Numerical and experimental investigation of filtration, coalescence and transport behavior in liquid-gas separation with special reference to mechanical vibration excitation

聚结过滤器是用于液滴分离的成熟元件。这些机理及其对操作参数、材料参数和其他因素的依赖，如滤芯的几何布置，导致在设计聚结过滤器时必须考虑总体分离效率和压降的复杂相互关系。在过去和当前的研究项目中，已经可以研究一些对此类过滤器分离行为的影响。特别是，卡尔斯鲁厄理工学院的Gas-Partikel-Systeme工作组对油雾过滤中的操作条件、介质的结构特性(润湿性、介质厚度、孔隙率、孔隙率分布)的各个方面进行了调查。与这项工作一样，在文献中，过滤元件一直被视为静态元件。然而，从已经观察到的机理来看，很明显，振动可以显著影响过滤的机理或工艺步骤。从气相中过滤液滴的过程分为几个过程步骤。这些包括液滴对纤维的影响、流体膜的形成以及液滴沿过滤元件的排出或脱离。在排出过程中，液体沿过滤元件输送，而在分离过程中，发生二次夹带进入气相。本应用旨在从微观层面系统地研究(周期性)激励过滤元件对液滴分离的影响、液滴的聚合行为以及液滴的脱离行为。数值研究和实验研究将结合起来。从观察振动单纤维上的单个液滴开始，将研究扩展到两个相互作用的液滴和振动单纤维上的雾化液滴链，研究的目的是描述不同激励、纤维特性和液滴尺寸下液滴的运动行为和相关的径流/脱离行为。此外，在两个或多个液滴的聚结方面也进行了同样的研究，激励型聚结过滤器的研究成果对于优化压降特性和分离行为具有重要的意义。为此目的，计划在第二个项目阶段向中观和宏观层面延伸。

Coalescing filters are well-established elements used for droplet separation. The mechanisms and their dependence on operating parameters, material parameters and other factors, such as the geometric arrangement of the filter elements, lead to complex interrelationships that must be considered in the design of a coalescing filter with respect to overall separation efficiency and pressure drop.In past and current research projects, some influences on the separation behavior of such filters could already be investigated. In particular, the working group Gas-Partikel-Systeme at the Karlsruhe Institute of Technology investigated various aspects of operating conditions, structural properties of the medium (wettability, media thickness, porosities, porosity distributions) in oil mist filtration. As with this work, in the literature filter elements have always been considered as a static element. However, from mechanisms already observed, it is clear that vibration can significantly influence the mechanisms or process steps of filtration. The filtration of droplets from the gas phase is divided into several process steps. These include the impact of the droplets on the fiber, the formation of fluid films, and the draining or detachment of the droplets along the filter element. In the process of draining, the liquid phase is transported along the filter element, and in the process of detaching, re-entrainment into the gas phase takes place. The present application aims to systematically investigate the effects of (periodically) excited filter elements on the separation of droplets, their coalescence behavior as well as detachment behavior starting from the micro level. Numerical and experimental investigations will be combined. Starting with the observation of a single droplet on a vibrating single fiber, the investigations will be extended to two interacting droplets and a mist-generated droplet chain on a vibrating single fiber.The aim of the studies is to describe the motion behavior of a droplet and the associated run-off/detachment behavior under different excitations, fiber properties and droplet sizes. In addition, the same studies are extended under the aspect of coalescence of two or more droplets.Findings on excited coalescing filters can make a significant contribution to the optimization of pressure drop characteristics and separation behavior. For this purpose, the extension to the meso and macro level is planned in a second project phase.