Mixture Models and a New Form of Empirical Fundamental Equations of State by Means ofMolecular Simulation and Hybrid Data Sets

今天，经验多参数模型已成功地用于精确描述测量良好的混合物的性质。然而，这种类型的模型是有限的多组分混合物的描述，其中相关的二元子系统没有或很差的实验描述。所观察到的问题都涉及到基本的多流体对应状态的方法和用于描述纯组分的状态方程的功能。从理论上讲，不同分子之间的相互作用显然不能用对应态方法来描述。事实上，在纯流体和混合物中，分子水平上的不同特征对总相互作用产生不同的贡献。然而，这些贡献很难分离的基础上，真实的流体的实验数据。在这一点上，分子模拟有一个巨大的优势：分子参数可以系统地改变。基于Lustig的方法，可以直接分析分子特征对亥姆霍兹能量及其导数的影响。 在此基础上，它成为可能开发的经验多参数状态方程的函数形式，反映了分子参数的影响。为了达到高精度，最终方程必须拟合混合数据集（包含实验和分子模拟数据的数据集）。有了这种新类型的经验多参数状态方程的混合物模型，它描述的相互作用的基础上的组合的贡献，从不同的分子功能的相互作用的结果。如果Lustig的方法可以适用于混合物的分子模拟，则可以直接研究分子相互作用对亥姆霍兹能量导数的影响。这将为发展多参数状态方程的分子混合规则奠定基础。为了达到高准确度的目标，也需要对混合物进行混合数据集拟合。然而，差或没有实验研究的二元子系统可以正确地描述（即使不太准确）的基础上的分子参数或分子模拟数据的基础上。拟议的项目旨在开发新一代的准确的（半）经验的属性模型，这是基于广泛的和新颖的分子模拟的结果，这是明显上级现有的模型方面的描述性能较差的实验研究纯流体和二元子系统的多组分混合物。

Today, empirical multiparameter models are successfully used to accurately describe properties of well measured mixtures. However, models of this kind are limited with regard to the description of multicomponent mixtures, in which relevant binary subsystems are not or poorly experimentally described. The observed problems are related both to the underlying multi-fluid corresponding states approach and to features of the equations of state used to describe the pure components. Theoretically it is obvious that interaction between unlike molecules cannot be described by corresponding states approaches. In fact, different features on a molecular level yield different contributions to the total interaction both in a pure fluid and in a mixture. However, these contributions can hardly be separated based on experimental data for real fluids. At this point molecular simulation has a severe advantage: molecular parameter can be varied systematically. Based on the approach by Lustig it is possible to directly analyse the impact of molecular features on the Helmholtz energy and its derivatives. On this basis it becomes possible to develop functional forms for empirical multiparameter equations of state, which reflect the influence of molecular parameters. To achieve high accuracy, the final equations have to be fitted to hybrid data sets (data sets containing both experimental and molecular simulation data). With this new type of empirical multiparameter equations of state mixture models can be developed, which describe interactions based on a combination of contributions that result from interactions of unlike molecular features. If the approach by Lustig can be adapted to molecular simulations for mixtures, it becomes possible to directly investigate the influence of molecular interactions on derivatives of the Helmholtz energy. This would establish the basis for the development of molecularly founded mixing rules for multiparameter equations of state. To achieve the aimed at high accuracy, fitting to hybrid data sets will be required for mixtures as well. However, poorly or not experimentally investigated binary subsystems can be described correctly (even though less accurately) on the basis of molecular parameters or on the basis of molecular simulation data. The proposed project aims to develop a new generation of accurate (semi-)empirical property models, which are based on results of extensive and novel molecular simulations, and which are clearly superior to existing models with regard to the description of properties of poorly experimentally investigated pure fluids and binary subsystems of multicomponent mixtures.