Convective mixing and chemical reactions in microchannels with high flow rates

This work presents a theoretical and experimental investigation of convective micromixing in various mixer structures and combinations with the aim of high mixing intensity and a high throughput. Different mixing elements are integrated on a silicon chip to achieve a device for high flow rates above 20 kg/h. Test structures are fabricated and characterized according to their flow behavior and mixing performance. Flow measurements with pH neutralization and indication by bromothymol blue confirm the numerical simulations of the flow characteristics and concentration fields. The integral mixing quality in the micromixer is measured with the iodide-iodate reaction (Villermaux-Dushman) and shows excellent values for high Re numbers. This offers the potential to use microstructures for new applications in the production of chemicals. With the help of the obtained experimental and theoretical results, a new class of dimensionless numbers is proposed which characterizes the effectiveness of a mixing device and of the mixing process and compares different mixing times.