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Vapor-liquid and liquid-liquid equilibrium ccompositions are presented for the ternary systems of H 2 O and propionic acid with refrigerant 23 (R23; CF 3 H), ethane, R13 (CCIF 3 ), SF 6 , and R116 (C 2 F 6 ) at 313 K, near the critical temperature of each solvent. Equilibria for most systems were determined at 15.0 MPa; the subcritical solvent SF 6 was studied at a pressure just above its vapor pressure at 313 K (4.0 MPa)

Experimental phase equilibrium measurements for the ternary system carbon dioxide - n-butanol - water are presented at 313 and 333 K and pressures from 2 to 15 MPa. The system exhibits extensive three-phase equilibrium regions. Equilibrium between four fluid phases was observed at 313 K and 8.25 MPa total pressure. A new density-dependent mixing rule with a cubic equation of state is proposed for modelling the experimental results. The model reproduces quantitatively many features of the experimentally observed behavior.

Kurnik, R.T. and Reid, R.C., 1982. Solubility of solid mixtures in supercritical fluids. Fluid Phase Equilibria, 8: 93-105 Supercritical fluids are receiving widespread attention as possible extraction agents for relatively non-volatile solids and liquids. Previous studies of the solubility of solids in supercritical fluids have been limited to pure solids. These pure-component data are interesting and indicate novel properties of supercritical fluids in this respect. The more general problem, however, lies in determining the solubility of multicomponent solids in supercritical fluids. Experimental data have now been obtained on the solubilities of binary, solid hydrocarbon mixtures in both supercritical carbon dioxide and supercritical ethylene. Most of the behavior exhibited by pure solids in supercritical fluids still exists for multicomponent solid solute systems (e.g., retrograde solidification, solubility extrema), but new phenomena were also found. The most interesting finding is that the solubility of a solid component when in a multicomponent solute system can be as much as 300% higher than the component solubility in a pure solid system at the same operating conditions. The multicomponent-solid-fluid data usually correlate well with thermodynamic theory.

Carbon dioxide and hydrogen will react over iron at 800° to 1 000°K and 1 bar pressure yielding water, carbon monoxide, methane, and carbon. In addition, iron oxides and carbides form during reaction. Phase diagrams are used to analyze this complex reaction system. Data are presented which suggest that the formation of magnetite (Fe3O4) or wustite (FexO) inhibits carbon formation. The water yield thus observed is limited by the time dependent iron-iron oxide-gas equilibrium. Preliminary data also suggest that the formation of carbides has little effect on water yield.

Currently available group-contribution methods for Tc, Pc, and Vc were evaluated using the Ambrose (1980) critical property data compilation. The Ambrose estimation methods were found to be the most accurate. Linear regression methods were also employed to develop alternate estimation methods which were found to have an accuracy comparable to those of Ambrose.

The solubilities of phenanthrene and benzoic acid were measured in supercritical carbon dioxide and ethane entrained with a small amount of benzene, acetone, methylene chloride or cyclohexane. Most of the experiments involved measuring the solubility of the solute as a function of entrainer composition, but some isocratic solubility data over a pressure range 100–300 bar was also obtained. It was found that the solubilities of both solutes increased with increasing amount of entrainer present in the supercritical gas, but that the specific entrainer used made little difference. Two elementary theoretical models of the entrained solvent were evaluated with the result that the data were better explained by considering the entrainer as a second solvent mixture rather than as a modifier of the supercritical fluid density. The solubilities of naphthalene and benzoic acid were also measured in a supercritical gas mixture containing 6.2 mol% ethane in carbon dioxide. In both cases the observed solubilities fell at an intermediate value between the known solubilities of the solutes in the pure supercritical solvents. Again, the addition of the second component to the gas appeared to behave as a chemical modifier of the solvent power of the fluid rather than only as a modifier of the solvent's PVT properties.

Etude experimentale de la migration de plusieurs antioxydants (BHT, Irganox 1076, et Irganox 1010) de polyolefines (polyethylenes basse densite, haute densite et basse densite lineaire) dans l'eau et determination du transfert de masse et des parametres d'equilibre

Experimental data are presented for the equilibrium solubility of styrene oligomers up to chain lengths of 25 monomeric units in ethane at 333 K and at pressures of 15, 25 and 34 MPa. It was observed that at a given pressure and temperature, a mass-based partition coefficient of an n-mer between the polymerich phase and the dense-gas phase is essentially independent of the compositions of the two equilibrium phases and depends only on the chain length of the n-mer. A new lattice model, developed from statistical-mechanics, is used to reproduce quantitatively the dependence of the partition coefficient on chain length and pressure. Only a single interaction parameter is necessary for all chain lengths and pressures. The practical viability of using supercritical fluids for polymer fractionatiion is also discussed.

Analyse theorique de l'effet mutuel entre les processus de transfert de masse lors de la diffusion du migrant dans la phase solide, partage a l'interface solide/fluide et le transfert de masse convectif du migrant dans la phase fluide avec reaction du migrant

Criteria are derived to specify the limit of stability for pure material and multicomponent thermodynamic systems. Through the use of Legendre transforms, the criteria may be expressed in a very simple form that only involves the determination of positiveness of a single second-order partial derivative of a potential function. Alternate and equivalent criteria are shown to result from a simple reordering of the independent variables in the Fundamental Equation of Gibbs. Certain criteria that are often stated as necessary conditions of stability (for example, Cv > 0) are shown to be insufficient for specifying the limit of stability; that is, a system will always become unstable for other reasons before Cb can attain a negative value.

Simple group-contribution methods are proposed to estimate eleven important physical properties of pure materials. A common set of structural groups was employed. High accuracy is not claimed, but the proposed methods are often as accurate as or more accurate than techniques in common use today.

(5) Eng, R.; Sandler, S. I. J . Chem. Eng. Data 1984, 29, 156. (6) Hauschild, T.; Wu, H. S.; Sandler, S. I. J . Chem. Eng. Data 1987, 32, 226. (7) Boubllk, T.; Fried, V.; Hala, E. The Vapor Pressures of Pure Substances; Eisevier: Amsterdam, 1984. (8) Wilhok, R. C.; Zwolinski. B. J. Handbook of Vapor Pressures and Heats of Vaporization of Hydrocarbons and Related Compounds. API44-TRC Publications in Science and Engineerlng No. 101; Texas AM London, 1976. (1 0) TRC Thermodynamic Tables Non-hydrocarbons ; Thermodynamics Research Center; The Texas ABM University System: College Station, TX, 1965; k-5380. (11) Eng, R. M.S. Thesis, University of Delaware, 1985. (12) Hayden, J. 0.; OConnell, J. P. Ind. Eng. Chem., Process Res. Dev. 1975, 14, 209. (13) Yen, L. C.; Woods, S. S. AIChEJ. 1966, 12, 95. (14) Casanova, C.; Rey, J.; Cobos, J. C. Int. DATA Ser., Sel. Data Mixtures, Ser. A 1986, 102. (15) Reid, R. C.; Prausnitz, J. M.; Poling, B. E. The Properties of gases & Llqukls, 4th ed.; McGraw-Hill: New York, 1987.

Legendre transform theory is: (1) developed to show the relationships among the common thermodynamic potential functions (that is, energy, enthalpy, and free energy); (2) extended to introduce other potential functions which are particularly convenient in certain applications (for example, stability and critical point phenomena of multicomponent systems). General derivative operators are employed to allow partial derivatives of a given potential functions to be transformed to derivatives of other potential functions.

Legendre transform theory is used to develop two general critical point criteria for a classical thermodynamic system. The problem of indeterminacy is discussed, as is the option of employing mole fractions (rather than mole numbers).

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1985.

An experimental and analytical study is reported of transient natural convection in a vertical cylinder. For the experiments a cylinder was partially filled with liquid and subjected to a uniform heat flux at the walls. Thermocouples were used to measure the unsteady temperature field within the liquid; dye tracers were used to study flow patterns. Parameters that were varied included the test liquid (water-glycerin mixtures), the liquid depth, and the wall heat flux. A range of Prandtl number from 2 to 8,000, L/D ratio from 1 to 3, and Grashof number from 103 to 1011 were studied, encompassing both laminar and turbulent flow regimes. An analytical model was developed by dividing the system into three regions: a thin boundary layer rising along the heated walls, a mixing region at the top where the boundary layer discharges and mixes with the upper core fluid, and a main core region which slowly falls in plug flow. The temperature of the core fluid was assumed to vary in the vertical direction but not in the horizontal direction. Natural convection boundary-layer equations were modified to allow for a temperature variation at the outer edge of the boundary layer. The model may be used with a step-by-step computational procedure to predict the temperature distribution in the fluid as a function of time for an arbitrary set of conditions. Results computed by using the model were in good agreement with the experimental data.

An experimental study was undertaken of simultaneous heat transfer and frost deposition inside a liquid nitrogen-cooled tube for a range of humidities and Reynolds numbers. The data indicate that diffusion of water vapor within the frost layer caused the frost density and thermal conductivity to increase with time. The increase was so great that the heat transfer rate became constant even while frost continued to accumulate. In a separate study the thermal conductivities of frosts formed on a cryogenic surface were measured and found to be lower than values near the freezing point of water.

Heat transfer coefficients were measured for the dissociating system 2 NO2 ⇋ NO + O2 in turbulent flow. Heat transfer rates to this reacting gas are limited by the kinetics of the decomposition and recombination reactions. Experimental results agree to within 10% with a film-theory solution for heat transfer accompanied by a nonequilibrium chemical reaction.

Experimental data and theory both support the contention that there is a maximum solubility in solid-fluid equilibria. An example system, naphthalene-ethylene, at temperatures between the upper and lower critical end points and at pressures from 1 to 1000 bar is considered. There is also a solubility minimum in this system.