| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 591622 | Colloids and Surfaces A: Physicochemical and Engineering Aspects | 2016 | 8 Pages |
•Both Euler–Euler and Euler–Lagrange model can resolve the flow pattern in the separation zone of the dissolved air flotation tank.•Euler–Euler multiphase model makes a better prediction of the air distribution in the separation zone.•Larger bubbles enhance the stratified flow pattern for bubbles diameter ranging from 30μm to 50μm.•The height of “white water zone” in the separation zone decreases with the increase of bubble size.
With computational fluid dynamics (CFD) methods, the influence of bubble size on the fluid dynamic behavior in a dissolved air flotation tank is investigated in this study. The choice of multiphase flow model between Euler–Euler and Euler–Lagrange approach is first addressed by comparing with the experimental results. The results indicate that Euler–Euler multiphase model is more suitable for the simulation of air/water flow in the DAF tank as it makes better performance in predicting air distribution. With the aid of Euler–Euler model, a systematic study was carried out to investigate the flow pattern and air distribution in the separation zone under bubble diameter from 30 μm to 70 μm. The results demonstrate that larger bubbles are conducive to the formation of stratified flow when bubble diameter ranges from 30 μm to 50 μm and show little impact on flow patterns when bubble diameter exceeds 50 μm. Bubble size has a significant influence on air distribution. Decreasing bubble size enlarges the height of “white water zone”.
Graphical abstractAir concentration distribution against height with various bubble sizes.The figure shows the air concentration distribution against height in the separation zone of the dissolved air flotation tank with various bubble diameters. The results indicate that bubble size has a significant impact on air distribution. If the area with air concentration above 1 ml/L is defined as the “white water zone”, the height of “white water zone” decreased with the increase of bubble diameter.Figure optionsDownload full-size imageDownload as PowerPoint slide
