ACS Omega
·
2019
·
IF 2.584
Hao Xu,Chao Chang,Nan Yi,Peng Tao,Chengyi Song,Jianbo Wu,Tao Deng,Wen Shang
This paper studied the coalescence, spreading, and rebound of two droplets with different temperatures on a superhydrophobic surface. When the temperature of the impacting droplet was the same as that of the stationary droplet, there was a large deformation of both droplets before the coalescence and the energy dissipation was also large. The coalescence happened at the time close to the maximum spreading. When the temperature of the impacting droplet increased, the deformation of both droplets became smaller before the coalescence and the coalescence happened at or even before the droplets started to spread. The energy dissipation and loss in the later situation is less than those in the previous case. The rebounding characteristics of the merged droplets were also found to be dependent on the temperature. There is an optimum temperature at which the merged droplets can rebound for more times due to the balance of energy loss and also the interaction of the merged droplets with the underlying superhydrophobic substrate. These findings may help further the fundamental understanding of droplet collision on a superhydrophobic surfaces and also offer an alternative strategy to remove droplets from the underlying surfaces for different industrial applications, including condensation heat transfer in steam power plants and phase-change-based thermal management systems.
研究领域:
物理学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2024
·
IF 4.1
Mofan Li,Donghai Yang,Lei Tian,Haotian Liu,Liangyu Cai,Limin He
Combining a magnetic field with an electric field offers a promising approach for enhancing oil–water separation, yet its underlying mechanisms are not fully understood. We systematically investigated the dynamic deformation of salt-containing water droplet suspended in oil under an electric–magnetic coupling field. Integrating high-speed camera experiments with molecular dynamics simulations, we found that the dynamic response amplitude of droplet is reduced compared to a single electric field. Our analysis suggests that ions deflect under electric–magnetic coupling, affecting ion enrichment and water molecule polarization, thereby weakening droplet tip charge and induced electric forces, which suppresses droplet deformation. Increasing the electric capillary number and ion concentration enhances suppression, whereas improving the electric field frequency to 500 Hz almost eliminates this suppression effect. Notably, the degree of droplet deformation inhibition remains consistent across different viscosity ratios. These research findings offer insights for designing dehydrators to intensify oil–water separation.
研究领域:
物理学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2024
·
IF 4.9
Mofan Li,Donghai Yang,Shiyi Lv,Xinming Zhao,Jianwei Wang,Minmin Xia,Limin He
Electric field-based synchronous coupling with magnetic fields has shown great potential in enhancing the efficiency of electric dehydration for crude oil. However, the mechanisms underlying electric-magnetic coupling and its influence on droplet coalescence are not yet entirely understood. This study aims to investigate the coalescence dynamics of salt-laden water droplets in oil under an electric-magnetic coupling field. Experimental investigations using high-speed cameras and simulations employing electrohydrodynamic/molecular dynamic methods were conducted to elucidate differences in critical coalescence conditions. The results revealed a significantly higher critical electric field strength required for droplet coalescence under the influence of an electric-magnetic coupling field compared to a single electric field. This behavior can be attributed to changes in the migration direction and aggregation region of ions caused by the electric-magnetic coupling effect. Consequently, the charge at the end of droplets decreases, and the weight of the electric field force competes with the capillary force, thereby hindering coalescence. Furthermore, the study revealed that at an ion concentration of 1000 mg·L −1 , the critical electric field strength exhibited a maximum enhancement rate of 18.2 %. This enhancement can be attributed to the combined effect of ionic migration, which becomes more pronounced at higher concentrations, and the influence on the polarization of water molecules. However, when the electric field frequency was increased to 500 Hz, the migration of ions was shortened, resulting in a significantly reduced enhancement rate of only 0.909 %. Finally, the mathematical relationships between the coupled magnetic field reinforced critical electric field strength for different control parameters were determined by fitting the data points. In summary, this study provides novel scientific insights into the deep dehydration of crude oil by investigating the effects of electric-magnetic coupling on droplet coalescence. The findings present valuable guidance for optimizing the efficiency of dehydration processes and ensuring the safe and stable production in oil industrial applications.
研究领域:
石油工程
·
电动力学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
·
2019
·
IF 2.829
Xin Huang,Limin He,Xiaoming Luo,Haoran Yin,Donghai Yang
Deformation and coalescence behaviors of water droplets in viscous fluid under a direct current electric field are investigated with experiments and numerical simulations. An electro-hydrodynamic model is developed based on fluid dynamics equations and electrostatic equations. A coupled level set and volume of fluid method is proposed to capture the dynamic interface. The numerical results are validated to be in good accordance with classic results in the literature. The effects of electric capillary number Ca and viscosity ratio λ on droplet deformation and coalescence are systematically analyzed. Two different droplet response modes are obtained, namely overdamping response and underdamping response. The conversion of response modes is discussed with the ( Ca, λ ) phase diagram. Moreover, the distributions of electric field and flow field before and after the droplets contact are compared and analyzed. Numerical results show the time evolution of liquid bridge is dominated by the interfacial tension and viscosity of continuous phase. The electric stress is extremely weak at the liquid bridge and has a slight influence on evolution of liquid bridge. The correlation formula between dimensionless liquid bridge radius and conical angle during the growth of liquid bridge is regressed. These results are helpful for the optimization of electro-coalescence process.
研究领域:
流体力学
·
电动力学
✓ 已验证
产品关联
DOI
高影响因子
ULTRASONICS SONOCHEMISTRY
·
2015
·
IF 4.321
Xiaoming Luo,Limin He,Hongping Wang,Haipeng Yan,Yahua Qin
The motion of a single water droplet in oil under ultrasonic irradiation is investigated with high-speed photography in this paper. First, we described the trajectory of water droplet in oil under ultrasonic irradiation. Results indicate that in acoustic field the motion of water droplet subjected to intermittent positive and negative ultrasonic pressure shows obvious quasi-sinusoidal oscillation. Afterwards, the influence of major parameters on the motion characteristics of water droplet was studied, such as acoustic intensity, ultrasonic frequency, continuous phase viscosity, interfacial tension, and droplet diameter, etc. It is found that when the acoustic intensity and frequency are 4.89 W cm −2 and 20 kHz respectively, which are the critical conditions, the droplet varying from 250 to 300 μm in lower viscous oil has the largest oscillation amplitude and highest oscillation frequency.
研究领域:
物理学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL PHYSICS LETTERS
·
2012
·
IF 2.337
Hao-Di Wu,Yan Xiao,Ge-Bo Pan
Micro rings of organic NPB have been prepared by evaporating chloroform solution on a silicon surface, which is assisted with a template of water droplets. The topography and optical properties of NPB rings were investigated by microscopy techniques. It is found that the polarized fluorescence microscope images of rings show pronounced polarization related to their central angle Φ . This indicates that the NPB molecules within a ring are ordered. Systematic investigation indicates that the water droplets condensed on silicon are essential for the ring formation. Such strategy is available for other small molecules, e.g., fullerene, porphyrin, and phthalocyanine.
研究领域:
材料科学
·
光学
·
分子自组装
✓ 已验证
DOI
高影响因子
Nature Communications
·
2024
·Vol. 15
·期 1
·1-9
·
IF 14.7
Chu Fuqiang,Li Shuxin,Zhao Canjun,Feng Yanhui,Lin Yukai,Wu Xiaomin,Yan Xiao,Miljkovic Nenad
Icing of seawater droplets is capable of causing catastrophic damage to vessels, buildings, and human life, yet it also holds great potential for enhancing applications such as droplet-based freeze desalination and anti-icing of sea sprays. While large-scale sea ice growth has been investigated for decades, the icing features of small salty droplets remain poorly understood. Here, we demonstrate that salty droplet icing is governed by salt rejection-accompanied ice crystal growth, resulting in freezing dynamics different from pure water. Aided by the observation of brine films emerging on top of frozen salty droplets, we propose a universal definition of freezing duration to quantify the icing rate of droplets having varying salt concentrations. Furthermore, we show that the morphology of frozen salty droplets is governed by ice crystals that sprout from the bottom of the brine film. These crystals grow until they pierce the free interface, which we term ice sprouting. We reveal that ice sprouting is controlled by condensation at the brine film free interface, a mechanism validated through molecular dynamics simulations. Our findings shed light on the distinct physics that govern salty droplet icing, knowledge that is essential for the development of related technologies.
研究领域:
物理化学
·
材料科学
✓ 已验证
DOI
高影响因子
ULTRASONICS SONOCHEMISTRY
·
2017
·
IF 4.218
Xiaoming Luo,Juhang Cao,Jing Ren,Haipeng Yan,Limin He
The suspension characteristics of water droplet in oil were investigated under ultrasonic standing waves with high-speed photography in this paper. Firstly, the suspension position of droplet was predicted by theoretical derivation. The motion trajectory of droplet was captured and a kinetic analysis was applied to characterize the suspension position of droplet. The effects of droplet size, acoustic pressure, frequency, as well as density ratio of water and oil on the suspension position of droplet were analyzed in details. It was proved that the droplet size had little effect on the suspension position at different frequencies. The suspension zone approached minimum at 39.4 kHz, and the suspension position of droplet was insensitive to acoustic pressure amplitude and density ratio at this frequency. These would be advantageous to maintain the stability of droplet banding and shorten the width of banding. In addition, it was proved that the suspension position of droplet is approximately linear with the density ratio at different frequencies.
研究领域:
物理学
·
化学工程
·
声学
✓ 已验证
DOI
高影响因子
ENERGY & FUELS
·
2020
·
IF 3.421
Chenwei Liu,Chongrui Zhang,Chenru Zhou,Yongfei Mi,Zhiyuan Wang
The presence of unconverted water drops in bulk hydrocarbon is likely to bridge hydrate particles and cause hydrate agglomeration, leading to hydrate accumulation or bedding in oil and gas pipelines. The knowledge of the interaction forces between hydrate particles and water drops can provide critical insights into hydrate agglomeration as well as potential prevention strategies. At high subcooling, the frequent solidification of the capillary bridge between hydrate particles could significantly affect the interaction force. However, the existing classic pendular liquid bridge model with a fixed liquid volume is not adequate for this unique case. A new interaction force model is required. Based on the pendular liquid bridge model and hydrate shell theory, a modified interaction force model was developed by considering the solidification of capillary bridges. Furthermore, using a self-built micromechanical force apparatus, the cyclopentane (CyC5) hydrate–droplet adhesion forces at a temperature range from 0.5 to 6 °C were measured to verify the proposed model. The experiments suggest that as the temperature was increased from 0.5 to 6 °C, the adhesion forces first increased and then decreased. Solidification could enhance the strength of the already formed liquid bridge. However, at lower temperatures (0.5–3 °C), the quick solidification led to smaller particle/bridge initial contact areas and weaker adhesion forces. By accurately predicting the evolution of the capillary bridge shape/outline, the predicted adhesion forces agree well with the experimental measurements. This study can provide more insights into hydrate agglomeration. The proposed model is an important supplement to hydrate adhesion theory and could more accurately evaluate hydrate plug risks in gas–oil flowlines.
研究领域:
石油工程
·
化学工程
·
热力学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2020
·
IF 8.758
Yihua Zheng,Chengchun Zhang,Jing Wang,Liang Yang,Chun Shen,Zhiwu Han,Yan Liu
Extensive studies of antiwetting have been restricted to stationary substrates, while dewetting mechanisms on moving interfaces are still poorly understood. Due to the hydrophobic and anisotropic surface characteristics of kingfishers, they are able to easily change flight direction even under high-intensity precipitation. The present study aims to mechanistically analyze how the synergy of interfacial movement, anisotropy, and superhydrophobicity affects rapid dehydration. We have designed a droplet-conveyor system to simulate the bouncing of droplets on moving anisotropic superhydrophobic targets and performed simulations via the lattice Boltzmann algorithm. The moving interface can induce a directional tumbling behavior of the droplet and effectively avoid continuous wetting in the same region. We found that droplet tumbling is essentially caused by transformed depinning velocity vectors at the interface downstream. Also, the hang time of a tumbling droplet is positively related to the angle between the motion vector and the texture. The oriented anisotropic motion facilitates the tumbling of droplets and decreases their hang time by up to 23% as compared to that on a stationary inclined superhydrophobic surface. Similar interfacial process dehydration also occurs on a nonwet kingfisher flying in the rain, and we believe that these findings provide valuable new insights for high-efficiency water repellency of surfaces.
研究领域:
材料科学
·
流体力学
·
生物物理学
·
表面科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
NANO LETTERS
·
2025
·
IF 9.1
Wei Deng,Yufeng Zhu,Kelan Zhang,Yuxuan Yuan,Tao Hu,Xiao Wang,Jidong Li,Xuemei Li,Zhuhua Zhang,Wanlin Guo,Jun Yin
Collective behavior enables groups of organisms to achieve feats far exceeding individual capability. Inspired by this, we present a novel droplet-based electricity generator that leverages the collective dynamics of multiple water droplets to significantly enhance electrical output, achieving orders of magnitude improvement compared with single-droplet devices. It is revealed that grouped water droplets, although spatially separated, coordinate via charge exchange with a solid surface and external charge transfer. Consequently, the solid surface charge density is significantly enhanced, elevating the charge transfer. This collective effect readily generates peak voltages exceeding one kilovolt, sufficient for air ionization and nitrogen fixation, with potential applications in nutrient production. We anticipate that this collective strategy will significantly advance the design and applications of droplet-based hydrovoltaic devices.
研究领域:
能源科学
·
材料科学
·
物理学
✓ 已验证
DOI
PubMed
高影响因子
MACROMOLECULAR MATERIALS AND ENGINEERING
·
2012
·Vol. 297
·期 10
·979-984
·
IF 1.986
Xiangzhong Pang,Shuaijun Pan,Shuo Feng,Hao Chen,Ling Li,Xiaolu Su,Yuanqin Xiong,Weijian Xu
A photoresponsive fluorinated azobenzene homopolymer is synthesized via TERP. UV irradiation of the surface based on a fluorinated azobenzene homopolymer with micro/nanostructures induces a tunable/switchable water droplet mobility. Water droplets can easily roll off the pristine surface at a small tilt angle (≈14°). The apparent water CA changes from 150 to 135° after UV illumination of the surface. Thus, water drops stick on the surface when the substrate is turned vertically or even upside down, indicating a very high adhesion force. Interestingly, the water droplet rolls off again under visible-light irradiation. The as-prepared surface may be useful for applications requiring switchable mobility of water droplets.
研究领域:
材料科学
·
表面化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）