Design and structural parameter optimization of Venturi-type microbubble reactor for wastewater treatment by CFD simulation

Microbubble reactors play an important role in the development of gas-liquid reaction process enhancement. However, the urgent demand for high efficiency and low energy consumption in gas-liquid reaction processes, as well as the trend towards large-scale production, have put forward higher requirements for the design and optimization of microbubble reactors. In this study, a self-priming microbubble reactor was designed and its structure parameters were optimized by (computational fluid dynamics) CFD simulations. Based on the grid division method combining structured and unstructured grids, the most suitable mesh number is selected, and the simulation calculation time is saved on the premise of ensuring the accuracy. The effects of five structural parameters on the gas content and energy loss was discussed and the optimal structural parameters of the microbubble reactor were determined as follows: the diffusion section length is 75 mm, the contraction angle is 22 degrees, the diffusion angle is 10.5 degrees, the inlet diameter of the gas phase is 6 mm, the inlet diameter of the liquid phase flowing into the gas chamber is 3 mm, the diffusion section inlet diameter is 5 mm. Under the condition of the same inlet flow rate, the outlet gas content of the optimized gas-liquid reactor is increased by 42.9% compared with the initial structure. In the wastewater treatment experiment, the microbubble reactor reduced the chemical oxygen demand of wastewater by 61% within three hours. This study provides significant references for the design of the self-priming microbubble reactor.