Soret effect in ternary fluids

由于索雷特效应（热扩散），多组分流体中的热量和质量传递是耦合的。根据最近的实验发展，由于提交者的重要贡献，三元体系的研究现在已经变得可行。三元系统是向现实的多组分系统迈出的第一步。与此同时，它们还不是太复杂，无法进行理论处理。在项目的第一阶段，研制了性能良好的多色OBD仪器（OBD =光束偏转），并成功地用于测量所谓的基准体系十二烷-异丁基苯-四氢萘（DCMIX1）。在新的项目期内，完成本系统的调研，调研新的示范系统。重点关注的是所谓的dcmix -体系甲醇-甲苯-环己烷（DCMIX2）和三乙烯乙二醇-乙醇-水（DCMIX3）。目前，在欧空局一个国际项目的框架内，在提交者的参与下，正在微重力条件下研究这些系统的一些选定组成部分。这里提出的项目的一个基本目标是在整个三元参数空间内确定这些系统的扩散，热扩散和Soret系数。光学多色技术中浓度测量的准确性，如本文所采用的OBD，决定性地取决于对比度因子矩阵的质量，而对比度因子矩阵需要被反转。通过对密度的额外了解，可以实现对对比度因素的理论化和一致的参数化。这也允许在适度病态的情况下，以足够的精度反演对比矩阵。与理论小组合作，二元混合物的概念将被转移到三元系统。

Heat and mass transport in multicomponent fluids are coupled due to the Soret effect (thermodiffusion). Based on recent experimental developments, with important contribution stemming from the group of the submitter, the investigation of ternary systems has now become feasible. Ternary systems are a first step towards realistic multi component systems. At the same time they are not yet too complex for a theoretical treatment. During the first period of the project a very well performing multicolor OBD instrument (OBD = optical beam deflection) has been developed and successfully been employed for measurements of the so-called benchmark system dodecane-isobutylbenzene-tetrahydronaphtalene (DCMIX1). In the new project period the investigation of this system shall be completed and new model systems shall be investigated. In the focus of interest are the so-called DCMIX-systems methanol-toluene-cyclohexane (DCMIX2) and triethylenglykol-ethanol-water (DCMIX3). A few selected compositions of these systems are presently investigated under microgravity conditions within the framework of an international ESA project with participation of the submitter. An essential aim of the here proposed project is the determination of the diffusion, thermodiffusion and Soret coefficients of these systems within the entire ternary parameter space. The accuracy of the concentration measurement in optical multicolor techniques, like the here employed OBD, decisively depends on the quality of the contrast factor matrix, which needs to be inverted. With the additional knowledge of the density, a theoretically motivated and consistent parameterization of the contrast factors can be achieved. This allows also in a moderately ill-conditioned case for an inversion of the contrast matrix with sufficient accuracy. In collaboration with theoretical groups the concepts developed for binary mixtures will be transfered to ternary systems.