The removal of the adsorbed oil droplet is critical to deoiling treatment of oil-bearing solid waste. Ultrasonic cavitation is regarded as an extremely useful method to assist the oil droplets desorption in the deoiling treatment. In this paper, the effects of cavitation micro-jets on the oil droplets desorption were studied. The adsorbed states of oil droplets in the oil-contaminated sand were investigated using a microscope. Three representative absorbed states of the oil droplets can be summarized as: (1) the individual oil droplet adsorbed on the particle surface (2) the clustered oil droplets adsorbed on the particle surface; (3) the oil droplet adsorbed in a gap between particles. The micro-jet generation during the bubble collapse near a rigid wall under different acoustic pressure amplitudes at an ultrasonic frequency of 20 kHz was investigated numerically. The desorption processes of the oil droplets at the three representative absorbed states under micro-jets were also simulated subsequently. The results showed that the acoustic pressure has a great influence on the velocity of micro-jet, and the initial diameter of cavitation bubbles is significant for the cross-sectional area of micro-jets. The wall jet caused by a micro-jet impacting on the solid wall is the most important factor for the removal of the absorbed oil droplets. The oil droplet is broken by the jet impinging, and then it breaks away from the solid wall due to the shear force generated by the wall jet. In addition to a higher sound pressure, the cavitation bubble at a larger initial diameter is more important for the desorption of the clustered oil droplets. Conversely, the micro-jet generated by the cavitation bubble at a smaller initial diameter (0.1 mm) is more appropriate for the desorption of the oil droplet in a narrow or sharp-angled gap. 相似文献
In this study, a semi-analytical model was developed to illustrate the relationship between filtration performance (filtration efficiency and pressure drop) and dust loading under two different particle deposit structures based on theoretical analysis and computational fluid dynamic (CFD) technology. Under the compact deposit structure, within the practical parameter ranges (fiber diameter, air velocity, dust loading mass), a slight efficiency enhancement (∼10%) occurred at the most penetration particle size (MPPS) and pressure drop increased significantly (∼100%) in response to the solidity increase from 5% to 15%. However, under the dendritic particle deposit structure, both filtration efficiency (∼40%) and pressure drop (∼600%) increased significantly with the same solidity increase due to the larger air velocity and swerve change between fibers. 相似文献
Summary: Fabrication of honeycomb‐patterned films from amphiphilic dendronized block copolymer (PEO113‐b‐PDMA82) by ‘on‐solid surface spreading’ and ‘on‐water spreading’ method is reported. Highly ordered honeycomb films with quasi‐horizontally paralleled double‐layered structure can be fabricated by the on‐solid surface spreading method. This work raises the possibility that such structures can be formed in amphiphilic dendronized block copolymers and extends the family of source materials.
The cover image is based on the Research Article Pressure boundary condition in a multi-phase lattice Boltzmann method and its applications on simulations of two-phase flows by Lei Wang and Ze-Rui Peng, https://doi.org/10.1002/fld.4800 .