用吉布斯相律对水相图的研究

本文用吉布斯相律对水相图进行了简要分析和研究。 1.自由度与条件自由度由吉布斯相律可知f为自由度,是描述一个特定的相平衡系统所需要的独立强度变量的数目;k和Φ分别表示平衡系统中的组分数和相数;2指平衡系统的温度和压力。如果某相平衡系统只受外界温度     

物理化学相平衡教学中几个问题的探讨与甄辨

就我国物理化学教材在介绍二组分固态不互溶系统液-固平衡相图和生成不稳定化合物的二组分凝聚系统相图中存在的若干问题进行了探讨与甄辨。探讨了在二组分固态不互溶系统液-固平衡相图的介绍中分平衡区来应用相律,以使相律的应用更有意义,使读者对相律的理解更加透彻;甄辨了在生成不稳定化合物的二组分凝聚系统相图的介绍中考虑“包晶”等动力学因素或称工程实际因素的重要性。以此为例,分析了教材与教师在教学中的关系。     

两相平衡体系的通用关系式及其应用

提出了一个能普遍适用于两相平衡体系的基本关系式，讨论了该式与其它相关方程式、定律的内在联系，并对相图中的恒沸点、临界点自由度进行了解释和说明。     

高压相图的形状及相互间的一致性

许多有关热力学和相平衡的专著都有关于高压气液平衡相图的章节和讨论。但其中有些高压气液平衡相图彼此相互矛盾,也有的与实际高压相图的形状相悖。比如,在P-x(y)图或T-x(y)图中就往往出现与实际相图不一     

二组分平衡体系的T-x相图

主要从3个方面介绍了二组分平衡体系的T-x相图。一是简单相图的介绍;二是简单相图的组合;三是实际体系复杂相图的认识。从而可以让学生理解和掌握相平衡中的二组分体系的气-液、液-液和液-固平衡的T-x相图,并为实际应用打下良好的基础。     

恒温截面法构制三维相图判误用数点分析法

以相图拓扑学规律为基础，提出了利用系列恒温截面分析相平衡空间结构以及绘制立体相图时的判误数点分析法，以实例说明数点法在相图分析中的应用，并提出了三维相图的构造的实用判误方法。     

数学函数在物理化学相平衡教学中的应用

理想完全互溶双液系、理想完全互溶固溶体相图是其他双组分相图的基础。以理想溶液热力学理论为基础,分别对这2类相图进行了函数解析并给出了理论上的相图,其与已知的标准相图一致,对学习和研究相平衡有一定指导与参考意义。     

三元水盐体系相图未饱和区25℃等密度线的计算

水盐体系相图反映了水盐体系的相平衡关系,在实际中,人们借助于水盐体系相图可以研究某种特定水盐体系的盐类析出规律,并以此为基础进行某些工业过程的设计.然而,在这些工艺过程的设计中,人们往往还需要了解体系的体积变化,以便对实现这些过程中的设备设计提供依据.同时这些过程的工业控制通常也是通过控制料液的重度来实现,因此,研究相图上的密度数据具有理论和实际意义.     

柔性高分子/液晶体系的相平衡理论

在Flory-HugginS柔性高分子溶液理论和Lebwohl-Lasher液晶模型的基础上;导出了柔性高分子/液晶复合体系的混合自由能和化学位,并计算了相应的相图。计算结果表明,体系可出现各向同性相(Ⅰ)和各向同性相(Ⅰ),以及各向同性相(Ⅰ)和向列相(N)间的相平衡。并且发现,高分子链段与液晶分子间的各向同性相互作用对I/N的相平衡有重要影响。与实验结果的比较表明,本理论能完整、正确地描述高分子/液晶体系的相平衡。     

50℃时P2O5-MgO-NH3-H2O四元体系相平衡研究

本文测定了P2O5-MgO-NH3-H2O四元体系在50℃时的相平衡数据, 绘出了干盐相图。应用Pitzer电解质溶液理论进行了活度系数关联, 计算了所研究体系在50℃的相平衡数据。     

Automated calculation of complete Pxy and Txy diagrams for binary systems

An algorithm for the calculation of global phase equilibrium diagrams has been recently developed [M. Cismondi, M.L. Michelsen, Global phase equilibrium calculations: critical lines, critical end points and liquid–liquid–vapour equilibrium in binary mixtures, J. Supercrit. Fluids 39 (2007) 287–295]. It integrates the calculation of critical lines, liquid–liquid–vapour (LLV) lines and critical end points, and was implemented in the software program GPEC: global phase equilibrium calculations [M. Cismondi, D.N. Nuñez, M.S. Zabaloy, E.A. Brignole, M.L. Michelsen, J.M. Mollerup, GPEC: a program for global phase equilibrium calculations in binary systems, in: Proceedings of the CD-ROM EQUIFASE 2006, Morelia, Michoacán, Mexico, October 21–25, 2006; www.gpec.plapiqui.edu.ar]. In this work we present the methods and computational strategy for the automated calculation of complete Pxy and Txy diagrams in binary systems. Being constructed from the points given by the global phase diagram at a specified temperature or pressure, their calculation does not require the implementation of stability analysis.     

Separation of systems based on uranium hexafluoride and some of halogen fluorides

The purpose of this paper is to present the results of the comprehensive study of the phase equilibriums liquid-solid and liquid-vapour in binary and ternary systems, formed by uranium hexafluoride, bromine trifluoride and iodine pentafluoride.Investigation of the phase equilibriums in condensed systems is done by methods of differential thermoanalysis and visual polythermal analysis. All systems belong to simple eutectics; formation of the compounds is not detected. For all systems under investigation diagrams of the phase equilibrium liquid-solid are plotted.Phase equilibriums liquid-vapour in studied systems were studied by statistical method. All systems are non-aseotropic. The article presents diagrams of the phase equilibrium liquid-vapour in binary systems, pressure of the saturated vapour dependences on liquid composition, surface of the boiling liquid and lines of the constant content of uranium hexafluoride and iodine pentafluoride in vapour phase of the ternary system UF₆-BrF₃-IF₅.     

Phase behaviour of ordered polymer solutions

Rules for equilibrium phase behaviour, laid down long ago on the basis of the two laws of thermodynamics, appear to be valid also for many polymer systems in which aggregates of various topology occur. The phase rule offers a useful tool for the construction and understanding of phase diagrams for systems in which order of some kind is prevalent in certain ranges in the diagram. ‘Double sickle’ type phase diagrams, found for surfactant solutions, microemulsions as well as block-copolymer solutions can be traced back to the considerable loss of translational entropy which accompanies aggregation.     

The solid-liquid phase diagrams of binary mixtures of even saturated fatty alcohols

This study is part of a work developed in the author's research group on the solid-liquid equilibrium of fatty substances. The phase diagrams of the following fatty alcohol systems were determined by differential scanning calorimetry (DSC): 1-octanol + 1-dodecanol, 1-octanol + 1-tetradecanol, 1-decanol + 1-tetradecanol, 1-decanol + 1-hexadecanol and 1-dodecanol + 1-octadecanol. The liquidus lines of three of these systems were previously reported in the literature but the other two systems were never published. Moreover other transitions, in addition to the eutectic temperature, were also detected in all the systems. A region of solid solution at the extreme left of the phase diagrams was observed for all the binary mixtures. Polarized light microscopy was used to complement the characterization of the systems for a full grasp of the phase diagrams. The solid-liquid equilibrium was modeled using the Margules 2-suffix, Margules 3-suffix, NRTL and UNIFAC Dortmund equations.     

A comparative study of particle swarm optimization and its variants for phase stability and equilibrium calculations in multicomponent reactive and non-reactive systems

Particle swarm optimization is a novel evolutionary stochastic global optimization method that has gained popularity in the chemical engineering community. This optimization strategy has been successfully used for several applications including thermodynamic calculations. To the best of our knowledge, the performance of PSO in phase stability and equilibrium calculations for both multicomponent reactive and non-reactive mixtures has not yet been reported. This study introduces the application of particle swarm optimization and several of its variants for solving phase stability and equilibrium problems in multicomponent systems with or without chemical equilibrium. The reliability and efficiency of a number of particle swarm optimization algorithms are tested and compared using multicomponent systems with vapor–liquid and liquid–liquid equilibrium. Our results indicate that the classical particle swarm optimization with constant cognitive and social parameters is a reliable method and offers the best performance for global minimization of the tangent plane distance function and the Gibbs energy function in both reactive and non-reactive systems.     

Spectral methods for the equations of classical density-functional theory: relaxation dynamics of microscopic films

We propose a numerical scheme based on the Chebyshev pseudo-spectral collocation method for solving the integral and integro-differential equations of the density-functional theory and its dynamic extension. We demonstrate the exponential convergence of our scheme, which typically requires much fewer discretization points to achieve the same accuracy compared to conventional methods. This discretization scheme can also incorporate the asymptotic behavior of the density, which can be of interest in the investigation of open systems. Our scheme is complemented with a numerical continuation algorithm and an appropriate time stepping algorithm, thus constituting a complete tool for an efficient and accurate calculation of phase diagrams and dynamic phenomena. To illustrate the numerical methodology, we consider an argon-like fluid adsorbed on a Lennard-Jones planar wall. First, we obtain a set of phase diagrams corresponding to the equilibrium adsorption and compare our results obtained from different approximations to the hard sphere part of the free energy functional. Using principles from the theory of sub-critical dynamic phase field models, we formulate the time-dependent equations which describe the evolution of the adsorbed film. Through dynamic considerations we interpret the phase diagrams in terms of their stability. Simulations of various wetting and drying scenarios allow us to rationalize the dynamic behavior of the system and its relation to the equilibrium properties of wetting and drying.     

Optimization and Calculation of the EuCl<Subscript>3</Subscript>–MCl (M = Na,K, Rb,Cs) Phase Diagrams

By using the CALPHAD technique, an optimization of the binary EuCl₃–MCl (M = Na, K, Rb, Cs) systems has been carried out. To describe the Gibbs energies of liquid phases in these systems the new modified quasi-chemical model was used in the pair-approximation for short-range ordering. From the measured phase equilibrium data and the experimental thermo-chemical properties, the EuCl₃–MCl phase diagrams were optimized and calculated. A set of thermodynamic functions has been optimized based on an interactive computer-assisted analysis. The calculated phase diagrams and thermodynamic data are self-consistent.     

ZnCl_2-氨基酸(Leu/Try/Val/Thr)- H_2O体系的等温溶度

α-氨基酸锌作为添加剂在药物、食品和化妆品中有广阔的应用前景 [1,2],有关氨基酸锌的合成方法文献已有系统报导 [3].用相平衡方法研究锌盐与氨基酸的配合行为,可探求它们在全浓度范围内形成化合物的可能性,提供相区大小和性质等信息 ,对可溶于水的新型锌添加剂的合成很有意义 .　　本研究组已研究了 ZnCl2- His/Phe/Met- H_2O体系在 25℃时的等温溶度 [4－ 6],为比较氨基酸结构不同对体系性质的影响,研究了 ZnCl2- Leu/Try/Val/Thr- H_2O体系在 25℃时的等温溶度,并在相平衡结果指导下,合成了未见文献报导的 6种氨基酸锌固…     

Microphase Separation in A2B Copolymer Melts

The microphase diagrams of special A2B copolymer melts were presented by using the self-consistent field theory for star copolymer systems. Unlike the phase diagram of diblock copolymer, only three classical structures, namely spherical phase, cylindrical phase and lamellar phase were discovered in the diagram of the A2B system. The change in chain architectures allowed sufficient shifts of phase boundaries and widened the range of fB for which lamellar phase occurred, to some degree. Simply, an asymmetric architecture for copolymer allowed control of the morphology independent of the volume fraction.     

稀碱金属铷、铯盐-混合溶剂多元体系相平衡研究进展

稀碱金属铷、铯资源的成功开发,需以相应的相平衡与相图研究成果为指导,开展稀碱金属盐-混合溶剂体系相平衡的研究,对这些金属盐的提纯开发利用具有重要的意义.本文主要从不同的铷、铯盐-混合溶剂三元及四元体系两个方面,归纳总结了此类体系的相平衡研究进展,探讨了研究中存在的一些问题,为深入研究稀碱金属-混合溶剂体系的相平衡奠定了基础.