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- 주제어 : phase equilibria (검색결과 148 건)
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Modeling hydrate-containing phase equilibria for mixtures with sulfur dioxide or alkali halides
Kim, S.H.,Kang, J.W.,Lee, C.S. Elsevier Scientific Pub. Co 2016 Fluid phase equilibria Vol.417 No.-
<P>Gas hydrate-containing phase behaviors are essentially required for flow assurance in carbon dioxide sequestrations and resources recovery. To model effects of weak electrolyte such as SO2 and strong electrolytes such as alkali halides on phase equilibria of hydrate systems, an electrolyte equation of state is used, which is based on hydrogen-bonding nonrandom lattice fluid equation of state for fluid phases and van der Waals and Platteeuw model for hydrate phases. A guest gas of SO2 is modeled as partially dissociating component in aqueous solution. Various phase behaviors of water and SO2 mixtures for hydrate-free and hydrate-forming conditions are analyzed by comparing the model results with experimental data. An improvement in accuracy of liquid liquid equilibria for the mixture is achieved by the inclusion of cross-association between water and SO2. The proposed model has been also found to provide with reliable predictions of hydrate-containing phase equilibria for a binary guest of CO2 and SO2. In the presence of NaCl or KCl as an inhibitor of formed hydrate, predicted incipient hydrate-forming conditions of single guests such as methane, ethane, propane, and CO2 are compared with experimental data and available models, showing good agreement with the data. (C) 2016 Elsevier B.V. All rights reserved.</P>
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Cha, J.H.,Kang, S.P.,Han, S.,Kang, J.W.,Kim, K.S. Elsevier Scientific Pub. Co 2016 Fluid phase equilibria Vol.413 No.-
<P>The equilibrium boundaries of CH4 and CO2 hydrates were examined in the presence of di-carboxylic acids, glutaric acid and malonic acid, at a mass fraction of 0.1 and 0.01. Including di-carboxylic acids in the water phase shifted the phase boundaries to higher pressure and lower temperature conditions. We attributed this to the formation of hydrogen bonding between the inhibitors and water molecules rather than to the formation of water structures serving as hydrate precursors. In addition, the inhibition effect of shorter carbon -chained malonic acid was better than that of longer-chained glutaric acid due to its higher mole fraction in water phase. This inhibition effect was compared with that of conventional thermodynamic hydrate inhibitors (THIs) used in commercial processes. The comparison showed that the effect of malonic acid was close to that of tri-ethylene glycol for inhibiting the CH4 hydrate. (C) 2015 Elsevier B.V. All rights reserved.</P>
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Kim, Jae Hyung,Lee, Jung Hee,Kim, Jong Min,Lee, Seong Hyuk The Japan Institute of Metals 2009 MATERIALS TRANSACTIONS Vol.50 No.7
<P>A non-equilibrium phase field model (NPFM) is proposed to examine the three-dimensional coalescence characteristics of low melting point alloy (LMPA) fillers, widely used for self-organized interconnection applications. This model sufficiently considers the non-equilibrium process during phase transitions, resulting in accurate prediction of interfaces between two different phases with a high density ratio. The preliminary simulation is carried out for validation of the present model and numerical predictions are in good agreement with analytical solutions for a one-dimensional solidification problem. The proposed NPFM successfully predicts the phase transition, the heat transfer from solid to liquid, and the coalescence behaviors of LMPA fillers, whereas the conventional enthalpy method fails to describe the non-equilibrium phase transition. Moreover, the results show that there exists grid dependency in the mush zone, suggesting that special care should be taken of the mush zone for better prediction of interfaces between different phases.</P>
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MULTIPHASE EQUILIBRIUM, PHASE STABILITY AND PHASE TRANSFORMATION IN NANOCRYSTALLINE ALLOY SYSTEMS
W. W. XU,X. Y. SONG,Z. X. ZHANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2012 NANO Vol.7 No.2
A nanoscale thermodynamic approach is developed to quantify the multiphase equilibrium in nanocrystalline alloy systems. The nanoscale multiphase equilibrium calculations indicate that the activities and mole numbers of phases in alloy systems change diversely as a function of the nanograin size at constant temperature, which results in distinctly different characteristics of phase stability and phase transformation behavior in nanocrystalline alloys with respect to coarse-grained polycrystalline counterparts. Take the nanocrystalline Sm–Co alloy system as an example, the diverse phase stabilities and phase transformations are demonstrated. To verify the thermodynamic predictions, a series of experiments on preparation and characterization of nanocrystalline SmCo3, Sm2Co7 and SmCo2 alloys have been performed. The experimental results are in agreement with the model calculations, which validate the present thermodynamic approach for nanoscale multiphase equilibrium.
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Dongdong Wang,Yang Lu,Zhuo Sun,Wei Liang,Dongshu Sun,Changli Qi,ChengZhuo Sheng,Xiaopeng Yu 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.2
An aqueous two-phase system (ATPS) containing an ionic liquid (1-(2-methoxyethyl)-3-methylimidazolium bromide) and three organic salts (K3C6H5O7, (NH4)3C6H5O7, and K2C4H4O6) at different temperatures was designed. Binodal data were correlated using two empirical equations, and tie-line data were fit with the utilization of Bancroft and Othmer-Tobias equations. In the systems investigated, three conclusions were drawn from the study of the phase-forming ability of salt through effective excluded volume, Gibbs free energy of ions, and the phase diagram. First, if the same cations of salt were present, the ability of salt to form phases increased with increasing valence of the anion. Second, the larger the effective excluded volume, the stronger the aforementioned ability of salt in forming phases. Third, salt had more ability to form phases if cations (or anions) contained in the salt possessed higher negative Gibbs free energy when the cation (anion) of the salt was the same. The effect of temperature on ATPSs was also investigated. It was found that it was easier to form ATPSs at lower temperature, and the tie-line slope showed growing absolute values as the temperature was decreased.
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Salt-Induced Protein Precipitation in Aqueous Solution: Single and Binary Protein Systems
Kim, Sang-Gon,Bae, Young-Chan The Polymer Society of Korea 2003 Macromolecular Research Vol.11 No.1
A molecular-thermodynamic model is developed for the salt-induced protein precipitation. The protein molecules interact through four intermolecular potentials. An equation of state is derived based on the statistical mechanical perturbation theory with the modified Chiew's equation for the fluid phase, Young's equation for the solid phase as the reference system and a perturbation based on the protein-protein effective two body potential. The equation of state provides an expression for the chemical potential of the protein. In a single protein system, the phase separation is represented by fluid-fluid equilibria. The precipitation behaviors are simulated with the partition coefficient at various salt concentrations and degree of pre-aggregation effect for the protein particles. In a binary protein system, we regard the system as a fluid-solid phase equilibrium. At equilibrium, we compute the reduced osmotic pressure-composition diagram in the diverse protein size difference and salt concentrations.
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임계규,이광희 한국수소및신에너지학회 2012 한국수소 및 신에너지학회논문집 Vol.23 No.6
Gas resources captured in the form of gas hydrates are an order of magnitude larger than the resources available from conventional resources. Focus of this research is to investigate the effect of DME on phase equilibria of methane hydrate, as well as the possibility of the use of the PRO/II computer simulation to estimate the phase equilibria. In systems containing water and a gaseous component like, for instance, methane, ethane , and propane, gas hydrates may occur, if conditions in terms of pressure and temperature are satisfied. Mixtures of gases, e.g. LPG or natural gas, are also able to form gas hydrates in the presence of water. The experiments presented here were performed at temperatures varying between 268.15K and 288.15K and at pressures varying between 1.88 MPa and 10.56 MPa. It was found that the phase equilibria of methane hydrate is influenced by the addition of DME to the system. The pressure for the equilibrium hydrate-liquid water-vapor (H - Lw - V) in the system water + methane is reduced upon addition of DME. The phase equilibria of methane hydrate can be estimated by the PRO/II computer simulation, whereas those of methane hydrate containing DME or LPG can't be estimated properly.
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Jeong-lae Kim,Hakmin Kim,Su In Park,Gyu Min An,Min Gi Kim,Moon Sam Shin 한국화학공학회 2019 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.57 No.7
Isothermal (vapor + liquid) equilibrium data measurements were undertaken for the binary mixtures of (propylene oxide + 1-pentanol) system at three different temperatures (303.15, 318.15, and 333.15) K. The Peng-Robinson- Stryjek-Vera equation of state (PRSV EOS) was used to correlate the experimental data. The van der Waals onefluid mixing rule was used for the vapor phase and the Wong-Sandler mixing rule, which incorporates the non-random two liquid (NRTL) model, the universal quasi-chemical (UNIQUAC) model and the Wilson model, was used for the liquid phase. The experimental data were in good agreement with the correlation results.
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Synthesis of Pt-Pd antimonide minerals at 1000 °C and the extent of Pt-Pd substitutions
Won Sa Kim 한국지질과학협의회 2009 Geosciences Journal Vol.13 No.1
Phase relations of the Pt-Pd-Sb system were investigated at 1000 °C, with an emphasis on the extent of Pt-Pd substitutions in Pt and Pd antimonide minerals and their stable assemblages. The sealed capsule technique was used, and the reaction products were examined using reflected light microscope, X-ray powder diffractometer, and electron microprobe. Pt-Pd alloy minerals, stumpflite (PtSb), geversite (PtSb2), mertieite II (Pd8Sb3), and stibiopalladinite (Pd31Sb12) occur as solid phases. In addition, solid phases with compositions of Pd20Sb7 and Pd5Sb2 are present. The extents of the Pd substitution for Pt in stumpflite and geversite were measured to be 18 and 7.2 atom (at.) %, respectively. Mertieite II (Pd8Sb3) and stibiopalladinite (Pd31Sb12,) show almost identical extent of the Pt-Pd substitution (22 at.%). The Pt substitutions for Pd in synthetic phases of Pd20Sb7 and Pd5Sb2 range up to 27 and 19.6 at.%, respectively. Pt and Pd form a complete solid solution and their solid solutions with Sb range from 7.5 at.% along the Pt-Sb binary join to 16.5 at.% along the Pd-Sb binary join.
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( Jeong-lae Kim ),( Hakmin Kim ),( Su In Park ),( Gyu Min An ),( Min Gi Kim ),( Moon Sam Shin ) 한국화학공학회 2019 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.57 No.1
Isothermal (vapor + liquid) equilibrium data measurements were undertaken for the binary mixtures of (propylene oxide + 1-pentanol) system at three different temperatures (303.15, 318.15, and 333.15) K. The Peng-Robinson- Stryjek-Vera equation of state (PRSV EOS) was used to correlate the experimental data. The van der Waals onefluid mixing rule was used for the vapor phase and the Wong-Sandler mixing rule, which incorporates the non-random two liquid (NRTL) model, the universal quasi-chemical (UNIQUAC) model and the Wilson model, was used for the liquid phase. The experimental data were in good agreement with the correlation results.
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