Phase Diagrams of Fluid Mixtures by Simulation

通过模拟绘制流体混合物的相图

• 批准号: 8708734
• 负责人: Athanassios Panagiotopoulos
• 金额: --
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-07-01 至 1989-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8708734&HistoricalAwards=false
• 关键词: Phase; Diagrams; Fluid; Mixtures; Simulation

Research Summary: The objective of this project is the investigation of phase equilibrium properties of fluid mixtures by computer simulation in a new ensemble. The Gibbs ensemble Monte Carlo simulation technique enables the direct determination of the properties of two coexisting fluid phases (e.g., a liquid at equilibrium with its vapor) from a single computer experiment. The first part of this project will be the extension of the Gibbs technique to multicomponent systems. The method will then be applied for the determination of the effect of intermolecular potential parameters (size, shape and polarity of the components of a mixture) on the mixture critical curves and the presence of azeotropes, liquid-liquid and fluid-fluid immiscibility gaps. By selecting appropriate models for the intermolecular interactions, the behavior of systems that approximate real mixtures of engineering interest will then be studied. Finally, a comparison between direct computer simulation results and theoretical or semi-empirical models will be performed. Innovation/Novelty: The Gibbs method (recently proposed by the PI) is the first practical technique available for exact determination of phase equilibria in complex systems with given intermolecular interactions. Until now, the calculation of phase equilibria from simulation was extremely difficult because a large number of laborious free-energy determinations was required. This research will provide extensive phase equilibrium data on well-defined model systems. Such data are not currently available, despite the significant role they can play in the development of improved theoretical and semi-empirical models for the thermodynamic behavior of fluids. In addition, realistic mixtures of engineering importance will be studied for the first time by exact simulation methods. Technical Impact and Significance: Detailed knowledge of the phase behavior of fluid mixtures is needed for the efficient design and operation of many separation processes in chemical engineering (e.g., distillation, liquid-liquid extraction, enhanced oil recovery), but similar needs may arise in many other fields, including geophysics, biomedicine and the study of dense planetary atmospheres. The proposed research will significantly contribute to the development of molecular simulation techniques (to complement experiment and theory) for this purpose. The new simulation methodology can also find applications for the molecular-based study of a wide range of industrially important phenomena. Examples of such possibilities would be the study of adsorption by solids and physical equilibria in microporous catalysts (relevant for the oil and chemical process industries), micelle formation and stability in surfactant sytems (important for the cosmetics and pharmaceuticl industries, as well as for the study of living systems), and equilibria in the presence of semi-permeable membranes (significant for the development of new separation methods for the biotechnology industry).

研究综述：本项目的目标是在一种新的系综中通过计算机模拟来研究流体混合物的相平衡性质。Gibbs系综蒙特卡罗模拟技术能够从单个计算机实验中直接确定两个共存的流体相(例如，处于平衡状态的液体及其蒸汽)的性质。该项目的第一部分将是将吉布斯技术扩展到多组分系统。然后，该方法将用于确定分子间势参数(混合物组分的大小、形状和极性)对混合物临界曲线的影响，以及共沸物、液-液和液-液不混溶间隙的存在。通过选择分子间相互作用的适当模型，然后将研究接近于工程上感兴趣的真实混合物的系统的行为。最后，将直接计算机模拟结果与理论或半经验模型进行比较。创新/新颖性：Gibbs方法(最近由PI提出)是第一个可用于精确确定具有给定分子间相互作用的复杂体系的相平衡的实用技术。到目前为止，从模拟中计算相平衡是非常困难的，因为需要大量费力的自由能测定。这项研究将在明确定义的模型体系上提供广泛的相平衡数据。尽管这些数据可以在改进的流体热力学行为的理论和半经验模型的发展中发挥重要作用，但目前还没有这些数据。此外，还将首次通过精确的模拟方法研究具有工程重要性的现实混合物。技术影响和意义：化学工程中许多分离过程(如蒸馏、液液萃取、提高石油采收率)的有效设计和操作需要对流体混合物相行为的详细了解，但在许多其他领域也可能出现类似的需求，包括地球物理、生物医学和对稠密行星大气的研究。建议的研究将对分子模拟技术的发展做出重大贡献(以补充实验和理论)。这种新的模拟方法还可以应用于对广泛的工业重要现象进行基于分子的研究。这种可能性的例子包括研究固体在微孔催化剂中的吸附和物理平衡(与石油和化工工业有关)、表面活性剂体系中胶束的形成和稳定性(对化妆品和制药工业以及生命系统的研究很重要)，以及在半透膜存在下的平衡(对生物技术工业新分离方法的开发具有重要意义)。