Investigation of the influence of transport processes on chemical reactions in bubble flows using space-resolved in-situ analytics and simultaneous characterization of bubble dynamics in real-time

通过发展新的实验技术，将对提高对气泡流动中流体力学和化学反应之间相互作用的理解作出重要贡献。在这种（特殊）情况下，实验方法基于一种新的实时拉曼过程分析系统，该系统允许对同时观察到的气泡附近的液相进行空间和时间分辨的原位分析。该系统是由申请人Simon教授在另一个dfg优先项目中实施的实时过程分析系统和Rinke博士建立的原位拉曼光谱仪的扩展，该系统将在这里进一步发展并与实时过程分析系统集成。利用这一系统，将详细研究与气泡动力学有关的化学反应动力学。与气泡和气泡形状的观察相关联，空间分辨分析产生有关物质输入的相关信息。在这方面，将对气泡形状进行广泛的自动化分析，以测量大量气泡，从而获得具有统计意义的结果。在这个项目中，气泡流，气泡固定的逆流有和没有湍流的影响（网格装置），以及泰勒流在微通道内进行了研究。为了确定化学成分，实时过程分析系统将用于确定每个激光脉冲在一个或多个测量点的局部物质浓度在一个定义的时间点的气泡流。为了完成这一任务，需要记录完整的拉曼光谱，以便对具有复杂拉曼光谱的化学反应进行评估，并使用实时拉曼过程分析系统，以灵活和通用的方式应用。在记录拉曼光谱的同时，以1000帧/秒的高帧率监测上升气泡、气泡群及其周围的流场，监测/跟踪观察到的上升气泡的轨迹和动力学，例如根据气泡的位置实时确定拉曼光谱的测量点或测量点。这是由实时拉曼过程分析系统通过使用集成的图像分析机制实时确定每个图像序列中观察到的气泡的位置来完成的。在实验布置上，实时拉曼过程分析系统的光轴垂直于气泡通道中气泡的流动方向，使系统可以横向集成在测试阵列中，可以实时记录和分析气泡的二维俯视图。

By developing new experimental techniques, important contributions to an improved understanding of the interaction between hydrodynamics and chemical reactions in bubble flows shall be achieved. In this (particular) case the experimental methods are based on a novel Real-Time Raman-Process-Analysis-System that allows for a spatially and temporally-resolved in-situ analysis of the liquid phase in the vicinity of the simultaneously observed bubble. This system is an extension of the Real-Time-Process-Analysis-System, which was implemented by the applicant Professor Simon in another DFG-Priority-Program, and the in-situ Raman spectrometer established by Dr. Rinke, which shall be further developed here and integrated with the Real-Time-Process-Analysis-System.With this System the kinetics of chemical reactions in relation to the bubble dynamics will be investigated in detail. In correlation with the observation of bubbles and bubble shapes, the spatially-resolved analysis yields the relevant information about the substance input. In this regard, an extensive automated analysis of bubble shapes will be conducted to measure a large number of bubbles and thereby obtain statistically meaningful results. In this project, bubbly flows, bubbles immobilized by counter-flow with and without the influence of turbulence (grid installations) as well as Taylor-flows within microchannels are to be investigated.In order to determine the chemical composition, the Real-Time-Process-Analysis-System will be used to determine the local substance concentration for each laser pulse at one or more measurement points within a bubble flow at a defined point in time. To achieve this task, a complete Raman spectrum is to be recorded so that chemical reactions with complex Raman spectra can be evaluated and the Real-Time-Raman-Process-Analysis-System is used and applied in a flexible and universal way. Simultaneously with the recording of the Raman spectra, the rising bubbles, bubbles swarms and the surrounding flow field are monitored with high frame rates such as 1000 frames/s, to monitor/track the trajectory and dynamics of the observed rising bubble, e.g., to determine the measurement point or the measurement points for the Raman spectroscopy with respect to the position of the bubble in real-time. This is done by the Real-Time-Raman-Process-Analysis-System by determining the position of the observed bubble of each image sequence in real-time using an integrated image analysis mechanism.With respect to the experimental arrangement, the optical axis of the Real-Time-Raman-Process-Analysis-System is perpendicular to the flow direction of the bubbles in the bubble channel, so that the system can be integrated laterally in the test array and a 2D top view of the bubbles can be recorded and analyzed in real-time.