Mixing is one of the key unit operations in micro chemical plants. The requirements for industrial micromixers are rapid mixing, rapid heat transfer, high throughput, low pressure drop, blockage prevention, and so on. To shorten mixing time, the interfacial area between the fluids should be increased, and the diffusion length should be decreased. Various types of passive and active micromixers have been presented in the literature, but such mixers mainly focus on how to achieve rapid mixing. For example, T-shaped micromixers have a simple structure and may offer the possibility of meeting the requirements for real production. Several papers say that mixing efficiency in T-shaped micromixers is drastically enhanced in the presence of convective flow generated at high flow rate. However, there are few papers investigating the effect of convective flow not only on mixing but on heat transfer, chemical reaction, and residence time distribution.

This work is intended to investigate both T-shaped micromixers and interdigital micromixers by using CFD simulations. In the first part of this work, the influences of design and operation parameters upon mixing, heat transfer, chemical reaction, and residence time distribution are investigated. The simulation results show that the convective flow in T-shaped micromixers is effective in increasing heat transfer to realize uniform temperature distribution. In addition, the effects of convective flow are highly dependent on design and operation parameters. In the second part of this work, a systematic design method is proposed. Namely, response surface method (RSM) is introduced into the CFD-based optimal design of micromixers. RSM is one of effective statistical analysis approaches and is often used in the product design works based on experimental data. The validity of the proposed design method is assessed through case studies. The combination of CFD and RMS promotes the design efficiency of various types of micromixer.