Experimental investigation of liquid–liquid mixing in T-shaped micro-mixers using μμ-LIF and μμ-PIV

Microreaction engineering enables new strategies in process intensification, e.g. reactions with high selectivity, through exploitation of the smallest scales. A basis for this is a precise analysis of local mass transfer and hydrodynamics in micro-mixers for different flow regimes. The micro-mixer we used for experimental investigations is a simple T-shaped micro-mixer with rectangular cross-sections and very smooth surfaces (reactive ion etching) to enable a good approximation by numerical models. Although the investigations were performed in the low Re   range without turbulence, the T-shaped micro-mixer intentionally promotes the generation of vortex structures. The goal of this research work is to show that despite laminar flow conditions short diffusion lengths are achievable and to clarify the mechanisms and required conditions. For the determination of the mixing quality and the specific contact area between the species the concentration field is measured using the technique “micro Laser-induced fluorescence” (μμ-LIF). For further understanding and verification of numerical models the velocity field is measured by “micro Particle Image Velocimetry” (μμ-PIV).