Experimental Investigation of Reactive Bubbly Flows - Influence of Boundary Layer Dynamics on Mass Transfer and Chemical Reactions
In chemical process engineering often a gaseous substance has to be mixed with a continuous liquid phase in order to perform a reaction with high yield and selectivity (e.g. oxidation or hydrogenation). For this purpose, the use of well-mixed bubble flows is preferred, in which the gaseous phase is dispersed in the liquid phase. The timescales of mixing are especially determined by the transport processes in the boundary layer close to the phase boundary and by the bubble swarm-turbulence. Tuning the transport timescales and the timescales of the chemical reactions can lead to a considerable potential for optimization of the actual yield and selectivity. Thus transport processes in the boundary layer and close to the interphase in bubble flows with a following chemical reaction are experimentally determined and subsequently modeled in the framework of this priority program. Especially the influence of dynamic interface deformation of the bubbles, due to shape dynamics (wobbling), the momentum exchange at the gas-liquid interface (swarm turbulence) and bubble collisions (bouncing) are taken into account. To accurately observe the local transport processes near the phase boundary Time Resolved Scanning - Laser Induced Fluorescence (TRS-LIF) and high-resolution Particle Image Velocimetry (PIV) are applied. In the second funding period, the newly developed chemical reaction systems will be used to enable the analysis, modeling and calculation of the yield and selectivity of consecutive-parallel reactions in bubble flows.