Ternary Vapor–liquid Equilibrium Research Articles

Prediction of azeotropes position of refrigerant mixtures using the PHSC EoS

The work aims is predict the azeotropes' position in refrigerant mixtures using the Perturbed Hard Sphere Chain (PHSC) equation of state (EoS). The vapor-liquid equilibrium (VLE) of seventeen binary refrigerant mixtures has been correlated using two model-adjustable parameters. The results show that the proposed model can calculate the bubble and dew points of binary systems, accurately. The average ARD value of binary VLE calculations has been obtained 1.28 %. The azeotropes pressure and composition of binary mixtures have been predicted using the PHSC EoS with the average ARD values of 1.043 % and 2.23 %, respectively. The maximum relative deviation has been observed for R717+R125 systems with two azeotropes points; ARDx=12.2 %. The performance of the PHSC EoS has been evaluated by predicting the azeotropes position of ternary mixtures. The PHSC EoS results have been compared to three cubic-based EoSs containing the PR-vdW, PR-BM, and PR-MHV2-NRTL models. The results show that the PHSC EoS can predict the ternary VLE data and azeotropes position satisfactory. The relative absolute deviation does not exceed 1.7 % for the azeotropes pressure. The PHSC EoS can be used as a robust and efficient model for the prediction of the azeotropes' position in binary and ternary refrigerant mixtures. Prediction of azeotropic composition helps us to find promising refrigerant candidates in the pre-design stage of the desired apparatus.

VLE measurement of binary systems 1-butyl-3-methylimidazolium-based ionic liquids and ethanol or water

Experimental vapor–liquid equilibrium (VLE) data for binary systems of ethanol or water with four ionic liquids (ILs) comprising 1-butyl-3-methylimidazolium cation and different anions were measured at atmospheric pressure within a broad region of IL concentrations, IL mole fraction ranging between 0 and 0.7 or even 0.87. Siwoloboff procedure of vapor–liquid phase transition temperature measurement was applied to estimate VLE of the binary mixtures. Obtained t–x data were fitted assuming ideal vapor and non-ideal liquid phase behavior, using the original NRTL equation to calculate component activity coefficients. VLE description results are presented in form of equilibrium diagrams and as the variation of activity coefficients with mixture composition. Quality of the VLE data fitting was assessed based on root mean square deviations and mean deviations in temperature. Some experimental binary t–x data sets were compared to those available in literature (measured in much narrower concentration range) or predicted from ternary VLE data. The selection of ILs in this study was related to the separation of ethanol−water mixture by extractive distillation. Principal IL selection criterium was its ability to affect the ethanol–water relative volatility. Thermodynamic description of the VLE data of IL-containing systems within a wide concentration range is an essential building block of the mathematical model of separation devices, especially in case of regeneration equipment where concentrated IL is present.

Isobaric Vapor–Liquid Equilibrium for Ethyl Acetate + Chloroform with Ionic Liquids [EMIM][OAc], [BMIM][OAc], and DMSO + [EMIM][OAc] as Entrainers at 101.3 kPa

Ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]), 1-butyl-3-methylimidazolium acetate ([BMIM][OAc]), and a mixture of [EMIM][OAc] and dimethyl sulfoxide (DMSO) were used as solvents to separate the maximum boiling azeotropic mixture of ethyl acetate and chloroform. The ternary vapor–liquid equilibrium (VLE) data of ethyl acetate + chloroform + [EMIM][OAc] were measured at 101.3 kPa. The liquid phase is partially soluble when the concentration of ethyl acetate and [EMIM][OAc] is high in the ternary system, and DMSO is employed to enhance the solubility of [EMIM][OAc] in ethyl acetate. Different entrainers were compared by measuring the VLE of ethyl acetate + chloroform + DMSO, ethyl acetate + chloroform + [BMIM][OAc], and ethyl acetate + chloroform + [EMIM][OAc] + DMSO at 101.3 kPa. All of the entrainers can improve the relative volatility of ethyl acetate to chloroform. The salting-out effects of the ILs [EMIM][OAc] and [BMIM][OAc] are significantly greater than that of DMSO. Organic solvent DMSO can enhance the selectivity of [EMIM][OAc] at high ethyl acetate concentration. The effects of the entrainers were analyzed by sigma-profiles. The nonrandom two-liquid (NRTL) activity coefficient model was adopted to correlate the experimental data. The binary interaction parameters of the NRTL equation were obtained, and the correlation results agreed well with experimental results.

Comprehensive Evaluation of COSMO-RS for Predicting Ternary and Binary Ionic Liquid-Containing Vapor–Liquid Equilibria

To develop efficient ionic liquid (IL)-based separation processes like extractive distillation, the knowledge of IL-involved vapor–liquid equilibria (VLE) is necessary. Since experimental measurements are usually time-consuming and expensive, reliable models for VLE prediction are highly desirable. In this work, the predictive performance of COSMO-RS is systematically evaluated for ternary and binary IL-containing VLE systems. A large experimental VLE database is established from the literature, including 6531 and 2265 data points for ternary and binary systems, respectively. The ternary and binary VLE systems are divided into five and three subsets based on the varieties of molecular solutes. The COSMO-RS performance in capturing the effects of IL and solute structures, IL dosage, and temperature on VLE is analyzed. COSMO-RS provides generally qualitative and in some cases quantitative description of the VLE behaviors and thus could be used as a valuable tool for prior IL screening and process analysis for related separations.

New association schemes for tri-ethylene glycol: Cubic-Plus-Association parameterization and uncertainty analysis

Transportation of natural gas extracted from subterranean reservoirs is subject to several risks introduced by the presence of water. These risks can be mitigated through subsea dehydration, the design of which requires an accurate understanding of the thermodynamics of these systems. Having previously investigated the use of mono-ethylene glycol as a dehydration agent, this research focusses on the industry workhorse: tri-ethylene glycol (TEG). The Cubic-Plus-Association (CPA) equation of state has previously provided a good description for systems of equal complexity and in this work the literature 4C and 6D association schemes, as well as four newly proposed association schemes (4F, 5F, 6F and 5C) are evaluated for the description of TEG. These association schemes, which are explained in the manuscript, represent different ways of self-association for TEG.Pure component parameters are estimated by fitting to vapor pressure, liquid density, and liquid-liquid equilibrium data, with statistical uncertainty analysis implemented to determine the confidence intervals of the parameters. Binary interaction parameters are similarly fitted to binary vapor-liquid equilibrium (VLE) data. Optimized parameters are evaluated by testing their performance in predicting binary and ternary VLE systems.Due to the strong influence of certain experimental data sets, the literature 6D parameters are shown to be unsuitable for the applications in this work. The need for consistent experimental data quantifying both vapor and liquid phases, specifically for TEG – CH4 has been highlighted. The best overall performance was obtained using the newly proposed 4F association scheme. Along with improved overall description of various VLE and LLE systems, with average absolute relative deviations generally between 2-20%, single parameter sensitivity analysis shows improved optimality for several systems also not included in the parameterization. This is indicative of a better fundamental characterization of the TEG molecule. The value of the uncertainty analysis is shown for the binary interaction parameters, where for TEG – CH4 VLE a temperature-dependent correlation is shown to be unnecessary using the optimum association schemes.

Isobaric Binary and Ternary Vapor–Liquid Equilibrium for the Mixture of n-Hexane, Methylcyclopentane and N-Methylpyrrolidone

Isobaric Binary and Ternary Vapor–Liquid Equilibrium for the Mixture of n-Hexane, Methylcyclopentane and N-Methylpyrrolidone

Phase Equilibria of Difluoromethane (R32), 1,1,1,2-Tetrafluoroethane (R134a), and trans-1,3,3,3-Tetrafluoro-1-propene (R1234ze(E)) Probed by Experimental Measurements and Monte Carlo Simulations

The combination of difluoromethane (R32), 1,1,1,2-tetrafluoroethane (R134a), and trans-1,3,3,3-tetrafluoro-1-propene (R1234ze(E)) has been recently proposed as a potential substitute (R456A) for hydrofluorocarbon working fluids. For the design and process simulation of refrigeration systems using refrigerant mixtures, precise knowledge of their thermophysical properties, especially vapor–liquid equilibrium (VLE), is crucial. To extend the experimental temperature range, a liquid-recirculation analytical apparatus, classified as AnTLcirCapValVis, was redesigned and VLE data for the binary mixtures of R32 + R134a, R32 + R1234ze(E), R134a + R1234ze(E), and the ternary system of R32 + R134a + R1234ze(E) were measured over the temperature range from 263.15 to 323.15 K. The standard uncertainties of the temperature, pressure, and the mole fractions of liquid and vapor phases are estimated to be within 10 mK, 0.5 kPa, and 0.005, respectively. The Peng–Robinson–Stryjek–Vera–Version-2 (PRSV2) equation of state combined with the Wong–Sandler (WS) mixing rule and the nonrandom two-liquid activity coefficient model (NRTL) was used to fit the mixing parameters of the binary data from this work and prior studies and to predict the ternary VLE properties. In addition, Gibbs ensemble Monte Carlo simulations with an all-atom force field were carried out to determine VLE properties and to characterize the microscopic structure of these mixtures. Good agreement is found between experiments, correlations, and simulations, which attests to the predictive capabilities of the PRSV2 + WS + NRTL model and molecular simulations.

Isothermal measurement and modeling of VLE properties for 2,3,3,3-tetrafluoroprop-1-ene + trifluoromethane + tetrafluoromethane ternary system at temperatures from 253.15 K to 273.15 K

Abstract At present, the difficulty in the research of auto cascade refrigeration system lies in the selection of the mixed refrigerant ratio and the design of system process. Accurate thermodynamic data is the key to solve those problems. In this paper, isothermal vapor liquid equilibrium (VLE) behavior was experimentally studied for the strongly-zeotropic ternary mixture 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) + trifluoromethane (R23) + tetrafluoromethane (R14) at 253.15 K, 263.15 K, and 273.15 K. The pressures and the vapor mass fractions were found to be thermodynamically consistent and were satisfactorily correlated with the NRTL-RK model and the MUNIFAC-SRK model. The average absolute relative deviations of pressure (AARD-p), and the average absolute deviations of vapor phase mass fraction (AAD-y1, AAD-y2 and AAD-y3) are less than 0.25%, 0.0032, 0.0048 and 0.0040 for the MUNIFAC-SRK model, respectively, which are better than those of 0.4%, 0.0138, 0.0198 and 0.0049 for the NRTL-RK model. The results of the MUNIFAC-SRK model showed excellent agreement with the experimental values. The isothermal three-dimensional VLE behavior and the isothermal-isobaric ternary VLE diagrams under 1500 kPa were also established using a flash calculation method.

Experimental isobaric vapour-liquid equilibrium data for binary systems of {sec-butyl acetate (SBAC) + acetamide} and {sec-butyl alcohol (SBA) + acetamide} and the ternary system of (SBAC + SBA + acetamide) at 101.3 kPa

Isobaric vapour - liquid equilibrium (VLE) data for the binary systems of sec-butyl acetate (SBAC) + acetamide and sec-butyl alcohol (SBA) + acetamide and the ternary system of SBAC + SBA + acetamide were measured at 101.3 kPa using a modified Othmer still. The thermodynamic consistency tests for the experimental data were checked by Van Ness point test and Wisniak’s L-W method. The experimental VLE data of the binary systems were correlated with NRTL, Wilson and UNIQUAC activity coefficient models. The results indicate that the binary and ternary VLE data predicted by the three models agree well with the experimental data. And the ‘pseudo-azeotropic’ phenomenon of sec-butyl acetate + sec-butyl alcohol mixture can be eliminated by acetamide.

Separation of azeotropic mixture isopropyl alcohol + ethyl acetate by extractive distillation: Vapor-liquid equilibrium measurements and interaction exploration

Isopropyl alcohol and ethyl acetate can be used to produce degradable and renewable fuel. Since isopropyl alcohol + ethyl acetate can form an azeotropic mixture, it is a tough task to separate the binary mixture by general distillation. In this work, extractive distillation process with N, N-dimethylformamide and dimethyl sulfoxide as entrainers was adopted to separate this azeotrope. The binary and ternary vapor-liquid equilibrium data for (isopropyl alcohol + N, N-dimethylformamide), (ethyl acetate + dimethyl sulfoxide), (isopropyl alcohol + ethyl acetate + N, N-dimethylformamide) and (isopropyl alcohol + ethyl acetate + dimethyl sulfoxide) were determined under 101.3 kPa. Meanwhile, the interaction energies between the molecules were calculated to provide the theoretical insight into the separation of the azeotrope of (EA + IPA) by the entrainers. In addition, the NRTL, UNIQUAC and Wilson models were used to fit the determined binary VLE data. The ternary VLE data for (isopropyl alcohol + ethyl acetate + N, N-dimethylformamide) and (isopropyl alcohol + ethyl acetate + dimethyl sulfoxide) were predicted using the NRTL, UNIQUAC and Wilson models with the parameters regressed from the experimental data.

Retraction of “Determination of Ternary Vapor–Liquid Equilibrium of Dimethyl Oxalate–Methanol-1,2-Butanediol under Atmosphere Pressure”

Isobaric vapor–liquid equilibrium (VLE) data for the dimethyl oxalate + methanol and methanol + 1,2-butanediol binary systems, as well as the VLE for the dimethyl oxalate + methanol + 1,2-butanedio...

Isobaric Vapor–Liquid Equilibrium for Binary and Ternary Systems of 2-Methoxyethanol, Ethylbenzene, and Dimethyl Sulfoxide at 100.00 kPa

The isobaric vapor–liquid equilibrium (VLE) data for the binary systems 2-methoxyethanol + ethylbenzene, ethylbenzene + dimethyl sulfoxide (DMSO), and 2-methoxyethanol + DMSO and the ternary system 2-methoxyethanol + ethylbenzene + DMSO were measured with a Fischer VLE 602 apparatus at 100.00 kPa. The VLE data for all the binary and ternary systems were thermodynamically consistent and passed the Wisniak’s L–W test. The binary VLE data were correlated with the Wilson, nonrandom two-liquid, and universal quasichemical models with minor deviations. The ternary VLE data predicted from the corresponding binary interaction parameters agreed well with the experimental data. The azeotropic temperature and composition of the 2-methoxyethanol and ethylbenzene azeotropic mixture at 100.00 kPa were 391.05 K and 60.15 mol % 2-methoxyethanol, respectively. Additionally, the azeotrope disappeared after adding DMSO, which confirms that DMSO can serve as a prospective entrainer for separating 2-methoxyethanol from ethylb...

Separation of acetonitrile and methanol azeotropic mixture using imidazolium-based ionic liquids as entrainers

In this work, three imidazolium-based ionic liquids (ILs) with different anions, namely 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]), 1-butyl-3-methylimidazolium bromide ([BMIM][Br]) and 1-butyl-3-methylimidazolium acetate ([BMIM][OAc]), were tested as entrainers to separate acetonitrile and methanol mixtures. Isobaric vapor-liquid equilibrium (VLE) data of the acetonitrile (1) + methanol (2) + IL ternary systems were measured at 101.3 kPa. Addition of ILs produced a salting-out effect on acetonitrile, thus leading to the increase of the relative volatility of acetonitrile to methanol. As IL content increased to a certain value, the azeotropic point of acetonitrile and methanol could be totally eliminated. In addition, the separation performance of ILs was closely related to anion structure, with [BMIM][OAc] producing the most significant salting-out effect orderly followed by [BMIM][Cl] and [BMIM][ Br]. Finally, the measured ternary VLE data were correlated with the nonrandom two-liquid (NRTL) model, and σ-Profiles were used to explain the separation performance differences of the three ILs.

Measurement and correlation of vapor–liquid equilibrium data for binary and ternary systems composed of (−)-β-caryophyllene, p-cymene and 3-carene at 101.33 kPa

Abstract New experimental vapor–liquid equilibrium (VLE) data for three binary systems composed of p-cymene + (−)-β-caryophyllene, 3-carene + (−)-β-caryophyllene, and 3-carene + p-cymene and for the ternary system of (−)-β-caryophyllene + p-cymene + 3-carene were obtained using a modified Ellis equilibrium still over the temperature range from 444.44 to 528.78 K at 101.33 kPa. The compositions of these mixtures were assessed using gas chromatography. The VLE data for the binary systems passed thermodynamic consistency tests based on the Herington method and Van Ness test. The thermodynamic consistency of the ternary system was checked by a Van Ness test. The VLE data for binary systems were correlated using the Wilson, NRTL, and UNIQUAC activity coefficient models with minor deviations. The ternary VLE data were also satisfactorily correlated using the Wilson, NRTL and UNIQUAC models. By comparing the experimental values for the ternary system with the values calculated using the three models, the average absolute deviation of the equilibrium temperature and vapor–phase composition were determined to be less than 0.57 K and 0.0060, respectively. These results indicated excellent agreement of the models with experimental values.

Ternary Vapor–Liquid Equilibrium Measurements and Modeling of Ethylene Glycol (1) + Water (2) + Methane (3) Systems at 6 and 12.5 MPa

Novel technologies in the field of subsea gas processing include the development of natural gas dehydration facilities, which may operate at high pressure due to their proximity to reservoirs. For the qualification and design of these processing units, ternary vapor–liquid equilibrium data are required to validate the thermodynamic models used in the design process. For this purpose, 16 new ternary data points were measured for ethylene glycol (1) + water (2) + methane (3) at 6.0 and 12.5 MPa with temperatures ranging from 288 to 323 K and glycol content above 90 wt %. Glycol in gas (y1), water in gas (y2), and methane solubility (x3) were measured with relative experimental uncertainties (ur(x) = u(x)/|x|) below 12%, depending on the type of data. The Cubic-Plus-Association (CPA) equation of state was used to model the data. Literature pure component and binary interaction parameters were used. It was found that the model provides a good qualitative description of the experimental data for y1 and y2, whi...

Experimental and Predicted Vapor–Liquid Equilibrium for Diisopropanolamine with m-Cresol and 2,6-Dimethylphenol at 20.0 kPa

Measurements of isobaric vapor–liquid equilibrium (VLE) results for binary systems of m-cresol (MC) + diisopropanolamine (DIPA) and 2,6-dimethylphenol (DMP) + DIPA and the ternary system of MC + DMP + DIPA were conducted at the pressure of 20.0 kPa. The binary VLE experimental data showed that DIPA had stronger interaction with MC than DMP. The ternary system experimental VLE data showed that DIPA could improve the relative volatility of DMP to MC. The binary experimental data were checked by using Herington area and point test methods, and the checked results were thermodynamically consistent. Meanwhile, the VLE data were correlated by Wilson, nonrandom two-liquid, and universal quasichemical models, and the binary energy interaction parameters for these models were obtained. These activity coefficient models were used to predict the ternary system VLE data. The predictive results suggested that the Wilson model had the best prediction.

Vapor–Liquid Equilibria for the Binary and Ternary Systems of Difluoromethane (R32), 1,1-Difluoroethane (R152a), and 2,3,3,3-Tetrafluoroprop-1-ene (R1234yf)

The combination of difluoromethane (R32), 1,1-difluoroethane (R152a), and 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) could be a potential substitute for hydro-fluorocarbon refrigerants. Reliable vapor liquid equilibrium (VLE) data are important thermodynamic data in evaluating the performance of refrigeration cycles and determining their optimal compositions. In this work, we measured the VLE data for binary mixtures of R32 + R152a and R152a + R1234yf, and ternary system of R32 + R152a + R1234yf. The measurements were carried out by using the AnTLcirCapValVis analytical method over the temperature range from 283.15 to 323.15 K. The standard uncertainties of temperature, pressure, and mole fractions are 10 mK, 0.5 kPa, and 0.005, respectively. The Peng–Robinson–Stryjek–Vera equation of state combined with the Wong–Sandler mixing rule and the nonrandom two-liquid activity coefficient model was employed to correlate the parameters of binary mixtures and predict the ternary VLE property. The predicted VLE data and K-value for the ternary system show good agreement with the experimental results.

Isobaric Vapor–Liquid Equilibrium for 2-Butanone + Ethanol System Containing Different Ionic Liquids at 101.3 kPa

In this work, ionic liquids (ILs) were selected as extractive distillation entrainers to separate the 2-butanone + ethanol binary azeotropic mixture because of their remarkable molecular designability, high selectivity, low volatility, and other excellent characteristics. The isobaric vapor–liquid equilibrium (VLE) data for the ternary systems of 2-butanone + ethanol + acetate-based ILs (1-ethyl-3-methylimidazolium acetate [EMIM][OAC], 1-butyl-3-methylimidazolium acetate [BMIM][OAC], and 1-hexyl-3-methylimidazolium acetate [HMIM][OAC]) were measured at 101.3 kPa in an all-glass dynamic recirculating still. The addition of ILs can significantly enhance relative volatility of 2-butanone to ethanol, and the azeotropy of the 2-butanone + ethanol binary mixture is eventually eliminated by increasing the IL content to a certain value. The separation efficiency of the three ILs follows the order [EMIM][OAC] > [BMIM][OAC] > [HMIM][OAC]. Additionally, the binary and ternary VLE data are well-correlated with the no...

Isobaric vapor–liquid equilibrium for ternary system of ethanol, ethyl propionate and para-xylene at 101.3 kPa

Isobaric vapor–liquid equilibrium (VLE) data for the binary system ethyl propionate (2) + para-xylene (3) and ternary system ethanol (1) + ethyl propionate (2) + para-xylene (2) at atmospheric pressure (101.3 kPa) were obtained by a VLE modified othmer still. All the experimental data passed a point to point consistency test of Van Ness method, which verified the data reliability. The Wilson and UNIQUAC activity coefficient models were employed to correlate the binary VLE data to obtain binary interaction parameters. Based on binary interaction parameters, ternary VLE data of ethanol (1) + ethyl propionate (2) + para-xylene (3) were predicted by Wilson and UNIQUAC models, which proved that predicted values are consistent with the experimental data. Furthermore, azeotropic phenomenon between ethanol and ethyl propionate disappears when the mole ratio of para-xylene and binary system of ethanol and ethyl propionate is 1:1. Therefore, this paper convinced that para-xylene is a proper extractive additive that could be used in extractive distillation to separate the binary azeotropic system of ethanol and ethyl propionate.

Vapor–liquid equilibrium in the ternary system isobutyl alcohol + isobutyl acetate + N, N-dimethyl acetamide and the binary systems isobutyl alcohol + N, N-dimethyl acetamide, isobutyl acetate + N, N-dimethyl acetamide at 101.3 kPa

The isobaric Vapor-Liquid Equilibrium (VLE) data at 101.3 kPa were measured for the binary systems isobutyl alcohol + N, N-dimethyl acetamide (DMAC), isobutyl acetate + N, N-dimethyl acetamide and the ternary system isobutyl alcohol + isobutyl acetate + N, N-dimethyl acetamide using an all glass dynamics recirculating still. The isobutyl alcohol + DMAC system exhibits negative deviation from Raoult's law and isobutyl acetate + DMAC system deviates positively from ideal solution. The thermodynamic consistency of the binary VLE data was checked by Herington method and Wisniak point-to-point method. The NRTL, UNIQUAC and Wilson activity coefficient models were used to correlate the binary VLE data in order to obtain the binary interaction parameters which were used to predict ternary VLE data. The predicted results agree well with the experimental data. The results indicate that the solvent DMAC can greatly enhance the relative volatility of isobutyl acetate to isobutyl alcohol, and azeotrope of isobutyl acetate and isobutyl alcohol will be broken if the mole fraction of DMAC is greater than 0.361. The effects of the solvents 1-hexanol, butyl propionate (BUP), N, N-dimethyl formamide (DMF) and N, N-dimethyl acetamide (DMAC) were compared, and the selectivity of DMAC was the largest. The solvent DMAC is a promising extractive agent for the separation of mixtures of isobutyl alcohol and isobutyl acetate by extractive distillation.