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The objective of this work was to study the behavior of the azeotropic points of the methanol + DMC system under elevated pressures. We obtained isothermal vapor–liquid equilibria (VLE) data for this system at 383.15, 403.15, and 413.15 K by a static method. The azeotropic points were determined from the experimental VLE data. The temperature and pressure dependencies of the determined azeotropic points are discussed and compared with ones measured at reduced pressure. The experimental VLE data were represented by two activity coefficient models (non-random two-liquid and Wilson models). We also tested the modified UNIFAC (Dortmund) model for prediction of the VLE and azeotropic points. The azeotropic points of this system could be obtained over the pressure range from reduced pressures to elevated ones.

Vapor-liquid equilibria (VLE) and distribution coefficients (K-values) of carbon dioxide (CO2) - ethanol - water ternary systems and CO2 - ethanol - water - flavonoid (flavone, 6-methoxyflavone or 7-hydroxyflavone) quaternary systems were measured with a flow type apparatus at (313 to 353) K and (10 to 20) MPa. CO2 - ethanol - flavonoid ternary systems were measured at a nominal range of temperatures and pressures. The K-values of all flavonoids increased with increasing pressure. It was also indicated that the K-values of relatively lipophilic components such as flavone and 6-methoxyflavone increased with increasing water composition in feed while those of relatively hydrophilic components such as 7-hydroxyflavone increased with increasing ethanol composition in feed. A simple dimensionless relationship in terms of the K-values of the solvents (KCO2, KEtOH, KH2O) and the entropy-based solubility parameters of the vapor and liquid phases was developed to correlate the K-values of the three solutes in the CO2 - ethanol - water systems over the full range of conditions studied.

Vapor-liquid phase equilibria of the H2S H2O mixture were correlated by use of a cubic EOS-GEX over temperature and pressure range of 0.1–30 MPa and 278–627K. Average absolute deviations (AAD%) between the modeling results and the experimental data taken from literature for both the H2S-rich and the aqueous phases were found less than 5%. The new sets of EOS-GEX model parameters for H2S H2O mixture were evaluated from the experimental data over the above-mentioned temperature and pressure range. The proposed model was compared with the three previous published models and we discussed the advantages and the disadvantages for each of them. This study demonstrated that the advantages of the cubic EOS-GEX model in calculating phase equilibria of H2S H2O mixture over currently available models, especially at high pressures. The hydrate equilibrium, the salt effect, and the chemical reactions in the aqueous phase were not considered during phase equilibrium calculation in this study.

Properties of the vapor-liquid interface of the binary mixture cyclohexane + CO2 as well as for the two pure substances are reported. The data were obtained from pendant drop experiments (Exp), molecular dynamics (MD) simulation, and density gradient theory (DGT) in combination with the PCP-SAFT equation of state. The following interfacial properties were studied: surface tension (Exp, MD, DGT), relative adsorption (Exp, MD, DGT), enrichment (MD, DGT), and interfacial thickness (MD, DGT). The measurements were carried out at temperatures between 303.15 K and 373.15 K and pressures up to 6 MPa. Furthermore, bulk VLE properties were computed by MD and PCP-SAFT and compared to experimental data from the literature. Data from experiment, MD, and DGT were found to be in good agreement throughout.

An automatic high-throughput computing (HTC) procedure is implemented for calculating vapor-liquid equilibrium (VLE) curves of binary systems using molecular dynamics simulation and coarse-grained force field. The HTC procedure builds simulation models, carries out the simulations, and validates the simulations automatically. The procedure is demonstrated by calculating the VLE curves for 16 binary mixtures of carbon dioxide and n-alkanes on 856 state points in the temperature range of 277.2–420.0 K and pressure range of 0.3–25.0 MPa. The averaged uncertainties in predictions are 0.119 MPa for pressure, 0.007 and 0.029 for liquid and vapor CO 2 molar fractions, and 0.005 and 0.010 for liquid and vapor densities respectively. The Validation against experiment data on 10 binary systems and 316 state points shows that the predictions are accurate with average deviation of about 5% for CO 2 mole fraction and 3.5% for saturated density at pressure range to P P c . This automatic procedure can only be used for the prediction of the vapor-liquid equilibrium. The computed data can be obtained from http://sun.sjtu.edu.cn/msd .

The PC-SAFT equation of state (EoS) was examined for the prediction of liquid–liquid equilibria (LLE) at high pressure on the basis of LLE data at 1 bar. New parameters set for 2-alkoxyethanol with the two-site association scheme were proposed. Mixtures of 2-alkoxyethanol with aliphatics, aromatics, alcohols, and water have been investigated. Different binary 2-methoxyethanol + alkanes systems at high pressure up to 4000 bars were also predicted using the PC-SAFT EoS. Satisfactory predictions of vapor-liquid equilibria and liquid-liquid equilibria can be achieved by using the same binary interaction parameter (k ij ) for a similar kind of mixtures. The results are finally compared to other association models.

Techniques have been developed to determine vapor-liquid phase boundaries and swelling factors of CO2-heavy oil systems and C3H8-n-C4H10-CO2-heavy oil systems under reservoir conditions. Experimentally, a pure substance of CO2 and a gas mixture consisting of 27.7 mol% C3H8, 23.9 mol% n-C4H10, and 48.4 mol% CO2 are respectively introduced to dilute the highly viscous heavy oil. A pressure-volume-temperature (PVT) setup is used to measure vapor-liquid phase boundaries (i.e., saturation pressures) and swelling factors at high pressures up to 11.1 MPa and elevated temperatures up to 373.35 K. Theoretically, the volume-translated Peng-Robinson equation of state (PR EOS) coupled with a recently modified alpha function is applied as the primary thermodynamic model to reproduce the experimental measurements. The heavy oil which is a complex mixture with unknown molecular structure is characterized as six pseudocomponents by using an exponential distribution splitting function and a logarithm-type lumping method. The optimal exponents in binary interaction parameter (BIP) correlations are obtained by best matching the measured saturation pressures. Subsequently, the comparisons have been performed between this work and a commercial simulator in terms of the overall prediction accuracy of saturation pressures for the quaternary C3H8-n-C4H10-CO2-heavy oil systems. It is found that the minimum absolute average relative deviation (AARD) of 6.7% is obtained by the methodology developed in this work, compared to the AARD of 35.6% obtained by running the commercial simulator.

Experimental measurement of vapor-liquid equilibria (VLE) was performed for 2,3,3,3-tetrafluoropropene (HFO-1234yf) + 1,1,1,2,2-pentafluoropropane (HFC-245cb) system. The VLE data were measured by a static-analysis apparatus at temperatures ranging from (283.15–313.15) K. Within the experimental temperature range, the binary system was slightly non-ideal; no azeotropic behavior was observed. Experimental results were correlated based on equations of state (EOS) method. Peng-Robinson EOS and van der Waals mixing rules were used to calculate both vapor and liquid phase fugacity coefficient. Correlation deviation was acceptable and thermodynamic consistency was well satisfied.

In this work, interaction energies between pairs of atoms for the Ag–Pb, Cu–Pb and Sn–Pb systems have been calculated using ab initio methods. These energies are then used as the interaction energy parameters in the Wilson equation. Phase diagram of vapor–liquid equilibria (VLE) for the Pb-based alloy systems in vacuum distillation are obtained based on the calculated parameters. The results indicate that this approach can lead to accurate VLE predictions for alloy systems in vacuum distillation based only on properties of pure components and the structure of the clusters. The comparisons show the computational results are in good agreement with the experimental data.

Supercritical fluid extraction (SFE) is one of the techniques used to obtain Illicium verum volatile oil, however, solubility of the volatile oil in CO2, one of the most important process variables from the SFE, is still unknown. In this work, vapor liquid equilibria experiments (VLE) were conducted in order to verify solubility of the major compound in the I. verum volatile oil, E-anethole, in CO2. In addition, SFE was carried with 750 g/h and 1500 g/h of CO2 at 308.15 K and 8000 kPa, 9000 kPa, 10,000 kPa and the antioxidant activity of the volatile oil accessed by the DPPH method. The VLE experimental data was modeled using the Peng–Robinson EOS (PR-EOS) with three mixing rules (vdW1, vdW2 and MKP). Moreover, SFE process was simulated using the equation proposed by Sovova and solubility data was compared with the values obtained by the PR-EOS.

This paper presents the measurements of isothermal vapor-Liquid equilibria (VLE) data for two binary systems of 2,3,3,3-tetrafluoropropene (HFO-1234yf) + 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) and 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) + 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb). The measurements were performed with an apparatus based on the static-analysis method. The HFO-1234yf + HCFO-1233xf system was measured at three temperatures from (293.15 to 313.15) K, and the HCFO-1233xf + HCFC-244bb system was measured at three temperatures from (303.15 to 323.15) K. The system of HFO-1234yf + HCFO-1233xf shows a small deviation from Raoult's law and dose not exhibit azeotropic behavior, while the system of HCFO-1233xf + HCFC-244bb exhibits near azeotropic behavior within the complete range of composition. All of the experimental data were correlated with the Peng–Robinson equations of state with the van der Waals mixing rules. Good consistency was obtained between the experimental data and correlated values for the both systems in the experimental temperature range. Thermodynamic consistency testing was also performed by the data-reduction method for the observed experimental data.

Tetrahydrofuran (THF) is a popular thermodynamic promotor for gas hydrates. Nonetheless, the phase equilibrium calculations of THF hydrates are limited given the abundant experimental data. In this work, we successfully applied the Chen–Guo hydrate model to the THF/CH4/N2 system with different compositions of CH4/N2 gas mixtures. In consideration of various reaction conditions, we proposed the vapor–hydrate two-phase and vapor–liquid–hydrate three-phase models for the equilibrium separations of THF/CH4/N2 via hydrate formation. The hydrate formation condition and equilibrium separation of CH4/N2 in 6 mol% THF solution were calculated and compared with experimental results. The average absolute relative deviations between the experimental and calculated data for hydrate formation pressure and equilibrium separation compositions are 6.86% and 7.56%, respectively. This demonstrates that the Chen–Guo model has relatively high accuracy for the equilibrium calculation of THF/CH4/N2 hydrates. This work provides an effective approach to predict the thermodynamic phase behavior of hydrates containing promotors or inhibitors.

The critical temperatures and pressures have been measured by the pulse-heating method for fifteen compounds: benzoic acid, 2-methylbenzoic acid, 3-methylbenzoic acid, 4-methylbenzoic acid, benzaldehyde, 4-methylbenzaldehyde, phenylmethanol, (4-methylphenyl)methanol, 2-carboxybenzaldehyde, 1,3-propanediol, 2,2-dimethyl-1,3-propanediol, methyl tetradecanoate, methyl hexadecanoate, methyl octadecanoate, and (Z)-9-methyl octadecenoate. The experimental critical properties have been compared with those estimated by the Wilson/Jasperson and Marrero/Gani methods.

The high-pressure vapor–liquid equilibria of butane/ethanol system and isobutane/ethanol system were measured by a minimum continuous flow method using a process gas chromatography at 313–403 K. Experimental PXY data were compared with references. The modified RK EOS parameters were regressed and PXY data were also compared with PSRK EOS.

In this work, the recently proposed Functional-Segment Activity Coefficient (F-SAC) model is revised and extended in order to simultaneously represent infinite dilution activity coefficient (IDAC), vapor–liquid (VLE), and liquid–liquid (LLE) equilibrium data. For this investigation, systems involving aromatics, alkanes, cycloalkanes, alkenes and n-Formylmorpholine were selected for the tests. The behavior of these mixtures vary from nearly ideal to partially miscible. A new parameter per group was introduced in order to better represent LLE data in wide temperature ranges. The revised model was calibrated with experimental IDAC and LLE (binary and ternary systems) data. F-SAC correlation results and predictions of VLE experiments were compared with different UNIFAC parametrizations available in the literature. For the systems tested, the proposed approach showed to be more general; there were good IDAC and LLE correlations as well as VLE predictions, all with a single parameter set.

A simple procedure has been proposed to estimate the Wilson parameters from molecular structures and pure-component properties. To evaluate the interaction energies due to attractive force between unlike molecules, the interaction parameters are required. These parameters can be obtained by using the empirical equations developed in this study with normal boiling points and solubility parameters. The procedure has been applied to binary mixtures containing various esters including isomers (ester + hydrocarbon and ester + alcohol) and it is found that vapor–liquid equilibria of the mixtures can successfully be predicted from pure-component properties alone.

This document describes the results of an investigation on the variation of the so-called fundamental derivative of gas dynamics, Γ, in the vapor–liquid critical region of well-measured substances, namely methane, carbon dioxide and water, for which accurate, scaled fundamental equations are available. The results demonstrate that for a pure fluid in the single-phase thermodynamic regime, Γ diverges to +∞ independent of the direction of approach of the vapor–liquid critical point. Furthermore, in the two-phase thermodynamic regime, Γ diverges to −∞ independent of the direction of approach of the vapor–liquid critical point. These two qualitative results, as well as the value of the exponent giving the power-law dependence of Γ along the critical isochore as a function of |T − TC|/T (T is the temperature and “C” indicates its critical point value), namely ≈−0.89, are similar for all pure, non-ionized fluids belonging to the class of 3-dimensional Ising-like systems, i.e., systems governed by short-range forces.

The main purpose of this study was to employ the algorithm of vapor–liquid–liquid–hydrate multiphase equilibrium to the multicomponent mixtures containing hydrogen. The Patel–Teja equation of state was used to perform the vapor–liquid–liquid (V–L HC –L W ) three-phase flash calculation and the Chen–Guo two-step hydrate model was employed to calculate the vapor–hydrate phase equilibria. This method is rather simple due to avoiding the complexity of simultaneous solution of the sophisticated equation group. The proposed algorithm was tested on gas-emulsion systems. The comparisons of calculated results with experimental data show that the proposed algorithm is very stable and effective.

Using canonical Monte Carlo simulations, the vapor-liquid phase diagrams of a square-well fluid confined in hard and weakly attractive cylindrical pores are calculated. The critical temperature shows a maximum as a function of the attraction strength between the fluid particle and the pore wall. This maximum is located where the fluid–fluid equals the wall–fluid interaction strengths. With the aid of combined density profiles in the axial and radial directions the maximum of the critical temperature is correlated with the structure of the confined fluid.

Vapor–liquid equilibrium (VLE) data for ternary systems of benzene + ethylbenzene, benzene + methylcyclohexane, toluene + methylcyclohexane, toluene + 1-hexene, toluene + cyclohexane, and toluene + ethyl benzene with ionic liquid of 1-methyl 3-octylimidazolium thiocyanate [Omim][SCN], were measured using headspace gas chromatography. The temperature was set at 323.15 K. The experimental data shows that the presence of ionic liquid improves the separation factors of these systems significantly. The VLE data of ternary systems were correlated using the Non Random Two Liquid (NRTL) model with a good accuracy.

Combining Peng–Robinson (PR) equation of state (EOS) with Liu et al.’s association contribution derived from shield-sticky model (SSM), a new cubic-plus-association (CPA) EOS is proposed to describe the thermodynamic properties of pure associating fluids and their mixtures. The CPA-SSM EOS contains five molecular parameters (a0, c1, b, ω and δɛ/k) for the pure associating fluids, while for non-associating fluids it reduces to PR EOS with three molecular parameters (a0, c1, b). The molecular parameters are obtained by fitting the saturated pressures and/or liquid molar volumes at wide temperature ranges. The overall average absolute deviations (AADs) of 58 pure associating fluids and 20 non-associating fluids are 0.74% and 0.54% for saturated vapor pressure, 2.00% and 1.85% for liquid molar volumes respectively. The enthalpies of vaporization for 13 pure associating fluids are well predicted by using these molecular parameters. The molecular parameter b for homologous substances shows a good linear relationship with respect to their corresponding molecular weights. Using one temperature-independent binary adjustable parameter kij, satisfactory results of vapor–liquid equilibria (VLE) for both self- and cross-associating systems are obtained. The overall AADs of the equilibrium temperatures, pressures and vapor phase mole fractions are 1.46 K, 1.26 kPa and 0.0197 respectively for 25 self-associating systems, and 0.75 K, 0.50 kPa and 0.0155 respectively for 29 cross-associating systems. Other caloric properties such as the excess molar enthalpies of mixing are also successfully computed. The CPA-SSM EOS proposed has been proved to have comparable accuracy as other models but with much simpler form.

We present the equilibrium and dynamical properties of liquid sodium (Na) and lithium (Li), based on embedded atom models, using molecular dynamics simulations. In particular, we present vapor–liquid equilibria, critical properties, diffusivity, shear viscosity and excess entropy of liquid Na and Li. Critical temperatures obtained in the current work are 2462 K and 5649 K for Na and Li, respectively. On the other hand, critical density for Na is 0.3493 g/cm 3 and that for Li is 0.1553 g/cm 3 . Critical pressures based on the exiting EAM models for Na and Li are 113 bar and 1686 bar, respectively. The relation of excess entropy and dynamical properties is examined in the framework of existing scaling laws. We observed an exponential nature between the dimensionless scaled diffusion constant and the approximate excess entropy for liquid Na and Li, as also observed for other liquid metals.

Volatility is an important issue for aqueous ammonia used as an absorbent for post-combustion CO2 capture. Vapor–liquid equilibrium (VLE) of NH3 in aqueous ammonia and aqueous blends of ammonia and piperazine (PZ) were measured at 20 °C, 30 °C and 40 °C. The experimental VLE results for NH3 cover the mole fraction ranges 2.5–15% NH3 (aq) in aqueous ammonia and 2.5–15% NH3 in the 0.4 M PZ blended solutions. Vapor pressures of NH3 for 5%, 10% and 15% NH3 (aq) were compared with available data in the literature. Activity coefficients for NH3 in NH3 (aq) and aqueous blends of NH3 + PZ were calculated and compared for different temperatures to obtain the effect of PZ on the volatility of aqueous ammonia. The eNRTL model was used to model the results and a comparison between model predictions and experimental data shows good agreement.

Experimental isobaric vapor–liquid–liquid and vapor–liquid equilibrium data for the ternary system water (1)–cyclohexane (2)–toluene (3) and the quaternary system water (1)–ethanol (2)–cyclohexane (3)–toluene (4) were measured at 101.3 kPa. An all-glass, dynamic recirculating still equipped with an ultrasonic homogenizer was used to determine the VLLE. The results obtained show that the system does not present quaternary azeotropes. The point-by-point method by Wisniak for testing the thermodynamic consistency of isobaric measurements was used to test the equilibrium data.

Vapor–liquid equilibria (VLE) for two binary systems 1-propanol + water and methyl acetate + methanol, and the ternary mixtures with the ionic liquid 1-ethyl-3-methylimidazolium ethyl sulfate [EMIM]+[EtSO4]− as entrainer were measured by headspace gas chromatography. From the experimental VLE data, the influence of the ionic liquid on the separation factors was investigated. The experimental results for the ternary systems show that [EMIM]+[EtSO4]− has a great influence on the separation factors of the systems investigated. Furthermore, the experimental separation factors were compared with the predicted ones of other ionic liquids and conventional selective solvents using modified UNIFAC (Dortmund).

The liquid–liquid and vapor–liquid equilibrium data for the binary system of ethane + methanol were measured at ambient temperature over a wide range of pressures using a designed PVT apparatus. The experimental liquid–liquid and vapor–liquid equilibrium data were compared with the modeling results obtained using the Peng Robinson and Soave–Redlich–Kwong equations of state.

Grand-canonical transition-matrix Monte Carlo (GC-TMMC) simulation, is used to investigate the effect of pore shape and surface-fluid strength on the vapor–liquid phase transition and crossover behavior of critical properties from 3D to 2D of a square well (SW) fluid. We present the vapor–liquid coexistence phase diagram in hard and attractive cylindrical pores of varying slit width from 4 to 50 molecular diameters. This investigation indicates that having same pore shape but different surface nature can significantly alter the coexistence envelopes and hence the critical point. Critical temperature is found to approach the 3D bulk value monotonically irrespective of the pore shape and surface nature. However, the rate of approach of critical point towards the 3D bulk value decreases as the effective confinement increases. On the other hand, approach of pore critical density towards the bulk 3D value follows a non-monotonic path, irrespective of pore shape and surface strength. Interestingly, with the same pore shape, attractive wall surface follows an opposite trend to approach the bulk critical density as compared to that of hard wall surface. Crossover from 3D to 2D behavior in the hard cylindrical pores is observed around 28 molecular diameters, which is significantly larger than that observed by earlier workers for hard and attractive slit pores.

The COSMO-SAC model has been revised for a better description of the nonideality of liquid mixtures, and thus more accurate predictions of both vapor–liquid equilibrium (VLE) and liquid–liquid equilibrium (LLE). Two major modifications are introduced. First, the electrostatic interaction parameter is made temperature-dependent, which is important in LLE predictions for non-hydrogen-bonding systems. Second, the variation in the strength of hydrogen-bonding interactions involving different types of functional groups is treated using separate sigma-profiles. The overall RMS error in LLE predictions of 278 binary mixtures (4281 data points) from the new model is 0.1047, which is 30% lower than that from the original COSMO-SAC (0.1446), 10% lower from that of UNIFAC-LLE (0.1161), and comparable to that from the modified UNIFAC model (0.1048). The accuracy in VLE predictions is also improved. The average deviation in total pressure at a fixed liquid composition is 6.54% and the overall average deviation in vapor phase composition is 2.57% for 1338 binary mixtures, compared to 7.25% and 2.83% from the original model.

A new experimental apparatus for performing simultaneous determination of high-pressure vapor–liquid equilibria (VLE) and saturated densities was developed in this work. The experimental methodology was verified by measuring these properties for the carbon dioxide + 1-propanol and carbon dioxide + 2-propanol systems from 313 to 363 K. The apparatus is based on the static-analytic method for VLE determinations and was slightly modified by coupling a vibrating U-tube densitometer to obtain saturated densities for both vapor and liquid phases. VLE measurements agreed with previous literature data and were correlated with the Peng–Robinson equation of state coupled to the Wong–Sandler mixing rules. Saturation densities at temperatures above 313 K have not been published up to now.

The liquid–liquid equilibria (LLE) data and vapor–liquid equilibria (VLE) data for the binary system of epichlorohydrin (EPCH) + water were studied at 101.3 kPa. An azeotropic behavior has been found in the EPCH + water. Both the experimental LLE and VLE data were compared with the correlated values obtained by means of the NRTL and UNIQUAC equations. Both models satisfactorily correlated the experimental data. Thermodynamic consistency has been tested for the VLE data.

Isobaric vapor–liquid equilibrium (VLE) data of the systems acetic acid + N,N-dimethylformamide (DMF), acetic acid + dimethyl sulfoxide (DMSO), DMSO + water, water + acetic acid + DMF, and water + acetic acid + DMSO have been measured at 13.33 kPa by using an improved Rose equilibrium still. The association of acetic acid in vapor phase has been considered, and the nonideality of vapor phase was accounted for using the Hayden–O’Connell (HOC) method. The experimental binary data have been correlated by the NRTL, Wilson and van Laar models. The NRTL model parameters obtained from the binary data have been used to predict the ternary VLE data. The ternary predicted values obtained in this way agree well with the experimental values.

New experimental vapor–liquid equilibrium data for binary mixtures of 1,4-dioxane with four isomeric butanols, have been measured in an ebulliometer at 15 conditions. Five popular activity coefficient models have been used to correlate each set of data through two different optimization methods to obtain values of the vapor compositions. The results of these correlations have been compared and discussed. Comparisons have also been made between the present data and the available published data on the systems containing isomeric butanols with 1,4-dioxane.

A dispersion force (DF) model was examined to determine if it can accurately predict the VLE data of alkane/alkane binaries in the literature. A total of 65 alkane/alkane binaries was found in the DECHEMA Chemistry Data Series. The mole fraction of the alkane in the liquid phase, x i , ranged from 0.1 to 0.9 in 62 binaries. VLE data were produced using Margules interaction parameters shown in the DECHEMA Data Series. The deviations between the representative pressure data and the pressures predicted by the DF, the ideal solution (IS) and the Flory–Huggins (FH) models, (AAD) P , are close to each other in the case of ideal solutions. However, the (AAD) P values calculated from the DF, IS and FH models for non-ideal solutions were 1.1%, 2.2% and 3.6%, respectively; the DF model accurately predicts the VLE of alkane/alkane binaries even if the system is under non-ideal conditions. The FH model less satisfactorily predicts the VLE data than the IS model for the non-ideal solutions. The entropy–enthalpy compensation holds for the partial molar excess quantities.

Vapor pressures of four pure pentaerythritol esters, PE, pentaerythritol tetrapentanoate, pentaerythritol tetraheptanoate, pentaerythritol tetranonanoate and pentaerythritol tetra 2-ethylhexanoate were measured between 334 and 476 K in a recently developed gas saturation apparatus. The experimental vapor pressure values for the four polyolesters range from 5.6 × 10−5 Pa to 0.94 Pa. These data together with density values were used to determined SAFT and PC-SAFT characteristic parameters. The linearity of molecular parameters for both models with the molecular weight permits to interpolate and extrapolate these parameters for pentaerythritol ester with linear chains. For pentaerythritol esters with ethyl-alkanoic chains, the parameters of SAFT and PC-SAFT have been estimated assuming that the slope of these straight lines is the same for PEs with linear chains that for PE with branched chains. This procedure was used to predict density of commercial POEs, estimating the molecular weight when it is not available from the viscosity at 313.15 K. PC-SAFT gives better performances than SAFT to predict density data for these four compounds at high pressures and for other PEs at atmospheric pressure. Furthermore, characteristic parameters for Soave-Redlich-Kwong and Peng Robinson EoSs were also estimated from the experimental vapor pressures and literature density values.

An apparatus based on the static-analytic method was used to measure the vapor–liquid equilibria (VLE) for CO2 + alkanol systems. Equilibrium measurements for the CO2 + 1-propanol system were performed from 344 to 426 K. For the case of the CO2 + 2-propanol system, measurements were made from 334 to 443 K, and for the CO2 + 1-butanol were obtained from 354 to 430 K. VLE data were correlated with the Peng–Robinson equation of state using the classical and the Wong–Sandler mixing rules. Moreover, compressed liquid densities for the n-dodecane and n-tridecane were obtained via a vibrating tube densitometer at temperatures from 313 to 363 K and pressures up to 25 MPa. The Starling and Han (BWRS), and The five-parameter Modified Toscani-Swarcz (MTS) equations were used to correlate them. The experimental density data were compared with those from literature, and with the calculated values obtained from available equations for these n-alkanes.

Isobaric vapor–liquid equilibria were measured for three binary systems of water + propyleneglycol monomethyl ether (PGME), water + propyleneglycol monomethyl ether acetate (PGMEA), and PGME + PGMEA at 93.3, 53.3, 26.7 kPa. The equipment used was a modified Rogalski-Malanoski equilibrium still and an ebulliometer. The NRTL equation correlated the experimental binary data with good accuracy.

Isothermal vapor–liquid equilibrium data for the binary systems of 1,1-difluoroethane (HFC-152a) + n-butane were measured at 273.15, 283.15, 293.15, 303.15, 313.15 and 323.15 K, respectively. The experiments were carried out using a circulation-type equilibrium apparatus to measure temperature, pressure, and the compositions of the liquid and vapor phases. The experimental data were correlated with the Peng–Robinson equation of state (EOS) using the Wong–Sandler mixing rules and the Carnahan–Starling–De Santis equation of state (CSD EOS). Calculated results showed good agreement with experimental data. It was found that this system has very strong positive azeotropes for all the temperature ranges studied here.

The cubic-plus-association (CPA) EoS is applied to multicomponent multiphase equilibria of systems containing MEG as a hydrate inhibitor. It is shown that the model provides very satisfactory prediction of the phase behavior for the systems tested. A more conventional engineering model for handling associating and polar molecules, an EoS/ G E model is also tested, both for binary and multicomponent systems, and compared to the performance of the CPA EoS. It is found that the performance of CPA is overall superior while using fewer interaction parameters than the EoS/ G E approach.

Vapor–liquid critical temperatures, pressures and densities of multi-component mixtures containing CO 2 and n -alkanes (C4–C7) were measured in a high-pressure view cell by direct visual observations. The molar ratio of alkanes was fixed during the experiment while the composition of CO 2 was varied over the whole range. The critical loci show type I fluid phase behavior if the n -alkanes mixture is treated as a pseudo-continuous component, while correspondingly, CO 2 is a discrete component. The critical properties were calculated by Redlich–Kwong–Soave equation of state (SRK) combined with a renormalization group correction (RG). The predictions of critical properties by SRK + RG are in good agreement with the experimental results.

Monte Carlo simulations in the isobaric–isothermal and Gibbs ensembles are used to compute liquid densities and vapor–liquid coexistence curves for a series of small organic molecules for the AMBER-96, CHARMM22, COMPASS, GROMOS 43A1, OPLS-aa, TraPPE-UA, and UFF force fields. The simulation results are compared with experimental measurements to provide an assessment of the accuracy expected when using these force fields to study unknown molecules.

Isothermal vapor–liquid equilibria data for the binary mixture of propylene (R-1270) + propane (R-290) at 273.15, 278.15, 283.15, 293.15, 303.15 and 313.15 K were measured by using a circulation-type equilibrium apparatus. The experimental data were correlated with the Peng–Robinson equation of state (PR-EOS) combined with the Wong–Sandler mixing rule. It is confirmed that the data calculated by this equations of state are in good agreement with experimental data. The azeotropic behavior was not found in this mixture over range of temperature studied here.

The critical temperature and pressure of squalane (2,6,10,15,19,23-hexamethyltetracosane) have been measured using the pulse-heating method. Residence times are from 0.03 to 1 ms. The experimental critical properties are compared with the results of measurement by a flow method, computer-simulation data, and the values calculated by the group-contribution methods. The critical temperature of squalane is about 2.5% lower and the critical pressure is 10% higher than those of its linear isomer-n-triacontane.

The binary vapor–liquid equilibrium (VLE) data for salt-containing systems of 1-propanol/CaCl2, 2-propanol/CaCl2, 1-butanol/CaCl2 and 2-butanol/CaCl2 were determined and correlated. The UNIQUAC model was used to correlate the VLE data, and optimal parameters of the model were obtained. The results show that the UNIQUAC model is suitable to correlate the VLE data.

Water activities of the polyvinylpyrrolidone (PVP) + (NH 4 ) 2 SO 4 + H 2 O system have been determined experimentally using the improved isopiestic method at 298.15, 308.15 and 318.15 K. The effect of temperature on the constant water activity lines has been studied. It was found that the slope of all constant water activity lines increased with increasing temperature. Furthermore, the extended Wilson theory has been used for the correlation of the experimental water activity data. The agreement between the correlation and the experimental data is good.

For the first time vapor–liquid equilibrium (VLE) data for ternary systems containing ionic liquids are reported. The data were measured by means of a computer-operated static VLE apparatus at 353.15 K with the ionic liquids 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [EMIM]+[(CF3SO2)2N]− and 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [BMIM]+[(CF3SO2)2N]− and acetone, 2-propanol and water. The experimental VLE data of the binary systems were correlated using the Wilson, NRTL and UNIQUAC models. The errors using Wilson, NRTL, and UNIQUAC are 3.92%, 1.45%, and 1.53%. The gE-model parameters of the binary systems were used to predict the VLE behavior of the ternary systems and the predictions were compared to the experimental datasets. The errors using Wilson-, NRTL-, and UNIQUAC-parameters are 5.61%, 7.22%, and 5.02%.

Alternative refrigerants HFC125 (CHF2CF3) and HFC 134a (CF3CH2F) are modeled as a dipolar two-center Lennard–Jones fluid and alternative refrigerant HFC32 (CH2F2) is modeled as a dipolar Lennard–Jones fluid. We calculate vapor–liquid equilibria of these refrigerants by Gibbs–Duhem integration and vapor–liquid equilibria of two binaries (HFC 125 + HFC 134a and HFC 134a + HFC 32) by the reaction Gibbs ensemble Monte Carlo method. Potential parameters of the model are fitted to the critical temperature and vapor–liquid equilibrium data. The predictions are very good, and of comparable accuracy to those obtained using the Wilson and the UNIFAC thermodynamic-based approaches, even though such approaches use experimental mixture information.