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
APPLIED SURFACE SCIENCE
·
2021
·
IF 6.707
Wuzhi Yuan,Zhixing Liao,Kui He,Quanbing Liu,Si-Min Huang
The self-cleaning of the superhydrophobic surface (SHS) attracted worldwide interest. However, in most cases it depends on the incoming droplet, which places additional constraints especially in arid area and/or narrow space. Herein, a condensation-induced self-cleaning of dust on the SHS is proposed. First, the SHS are prepared and dust is deposited on the surface, and then the dust removal process is studied on the condensation visualization platform. During condensation, a liquid bridge is initially formed at the contact points between particles on the SHS, which governs dust removal behavior. Specially, three consecutive processes are accounted for the self-cleaning including dust agglomerating, condensate sliding and rolling as the condensate prolongs. As far as the sizes and coverage rate of dust particles are concerned, over 95% of particles can be removed by condensation within 90 min (air temperature 26 ± 0.5 ℃, air humidity 60 ± 5% and cooling-stage temperature 10 ± 0.5 ℃). This study aims to provide a useful, in-depth understanding of dust mitigation by condensation on SHS, which has potential application in PV module and heat exchanger.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
Small
·
2024
·
IF 13
Mingshuo Chen,Wei Sun,Hongtao Liu,Qiang Luo,Yining Wang,Jinmu Huan,Yongping Hou,Yongmei Zheng
Conventional fog collection efficiency is subject to the inherent inefficiencies of its three constituent steps: fog capture, coalescence, and transportation. This study presents a liquid bridge synergistic fog collection system (LSFCS) by synergistically utilizing a liquid bridge and interconnected porous superhydrophilic structures (IPHS). The results indicate that the introduction of liquid bridge not only greatly accelerates water droplet transportation, but also facilitates the IPHS in maintaining rough structures that realize stable and efficient fog capture. During fog collection, the lower section of the IPHS is covered by a water layer, however due to the effect of the liquid bridge, the upper section protrudes out, while covered by a connective thin water film that does not obscure the microstructures of the upper section. Under these conditions, a one-step fog collection mode is realized. Once captured by the IPHS, fog droplets immediately coalesce with the water film, and are simultaneously transported into a container under the effect of the liquid bridge. The LSFCS achieves a collection efficiency of 6.5 kg m −2 h −1 , 2.3 times that of a system without a liquid bridge. This study offers insight on improving fog collection efficiency, and holds promise for condensation water collection or droplet manipulation.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2019
·
IF 6.361
Xiaoming Luo,Haoran Yin,Jing Ren,Haipeng Yan,Xin Huang,Donghai Yang,Limin He
The mixing of binary droplets is of paramount importance in microfluidic systems. In order to reveal the mixing mechanism of two free droplets suspended in the immiscible phase, we have developed a novel experimental setup to study the internal mixing in coalescing droplets with varying interfacial tension differences and droplet sizes. It is confirmed that the interfacial energy of droplets supports the jet flow and liquid bridge expansion during the coalescence of droplets. The increase of interfacial tension difference can increase the intensity of jet flow accompanied with slower liquid bridge expansion, which enhances the mixing of droplets. The decrease of droplet size can increase the initial velocity of jet flow. However, the intensity of jet flow decreases due to the rapid expansion of the liquid bridge, which results in weaker internal mixing. On this basis, a Reynolds number incorporating the jet velocity and droplet size is proposed to characterize the vortex size, which represents the degree of droplet mixing. This study presents an effective approach for enhancing the mixing of droplets.
研究领域:
微流控技术
·
流体力学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
FUEL
·
2023
·
IF 7.4
Pengfei Li,Shikun Tong,Jihao Pei,Jianbo Zhang,Yukun Guo,Xiao Liu,Weiqi Fu,Zhiyuan Wang
Hydrate aggregation and deposition on the pipe wall are the main causes of hydrate plugging in pipelines. Microscopic forces between hydrate particles are an important reference for determining the behavior of aggregation or separation from the pipe wall of hydrate particles. Based on a high-pressure visual micro-force measurement system, this study measured the hydrate particle-hydrate particle cohesive force and hydrate particle–wall liquid droplet adhesion force under pure water, as well as hydrate particle–wall liquid droplet adhesion force under anti-agglomerants (AAs). It was found that the magnitude of hydrate particle-hydrate particle cohesive force was ×10 mN/m, and the magnitude of hydrate particle–wall liquid droplet adhesion force was ×10 3 mN/m. The effects of 4 AAs in the methane gas-dominated system were evaluated from a micro-perspective, revealing that after adding DDBAB, D1021, AEO-9, and CDEA, the maximum reduction of adhesion force was 67%, 64%, 51%, and 53% compared with that under pure water, respectively. The mechanism of AAs reducing adhesion force was further explored, revealing that the adhesion force arose from a liquid bridge and was affected by the gas–water interfacial tension of solutions at low subcoolings. While at high subcoolings, the force was determined by the combined force of the liquid bridge and the hydrate shell. The addition of AAs reduced the gas–water interfacial tension of solutions, and the steric hindrance effect of AA molecules also weakened the tensile strength of the hydrate shell, leading to a decreased adhesion force. These experimental data can help deepen our understanding of the microscopic forces between methane hydrate particles, and provide experimental data and scheme design basis for wellbore flow assurance of deepwater gas wells.
研究领域:
石油工程
·
化学工程
✓ 已验证
DOI
高影响因子
PHYSICS OF FLUIDS
·
2024
·Vol. 36
·期 7
·
IF 4.1
Li Mofan,Yang Donghai,Chen Conglei,Lv Shiyi,Miao Jiaxu,He Limin
Unconventional crude oil and offshore oilfield extraction often lead to the formation of stable oil–water emulsions with high mineralization, posing significant threats to environmental protection and pipeline transportation safety. Electric–magnetic coupling separation technology represents a novel approach to emulsion breaking, offering superior separation performance compared to the conventional electric coalescence methods. However, its underlying mechanism remains elusive. To address this gap, this study comparatively investigates the liquid bridge dynamic during droplet coalescence under a single electric field and electric–magnetic coupling field conditions. High-speed camera experiments reveal that synchronized coupled magnetic fields suppress the extension of liquid bridges, with this suppression effect being augmented by increasing ion concentration and electric field strength. Nevertheless, the enhancement of the inhibition effect is not pronounced at electric field strengths up to 224 kV m −1 and within the frequency range of 50–500 Hz. Molecular dynamics simulations demonstrate that the mutual repulsion effect between water molecules and the hydration effect between water molecules and ions are intensified under the coupling field. Finally, by integrating flow field and velocity analyses, a mechanism is proposed to elucidate the hysteresis in the evolution of liquid bridges, attributed to the mutual repulsion of water molecules hydrated by deflecting ions and convecting water molecules in the coupled field. This study offers valuable insights for the development of electric–magnetic coupling separation techniques, with implications for mitigating oil contamination and facilitating dewatering treatments.
研究领域:
石油工程
·
环境科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
Biomimetics
·
2022
·Vol. 7
·期 2
·72
·
IF 3.743
Yahua Liu,Zhixin Feng,Haiyang Zhan,Wenna Ge,Yuhang Xia,Junqiu Zhang,Shile Feng
Hot-water repellency is of great challenge on traditional superhydrophobic surfaces due to the condensation of tiny droplets within the cavities of surface textures, which builds liquid bridges to connect the substrate and hot water and thus destroys the surface water-repellence performance. For the unique structural features and scales, current approaches to fabricate surfaces with hot-water repellency are always complicated and modified by fluorocarbon. Here, we propose a facile and fluorine-free one-step vapor-deposition method for fabricating excellent hot-water-repellent surfaces, which at room temperature even repel water droplets of temperature up to 90 °C as well as other normal-temperature droplets with surface tension higher than 48.4 mN/m. We show that whether the unique hot-water repellency is achieved depends on a trade-off between the solid–liquid contact time and hot-vapor condensation time, which determines the probability of formation of liquid bridges between the substrate and hot-water. Moreover, the designed surfaces exhibit excellent self-cleaning performance in some specific situations, such as oil medium, hot water and condensation environments. We envision that this facile and fluorine-free strategy for fabricating excellent hot-water-repellent surfaces could be valuable in popularizing their practical applications.
研究领域:
材料科学
·
表面工程
✓ 已验证
DOI
高影响因子
RSC Advances
·
2022
·Vol. 12
·期 23
·14456-14466
·
IF 4.036
Yang Liu,Chengxuan Wu,Xiaofang Lv,Xinyi Xu,Qianli Ma,Jiawei Meng,Shidong Zhou,Bohui Shi,Shangfei Song,Jing Gong
In the exploitation of deep-sea oil and gas resources, the multiphase production and transportation process is frequently plagued by pipeline blockage issues. Especially when hydrates and wax coexist simultaneously, the viscosity and plugging tendency of multiphase flow systems will synergistically increase. Understanding the evolution of morphology of hydrate particles and the agglomeration characteristics of hydrate particles in the presence or absence of wax crystals is crucial to flow assurance industry. With the assistance of a visualized reactor equipped with a three axis moving platform, microscopic images of cyclopentane hydrate during hydrate growth were obtained, and the cohesive force between hydrate particles was measured. It was found that during the hydrate growth on wax-free water droplets, the untransformed water inside the particles gradually wetted the surface of the particle. With the increase in temperature and contact time, the shell of hydrate particles changed from solid and rough to smooth and moist. The cohesive force measured in this work ranges from 3.14 ± 0.52 to 11.77 ± 0.68 mN m−1 with different contact times and temperature. When the contact time was 0 s and 10 s, the cohesive force between particles increased first and then stabilized with temperature. When the contact time was 20 s, the cohesive force was greater than the first two cases and showed an overall stable trend. An interesting phenomenon was also discerned: a large water bridge between particles formed during their separation process. For the wax-containing system, it required a longer time for water droplets to be converted into hydrate particles than that for wax-free systems. After wax participated in hydrate growth, hydrate particles showed the properties of elasticity and stickiness, which resulted in a larger liquid bridge between hydrate particles after their contact. It was suggested that wax crystal would alter the shell structure of hydrate particles, and change the surface properties of hydrate particles and the formation process of the liquid bridge, leading to significant and rapid increase in the cohesive force.
研究领域:
流变学
·
海洋油气开发
·
胶体与界面科学
·
能源工程
·
流动保障
✓ 已验证
DOI
高影响因子
Journal of Physical Chemistry C
·
2018
·
IF 4.484
Xiaoming Luo,Haoran Yin,Haipeng Yan,Xin Huang,Donghai Yang,Limin He
In this study, the electrocoalescence characteristic of two drops with different surfactant concentrations suspended in oil is revealed. Different from the symmetrical coalescence of identical drops, the asymmetrical liquid bridge is induced by the capillary force, which involves the interfacial tension gradient between the drops. In addition, a mushroom-like jet is formed during asymmetrical coalescence, causing mixing of drops. A characteristic time considering the interfacial tension gradient is proposed to describe the asymmetrical liquid bridge evolution. The mushroom-like jet is found to be driven by the pressure difference between drops, which has a positive correlation with the interfacial tension gradient. Moreover, it is found that the electrocoalescence time is shortened as the interfacial tension increases. This study indicates that increasing the interfacial tension gradient will enhance the jet flow rate and reduce the coalescence time, which is of significance to improve the mixing efficiency of the drops.
研究领域:
物理学
·
化学工程
·
流体力学
✓ 已验证
产品关联
DOI
高影响因子
AICHE JOURNAL
·
2022
·Vol. 69
·期 4
·e17975
·
IF 4.167
Xin Huang,Yijia Lu,Wanrui Li,Xiaoming Luo,Weidong Li,Jiaqing Li,Pengbo Yin,Lin Teng
The droplet non-coalescence characteristics and mechanism under a DC electric field are investigated by comprehensively using high-speed microscopic experiments, molecular dynamics simulations, and interface dynamics simulations. The researches show whether two droplets coalesce or not depends on the evolution of liquid bridge. The liquid bridge evolution is not only dominated by the electric force F E and the capillary force F i , but also slowed down by the viscous force. The relative strength of F E and capillary force F i relies on the electric capillary number Ca and the maximum liquid bridge radius R * max . The droplet non-coalescence is more likely to happen as the Ca increases or the R * max decreases. Furthermore, the critical value Ca c for droplet non-coalescence reduces as the R * max decreases. The ion transportation causes uneven distribution of ions and thus strengthens the F E , resulting in the non-coalescence. These results provide significant guidance for efficient demulsification of water-in-oil emulsion.
研究领域:
物理学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2018
·
IF 3.306
Xiaoming Luo,Haoran Yin,Haipeng Yan,Xin Huang,Donghai Yang,Limin He
The electrocoalescence behavior of surfactant-laden droplet pairs in oil under a DC electric field was investigated in this paper. The characteristic parameters such as coalescence time, liquid bridge diameter and contact angle were analyzed for varying surfactant concentrations and electric capillary numbers. The results show that the horizontal electrocoalescence of two identical droplets with the same physical properties is symmetrical. Moreover, the surfactant has a significant influence on the pressure difference at the liquid bridge, which results in a variation of the liquid bridge growth and coalescence time. The pressure difference between the droplet and the liquid bridge is significantly dependent on the initial contact angle, which is determined by the electric capillary number Ca and surfactant concentration. The theoretical analysis and experimental results show that the large initial contact angle restrains the growth of the liquid bridge in the initial coalescence stage. Considering the effect of the initial contact angle, a characteristic time is proposed to describe the evolution of the liquid bridge.
研究领域:
物理学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Sensors
·
2024
·
IF 8.2
Libang Xu,Xiaobing Feng,Dazhi Wang,Fang Gao,Chenxu Feng,Qiji Shan,Ge Wang,Fang Yang,Junfeng Zhang,Jingwei Hou,Donglei Sun,Tiesheng Wang
Intravital microscopy (IVM) is a valuable method for biomedical characterization of dynamic processes, which has been applied to many fields such as neuroscience, oncology, and immunology. During IVM, vibration suppression is a major challenge due to the inevitable respiration and heartbeat from live animals. In this study, taking liver IVM as an example, we have unraveled the vibration inhibition effect of liquid bridges by studying the friction characteristics of a moist surface on the mouse liver. We confirmed the presence of liquid bridges on the liver through fluorescence imaging, which can provide microscale and nondestructive liquid connections between adjacent surfaces. Liquid bridges were constructed to sufficiently stabilize the liver after abdominal dissection by covering it with a polymer film, taking advantage of the high adhesion properties of liquid bridges. We further prototyped a microscope-integrated vibration-damping device with adjustable film tension to simplify the sample preparation procedure, which remarkably decreased the liver vibration. In practical application scenarios, we observed the process of liposome phagocytosis by liver Kupffer cells with significantly improved image and video quality. Collectively, our method not only provided a feasible solution to vibration suppression in the field of IVM, but also has the potential to be applied to vibration damping of precision instruments or other fields that require nondestructive ″soft″ vibration damping.
研究领域:
生物医学工程
·
显微成像
·
肝病学
·
细胞生物学
·
免疫学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）