AN EQUATION OF STATE CHEMICAL ASSOCIATION MODEL FOR FLUORINATED HYDROCARBONS AND HF

A modification of the Peng-Robinson equation of state (PR EOS) is desc ribed that has been used to calculate physical properties and phase eq uilibria for fluorinated hydrocarbons, HF, and mixtures containing the se compounds. The key modifications are improved mixing rules for mixt ures containing hydrofluorocarbons and an association model for HF tha t assumes a chemical equilibrium between HF monomers and hexamers. Equ ation-of-state parameters are presented for 21 pure compounds, includi ng many halogenated compounds, ammonia, chlorine, hydrogen chloride, d imethyl ether, n-butane, and water. Generalized correlations are also presented that allow estimation of the EOS parameters for other compou nds based on the measurement of liquid density and vapor pressure at a single temperature. Chemical association constants for HF and the PR EOS parameters for HF monomer and hexamer are also reported over the t emperature range from -78 to 180 degrees C.