Study on the properties of bulk micro-nanobubbles water generated by multi-jet hydrodynamic cavitation

Abstract

The micro-nanobubbles (MNBs) technology provides an innovative theoretical basis and application prospect for solving the problem of water treatment. However, the fabrication of bubble generators with high MNBs generation efficiency has always been challenging. Herein, we developed a new hydrodynamic cavitation bubble generator by equipping the multi-jet reactor to enhance the shear breakage effect of bubbles. The breakup behavior of bubbles with different diameters and velocities in jet orifices was investigated by numerical simulation. At the same time, the turbulent model of two-phase flow in the Venturi gas-liquid mixer was established to analyze the internal flow field under different intake rates. The bubble size and dissolved oxygen (DO) concentration of bulk MNBs water were determined through image analysis and a DO sensor, respectively. The results showed that the cavitation generator produced bubbles with diameters no larger than 27.85 μm. Moreover, the MNBs generator exhibited a superior oxygen-dissolving capability, which was 1.48 times that of general aerated water. This study has deepened the comprehension of the bubble breakup mechanism, providing a reference for designing and developing of MNBs generation technology.