Mixing Enhancement in Microchannels by Periodic Pressure Disturbances

This study reports flow visualization and measurements of the enhanced mixing that is effectively achieved by introducing pressure disturbance in a double T-junction micromixer. The disturbance of sinusoidal waveform was introduced through the perturbation channels with either symmetric or asymmetric arrangement. Quantification of the mixing efficiency is based on the color change resulting from the chemical reaction of two species, one is ferric chloride and the other is ammonium thiocyanate, contained in the two the streams for mixing. The mixing efficiency was measured as a function of oscillation frequency in a range of 2-60 Hz while maintaining the oscillation amplitude constant for flow rates between 5-15 mL/hr. It is found that the mixing efficiency grows with increasing frequency in the lower frequency range until reaching a maximum that can be as much as nearly ten times the undisturbed case. Then a further increase of the frequency may lead to reducing or retarding the growth. In the cases of asymmetric disturbance, the maximum mixing efficiency occurs at higher frequency for larger flow rate. It is also found that the mixing efficiency can be effectively raised with increasing disturbance amplitude, and the symmetric disturbance seems more effective in enhancing the mixing than the asymmetric disturbance.

並列關鍵字

Microchannel flow ； Two-phase mixing ； Pressure perturbation ； Mixing efficiency

國際替代計量

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