CHEMICAL ENGINEERING SCIENCE
·
2020
·
IF 3.871
Ajuan Song,Yiming Ji,Chao Li,Yijun Cao
Microbubbles are applied in various industrial fields. The bubble size is crucial to the process efficiency. Recent studies have shown that the replacement of steady air supply by oscillatory air supply could significantly decrease the sizes of bubbles formed from submerged orifices, owing to the increased momentum force, which is a lifting force for bubble formation. However, the responses of the momentum force to the oscillatory air supply are not yet clear. This study provides a qualitative model for the momentum force as a function of the characteristics of the oscillatory air supply, including the switching frequency, on/off time ratio, and gas flow rate. The model was experimentally validated by investigating the variations in the momentum force with the characteristics of the oscillatory air supply. In addition, the correlation between the momentum force and bubble size under the oscillatory air supply was also investigated.
研究领域:
化学工程
·
流体力学
✓ 已验证
产品关联
DOI
高影响因子
Processes
·
2022
·Vol. 10
·期 5
·997
·
IF 3.352
Ajuan Song,Sijia Zhao,Yijun Cao,Chao Li
The size of bubbles generated from a porous sparger is at least an order of magnitude larger than the pore diameter under the steady air pattern. Recent studies have shown that the bubble size can be significantly reduced when the steady air flow is replaced by an oscillatory pattern. However, the effectiveness of oscillatory air flow on reducing bubble size under different sparger characteristics is yet to be studied. This work fundamentally investigates the response of bubble size to sparger characteristics under an oscillatory air pattern by segregating the bubble formation subprocesses into bubble detachment and consequent coalescence. The results show that bubble size significantly decreased with hydrophilic plates regardless of contact angle, owing to depressed coalescence, while no impact was observed for a hydrophobic plate. The influence of the oscillatory air pattern on decreasing bubble size was weakened as the chamber volume was increased, and above a critical volume the bubble-formation process became similar with that under a steady air pattern. An optimum plate thickness was obtained for bubble generation by avoiding weeping, and meanwhile taking full advantage of the momentum force by the oscillatory airflow. The outcomes show that the oscillatory air pattern in determining bubble formation closely depends on the sparger characteristics, which should be appropriately determined.Keywords:bubble size;sparger configuration;oscillatory air pattern;coalescence
研究领域:
化学工程
·
流体力学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING RESEARCH & DESIGN
·
2022
·
IF 4.119
Sijia Zhao,Ajuan Song,Yijun Cao,Siyuan Yang,Chao Li
The diameter of bubbles generated from submerged orifices is closely related to the air pressure, which consists of static and dynamic pressures. It has been proven that switching the air supply from a steady to oscillatory flow can improve the dynamic pressure and thus lead to smaller bubbles. To complement the control strategy for bubble size optimization, this study proposes an approach to enhance static pressure by introducing a Y-junction shunting configuration under an oscillatory air supply. A model of gas pressure as a function of the shunting ratio was developed and validated experimentally. A positive correlation was observed between the shunting ratio and static pressure. The bubble size first decreased and then increased as the shunting ratio increased from 0 to 3.0. The smallest bubbles were obtained at a shunting ratio of 1.5 with a diameter reduction of 26% compared with no shunting. By segregating the bubble formation process, the bubble diameter at detachment continuously decreases over the shunting ratio. However, the number of coalesced bubbles first decreased and then increased, and the underlying mechanism is discussed. The findings indicated that the shunting air supply could facilitate bubble size optimization when the shunting ratio was appropriately controlled.
研究领域:
流体力学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
Processes
·
2021
·Vol. 9
·期 4
·638
·
IF 2.847
Yiming Ji,Ajuan Song,Chao Li,Yijun Cao
Bubble size is crucial for determining flotation efficiency. Fine bubbles can be cost-effectively generated using a multi-orifice sparger with oscillatory air supply. Sparger configuration is defined by the orifice size, the plate thickness and the chamber volume. To date, the effect of sparger configuration on bubble size with oscillatory air supply is not clear yet. To facilitate the control of bubble size formed with oscillatory air supply, the present work investigated the dependence of bubble size on sparger configuration. It was found that bubble size was positively correlated with the chamber volume and the orifice size, while a nonlinear relationship was observed with the plate thickness. Besides, it was found that flotation recovery decreased over increasing bubble size when changing the sparger configuration. The results indicated that sparger configuration exhibited a significant effect on flotation performance via influencing bubble size when oscillatory air supply was applied.
研究领域:
矿物加工工程
·
化学工程
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2023
·
IF 4.7
Jingwei Zhang,Yiwei Zhou,Zhuo Chen,Jianhong Xu
Gas-liquid–liquid three-phase flow in cross microchannels has been widely used in flow chemistry and process intensification. At present, the flow and mass transfer characteristics in this type of channel are not well understood. In this work, the hydrodynamics and liquid–liquid mass transfer characteristics of gas–liquid–liquid three-phase flow were systematically investigated. For the gas–liquid–liquid hydrodynamics, the general regulation laws of bubble and droplet size were obtained by considering the synergistic effect of shearing phases, and the bubble/droplet size prediction model based on the multiphase cooperative behavior was proposed, which could be used in predicting droplet/bubble size in flow systems. For the gas–liquid–liquid mass transfer process, the experimental results showed that the mass transfer coefficient first increased and then decreased with the increase of gas flow rate when the oil phase flow rate was fixed. The semi-empirical prediction formula of the mass transfer coefficient was obtained by considering the vortex strength, the interfacial area and the effective mass transfer area at the same time, which was in good agreement with the experimental results. This work could be the comprehensive study of gas–liquid–liquid three-phase flow and liquid–liquid mass transfer under gas enhancement in a cross microchannel.
研究领域:
化学工程
·
传质学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2018
·
IF 3.927
Yaran Yin,Taotao Fu,Chunying Zhu,Rongwei Guo,Youguang Ma,Huaizhi Li
The evolution of the size and velocity of CO 2 bubble absorbed into MEA/[Bmim][BF 4 ] aqueous solutions was in-line investigated by a high-speed camera. The coupling effect between the variation of volume and the velocity of bubbles was highlighted. According to the evolution of average mass transfer coefficient, the mass transfer performance in the whole flow process was studied. The results indicated that both the length and velocity of bubble decreased gradually in the flow process due to mass transfer. A linear correlation between the relative velocity (the ratio of average bubble velocity to two-phase superficial velocity) and the relative lost length (the ratio of the lost length to the initial length) was proposed. The increase in overall liquid-phase volumetric mass transfer coefficient ( k L a ) at higher gas flow rate could be ascribed to the shorter residence time and larger specific surface area. While the increase of k L a at higher liquid flow rate and MEA or [Bmim][BF 4 ] concentration was resulted from intensified mass transfer. An empirical correlation of overall liquid-phase volumetric mass transfer coefficient was proposed taking the gas-phase Reynolds number, liquid-phase Reynolds number and Damköhler number into account.
研究领域:
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
POWDER TECHNOLOGY
·
2024
·
IF 4.5
Xinyu Liu,Han Guo,Shihao Ding,Qinglin Yin,Yaowen Xing,Xiahui Gui
Studies have reported that bubble coalescence causes particle–bubble detachment in the flotation pulp and foam phases. Most coalescence experiments have been conducted using bubble pairs with the same diameter; however, this is not the case in real flotation. In this study, particle–bubble detachment behavior during the coalescence of two bubbles with different sizes was investigated using a high–speed camera, and the variation of the coalescing bubble area was fitted to a damped oscillatory equation and analyzed. To explore the intrinsic detachment mechanism of the bubble size effect, the flow field variation in the bubble periphery was simulated using COMSOL 6.1. Results show that the particle–bubble detachment probability decreased with increasing bubble size difference. The released energy is greatest when the two equal bubbles coalesced, thus leading to the strongest oscillation and highest detachment probability. The simulation results show that turbulent kinetic energy affects particle-bubble stability and is an important reason for inducing particle-bubble detachment. Notably, particle–bubble detachment did not occur at the maximum turbulent energy, because there was a delay due to the time required for the sliding contraction of the three–phase contact line. The research finding provides new insights into the mechanism of particle–bubble detachment.
研究领域:
矿物加工工程
·
流体力学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Chao Li,He Kang,Ai Wang,Boai Zhang,Yijun Cao
Fluidized-bed flotation is a novel process with combined features of flotation and density separation. The application of fluidized-bed flotation in grinding circuit to reject coarse gangues for sulfide ores has been increasingly attracting attentions. Previous studies have focused on the effect of mineral liberation on coarse particle separation. Little work has yet been conducted to simultaneously investigate the effect of mineral liberation, particle and bubble sizes on the fluidized-bed flotation efficiency. The lack of this work has hindered the process optimization to some extent. In this study, three sizes of bubbles (498 μm, 1200 μm, 1952 μm) were generated to separate molybdenite ores under three particle size fractions (150–450 μm, 450–700 μm and 700–1000 μm) in a fluidized-bed flotation column (80 mm in diameter). For the 150–450 μm and 450–700 μm particles, small bubbles of 498 μm could achieve separation by effectively reducing the particle density. For the 700–1000 μm particles with greater mass, intermediate bubble of 1200 μm was required to reduce the particle density for separation. No separation was observed for the three particle size classes with the oversized bubbles of 1952 μm due to high bubble detachment probability. It was concluded that fluidized-bed flotation is a consequence of matched bubble and particle sizes affected by the exposure rate of hydrophobic mineral and its distributing discreteness, the underlying mechanism for which was discussed. It is believed that the outcomes of this work could facilitate the optimization of fluidized-bed flotation in coarse gangue rejecting for sulfide ores.
研究领域:
矿物加工
·
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2021
·
IF 7.312
Yanan Liu,Qiancheng Wang,Cihao Wang,Ai Zhang,Keliang Huang,Jinxia Liu,Andere Clement Miruka,Qianhan Han,Ying Guo
The development of feasible and environmentally friendly technologies to remove dichloroacetic acid (DCAA) from water is needed worldwide to reduce human exposure to this common disinfection byproduct and to minimize cancer risk. In this study, we reported a novel, independently designed water-recirculation-continuous- flow corona discharge reactor (WCD) with integrated microbubble (MB) generation for DCAA treatment. Compared with the performance of WCD or MBs alone, the integrated system (WCD/MBs) showed synergistic effects on DCAA degradation. The functional active species were confirmed to be •OH, •O 2 – , ONOO – , and e - . The effects of the discharge power, bubble size, and carrier gas were evaluated. At a discharge power of 22.9 W and a bubble size of 34.5 μm, the DCAA removal efficiency reached 76% after treatment for 120 min in the air-WCD/MBs reactor. Based on the intermediates detected by IC, GC–MS, and HPLC-QTOF, several DCAA degradation pathways were proposed, including H-abstraction, dechlorination, carbon–carbon bond cleavage, nitrogen dioxide radical reaction, and ipso attack by amine and azido groups. The WCD/MBs system can be applied to tap water, and its energy yield compares favorably with that of other technologies. The novel non-thermal plasma treatment system provides a sustainable and feasible solution for DCAA removal.
研究领域:
环境工程
·
水处理
·
等离子体化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）