Dew-Point Densities of Fluid Mixtures - New Approaches for Measurement and Modeling

拟议研究项目的目的是开发新的实验技术，用于精确测量流体混合物的露点密度，克服现有技术中的困难。这包括吸附效应的量化，从而大大减少不确定性。一个新的理论将被锻造，这将联合收割机，第一次，热力学性质测量和吸附现象的成熟领域。此外，测量数据将被用来建立多参数基本状态方程，从而有关的拟合策略的新想法将被检查。流体混合物的相行为的调查是热物理性质研究的一个主要焦点。为了使这项研究的成果适用于科学和工业，例如在天然气加工和碳捕获和储存领域，需要精确描述液体和蒸汽之间的相边界的属性模型。开发这种模型的最重要的先决条件是准确的实验数据，然而，现有的数据集存在差距和不足。为了发展能够描述混合物相平衡的状态方程，主要使用VLE（汽液平衡）数据。然而，只有很少的汽液平衡数据考虑饱和液体和饱和蒸汽密度。但是，正是这些数据提供了完整的实验信息的汽液平衡状态，这将是绝对需要的，以推进现有的状态方程的最先进的状态。准确的饱和液体密度的流体混合物在NIST测量在20世纪80年代，并在鲁尔大学的一个新的和高度精确的实验装置，现在可以专门设计来测量这种类型的数据。与此相反，流体混合物露点密度的准确数据几乎从来没有存在。实验方法来测量流体混合物的饱和液体和饱和蒸汽密度的汽液平衡特性的全套非常稀缺。所谓的分析测量方法的最重要的不确定性来源是对相进行取样以进行组成分析，因为会出现实质性的问题（例如，改变组成并扰乱平衡）。另外，密度测量技术对于气态不够准确。因此，需要一种合成方法，这意味着样品的成分是准确已知的，并结合准确的密度测量技术。在这种情况下，最近的研究表明，准确地知道的组成是不够的，当吸附效应和毛细冷凝不考虑。这些干扰效应使测量的密度失真，因此需要理解和考虑这些干扰效应。

The aim of the proposed research project is to develop new experimental techniques for the accurate measurement of dew-point densities of fluid mixtures, which overcome difficulties in currently existing techniques. This includes the quantification of sorption effects, thus, significantly reducing uncertainties. A new theory will be forged, which will combine, for the first time, the well-established fields of thermodynamic property measurement and sorption phenomena. Furthermore, the measured data will be used to establish multiparameter fundamental equations of state, whereby new ideas regarding the fitting strategy will be examined.The investigation of the phase behavior of fluid mixtures is a major focus of thermophysical property research. To make the outcome of this research applicable for science and industry, for example in the fields of natural gas processing and carbon capture and storage, property models accurately describing the phase boundary between liquid and vapor are required. The most important prerequisite for the development of such models are accurate experimental data, however, there are gaps and deficiencies in the presently existing data sets. For the development of equations of state, which are able to describe the phase equilibrium of mixtures, mainly VLE (vapor-liquid equilibrium) data are used. Nevertheless, only very few VLE data consider the saturated liquid and saturated vapor densities. But it is exactly these kinds of data that provide complete experimental information on the VLE state, which would be absolutely required to advance the state of the art of the existing equations of state.Accurate saturated liquid densities of fluid mixtures were measured at NIST in the 1980s, and at Ruhr-University a new and highly accurate experimental apparatus is available by now specifically designed to measure this type of data. In contrast, accurate data for fluid mixture dew-point densities virtually never exist.Experimental approaches to measure the full set of VLE properties of fluid mixtures including the saturated liquid and saturated vapor densities are very scarce. The most significant source of uncertainty of so-called analytic measurement approaches is sampling the phases for composition analysis because substantial problems occur (e.g., changing the composition and disturbing the equilibrium). Additionally, the density measurement techniques are not sufficiently accurate for gaseous states. Hence, a synthetic approach, which means the composition of the sample is accurately known, in combination with an accurate density measurement technique is required. In this context, recent studies have shown that exactly knowing the composition is not sufficient when sorption effects and capillary condensation are not considered. These disturbing effects distort the measured density and, therefore, they need to be understood and taken into account.