(97c) Numerical and Experimental Study of Mixing Enhancement in Micromixers Using Residence Time Distribution (Rtd)

The small physical dimensions of micromixers/reactors in combination with low processing flow rate, imply laminar flow, which precludes convective turbulent mixing normally relied upon for effective mixing in conventional-size processing equipment. Laminar flow poses a challenge, and mass transfer enhancement is therefore a critical issue in micro-channel mixers/reactors. The objective of this work is to utilize a combination of well-designed micromixers, a unique numerical approach, and a matching experimental set-up and procedure along with a mixing characterization measure for the study of mixing in micromixers/reactors, the development of which will greatly benefit the numerous potential applications of microchemical systems, and other related novel technologies. In this mixing enhancement study, three multilaminated/elongational flow mixers (MEFMs), uniquely designed to effect mixing using passive mixing structures by creating folding as well as local and global re-orientation of fluid interfaces, are investigated along with the standard T-junction mixer for their mixing performance. The knowledge base necessary for establishing the experimental platform for this mixing study is created first using Computational Fluid Dynamics (CFD) approach. Using the residence time distribution (RTD) and species mass fraction distribution (SMFD) as the mixing characterization measures, the results obtained from the numerical study show that the MEFMs give excellent mixing performance when compared with the standard T-junction mixer and a cross-shaped micromixer reported in the literature. The RTD is an innovative technique for experimental characterization of mixing in micromixers/reactors. The preliminary results from the experimental procedure that utilizes UV-vis absorption spectroscopy detection technique to obtain RTD in the micromixers will also be presented.