Molecular and Macroscopic Modeling of Fluid Phase Equilibrium

摘要：0081138F。尽管最近在模拟方法学方面取得了许多方法学上的进展，但还没有建立一个面向工程的框架。如果成功，拟议的工作将为构建这样一个面向工程的框架提供一般指导方针和具体算法。在短期内，这项工作将提供有效的方法，科学家和工程师可以用来生成任何类型的流体混合物相图，这些相图可能是理解和揭示特定现象或促进分离过程设计中的工程计算所必需的。从长远来看，这项工作的结果可能为开发具有热力学数据生成分子模拟“模块”的过程模拟软件铺平道路。一旦有了更好的力场和更快的计算机，未来将毫无疑问地探索相对较新的系统和过程在研究中的应用。第一步是开发通过单阶段模拟来模拟不同类型相图的方法。将开发新的Gibbs系综变体和新的伪系综方法来实现这一点。伪系综提供了一个将任意相平衡规范与模拟所选系综所需的参数联系起来的通用框架；因此，这些方法提供了一个方便的工具来生成系统热力学相空间的任意投影(相图)。第二步包括开发新的方法来绘制与多组分系统的多阶段过程中的相平衡的模拟相关的相空间的特定子域。这些方法将模拟数据和工程热力学模型结合起来，以利用分子模拟的预测能力和工程模型的效率。将研究新的准高斯分析模型，它在设计上比传统的工程模型合成了更多关于潜在系综密度分布函数的信息(可从模拟输出获得)。将对几个系统进行研究，以测试所建议方法的有效性，特别是通过超临界抗溶剂分馏分离低聚混合物。

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.