Generation of micro-nano bubbles by self-developed swirl-type micro-nano bubble generator

The fabrication of bubble generator with high micro-nano bubble generation efficiency has always been chal-lenging. Strong turbulence is considered to be beneficial. Herein, we developed a swirl-type micro-nano bubble generator by equipping a variable-pitch spiral cavitation reactor to enhance the shear breakage effect of bubbles. The variable-pitch spiral guide vanes and central column were innovatively installed into the cavitation reactor to generate swirling liquid flow so as to intensify gas-liquid contacting and mixing. The effect of geometric parameters on the flow field structure was investigated through numerical simulations and the optimum structure was obtained. Then the lab-scale swirl-type micro-nano bubble generator was manufactured to conduct flow tests. The bubbles with size down to 0.301 mu m were generated. In addition, the bubble generator displayed superior oxygen enrichment capacity, which was higher than that of the traditional venturi tube. The insights from this study provide a guideline for the development of efficient micro-nano bubble generators.

Automated summary

In this study, a swirl-type micro-nano bubble generator was developed, using a variable-pitch spiral guide vanes and central column to generate swirling liquid flow for enhanced gas-liquid contacting and mixing. Numerical simulations were conducted to optimize the geometric parameters, and a lab-scale generator was successfully manufactured to produce small-sized bubbles. The generator showed superior oxygen enrichment capacity.