Fredenslund, and Rasmussen Equation of State

Holten-Andersen et al. (1987) modified the Flory equation of state in order to develop an equation that is applicable to the vapor phase, to make it more applicable to associating fluids, and to introduce a group contribution approach. Chen et al. (1990) revised and improved the equation of state. The final model takes the following form. 

The Chen et al. equation of state is not as accurate as the Oishi-Prausnitz method described previously, but the Chen et al. equation of state has the advantage of not requiring the pure component densities. The densities of the pure components and the mixtures are calculated through a group contribution approach. The types of groups available include the alkanes, aromatics, ketones, esters, ethers, alcohols, alkenes, and chloroalkenes. There are fewer groups available in the Chen et al. equation of state than the Oishi-Prausnitz model. More details of the Chen et al. equation of state are provided in Procedure 3D of this Handbook. 

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