Fluid Phase Equilibria最新文献

{"title":"Solving the UVN-flash problem in TVN-space","authors":"Pardeep Kumar ,&nbsp;Patricio I. Rosen Esquivel","doi":"10.1016/j.fluid.2025.114528","DOIUrl":"10.1016/j.fluid.2025.114528","url":null,"abstract":"<div><div>In this paper, we investigate the phase equilibrium problem for multicomponent mixtures under specified internal energy (<span><math><mi>U</mi></math></span>), volume (<span><math><mi>V</mi></math></span>), and mole numbers (<span><math><mrow><msub><mrow><mi>N</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><msub><mrow><mi>N</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>N</mi></mrow><mrow><mi>n</mi></mrow></msub></mrow></math></span>), commonly known as the UVN-flash problem. While conventional phase equilibrium calculations typically use pressure–temperature-mole number (<span><math><mrow><mi>P</mi><mi>T</mi><mi>N</mi></mrow></math></span>) specifications, the UVN formulation is essential for dynamic simulations of closed systems and energy balance computations. Existing approaches, including those based on iterative pressure–temperature updates and direct entropy maximization, can suffer from computational inefficiencies due to inner Newton iterations needed to solve for temperature <span><math><mi>T</mi></math></span> at specified internal energy <span><math><mi>U</mi></math></span> and volume <span><math><mi>V</mi></math></span>.</div><div>In this work, we present a reformulation of the UVN-flash problem that eliminates the need for the inner Newton iterations, addressing a computational bottleneck. We begin with stability analysis and discuss a strategy to generate the initial guess for the UVN-flash from the stability analysis results. We then reformulate the UVN-flash problem in TVN-space as constrained entropy maximization. We provide a detailed derivation of Michelsen’s Q-function using the method of Lagrange multipliers, illustrating its direct application in solving the UVN-flash problem. Furthermore, we discuss the numerical methods used, including gradient and Hessian computations. The reformulation is validated against benchmark cases, demonstrating improved efficiency.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"599 ","pages":"Article 114528"},"PeriodicalIF":2.8,"publicationDate":"2025-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144672324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molecular dynamics simulation study on the selective extraction of 1,3 propanediol from fermentation broth using imidazolium-based hydrophobic ionic liquids","authors":"Raj Akshat ,&nbsp;Anand Bharti ,&nbsp;Padmini Padmanabhan","doi":"10.1016/j.fluid.2025.114530","DOIUrl":"10.1016/j.fluid.2025.114530","url":null,"abstract":"<div><div>Selective extraction of dilute 1,3 propanediol (1,3-PDO) (&lt;20 wt %) from the fermentation broth is challenging via conventional distillation as the process becomes energy-intensive. Liquid-liquid extraction (LLE) using solvents such as ionic liquids (ILs) may significantly reduce costs. Therefore, this study explored the potential of imidazolium-based hydrophobic ILs for the selective extraction of 1,3-PDO from a fermentation broth containing 1,3-PDO, 2,3-butanediol (2,3-BDO), glycerol (Gly), and water using molecular dynamics simulations. Three ILs, having the same cation, 1‑butyl‑3‑methylimidazolium ([Bmim]⁺), but different anions-hexafluorophosphate ([PF₆]⁻), bis(trifluoromethylsulfonyl)imide ([NTF₂]⁻), and trifluoromethanesulfonate ([TFO]⁻)-were investigated. The local mass density profiles confirmed a well-defined biphasic system for all ILs. [Bmim][PF₆] and [Bmim][TFO] showed excellent results, with 1.3-PDO distribution coefficients ranging from 2.53 to 6.71 and 4.12 to 15.40, respectively. The selectivity towards 1.3-PDO relative to water ranged from 50.6 to 192.50, while selectivity relative to glycerol (2.88–13.83) and 2,3-BDO (4.59–25.67) was also notably high. [Bmim][TFO] exhibited the strongest affinity for 1,3-PDO, with the highest binding energies and more favorable hydrogen bonds. Furthermore, diffusion coefficient analysis indicated that PDO exhibited lower diffusion rates in the extraction phase. Radial distribution function (RDF), spatial distribution function (SDF), and coordination number (CN) analyses confirmed a compact solvation shell and higher 1,3-PDO density around [Bmim][TFO]. Supported by COSMO-SAC thermodynamic model predictions, the study demonstrated that the anion plays a critical role in IL performance. Overall, the results established the extraction performance trend as [Bmim][TFO] &gt; [Bmim][PF₆] &gt; [Bmim][NTF₂], highlighting [Bmim][TFO] as a promising candidate for selective PDO recovery.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"599 ","pages":"Article 114530"},"PeriodicalIF":2.8,"publicationDate":"2025-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144633706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental determination and correlation of solubility for R1234ze(E) in POE, PVE, and PAG base oils","authors":"Tao Jia ,&nbsp;Jinpeng Yang ,&nbsp;Jia Yu","doi":"10.1016/j.fluid.2025.114529","DOIUrl":"10.1016/j.fluid.2025.114529","url":null,"abstract":"<div><div>Detailed knowledge about the solubility of refrigerant in oil is essential for the design, operation, and long-term reliability of HVAC and refrigeration systems. Herein, as the leading candidates, the solubilities of R1234ze(E) in polyol ester (POE), polyvinylether (PVE), and polyalkylene glycol (PAG) base oils were investigated using the isochoric saturation method at temperatures from 283 K to 353 K. The viscosity grade of the three base oils is ISO VG 68. Additionally, the Peng-Robinson (PR) + Wilson model was successfully applied to correlate the experimental data. The absolute average relative deviations between the experimental and calculated pressures for R1234ze(E) in POE, PVE, and PAG base oils were 1.56 %, 0.91 %, and 1.46 %, respectively. These results provide valuable physical property data for the selection of suitable oils in vapor compression refrigeration systems.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"599 ","pages":"Article 114529"},"PeriodicalIF":2.8,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144633707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Graph neural networks embedded into Margules model for vapor–liquid equilibria prediction","authors":"Edgar Ivan Sanchez Medina ,&nbsp;Kai Sundmacher","doi":"10.1016/j.fluid.2025.114520","DOIUrl":"10.1016/j.fluid.2025.114520","url":null,"abstract":"<div><div>Predictive thermodynamic models are crucial for the early stages of product and process design. In this paper the performance of Graph Neural Networks (GNNs) embedded into a relatively simple excess Gibbs energy model, the extended Margules model, for predicting vapor–liquid equilibrium at low pressures (less than 5 bar) is analyzed. By comparing its performance against the established UNIFAC-Dortmund model it has been shown that GNNs embedded in Margules achieves an overall lower accuracy. However, higher accuracy is observed in the case of various types of binary mixtures. Moreover, since group contribution methods, like UNIFAC, are limited due to feasibility of molecular fragmentation or availability of parameters, the GNN in Margules model offers an alternative for VLE estimation. The findings establish a baseline for the predictive accuracy that simple excess Gibbs energy models combined with GNNs trained solely on infinite dilution data can achieve.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"599 ","pages":"Article 114520"},"PeriodicalIF":2.8,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144595919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel cubic equation of state of a flexible Zc","authors":"Lihang Bai ,&nbsp;Yulong Ji ,&nbsp;Haifeng Ma ,&nbsp;Bohao Wu ,&nbsp;Maogang He ,&nbsp;Wenze Zhu","doi":"10.1016/j.fluid.2025.114527","DOIUrl":"10.1016/j.fluid.2025.114527","url":null,"abstract":"<div><div>Classical cubic equations of state (EoSs) cannot produce satisfactory predictions for dense-state fluids because of the missing molecular repulsion effect. This work introduces a newly developed cubic EoS of a flexible critical compressibility Z_c by incorporating a repulsion term. Its <em>α</em>-function is redefined and capable of reliable extrapolation throughout the entire temperature range. As straightforward as the Soave-Redlich-Kwong (SRK) EoS, all the necessary parameters of the new EoS can be determined using the critical properties (<em>T</em>_c, <em>p</em>_c, <em>v</em>_c) and acentric factors. Tested upon pure and multi-component fluids, the new EoS demonstrates superior robustness and accuracy compared to the SRK EoS.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"599 ","pages":"Article 114527"},"PeriodicalIF":2.8,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144632860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Water content in pure CO2 and CO2-rich mixtures using the DSH analytical technique","authors":"Larissa F. Torres ,&nbsp;Antonin Chapoy ,&nbsp;Rod Burgass ,&nbsp;Cláudio Dariva ,&nbsp;Papa M. Ndiaye ,&nbsp;Frederico W. Tavares","doi":"10.1016/j.fluid.2025.114523","DOIUrl":"10.1016/j.fluid.2025.114523","url":null,"abstract":"<div><div>The accurate determination of water content in equilibrium with hydrates helps to prevent operational problems related to flow assurance, and it is essential for the emerging Carbon Capture and Storage (CCS) processes for decarbonization. However, the experimental challenges associated with these measurements cause a scarcity of data. The development of the Differential Scanning Hygrometer (DSH) method has increased the number of water content reports for CO₂-rich systems in equilibrium with hydrates. It monitors not absolute values but fluctuations in the water content due to the formation of ice or dew inside a temperature-controlled tube. Here, we provide experimental and modeling investigation for water content on pure CO₂ and two CO₂-rich mixtures (CO₂+CH₄ and CO₂+CH₄+N₂) in equilibrium with hydrates: the sCPA and the SRK+EMS equations of state were used to model the obtained experimental data, both using the van der Waals-Platteeuw (vdW-P) model for the hydrate phase.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"599 ","pages":"Article 114523"},"PeriodicalIF":2.8,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144595438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phase equilibria of carbon dioxide + sulfur hexafluoride mixed gas hydrate as fundamental data toward improving the mechanical properties of marine sediments","authors":"Tasuku Ishikawa ,&nbsp;Takeshi Sugahara ,&nbsp;Takayuki Hirai ,&nbsp;Norimasa Yoshimoto","doi":"10.1016/j.fluid.2025.114525","DOIUrl":"10.1016/j.fluid.2025.114525","url":null,"abstract":"<div><div>Isothermal phase equilibria of carbon dioxide (CO₂) + sulfur hexafluoride (SF₆) mixed gas hydrate at temperatures of 281.85 K, 284.05 K, 288.05 K, 291.05 K, 291.74 K, and 292.20 K were measured so as to improve the mechanical properties of marine sediment by hydrate cementation. The addition of SF₆ significantly reduces the equilibrium pressure of CO₂-containing mixed gas hydrate at each temperature. At temperatures above the quadruple point Q₂ (pure CO₂ hydrate + aqueous + CO₂-rich liquid + vapor phases) of 283.22 K, the four-phase (mixed gas hydrate + aqueous + guest-rich liquid + vapor phases) equilibrium point(s) exists(exist) on the isotherms of the CO₂+SF₆ mixed gas hydrate system. The four-phase equilibrium curve was connected from the quadruple point Q₂ of pure CO₂ hydrate to that of pure SF₆ hydrate and had a maximum temperature point at 292.0 ± 0.2 K, which is higher than both the Q₂ temperatures of pure CO₂ hydrate and pure SF₆ hydrate. Therefore, the addition of SF₆ to CO₂ brings a significant effect to expand the thermodynamically stable region of CO₂-containing mixed gas hydrate in order for simultaneous CO₂ storage and sediment improvement to be realized at marine sediment.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"599 ","pages":"Article 114525"},"PeriodicalIF":2.8,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144579991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating the dissolution behavior and revealing the thermodynamic mechanism of Ethyl L-phenylalaninate hydrochloride in several neat and binary solvents","authors":"Pengshuai Zhang ,&nbsp;Binbin Wu ,&nbsp;Ranran Feng ,&nbsp;Jiaxuan Xu ,&nbsp;Jiaqi Li ,&nbsp;Shuoye Yang ,&nbsp;Peng Li","doi":"10.1016/j.fluid.2025.114524","DOIUrl":"10.1016/j.fluid.2025.114524","url":null,"abstract":"<div><div>This study investigated the solubility of ethyl l-phenylalaninate hydrochloride (H-Phe-OEt.HCl) in seven neat solvents (1-Propanol, 1,4-Dioxane, 2-Butoxyethanol, 2-Propoxyethanol, Isopropyl alcohol, 1-Butanol, THF) and two binary (2-Propoxyethanol + THF, 2-Butoxyethanol + 1-Propanol) solvent mixtures from 283.15 K to 323.15 K under atmospheric pressure. The solubility of H-Phe-OEt.HCl in the neat solvents was correlated by the NRTL, Buchowski-Ksiazczak λh, Margules, NRTL-SAC, Jouyban and van't Hoff model. For the binary solvent mixtures (2-Propoxyethanol + THF, 2-Butoxyethanol + 1-Propanol), the NRTL, van't Hoff, Jouyban-Acree van't Hoff and Ma model were employed to correlate the obtained solubility. Hansen solubility parameters (HSPs) was used to evaluate the dissolution trend of H-Phe-OEt.HCl in the selected solvents. In addition, the apparent thermodynamic parameters such as Δ_sol<em>H</em>° (apparent standard enthalpy change), Δ_sol<em>S</em>° (apparent standard entropy change) and Δ_sol<em>G</em>° (apparent standard Gibbs energy change) was calculated to evaluate the dissolution mechanism, all the positive values of Δ_sol<em>H</em>°, Δ_sol<em>S</em>° and Δ_sol<em>G</em>° illustrated that the dissolution of H-Phe-OEt.HCl was an endothermic and entropy-increase process. The current study could provide critical insights for optimizing industrial crystallization, purification, and separation processes of H-Phe-OEt.HCl.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"599 ","pages":"Article 114524"},"PeriodicalIF":2.8,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144595439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Predictive QSPR modeling of pyridine extraction from fuels using deep eutectic solvents: Structural descriptors and neural network insights","authors":"Fatemeh Ghadimi,&nbsp;Mohammad Amin Sobati,&nbsp;Mahdieh Amereh","doi":"10.1016/j.fluid.2025.114522","DOIUrl":"10.1016/j.fluid.2025.114522","url":null,"abstract":"<div><div>This study employs the Quantitative-Structure-Property-Relationship (QSPR) method to investigate the extractive denitrogenation process of fuels employing deep eutectic solvents (DESs). In this regard, the distribution of pyridine (PY) as a typical nitrogen compound between the hydrocarbon and DES-rich phases was predicted. A comprehensive dataset, covering liquid-liquid equilibrium (LLE) data for 43 ternary systems was collected from various hydrocarbons and DESs containing different hydrogen bond donors (HBDs) and hydrogen bond acceptors (HBAs), enabled an extensive investigation of structural effects on PY distribution. Predictive linear model employing multiple linear regression (MLR) and non-linear models employing multi-layer perceptron (MLP), Radial Basis Function (RBF), Support Vector Machine (SVM), and Random Forest (RF) were developed. The linear model achieved statistical values of R² = 0.8025 and Average Absolute Relative Deviation (AARD) = 21.52 %, while among the non-linear models, the MLP model demonstrated the best performance with R² = 0.9581 and AARD = 9.30 %. The examination of molecular descriptors in the QSPR model demonstrated that PY distribution between the DES and hydrocarbon-rich phases is strongly affected by the average molecular weight of the HBA component and the hydrophilic characteristics of the HBD structure. These observations offer benefical insights for selecting and fine-tuning of molecular structure of DESs in the extractive denitrogenation applications.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"599 ","pages":"Article 114522"},"PeriodicalIF":2.8,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144655478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vapor–liquid equilibrium measurements of the carbon dioxide ＋ water (CO2＋H2O) system and carbon dioxide ＋ water ＋ sodium chloride (CO2＋H2O+NaCl) system","authors":"Yannick Jooss,&nbsp;Anders Austegard,&nbsp;Jacob H. Stang,&nbsp;Ingeborg Treu Røe,&nbsp;Bjørn Strøm,&nbsp;Ailo Aasen","doi":"10.1016/j.fluid.2025.114516","DOIUrl":"10.1016/j.fluid.2025.114516","url":null,"abstract":"<div><div>Accurate phase equilibrium data for CO₂ mixtures are essential for safe and cost-effective design of carbon capture, transport and storage chains. We report measurements of the saturation water content of the carbon dioxide-rich phase for both the CO₂+H₂O and the CO₂+H₂O+NaCl system. The experiments span the temperatures 35–120 °C, pressures 1–70 MPa, and NaCl concentrations of 0, 78 and 150 g NaCl/kg water (NaCl molalities 0, 1.3 and 2.6). Total uncertainties in the reported water mole fractions are mostly between 100 and 300 ppm. The measurements are compared to previous literature data, and two equations of state: the Spycher model and EOS-CG. The EOS-CG model agrees well with our CO₂+H₂O data at high pressures, but generally overpredicts the water content at pressures below <span><math><mo>∼</mo></math></span> 15 MPa. The Spycher model agrees well with our data for CO₂+H₂O at pressures below <span><math><mo>∼</mo></math></span> 15 MPa, but exhibits some systematic deviations that can be traced to simplifying assumptions made in the model development. The Spycher model predicts the influence of NaCl on water content fairly well, but surprisingly we find that better results are obtained simply by applying Raoult’s law for the influence of ions on water activity. We derive theoretically-based bounds on the influence of salt on water content, and use them to investigate systematic errors in the measurements presented herein and in the literature. The present work indicates a clear potential to improve both models and that some previous water content measurements of the CO₂-rich phase may have substantial systematic errors.</div></div>","PeriodicalId":12170,"journal":{"name":"Fluid Phase Equilibria","volume":"599 ","pages":"Article 114516"},"PeriodicalIF":2.8,"publicationDate":"2025-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144548555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}