Compact Mixing Using Multiple Splitting, Stretching, and Recombining Flows

The working principle of static mixers is based on repeated stretching, cutting, and stacking operations. Two-way splitting (cutting) elements are most commonly used. Multiple splitting elements increase the compactness of the mixer, but an issue is the pressure consumption. Here we first investigate how to improve existing two way splitting and recombining flows. We use the serpentine channel geometry which relevance is that it is easy to fabricate on the interface between two halves of a mold or device. Next a parallel multiple splitting method is developed which is compact and efficient in terms of pressure consumption and uniformity of the resulting layer distribution. The final design represents a fully parallel multiple mixer, circularly shaped, that uses fan shaped channels (for a uniform flow length distribution) to guide the flow to its splitting channels, where it is turned and recollected in a second fan shaped channel. Because of its twelve-way parallel splitting design, the device produces 24 layers in one mixing element and 288 layers in the second element and so on. Prototypes are fabricated, tested on performance, and compared with some existing static mixers using mixing speed, volume, length, and pressure drop as criteria. The new mixer outperforms the other designs, with an exception of the volume used.