate that a new mixing rule allows cubic equations of state to be used for a broad range of nonideal mixtures which previously could only be described by activity coefficient models. Further, we show that there is no need to recorrelate phase equilibrium data to do this; activity coefficient model parameters currently reported, for example in the DECHEMA Data Series, can be used directly in our model. Perhaps most important is that we also find that we can use the parameters in our model obtained from one low pressure-low temperature isotherm to make accurate predictions at conditions which are hundreds of degrees and hundreds of bars above the experimental data used to obtain those parameters. Consequently, this new model provides a way of being able, with confidence, to use data for nonideal mixtures obtained at moderate laboratory conditions for design at harsh processing conditions.