Molecular and Macroscopic Modeling of Fluid Phase Equilibrium

abstractcts - 0081138 f。尽管最近在模拟方法方面取得了许多进展，但尚未建立一个面向工程的框架。如果成功，提议的工作将提供一般的指导方针和具体的算法来构建这样一个面向工程的框架。在短期内，这项工作将为科学家和工程师提供有效的方法来生成任何类型的流体混合物相图，这些相图可能需要理解和揭示特定现象，或促进分离过程设计中的工程计算。从长远来看，这项工作的结果可以为过程模拟软件的开发铺平道路，该软件具有用于热力学数据生成的分子模拟“模块”。毫无疑问，一旦更好的力场和更快的计算机出现，研究相对较新的系统和过程的应用将在未来得到探索。第一步是发展通过单阶段模拟来模拟不同类型相图的方法。将开发新的吉布斯系综变体和新的伪系综方法来实现这一目标。伪系综提供了一个通用框架，将任意相平衡规范与模拟选定系综所需的参数联系起来；这些方法为生成系统热力学相空间的任意投影（相图）提供了方便的工具。第二步涉及开发新的方法来绘制相空间的特定子域，这些子域与具有许多组件的系统的多阶段过程的相平衡模拟有关。这些方法结合了模拟数据和工程热力学模型，以利用分子模拟的预测能力和工程模型的效率。新的准高斯分析模型将被研究，通过设计，合成更多的信息关于潜在的集合密度分布函数（可从仿真输出）比传统的工程模型。将研究几种系统，以测试所提出方法的有效性，特别是通过超临界反溶剂分馏分离低聚物混合物。

ABSTRACTCTS-0081138F. Escobedo/Cornell U.In spite of the numerous recent methodological advances in simulation methodologies, an engineering-oriented framework has not been established. If successful, the proposed work will provide general guidelines and specific algorithms to construct such an engineering-oriented framework. In the short term, this work will provide efficient methods that scientists and engineers can use to generate any type of phase diagram for fluid mixtures that could be needed to understand and unveil a particular phenomena or to facilitate engineering calculations in the design of separation processes. In the long term, the results of this work could pave the way to the development of process simulation software having a molecular simulation "module" for thermodynamic data generation. Applications to the study relatively new systems and processes will unquestionable be explored in the future once better force-fields and faster computers become available.The first step is the development of methods for the simulations of different classes of phase diagrams through single-stag simulations. Novel Gibbs ensemble variants and novel pseudo-ensemble methods will be developed to accomplished this. Pseudo-ensembles provide a general framework to connect arbitrary phase equilibrium specifications with the parameters needed to simulate a selected ensemble; these methods thus provide a convenient tool to generate arbitrary projections (phase diagrams) of the thermodynamic phase space of the system. The second step involves the development of new approaches to map out specific sub-domains of phase space that are relevant to the simulation of phase equilibria in multi-stage processes for systems with many components. These approaches combine simulation data and engineering thermodynamic models in order to harness the predictive power of molecular simulation and the efficiency of engineering models. Novel quasi-Gaussian analytical models will be investigated which, by design, synthesize more information about the underlying ensemble density distribution function (available from simulation output) than conventional engineering models. Several systems will be investigated to test the usefulness of the proposed methods, in particular, the separation of oligomeric mixtures by supercritical antisolvent fractionation.