Kwang-Chu Chao

Vapor-liquid equilibrium in mixtures of cyclohexane + benzene, + octene-1, + m-xylene, and + n-heptane

Abstract Vapor-liquid equilibrium has been determined for four binary hydrocarbon mixtures: cyclohexane + benzene, + m -xylene, + n -heptane, and + octene-1. Isothermal variation of the saturation pressure with liquid-phase composition was determined experimentally in a static apparatus over the entire composition range. The composition of the equilibrium vapor phase is obtained by calculation with Barkers method using the Redlich-Kister equation for the activity coefficients.

Vapor-liquid equilibrium of molecular fluid mixtures by equation of state

Abstract The description and prediction of the vapor-liquid equilibrium of molecular fluid mixtures by equation of state is reviewed. Seven equations of state are compared with experimental data. Results of the comparison are reported for mixtures of non-polar and slightly polar substances over a wide image of pressure, temperature, and molecular variety. The experimental data base of the comparison includes 20 symmetric mixtures, 20 methane-containing mixtures, 17 hydrogen mixtures, 18 carbon dioxide mixtures, and 12 nitrogen mixtures. Interaction constants are determined and reported for all the mixtures studied.

vapor—liquid and liquid-liquid equilibria and critical states of water + n-decane mixtures

Abstract vapor—liquid equilibrium and liquid-liquid equilibrium are observed in disjointed regions at 573.2, 593.2, and 613.2 K for mixtures of water + n-decane at pressures up to 230 bar. vapor—liquid critical states are determined at the temperatures studied.

Chain-of-rotators group contribution equation of state

Abstract A group contribution equation of state is developed from the chain-of-rotators equation and parameters for 20 groups are reported. It is shown that the new equation allows predictions with good accuracy of phase equilibrium and volumetric properties for a variety of non-polar fluids and their mixtures over wide ranges of temperature and pressure.

Molecular hard cores of normal fluids

Molecular hard cores of normal fluids have been deduced from analysis of isothermal compressiblity data of dense fluids in light of Gibbons’s hard core equation of state. The hard cores thus obtained are found to follow the principle of corresponding states in the extended three parameter form. The shapes and sizes of the hard cores of some common molecules calculated from the general equations are shown graphically.

The complete local concentration model activity coefficients

Abstract Wilsons local concentration model of solution non-ideality is extended to include an enthalpic contribution in addition to the original exclusively entropic contribution. The new complete model improves the Wilson equation and makes it possible to describe liquid—liquid immiscibility phenomena. We report the representation of vapor—liquid equilibrium data of a number of mixture systems with the new complete equation. Examples are shown of application to liquid—liquid equilibrium.

Hard‐cores of molecules of simple fluids

The diameters of hard−cores of molecules of simple fluids (Ar, Kr, Xe) have been deduced from analysis of isothermal compressibility data in light of hard−sphere equations of state. The hard−core diameter σ thus obtained is found to decrease slightly as temperature is increased. The results can be represented in a generalized form in terms of reduced variables σ[(6/π)(?c/?)]−1/3 = 0.549058 − 0.010827 T/Tc with standard deviation of 0.000731.

Fluid phase equilibrium and volumetric properties from the Chain-of-Rotators group contribution equation of state

Abstract A new group contribution equation of state, the Chain-of-Rotators Group Contribution (CORGC) equation, has been developed recently for the calculation of vapor—liquid phase equilibrium and volumetric properties of paraffins, naphthenes, aromatics, olefins, light gases and their mixtures. Comparisons of CORGC calculations with data are presented here for pure fluid and mixture vapor—liquid coexistence properties. Predictions of the equation for systems not included in the original data base are also shown for pure fluid vapor pressures and mixture vaporization equilibrium ratios.

A new vapor-liquid equilibrium cell and VLE data for mixtures of 1-propanol + p-xylene

Abstract Chen, A.-Q., Urbanus, G.J. and Chao, K.-C., 1994. A new vapor-liquid equilibrium cell and VIE data for mixtures of 1-propanol + p -xylene. Fluid Phase Equilibria , 94: 281-288. A vapor-liquid equilibrium cell of a new design to withstand high temperature, high pressure and corrosive fluids is constructed. Vapor-liquid equilibrium is measured for mixtures of 1-propanol and p -xylene at 160.0 and 221.1°C at pressures to 26 bar. The VLE data are correlated with Wong and Sandlers equation of state method using activity coefficient model parameters.

Statistical thermodynamics of group interaction in n-alkane-n-alkanol and n-alkanol-n-alkanol solutions

The statistical thermodynamics previously developed for pure liquids of non-polar and polar chain molecules is extended to their mixtures. An orientation factor is introduced into the quasi-chemical relation of the hydrogen bond to reduce the calculated preferential bonding. Excess properties are calculated for n-alkane-n-alkanol-1 and n-alkanol-1-n-alkanol-1 solutions. The heat of mixing and excess free energy calculated with the group properties reported previously are in good agreement with data for solutions in which the alkanol is higher than ethanol.