Spatially resolved experimental analysis and modeling of mass transfer from rising gas bubbles under influence of swarm turbulence with superimposed chemical reaction

从分散的气相到液相的传质在化学工业和生物技术中非常重要，特别是当化学反应叠加时。然而，对于气-液反应器的设计，只有经验关联式是可用的，这表明有限的可移植性。这是因为它们基于在特定条件下获得的整体测量数据。为了更一般地描述反应系统和群湍流条件下通过平衡方程的传质性能，需要三维速度场以及浓度场。在第一个项目阶段，群序，诱导粒子网格，验证了某些气体流量。在此基础上，进一步发展了利用激光诱导荧光（LIF）技术测量、评价和重建气泡尾迹三维浓度场的方法。现在，这允许在流体动力学群条件下进行测量。三维浓度尾流的分析表明，在气泡膨胀的情况下，舍伍德数Sh = 470，这完全在预期范围内。这表明，开发的光学方法是非常适合验证数值传质计算。然而，当包括粒子图像测速技术（PIV）时，可以期望得到更精确的速度场。在即将到来的项目阶段，将研究气泡尾流中叠加反应对传质的影响，以及相反地，与反应相互作用的传质对其选择性的影响。根据swarm beneficences，PIV/LIF测量的SPP反应系统Fe-NO的传质数据，以及核磁共振（NMR）测量的复杂性降低的流动条件（泰勒流）。为此，我们将调整SPP的领导实验泰勒流的NMR测量SPP反应体系Fe-NO和Cu-O2的要求。此外，我们要描述的相似性和差异，在层流泰勒流以及湍流群条件下的单气泡尾流的传质现象。连同化学，实验和数值工作组的SPP，这种分析的目的是导致识别的现象学建模的气液反应器中的传质。

The mass transfer from a dispersed gas phase into the liquid phase is of high importance in chemical industry and biotechnology, especially when a chemical reaction is superimposed. However, for a design of gas-liquid reactors, only empirical correlations are available, which show limited transferability. This is because they are based on integrally measured data obtained under specific conditions. For a more general description of the mass transfer performance for reactive systems and under swarm turbulence conditions via balance equations, three-dimensional velocity fields as well as concentration fields are required. In the first project phase swarm turbulences, induced by particle grids, were validated for certain gas flows. Based on this, the method of measuring, evaluating, and reconstructing three-dimensional concentration fields of bubble wakes were developed further by the laser induced fluorescence (LIF). This now allows measurements under hydrodynamic swarm conditions. The analysis of the three-dimensional concentration wake showed in case of a zigzagging gas bubble a Sherwood number of Sh = 470, which lies perfectly within the expectations. This shows that the developed optical method is very well suitable for validating numerical mass transfer calculations. When including Particle Image Velocimetry (PIV), however, even more precise velocity fields can be expected.In the project phase to come, the influence of superimposed reactions on mass transfer within bubble wakes is to be investigated as well as conversely the influence of mass transfer, interacting with reactions, on their selectivity. Under swarm turbulences, PIV/LIF measurements of mass transfer data for the SPP reaction system Fe-NO are scheduled as well as Nuclear Magnetic Resonance (NMR) measurements for flow conditions of reduced complexity (Taylor flow). For this purpose we will adapt the SPP's lead experiment Taylor flow on NMR requirements for measuring SPP reaction systems Fe-NO and Cu-O2.Furthermore we want to describe analogies and differences of mass transfer phenomena in wakes of single bubbles in laminar Taylor flow as well as under turbulent swarm conditions. Together with chemically, experimentally, and numerically working groups of the SPP, this analysis is intended to lead into the identification of a phenomenological modelling of mass transfer in gas-liquid reactors.