THERMODYNAMIC PROPERTIES OF FLUIDS--EXPERIMENTAL DETERMINATION AND PREDICTION USING THE PRINCIPLE OF CORRESPONDING STATES
Abstract
The shape factor method of corresponding states theory using methane as the reference fluid is examined to determine its usefulness for the prediction of phase equilibrium of pure fluids and their mixtures beyond the methane to pentane range. Vapor pressure and saturated fluid densities of both nonpolar and polar molecules are studied to give indications of the applicability of the method to their mixtures. The van der Waals one-fluid model is used to represent mixture behavior. Two binary interaction parameters are introduced and their values determined for each of the binary systems studied. Equilibrium ratios are calculated for binary mixtures of methane, carbon dioxide, hydrogen, and hydrogen sulfide with various hydrocarbons. Henry's constants and saturated fluid densities of binary mixtures, and bubble points of ternary mixtures are predicted using binary interaction parameters determined from the bubble point pressures and equilibrium ratios of binary systems. The predictions are compared with experimental results. Vapor-liquid equilibrium data, in terms of excess Gibbs free energies, are calculated for binary mixtures of polar and nonpolar molecules. The nonpolar molecules are principally hydrocarbons with from six to eight carbon atoms, while the polar molecules are of similar molecular weight. Two binary interaction parameters are suitable for correlating the data over a narrow temperature range. Excess enthalpies for binary mixtures of hydrocarbons are correlated in terms of two binary interaction parameters on each isotherm. Vapor-liquid equilibrium data are reported for the following four binary hydrocarbon mixtures at temperatures of 25, 40, and 55(DEGREES)C: benzene + cyclohexane, benzene + methylcyclopentane, n-heptane + ethylbenzene, and n-heptane + p-xylene. The isothermal dependence of total solution pressure on liquid phase composition is determined in a static apparatus. Mixtures are prepared by volumetrically metering pure degassed chemicals into an equilibrium cell, immersed in a constant temperature bath. The composition of the vapor phase is calculated from Barker's procedure using the Redlich-Kister equation for the activity coefficients.
Degree
Ph.D.
Subject Area
Chemical engineering
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