Phase Equilibrium Data Research Articles

Experimental investigation and thermodynamic calculation of the Cu–Cr–Ti ternary system

The phase equilibria of the Cu–Cr–Ti ternary system were investigated based on key experiments coupled with thermodynamic modeling. Eighteen ternary alloys were prepared to determine the isothermal sections of the Cu–Cr–Ti system at 600 and 800 °C by means of X-ray diffraction (XRD) and scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM/EDS). Seven three-phase regions have been determined. A ternary compound τ1 was confirmed. The solubilities of Cr in the Cu–Ti binary compounds and Cu in the Cr–Ti binary compounds were measured. The substitutional and sublattice models were used to describe the solution phases and intermediate phases, respectively. Based on the thermodynamic descriptions of three binary systems as well as the experimental phase equilibria data available from the literature and the present work, thermodynamic assessment of the Cu–Cr–Ti system was carried out using the CALPHAD (CALculation of PHAse Diagrams) approach. A set of thermodynamic parameters was obtained and the isothermal sections and the liquidus projection of the Cu–Cr–Ti system were calculated. The calculated results agree well with the experimental data.

Experimental Study of Liquid–Liquid Equilibrium and Thermodynamic Modeling for Systems Containing Alcohols + Biodiesel + Diesel

Energy crisis and emission problems have led to investigations on alternative fuels. In this respect, partial substitution of diesel with alcohol and biodiesel has proved to be successful. The present study focuses on the use of biodiesel as an additive to stabilize alcohols in diesel blends and proposes new fuel formulations based on thermodynamic studies of liquid–liquid equilibrium (LLE) data from ternary systems containing methanol/ethanol/1-butanol + biodiesel + diesel at atmospheric pressure and 300.15 K. The authenticity of phase equilibrium data was validated by the Othmer–Tobias and Hand equations. The distribution and selectivity coefficients calculated for immiscibility regions indicated that an increase in the carbon chain strengthens biodiesel solubility. Experimental data also correlated with universal quasi-chemical (UNIQUAC) and non-random two liquids (NRTL) thermodynamic models. Both models showed high agreement with the experimental data, with deviation values (root-mean-square deviation, RMSD) less than 1.78%.

Thermodynamic modeling of the Nb-Ni system with uncertainty quantification using PyCalphad and ESPEI

The Nb–Ni system is remodeled with uncertainty quantification (UQ) using software tools of PyCalphad and ESPEI (the Extensible, Self-optimizing Phase Equilibria Infrastructure) with the presently implemented capability of modeling site fraction based on Wyckoff positions. The five- and three-sublattice models are used to model the topologically close pack (TCP) μ-Nb7Ni6 and δ-NbNi3 phases according to their Wyckoff positions. The inputs for CALPHAD-based thermodynamic modeling include the thermochemical data as a function of temperature predicted by first-principles and phonon calculations based on density functional theory (DFT), ab initio molecular dynamics (AIMD) simulations, together with phase equilibrium and site fraction data in the literature. In addition to phase diagram and thermodynamic properties, the CALPHAD-based predictions of site fractions of Nb in μ-Nb7Ni6 agree well with experimental data. Furthermore, the UQ estimation using the Markov Chain Monte Carlo (MCMC) method as implemented in ESPEI is applied to study the uncertainty of site fraction in μ-Nb7Ni6 and enthalpy of mixing (ΔHmix) in liquid.

A mini-review on cryogenic carbon capture technology by desublimation: theoretical and modeling aspects

Carbon capture, utilization, and storage (CCUS) technologies are the most effective methods to reduce CO2 emissions from fossil fuel power plants. Of the different CCUS technologies, cryogenic carbon capture (CCC) methods are the most mature technology as they can obtain remarkably high CO2 recovery and purity (99.99%). The significant advantage of the CCC process is that it can be easily retrofitted to existing systems and can handle the gas stream’s impurities. Different desublimation-based CCC technologies like Cryogenic packed bed, Anti sublimation, External cooling loop, CryoCell process and Novel low-cost CO2 capture technology (NLCCT) are reported in the literature. The significant limitations of these processes are the continuous removal of the dry ice into storage tanks. For the efficient design of CCC systems, accurate prediction of the phase equilibria data and modeling of the frost formation is called for. This paper reviews the recently reported cryogenic desublimation technologies and analyses the various challenges in making them economically viable. The article also examines the different heat and mass transfer models employed to model CO2 frost formation.

Separation mechanism and thermodynamic phase behavior of n-propanol/p-xylene azeotrope from petrochemical wastewater by green solvents

P-xylene, n-propanol and water are widely present in the petroleum production process, so the effective separation of these substances is of great significance to environmental protection and resource conservation. In this study, deep-eutectic solvents (DESs) were used to separate the n-propanol/p-xylene/water ternary azeotrope system for the first time and compared with the commonly used solvents. The difficulty of forming hydrogen bonds and the interaction between the extractants and the system to be separated were determined by quantum chemical calculations. Quantitative analysis was performed using σ-profile, interaction energy and electrostatic potential (ESP) energy. The order of interaction strength was N-formylmorpholine (NFM) > cyclohexanol, (DL-Menthol/Lauric acid)2:1 (DES1) > (DL-Menthol/Decanoic acid)1:1 (DES2). Qualitative analyses were performed using interaction region indicator (IRI) and independent gradient model based on Hirshfeld partition (IGMH). It can be visually shown that the H atoms on the hydroxyl groups of n-propanol play a major role in the interaction, and all form hydrogen bonds with the O atoms of the entrainers. Finally, phase equilibria data for entrainers and azeotropes were supplemented with the improved new Rose VLE kettle. A series of relevant calculations and experimental data show that the selected four extractants can achieve component separation. Among them, NFM and DES1 are the best extractants. This study provides a solvents screening process through quantum chemical calculations and phase equilibrium experimental multi-scale studies, which provide guidance for the application of solvents screening and DESs in extractive distillation separation processes.

Phase equilibrium and evaporation process simulation for the lithium recovery from NaCl-LiCl-H2O system with high presence of organic NMP

In the production process of polyphenylene sulfide (PPS), there is a waste liquid with the main composition of NaCl-LiCl-NMP-H2O. For the recovery of LiCl, the phase equilibrium data of the NaCl-LiCl-H2O system at a temperature of 333.15 K and 348.15 K with the highest presence of 24 % NMP in the solvent was experimentally measured. The results show that the phase diagram has one invariant point, two univariant curves and two single-salt crystallization regions corresponding to NaCl and LiCl·H2O, respectively. Neither double salt nor solid solution is found in the system. Meanwhile, the Electrolyte NRTL model was successfully developed to reproduce the phase equilibrium of the systems. Finally, the evaporation crystallization process was developed for the lithium enrichment and sodium separation. The different process operations of multi-effect evaporation (MEE), mechanical vapor recompression (MVR), and hierarchical compression MVR were compared with the focus on the energy consumption. The results show that compared with the other two processes, for this high boiling point rise system, the total annual cost and exergy loss can be reduced by 53.57 % and 64.81 % to the maximum extent by using the hierarchical compression MVR system.

Vapor-liquid-liquid equilibria of binary and ternary aqueous systems containing C6-hydrocarbons

BackgroundTo develop process for separating water and C6-hydrocarbons, the vapor-liquid-liquid equilibrium (VLLE) data of the related mixtures are fundamentally important. MethodsThe isothermal vapor-liquid-liquid equilibrium (VLLE) data were measured for the binary and the ternary aqueous mixtures containing C6 hydrocarbons (benzene, n-hexane, and cyclohexane) at temperatures from 343 K to 383 K by using a modified static-type apparatus equipped with a visual cell. The VLLE data were correlated with the NRTL-HOC and the UNIQUAC-HOC models, respectively. Significant findingsIn addition to literature data, the experimental results of the binary systems reveal the temperature and molecular structure effects on the saturated compositions in three coexistent phases. The experimental ternary VLLE properties form a basis to verify the prediction by using the determined parameters of constituent binaries and also to modify the values of the binary parameters for improving the ternary VLLE calculations. The findings of this study offer new phase equilibria data for model development and process design for the related separation units.

High-pressure phase equilibrium data of carbon dioxide/food-relevant systems (2011-2022): Experimental methods, multiphase behavior, thermodynamic modeling, and applications

High-pressure phase equilibrium data involving food-type substances and pure or cosolvent-modified pressurized carbon dioxide (CO2) published in the last decade are reviewed. Experimental data regarding binary, ternary, and multicomponent systems studied at 293–373 K and pressures up to 55 MPa are compiled. CO2/lipid-like substances (fatty acids, esters, triacylglycerols), essential oils, and their components are the most studied food systems, followed by systems containing biopolymers. The Vapor-Liquid Equilibrium is the most observed fluid-fluid transition at experimental conditions. The cosolvent effect of organic solvents in removing immiscibility gaps like the Vapor-Liquid-Liquid and the Liquid-Liquid boundaries, the antisolvent role of CO2 to some solutes, and its plasticizing effect on polymers and solid lipids are also highlighted in the context of solid-fluid equilibrium. The Peng and Robinson Equation of State coupled with the Van der Waals type mixing rules is still the main thermodynamic model applied for modeling phase equilibrium of these systems, despite some correlative limitations regarding multicomponent mixtures containing polar molecules. Combining classical Equations of State with the associative term and predictive models as Group Contribution methods is a reliable tool to improve the modeling of systems with complex phase behaviors. Fluid phase immiscibility regions and experimental conditions that favor the presence of a solid phase are mainly useful to set the appropriate operating point based on phase diagrams and the observed equilibria. For many applications, phase equilibrium is relevant in processing food-type substances destined for food or food-related applications and human consumption by processes employing CO2 as an extraction solvent, a fractionating, dispersant, precipitative, or atomizing (antisolvent) agent, or as a reaction medium for biocatalysis.

Correlation and Prediction of Isobaric Vapor–Liquid Equilibria of Binary and Ternary Systems Containing Oxygenated Biofuel Compounds (Butan-2-one + 2-Methylpropan-1-ol + Cyclopentanone) at Atmospheric Pressure

Process modeling and feasibility studies for biofuel production require accurate phase equilibria data. Binary mixtures of common biofuel compounds butan-2-one + 2-methylpropan-1-ol, butan-2-one + cyclopentanone, 2-methylpropan-1-ol + cyclopentanone, and a ternary system of all three components were studied to obtain vapor–liquid equilibrium data at atmospheric pressure. The experimental data were validated and verified thermodynamically by employing the modified McDermott–Ellis, Van Ness, and Herington methods. The binary vapor–liquid equilibrium (VLE) data were successfully correlated with the Wilson, NRTL, and UNIQUAC activity coefficient models and predicted with the PSRK model. Further, the PSRK model and NRTL with the obtained binary interaction parameter (BIP) model were applied to forecast VLE data for the ternary system of butan-2-one + 2-methylpropan-1-ol + cyclopentanone. Both PSRK and NRTL models showed good accuracy in predicting the equilibrium temperature. At the same time, the PSRK model outperformed the NRTL model in predicting the composition of the vapor phase. The PSRK model was quite accurate for predicting the VLE of these biofuel components, even without any experimental data.

Extraction of methylcyclohexane−toluene mixture using imidazolium ionic liquids

Separation of aromatics from non-aromatic hydrocarbons was exemplified assuming the liquid-phase extraction process for methylcyclohexane−toluene model mixture separation using the newly tested 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMim][NTf2]) ionic liquid (IL). For this process a separation unit was proposed consisting of separation part represented by a counter-current extraction column and regeneration part including a vacuum evaporator and a vacuum distillation column. Separation of feed composed of 10 mole% of toluene in methylcyclohexane was considered in the designed separation unit. Designed separation efficiency of the unit was based on the following specifications: minimum methylcyclohexane and toluene content in the product streams of 99.5 mole% and the purity of regenerated extraction solvent recycled to the extraction column above 99 mole%.Mathematical model of a counter-current extractor was compiled and its operation was simulated in the Matlab environment. In extractor simulations, proprietary phase equilibrium data were employed. Ternary liquid–liquid equilibrium (LLE) of the methylcyclohexane−toluene−[EMim][NTf2] system was estimated experimentally, from which the model parameters of the original NRTL equation were evauated and used for the ternary phase equilibrium description.Aspen Plus was used to design a separation unit for the title hydrocarbons mixture separation, including the extraction solvent regeneration. Simulation of the proposed separation unit operation was focused not only on its separation efficiency but also on the evaluation of the unit energetic requirements.Results of the unit design calculations (parameters of individual equipment, heat duties) obtained for the tested ionic liquid [EMim][NTf2] were confronted with the simulation results obtained for two ILs recommended in the literature for the non-aromatic–aromatic hydrocarbon mixture separation, namely 1‑butyl‑3-methylimidazolium tetracyanoborate [BMim][TCB] and 1-hexyl-3-methylimidazolium tetracyanoborate [HMim][TCB]. Based on the energetic analysis, the heat integration of the suggested separation unit was carried out for ionic liquid [HMim][TCB], which appeared to be the most efficient extraction solvent among those tested in this study, The heat integration resulted in about 71% reduction of the heat demand of the proposed separation unit.

Phase equilibrium data for clathrate hydrates formed in the systems of urea + (methane or carbon dioxide) + water

Subsea methane hydrates are expected as a potential natural gas resource. To develop gas production methods for the subsea methane hydrates, flow assurance technologies are necessary. Urea is one of the environmentally-friendly thermodynamic hydrate inhibitors (THIs) which is expected to be applicable for subsea methane hydrate systems. To evaluate its performance as a THI, a set of phase equilibrium data are necessary. In this study, we report phase equilibrium data for systems of urea + methane + water and urea + carbon dioxide + water in the range of aqueous compositions of urea up to its solubility limits. The present data for urea + methane + water ranged in pressures from 5 to 13 MPa and in urea mass fractions from 0.05 to 0.5. The comparison with the literature found that the inhibition effect of urea is a few kelvin weaker than that of methanol in the present measurement range. With the dense urea solutions, the system reached four phase equilibrium, i.e., solid urea–aqueous solution–gas–hydrate. At 13 MPa, approximately 13 K of inhibition temperature was obtained with 0.500 of feed mass fraction where solid urea was precipitated from the aqueous phase. In the urea + carbon dioxide + water systems, urea also worked as a THI. The maximum inhibition temperature was approximately 10 K with 0.400 of urea mass feed fraction at the four phase equilibrium. Based on the present equilibrium data and seafloor conditions of the subsea methane hydrates, it was found that urea can be used for the both systems of the methane gas production and the hydrate based carbon capture and storage.

Modelling the solid–liquid–vapour phase behaviour of n-alkanes in a TPT-1 framework

We study the global phase behaviour of n-alkanes applying Wertheim's first order thermodynamic perturbation theory (TPT1). The molecules are modelled as homonuclear chains comprised of m freely jointed spherical segments interacting via the Lennard-Jones potential. Vega et al. [J. Chem. Phys. 116, 17 (2002)] have shown that the TPT1 is suitable to treat solid phases as well as fluid phases when model chains are considered, but that the adoption of a fully flexible chain model leads to the under-prediction of triple point temperatures and overestimation of the fluid ranges in comparison to experiment. Here, we propose a model in which a different number of segments are used to treat the fluid and the solid phase. The number of segments used to model the molecules in the fluid phase , and the LJ monomer potential parameters σ and ε are taken from published soft-SAFT values, whereas in the case of the solid phase a reduced temperature-dependent effective chain length is determined through a minimisation between theoretical and experimental liquid-solid phase equilibrium data. We refer to this model as effective-solid TPT1 (es-TPT1). We use the model proposed to calculate the solid–liquid–vapour phase diagrams of several n-alkanes and compare with experimental data. In the approach proposed, the conformation of chains in the solid phase is decoupled from the fluid phase, and an excellent description of the melting properties, as well as accurate predictions of the triple point temperatures for the n-alkanes examined is obtained. This simple solution provides an avenue to model the solid–liquid–vapour phase behaviour of other real substances in a TPT1 framework, and hence within the SAFT family of equations.

Thermodynamic modeling of KCl-PrCl3 and KCl-LiCl-PrCl3 systems

Molten salt electrolysis can recover the actinides from spent nuclear fuels, and it involves a eutectic LiCl-KCl in molten form as an electrolyte. During reprocessing, the concentration of fission products such as La, Nd, Pr, etc., increases and affects the recovery efficiency of the electrolyte. In this work, thermodynamic modeling of KCl-PrCl3 and KCl-LiCl-PrCl3 systems was carried out using the CALPHAD (Calculation of Phase Diagrams) approach for the first time. The thermodynamic functions for the pure salts were taken from the SGTE (Scientific Group Thermodata Europe) Substances (SSUB) database. The experimental thermochemical and phase equilibria data available in the literature were used as input for the assessment of KCl-PrCl3 and KCl-LiCl-PrCl3 systems. The model parameters for the KCl-LiCl system were adjusted to include the new Gibbs energy descriptions for the pure salts. In addition, the sublattice model for the liquid phase in the LiCl-PrCl3 system was modified and reassessed to ensure the model compatibility for higher-order extrapolation. There is a good agreement between the experimental and calculated thermochemical and phase diagram data for all the optimized constituent binaries and the ternary system. This work will be beneficial for determining the solubility limit of PrCl3 in molten LiCl-KCl electrolytes and their thermodynamic properties for improving the efficiency of the pyrochemical process.

Investigation of the intermetallic phase stabilities and phase equilibria in Cu-Co-Sm system. Part 1: Cu-Sm system

The binary Cu-Sm system is one of the basic sub-systems, necessary for the development of the materials used as permanent magnets. Nonetheless, there can be found numerous inconsistencies in the phase equilibria data for the system. The current work deals with the evaluation of the phase stabilities of the intermetallic phases in the system and phase equilibria in the Cu-Sm system with the DTA, SEM/EPMA and XRD methods. Cu6Sm and Cu5Sm have been found to express some homogeneity ranges. It was confirmed that CuSm is forming by a peritectic reaction, rather than by congruent melting. The updated phase equilibria data was summed up in a new version of the Cu-Sm phase diagram. The hardness of the Cu6Sm phase was found to be 335 ± 29 HV.

Vapor Equilibrium Data for the Binary Mixtures of Dimethyl Carbonate and Ethyl Methyl Carbonate in Compressed Carbon Dioxide

Phase equilibrium data (p, T, y) for the binary systems of carbon dioxide + dimethyl carbonate and carbon dioxide + ethyl methyl carbonate were obtained. All systems were measured for isotherms ranging from 298.2 K to 328.2 K with pressure ranging between 0.13 MPa and 10.6 MPa. A static equilibrium technique was established with samples quantified using an offline method. The results were modeled using the Peng–Robinson equation of state with van der Waals one-fluid mixing rules.Graphical

Thermodynamic modeling and solidified microstructure of Ag—Sn—Zr ternary system

The phase equilibria of the Ag—Sn—Zr ternary system were investigated over the whole composition via thermodynamic modeling coupled with key experiments. Twenty-two equilibrated alloys were prepared to determine the isothermal sections of the Ag—Sn—Zr system at 500, 700 and 900 °C by means of X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS), and eight as-cast alloys were prepared to study the solidification behavior of the alloys. The solubilities of Zr, Sn and Ag in binary compounds of the Ag—Sn, Ag—Zr and Sn—Zr systems were measured. No ternary compound was found. Based on the thermodynamic descriptions of three constitutive binary systems as well as the experimental phase equilibria data obtained from the present work, thermodynamic assessment of the Ag—Sn—Zr system was carried out by the CALPHAD (Calculation of phase diagrams) approach. A set of thermodynamic parameters of the Ag—Sn—Zr system were obtained. The calculated isothermal sections are in good agreement with most of the reliable experimental data. The liquidus projection and reaction scheme of the Ag—Sn—Zr system over the whole composition were also presented. The solidification behaviors of as-cast alloys were simulated under Gulliver—Scheil non-equilibrium condition. The simulated and experimental results are consistent with each other.

Thermodynamic modeling of the Al–Co–W, Al–Ni–Ta and Co–Ni–W ternary systems

Thermodynamic descriptions of the Al–Co–W, Al–Ni–Ta and Co–Ni–W ternary systems are the foundation for developing thermodynamic database and material design for the Ni-based alloys. In the present work, the Al–Co–W, Al–Ni–Ta and Co–Ni–W systems were optimized based on the reliable experimental data by means of the CALPHAD method. The liquid, γ (Fcc_A1) and β (Bcc_A2) phases were described as substitutional solution model, and the γ’ (Fcc_L12), B2 (Bcc_B2), μ (Co7W6) and Ni3Ta phases were described with sublattice models. The Co3W phase was treated as a stoichiometric compound due to the limited homogeneity range in the Al–Co–W system and described as (Co, Ni)3W in the Co–Ni–W system. The self-consistent thermodynamic parameters for the Al–Co–W, Al–Ni–Ta and Co–Ni–W systems were obtained. Comprehensive comparisons between the calculated results and measured phase equilibrium data show that most experimental information is satisfactorily accounted for by the present thermodynamic description.

Study on Stable Phase Equilibria of Quinary System LiBr–NaBr–KBr–MgBr2–H2O at 298.15 K

According to the composition characteristics of mineral elements in underground brine in the Sichuan basin of China, the complete phase equilibria and phase diagram of the quinary system LiBr–NaBr–KBr–MgBr2–H2O were studied at 298.15 K. Using the experimentally determined solubilities and equilibrium solids, the spatial stereo phase diagram of the quinary system, the dry base projection phase diagrams of the saturated surfaces of the four salts MgBr2·6H2O, KBr, LiBr·2H2O, and NaBr·2H2O, and the corresponding water content diagrams were plotted, respectively. The experimental results show that at 298.15 K, in addition to the four original components, the anhydrous salt NaBr and the double salt KBr·MgBr2·6H2O are formed. The phase diagram of the quinary system at 298.15 K contains 10 univariate curves, three invariant points, and six equilibrium solid-phase crystallization regions (KBr crystallization region, NaBr crystallization region, NaBr·2H2O crystallization region, MgBr2·6H2O crystallization region, LiBr·2H2O crystallization region, KBr·MgBr2·6H2O crystallization region). When MgBr2·6H2O or KBr is saturated, LiBr has a strong salting-out effect on KBr, NaBr, or MgBr2 and NaBr, while when LiBr·2H2O is saturated, MgBr2 has a salting-out effect on KBr and NaBr. All four saturated projection surfaces have MgBr2·6H2O, and NaBr is generated. These phase equilibrium data can provide a theoretical basis to guide underground brine mining and extract useful components.

Thermodynamic re-modeling of the Yb-Sb system aided by first-principles calculations

The thermodynamic description of the Yb-Sb binary system is developed by means of the CALculations of PHAse Diagrams (CALPHAD) method by combining experimental data in the literature and predictions from first-principles calculations based on density functional theory (DFT) in the literature and the present work. Two pseudopotentials of Yb are compared in the present DFT-based calculations with 14 and 13 f-electrons frozen in the core, i.e., 5p66s2 and 5p66s25 d1 electrons as valence electrons, termed Yb_2 and Yb_3, respectively. It is shown that the phonon spectrum of the YbSb phase calculated using the Yb_3 pseudopotential does not have imaginary phonon modes and is subsequently used to predict its temperature dependent thermodynamic properties by the DFT-based quasiharmonic phonon calculations. The present thermodynamic database includes the Yb16Sb11 phase in addition to five intermetallic phases that were considered in previous modeling studies, i.e., YbSb2, YbSb, Yb11Sb10, Yb4Sb3, and Yb5Sb3. The high temperature orthorhombic structure of the Yb5Sb3 phase is not considered in the present work as it was stabilized by hydrogen. The associate solution model is used to describe the short-range ordering behavior in the liquid phase. The calculations from the present thermodynamic model show good agreement with thermochemical and phase equilibrium data from both the present work and the literature.

P-T-x Measurement and Modeling of Methane + Propane + Methanol or 2,2′-[Ethane-1,2-diylbis(oxy)] Di(ethan-1-ol) and Methane + Propane + Methanol + 2,2′-[Ethane-1,2-diylbis(oxy)] Di(ethan-1-ol) Systems

Limited phase equilibria data exist for multicomponent systems encountered in the natural gas processing industry. To address this gap, bubble point measurements were performed for methane + propane + methanol; methane + propane + (2,2′-[ethane-1,2-diylbis(oxy)] di(ethan-1-ol) or triethylene glycol); methane + propane + methanol + triethylene glycol systems in the temperature range of 283.16 to 323.16 K and a pressure range of 0.78 to 13.79 MPa. A visual synthetic high-pressure cell comprising a sapphire tube of 33 cm3 working volume was used. The new experimental P-T-x data were modeled using the Cubic Plus Association (CPA) model and the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) model. Model correlations with the CPA model yielded better results than those with the PC-SAFT model, with a maximum absolute average relative deviation in pressure of 6.97% and 7.33%, respectively. The CPA model predictions based on binary parameters alone do not adequately describe phase behavior of multicomponent systems.