Abstract:

The bubble diameter and gas phase distribution in the micro-bubble generator were calculated and analyzed by computational fluid dynamics-population balance model(CFD-PBM) simulation method. The effects of changes in flow field and bubble distribution characteristics were researched, the process parameters and fluid properties on bubble distribution were investigated, and the liquid inlet structure was optimized. The research results indicated that the proportion of large bubbles was high at the outlet of conventional straight tubes, while small bubbles with a diameter of less than 40 μm were gathered at the bottom center of the micro porous tube. The increase in gas flow rate, decrease in liquid flow rate, and increase in surface tension all caused the size distribution of bubbles at the outlet of the pipe to shift towards larger sizes, and the volume fraction of large bubbles increased. The increase in liquid viscosity led to an increase in both small-sized and large-sized bubbles. The decrease of outlet pressure could also cause the size distribution of bubbles at the outlet of the pipe to shift towards larger sizes, but it had no significant effect on the volume fraction of large bubbles. Compared to straight tubes, the gas phase diffusion distribution inside the swirl tube was more uniform, resulting in smaller and more micro bubbles, and a larger amount of dissolved gas in the liquid.

Key words: microbubbles, bubble distribution, structural optimization

摘要：

通过计算流体动力学-群体平衡模型（CFD-PBM）仿真方法对微孔管微气泡发生器内气泡直径及气相分布进行计算分析，研究管内流场及气泡分布特性，考察工艺参数和流体性质的变化对气泡分布的影响并对液体入口结构进行优化。结果表明，常规直管出口处大气泡占比较高，直径40 μm以下的微小气泡聚集在微孔管底部中心处。气体流速增加、液体流速减小以及表面张力增加均造成管出口处气泡尺寸分布向大尺寸方向偏移，大气泡体积分数增加；液体黏度增加，小尺寸和大尺寸气泡均增加；出口压强减小也可使管出口处气泡尺寸分布向大尺寸方向偏移，但对大气泡体积分数无明显影响。相较直管而言，旋流管内气相扩散分布更均匀，产生的气泡更小且微气泡占比更大，液体中溶解气量更大。

关键词: 微气泡, 气泡分布, 结构优化

CLC Number: 

• X703