Comparison of mixing performances of T, Y and arrow-shaped micromixers using Villermaux-Dushman protocol at low Reynolds number

Abstract

Mixing performance is commonly assessed using the Villermaux–Dushman protocol. Mixing in passive mixers may need to be at very low Rey­nolds number (Re). This study is aimed at comparing the mixing performances of T, Y and arrow-shaped micromixers using the Villermaux–Dushman proto­col at Re < 100. The mixing performance test was run at flow rates of 500 to 1 mL h-1 with the pressure drop measurement. Based on UV absorbance values and experimental mixing times of mixed fluids from the three micromixers, the order of mixing performance at Re > 26.5 was Y < T < arrow-shaped micro­mixers. At lower Re values, the order of performance based on the absorbance and the experimental mixing times, became inconsistent. However, the com­parison of mixing performance based on predicted mixing time gave consistent order of performance at all Re values. The instability in UV absorbance of mixed reagents in Villermaux–Dushman protocol was noted as the major cause of the reported inconsistency at very low Re. The inadequacy of Villermaux–Dushman protocol at low Re was verified via facile solvent extraction test. A more reliable technique should be used to assess the mixing performance of micromixers at very low Re and on-line UV measurement should be adopted for the Villermaux–Dushman experiment.