Isothermal Vapor Liquid Equilibrium Research Articles

Vapor-liquid equilibrium (VLE) measurements of ethanol – heptane at isothermal (363.15, 393.15 and 423.15 K) and isobaric (101.33 kPa) conditions and correlation of liquid viscosity data

Vapor-liquid equilibria (VLE) were measured for ethanol – heptane by a modified Rose-Williams equilibrium still combined with ebulliometer at three isotherms (363.15, 393.15 and 423.15 K) and an isobar (101.33 kPa). The azeotropes were observed in VLE, and the experimental data were correlated with the Peng-Robinson-Stryjek-Vera (PRSV) equation of state. The conventional mixing rule, with kij equal to zero calculates the azeotropic pressure close to the vapor pressure of ethanol. The Adachi-Sugie (AS) mixing rule provides 0.282% average absolute relative deviation (AARD) in temperature for isobaric VLE and 1.711% AARD for isothermal VLE. Eyring theory combined with the PRSV equation enabled an average of 2.810% AARD in correlation of literature liquid viscosity data, which is sufficient for considering biofuel injector. The method will be applied to flow analysis in general process design using mixtures because viscosity can be evaluated from equation of states.

Isothermal Vapor–Liquid Equilibrium (P–T–x–y) Measurements and Modeling of Propan-2-ol +n-Octane/n-Decane in the Range ofT= 313.2–353.2 K

Isothermal Vapor–Liquid Equilibrium (<i>P</i>–<i>T</i>–<i>x</i>–<i>y</i>) Measurements and Modeling of Propan-2-ol +<i>n</i>-Octane/<i>n</i>-Decane in the Range of<i>T</i>= 313.2–353.2 K

Thermodynamic properties of N-octyl pyridinium hexafluorophosphate ionic liquid: Characterization and application in separation of the azeotrope

The experimental data of the weight fraction activity coefficient (Ω12∞), the Flory–Huggins interaction parameter (χ12∞), the activity coefficient at infinite dilution (γ12∞) and the Hildebrand solubility parameters (δ2) involving N-octyl pyridinium hexafluorophosphate ([OPY][PF6]) ionic liquid (IL) have been evaluated by Inverse gas chromatography (IGC). The values indicated the interaction of solvents-IL depended on the structure of the solvents and the experimental temperatures. Based on IGC data, the isothermal vapor–liquid equilibrium (VLE) data of solvent-IL at 343.15 K were derived and related to the NRTL model. The acquired binary interaction parameters have a great significance in order to model. The equilibrium phase diagram of the [OPY][PF6]-acetone/chloroform–methanol ternary system was obtained by Aspen Plus simulation. The result showed that the IL can be used as a potential solvent for separating azeotropic mixtures of chloroform (1)/methanol (2) and acetone (1)/methanol (2).

Methane + neo-pentane system: VLE measurements, modeling of the phase diagram including solid phases

New measurements of isothermal vapor–liquid equilibrium for the (CH4 + neoC5H12) system have been carried out using a static-analytic method for temperatures from 213 K up to 345 K and pressures up to 13 MPa. The method of Ungerer et al. has been used to extrapolate the VLE data to the critical-points region.Measured VLE data have been compared with literature values and used for investigating the low-temperature phase equilibrium behavior of the system (temperatures lower than the triple-point temperature of neo-pentane down to 213 K) where literature SVE data and thermodynamic models are in partial disagreement.Measured VLE data agree with literature VLE data and low-temperature VLE calculated from predictive models (PPR78 and PSRK EoSs). The new phase equilibrium measurements obtained at temperatures lower than the triple point temperature of neoC5H12 have allowed solving the discrepancy between literature data and model predictions and determining the global phase diagram of the system following the van Konynenburg and Scott’s and the Kohn and Luks’ classifications.

Solubility measurements of refrigerants in polyolesters lubricants at temperature from 323.K to 383.K

In refrigeration systems and heat pumps, lubricant selection is important to avoid issues that can lead to a breakdown of the compressor and the entire system. Daniel plots are a great tool to make the selection. Half of the graph is the solubility of refrigerant in lubricating oil. Isothermal vapor-liquid equilibrium (VLE) data are measured for five refrigerants in four oils. Refrigerants include HFC-32 (dichlorofluoromethane), HFC-134a (1,1,1,2-tetrafluoroethane), HFO-1234yf (2,3,3,3-tetrafluoropropene), HFO-1336mzz(Z) (cis-1,1,1,4,4,4-hexafluoro-2-butene) and HCFO-1233zd(E) (trans-1‑chloro-3,3,3-trifluoroprop-1-ene) in four oils named POE 80, SE 55, SE 170 and SE 220, based on their viscosity grade. The experimental technique used is based on static synthetic methods. All of the data are correlated with the cubic equation of state developed by Yokozeki.

3-5-1 エタノール添加ヘプタンの定圧および定温気液平衡測定と状態方程式による相平衡と液粘度相関

3-5-1 エタノール添加ヘプタンの定圧および定温気液平衡測定と状態方程式による相平衡と液粘度相関

High-pressure phase equilibria of carbon dioxide + 1,4-dioxane binary system

New isothermal vapor–liquid equilibrium (VLE) data for the carbon dioxide + 1,4-dioxane system are reported at four temperatures (323.15, 333.15, 343.15, and 353.15) K and pressures up to 122.7 bar. The critical curve was also measured up to 158.8 bar and 420.15 K. Phase behavior measurements were performed in a high-pressure windowed cell with variable volume, using a static-analytical method with phases sampling by rapid online sample injectors (ROLSI) coupled to a gas chromatograph (GC) for analysis. The experimental results of this study are compared with the scarce available literature data. The new and all available literature data for the carbon dioxide + 1,4-dioxane binary system are modelled with the cubic Soave–Redlich–Kwong (SRK) and Peng–Robinson (PR) equations of state (EoS) with classical van der Waals mixing rules (two-parameter conventional mixing rules, 2PCMR). The modeling showed that SRK and PR models can accurately predict the phase behavior of the system studied.

Tetrathiocyanatocobaltate and bis(trifluoromethylsulfonyl)imide-based ionic liquids as mass agents in the separation of cyclohexane and cyclohexene mixtures by homogeneous extractive distillation

In this work, the suitability of two tetrathiocyanatocobaltate-based ionic liquids, namely bis(1-ethyl-3-methylimidazolium) tetrathiocyanatocobaltate ([emim]2[Co(SCN)4]) and bis(1-butyl-3-methylimidazolium) tetrathiocyanatocobaltate ([bmim]2[Co(SCN)4]), and two bis(trifluoromethylsulfonyl)imide-based ionic liquids, namely 1-ethyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide ([4empy][Tf2N]) and 1-butyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide ([4bmpy][Tf2N]), as mass separating agents to separate cyclohexane and cyclohexene mixtures by homogeneous extractive distillation was analysed. Isothermal vapour-liquid equilibria (VLE) for the binary systems {cyclohexane or cyclohexene + ionic liquid} and the ternary systems {cyclohexane + cyclohexene + ionic liquid} were determined at 323.2, 363.2 and 403.2 K by headspace-gas chromatography (HS-GC). All the ternary systems were studied with a solvent-to-feed ratio on mass basis of 10. In addition, solvent-to-feed ratios on mass basis of 8 and 6 were evaluated for the ternary systems containing [Tf2N]-based ionic liquids. The Non-Random Two Liquids (NRTL) model was used to describe the experimental VLE data accurately. The values of cyclohexane/cyclohexene relative volatilities provided by the four ionic liquids enhanced those obtained with conventional mass agents such as ethylene glycol. The highest relative volatilities were obtained with the [Co(SCN)4]-based ionic liquids. However, taking into account the viscosity and thermal stability of the four ionic liquids studied here, the [4empy][Tf2N] was considered the most promising alternative from an extractive distillation approach.

Phase equilibria for the carbon dioxide + cyclopentane + cyclohexane system at high pressures

Isothermal vapor–liquid equilibrium measurements for the ternary mixture carbon dioxide + cyclopentane + cyclohexane at 353.15 K are reported. Phase equilibrium measurements were made in a high-pressure visual cell with variable volume using a static-analytical method with phases sampling by rapid online sample injectors (ROLSI) coupled to a gas chromatograph (GC) for analysis. The new measured data were modelled with the RK–PR equation of state (EoS) coupled with classical van der Waals (two-parameter conventional mixing rule, 2PCMR).

Isothermal Vapor–Liquid Equilibrium (P–x–y) Measurements and Modeling of n-Hexane + Pentan-2-one/4-Methylpentan-2-one

Isothermal vapor–liquid equilibrium (VLE) data were measured for the hexane + pentan-2-one/4-methylpentan-2-one systems to characterize the separation limits. Phase equilibrium measurements were un...

Isothermal vapour-liquid equilibrium of (difluoromethane + trifluoroiodomethane) at temperatures ranging from 253.150 K to 293.150 K

In this paper, the isothermal vapour-liquid equilibrium (VLE) data for pure difluoromethane (R32) and trifluoroiodomethane (R13I1) and their binary mixtures have been measured based on a vapour – phase single recirculation method. The data were collected for five temperatures from 253.150 K to 293.150 K. The experimental VLE data were regressed by PR-MHV2-NRTL model and PR-vdW model. The deviation curves of pressures and vapour compositions for the binary system between experimental and calculated values were given. The results indicated that the maximum mean absolute relative deviation of pressure (MARDp) for PR-MHV2-NRTL is 0.54%, which shows a better fit than PR-vdW with a maximum MARDp of 2.73%. The maximum mean absolute deviation of vapour phase mole fraction (MADy) for PR-MHV2-NRTL and PR-vdW are 0.013 and 0.010, respectively. The azeotropic behaviours were found at T = (253.150, 263.150, 273.150) K, while the zeotropic behaviours were found at 283.150 K and 293.150 K.

Experimental measurement and modelling of vapor-liquid equilibrium for 3,3,3- Trifluoropropene (R1243zf) and trans-1,3,3,3-Tetrafluoropropene (R1234ze(E)) binary system

• Experimental measurement of VLE data for R1243zf + R1234ze(E) by a static analytical method. • The R1243zf + R1234ze(E) system is a zeotropic system within 283.15 to 323.14 K. • Experimental data show good agreement with the predicted results of PR-MC-vdW and PR-MC-MHV2 models. The environmental performance becomes the critical factor of the selection of refrigerant. 3,3,3-trifluoropropene (R1243zf) and trans-1,3,3,3-tetrafluoropropene (R1234ze(E)) are environmental friendly candidates to replace R134a. Whereas, in the consideration of environmental factor, safety, and energetic efficiency at the same time, none of the pure refrigerants has been proved to be a suitable solution. Mixed refrigerants provide an approach to this problem because the characteristics of refrigerant blends can be optimized for particular applications in the way pure component refrigerant alone cannot be. The purpose of this work is to explore an R1243zf/R1234ze(E) blend which can be possibly used as a long-term alternative to replace hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs). We report the measurements of saturated vapor pressures of R1234ze(E) and R1243zf ranging from 273.17 to 353.13 K, and isothermal vapor-liquid equilibrium of R1243zf + R1234ze(E) systems from 283.15 to 323.14 K. The measurements are performed by static-analytic type apparatus coupled with two electromagnetic capillary samplers (ROLSI®, patent of Armines). The experimental data are correlated by the Peng-Robinson (PR) equation of state (EoS) associated with Mathias-Copeman (MC) alpha function and classical mixing rules. For the comparison of conventional mixing rules and excess free energy ( G E ) mixing rules models, classic van der Waals one fluid mixing rules and modified Huron-Vidal second-order (MHV2) mixing rules are employed respectively to the correlation of experimental VLE data. The modeling results are in good agreement with the measured data, while the PRMC-MHV2 model exhibits better performance in VLE prediction.

Vapor–Liquid Equilibrium Measurement and Thermodynamic Correlations of 4-Nonyl Phenol Diethoxylate with sec-Butanol at Elevated Pressures

The isothermal vapor–liquid equilibrium (VLE) data for a binary system of 4-nonyl phenol diethoxylate with sec-butanol at (333.0 to 425.0) K have been measured by using a static-type apparatus. The system pressures at a given feed composition were measured to generate the P–T–x data and are further compared to the pressure values calculated using the Antoine equation. Two thermodynamic models, the UNIQUAC and the NRTL models, were selected to correlate the VLE data at various temperatures. The analysis showed that the experimental data agree well with these activity coefficient models. Finally, the solvent activities were estimated, and the values are consistent with the values calculated from the phase equilibrium data.

Vapor–Liquid Equilibria of Mixtures Containing Ethanol, Oxygen, and Nitrogen at Elevated Pressure and Temperature, Measured with In Situ Raman Spectroscopy in Microcapillaries

Ethanol and oxygen containing gases are mixed in a T-junction at elevated pressure and then passed into a fused silica microcapillary, located in a heating block. Inside the microcapillary a Taylor flow of alternating liquid and vapor segments is formed. The thermodynamic equilibrium composition of the liquid and vapor segment depends on pressure and temperature. Their compositions are measured inside the microcapillary using in situ Raman spectroscopy. The main results obtained therefrom are temperature–composition (Tx) diagrams at conditions relevant for combustion engines [p = (3 to 8) MPa; T = (303 to 473) K]. Isothermal vapor–liquid equilibria (VLE) data are derived and given in pressure–composition (px) diagrams. The investigation of different gas mixtures containing oxygen and nitrogen allows furthermore the illustration of VLE data at constant pressure and temperature in ternary diagrams. The obtained results are compared to scarce literature data. An equation of state (Peng–Robinson EOS) is furthermore adjusted to the measured results.

Vapour-liquid equilibria for the binary systems of pentafluoroethane {(R125) + 2,3,3,3-tetrafluoroprop-1-ene (R1234yf)} and {trans-1,3,3,3-tetrafluoropropene R1234ze(E)}

In this work, isothermal vapour-liquid equilibrium (VLE) data for the binary mixtures of pentafluoroethane (R125) + 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) and trans-1,3,3,3-tetrafluoropene (R1234ze(E)) have been investigated. The experimental measurements were carried out by using the AnTLcirCapValVis analytical method over the temperature range from 283.15 K 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 (PR) equation of state (EoS) and its modifications from Stryjek and Vera (PRSV and PRSV2) combined with Wong-Sandler (WS) mixing rule and the non-random two-liquid activity coefficient model (NRTL) were employed to correlate the parameters of binary mixtures, respectively. The PRSV2 + WS + NRTL model shows the best consistency with the experimental VLE data compared with the other two models (PR + WS + NRTL and PRSV + WS + NRTL). The average absolute relative deviation of pressure (AARD(p)) and average absolute deviation of vapour phase mole fraction (AAD(y)) are 0.10% and 0.0012 for R125 + R1234yf, 0.16% and 0.0014 for R125 + R1234ze(E), respectively. Both the experimental data and the calculated results imply that R125 + R1234yf and R125 + R1234ze(E) are zeotropic binary mixtures over the studied temperatures.

Excess Gibbs Energies and Isothermal Vapor–Liquid Equilibrium for Citral + Linalool, Citral + α-Pinene, and Linalool + α-Pinene Systems Using Headspace Gas Chromatography

Isothermal vapor–liquid equilibrium (VLE) data for expensive and thermosensitive Litsea cubeba oil systems, citral + linalool, citral + α-pinene, and linalool + α-pinene, were measured at 333.15, 3...

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.

Isothermal Vapor–Liquid Equilibrium of the Binary Mixture Difluoromethane (R32) + Octafluoropropane (R218) at Temperatures from 253.150 to 283.150 K

The data for the isothermal vapor–liquid equilibria of a binary mixture of difluoromethane (R32) and octafluoropropane (R218) were obtained from 253.150 to 283.150 K using a vapor phase single reci...

Vapor-liquid equilibrium measurements for 5 binary mixtures involving HFO-1336mzz(E) at temperatures from 313 to 353 K and pressures up to 2.735 MPa

Performances of systems using refrigerants are highly dependent on the selection of the working fluids. In order to guide this choice, the thermophysical properties of these fluids need to be correctly correlated. Experimental data are required for models to work; The knowledge of thermophysical properties of working fluids is required for designing ORC and High Pump (HP) systems. Isothermal vapor-liquid equilibrium (VLE) data for the HFO-1336mzz(E) (trans-1,1,1,4,4,4-hexafluoro-2-butene) binary mixture with HFC-290 (Propane), HFC-134a (1,1,1,2-tetrafluoroethane), HFC-152a (1,1-difluoroethane), HFC-227ea (1,1,1,2,3,3,3-heptafluoropropane) and HFO-1234ze(E) (trans-1,3,3,3-tetrafluoropropene) were measured at 313 K, 333 K and 353 K. The experimental technique used is based on static analytic methods. All of the data (P-x-y) were well correlated with the Peng-Robinson equation of state, associated with a Mathias-Copeman alpha function and classical mixing rules. The results of such modeling are in good agreement with the measured data.

High-pressure phase equilibria of carbon dioxide + 2-octanol binary system

New isothermal vapor–liquid equilibrium (VLE) data for the carbon dioxide + 2-octanol system are measured at five temperatures between 298.15 and 333.15 K and pressures up to 103 bar. The experimental method used is the static-analytical one with phases sampling. The new experimental data obtained in this study are compared with all available literature data and discussed. The new and all available literature data for the carbon dioxide + 2-octanol binary system are modeled with three cubic equations of state, namely the General Equation of State (GEOS), Soave–Redlich–Kwong (SRK), and Peng–Robinson (PR) equations of state (EoS) with classical van der Waals mixing rules. The phase behavior of the carbon dioxide + 2-octanol binary system (critical curves, the three-phase equilibrium curves, isothermal VLE, and vapor–liquid–liquid equilibria) was modeled using a semi-predictive methodology. The results of the calculations are compared to both the new data reported in this work and all available literature data. The results show a satisfactory level of agreement between the models and the experimental data.