Molecular Thermodynamic Models for Fluids of Chain-Like Molecules, Applications in Phase Equilibria and Micro-Phase Separation in Bulk and at Interface

Abstract In this study, new experimental data using a reliable approach are reported for solid-fluid phase equilibrium of ternary mixtures of Methane-Carbon-dioxide- n-Hexadecane for 30-73 mol% CO2 and pressures up to 24 MPa. The effect of varying CO2 composition on the overall phase transition of the systems were investigated. Three thermodynamic models were used to predict the liquid phase fugacity, this includes the Peng Robison equation of state (PR-EoS), Soave Redlich-Kwong equation of state (SRK-EoS) and the Cubic plus Association (CPA) equation of state with the classical mixing rule and a group contribution approach for calculating binary interaction parameters in all cases. To describe the wax (solid) phase, three activity coefficient models based on the solid solution theory were investigated: the predictive universal quasichemical activity coefficients (UNIQUAC), Universal quasi-chemical Functional Group activity coefficients (UNIFAC) and the predictive Wilson approach. The solid-fluid equilibria experimental data gathered in this experimental work including those from saturated and under-saturated conditions were used to check the reliability of the various phase equilibria thermodynamic models.

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Metamorphic Fluids in Orogenic Settings

Elements ◽

10.2138/gselements.16.6.381 ◽

2020 ◽

Vol 16 (6) ◽

pp. 381-387 ◽

Cited By ~ 1

Author(s):

Katy A. Evans ◽

Andrew G. Tomkins

Keyword(s):

Phase Equilibria ◽

Melting Temperature ◽

Fluid Inclusions ◽

Indirect Evidence ◽

Ore Deposits ◽

Variable Composition ◽

Future Research ◽

Temperature Cycle ◽

Thermodynamic Models ◽

Metamorphic Fluids

Metamorphic reactions within the Earth’s crust produce fluids of variable composition that play a major role in the evolution of continents. Metamorphic fluids facilitate reactions that alter crustal rheology, reduce melting temperature, cycle elements between geological reservoirs and form ore deposits. These fluids are relatively inaccessible, other than by study of fluid inclusions, so most studies rely on a combination of indirect evidence and predictive thermodynamic models to determine the characteristics and roles of the fluids. In this article, the origins, compositions, controlling phase equilibria, and roles of metamorphic fluids are reviewed, followed by a discussion of selected areas of current and future research.

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Phase equilibria in the system ZnCl2 + KI

Australian Journal of Chemistry ◽

10.1071/ch9740035 ◽

1974 ◽

Vol 27 (1) ◽

pp. 35 ◽

Cited By ~ 2

Author(s):

AJ Easteal ◽

PJ O'Rourke

Keyword(s):

Phase Separation ◽

Phase Equilibria ◽

Glass Transitions ◽

Heating Rates ◽

Glass Transition Temperatures ◽

X Ray ◽

Critical Composition ◽

Congruently Melting ◽

Nitrogen Yields ◽

Liquidus Temperatures

Phase equilibria in the ZnCl2+KI system have been investigated by differential thermal analysis (DTA), and by examination by X-ray powder diffraction of solidified melts. The system evidently behaves as a simple binary, and three congruently melting compounds are formed, viz. 2KI.ZnCl2, 2KI.3ZnCl2 and KI.4ZnC12. Supercooled mixtures from c. 60-90 mole % ZnCl2 visibly phase separate at temperatures for the most part about 30K below the liquidus temperatures, and the phase separation temperatures have been determined by DTA. The composition limits of the metastable immiscibility dome have not been established, but the region of phase separation extends at least to mixtures containing as little as 53 mole % ZnCl2. The critical composition is approximately 80 mole % ZnCl2, and the critical temperature 470 K. Quenching of melts containing 34-100 mole % ZnCl2, in liquid nitrogen, yields glasses. In the region 34-43 mole % ZnCl2 the glasses are partly crystallized. Glass transition temperatures for the wholly glassy mixtures have been evaluated from DTA traces, with heating rates in the range 0.11-0.25 K s-1. Two glass transitions have been observed for mixtures of composition 53-75 mole % ZnCl2.

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