LANGMUIR
·
2022
·
IF 4.331
Guangyu Ou,Jun Li,Yang Jin,Ming Chen,Yujing Ma,Kaige Gao
Electric fields, which can promote the approach of droplets and break the liquid film, are extensively used in the separation of the water phase in water-in-oil emulsions. However, there is an evolution of droplet behavior under an electric field. After the two droplets meet with each other, the electric force becomes undesirable, which would even cause breakup of the merged droplet. When the electric field strength E reaches a particular value, the final behavior of droplets is made, which goes against coalescence, and there are lots of behavior evolution types. Several research studies have studied on whether droplets coalesce and the critical condition, but few works have focused on the classification and mechanism of non-coalescence behaviors. In this paper, the behavior evolution of two single droplets suspended in castor oil under an alternating current electric field is studied by a high–speed camera. Six distinct behavior evolution modes are observed and summarized: coalescence, bounce, partial coalescence, partial rupture, coalescence–rupture, and rupture. The behavior evolution mode is influenced by the initial separation distance s0 between droplets and the electric field strength. Moreover, there exist critical electric field strengths among different behavior evolution modes. As E gradually increases, two water droplets go through coalescence, partial coalescence, and coalescence–rupture in sequence when s0 is small and coalescence, bounce, partial rupture, and rupture when s0 is large. The mechanisms of behavior evolution are revealed by investigating the confrontation between electric force and capillary force in the condition with liquid bridge or pressure difference from the surrounding fluid and electric force in the condition without a liquid bridge. In addition, a cone–dimple mode of water droplets in castor oil is found, demonstrating the rationality of electric force theory.
研究领域:
物理学
·
流体力学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF PHYSICAL CHEMISTRY B
·
2020
·
IF 2.857
Xin Huang,Limin He,Xiaoming Luo,Ke Xu,Yuling Lü,Donghai Yang
Enhancing the electric field strength can facilitate the approach of droplets and the drainage of liquid film. However, two droplets do not coalesce but bounce off after contact under an excessively high electric field strength. To reveal the underlying mechanism, the dynamic behaviors of two free droplets suspended in low-viscosity silicone oil under a DC electric field were investigated herein. Three distinct behavior modes were successively observed by a high-speed camera with the increase in electric field strength: coalescence, partial coalescence, and noncoalescence. The mechanisms and key criteria of partial coalescence and noncoalescence were explored by studying the competition between electric force and interfacial force. The theoretical formula of critical electric field strength for droplet coalescence was derived and validated by experiments. The results indicated that the electric capillary number Ca can be used as the criterion to identify the behavior modes of two free droplets. The droplets undergo partial coalescence or noncoalescence when Ca > 0.11; otherwise, the droplets experience coalescence.
研究领域:
物理学
·
流体力学
✓ 已验证
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2023
·
IF 4.7
Donghai Yang,Huayao Sun,Mofan Li,Qing Li,Xuedong Gao,Chaohui Chen,Limin He
Under high-strength electric fields, partial coalescence may occur, thus producing fine secondary droplets, which are undesirable for separating water from oil. In this study, experimental and numerical methods are employed to investigate the coalescence behavior under a DC electric field to comprehensively understand the effect of electric field strength ( E ) and droplet diameter ( D ) on coalescence. The Level-set method is employed to capture the moving interface, and the numerical data are validated through experimental tests. The results reveal the easy formation of secondary droplets with increasing E and D values. In particular, the electric field strength suppresses the expansion of the liquid bridge and hinders the vertical collapse of the droplets. The distortion of the electric field at the liquid bridge and the polarized charge both increase with E , thus resulting in stronger electric field repulsion. Moreover, the enhancement in D significantly affects the shrinkage of the liquid bridge and prevents the vertical collapse of the droplet. The pressure gradient at the liquid bridge from the outside to inside decreases as a function of D , thereby inhibiting the contraction speed. Furthermore, the number of polarized charges concentrated on the top of the droplet increases, thus resulting in an enhanced electric field tension. The results obtained herein can potentially act as guide for the design and optimization of electric dehydrators.
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 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
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
Journal of Advanced Ceramics
·
2022
·Vol. 11
·期 11
·1777-1788
·
IF 11.534
Niu Xiang,Jian Xiaodong,Gong Weiping,Liang Wei,Gong Xuetian,Zhang Guangzu,Jiang Shenglin,Yu Kun,Zhao Xiaobo,Yao Yingbang,Tao Tao,Liang Bo,Lu Sheng-Guo
Solid-state cooling technology based on electrocaloric effect (ECE) has been advanced as an alternative to replace the vapour-compression approach to overcome the releasing of the global warming gases. However, the development in high ECE materials is still a challenge. In this work, polarization merging strategy was proposed to achieve a large ECE in x Ba(Sn 0.07 Ti 0.93 )O 3 -( 1 − x )Ba(Hf 0.1 Ti 0.9 )O 3 ferroelectric ceramics, where x = 0, 0.2, 0.4, 0.6, 0.8, and 1. Ba(Sn 0.07 Ti 0.93 )O 3 with an orthorhombic phase and Ba(Hf 0.1 Ti 0.9 )O 3 with a rhombohedral phase at room temperature were prepared beforehand as precursors, and phase-coexisted x BSnT-(1− x )BHfT ceramics were formed via a solid-state reaction approach. Phase coexisting structures were confirmed using the X-ray diffraction. The merged polarization was confirmed by the dielectric and ferroelectric properties. Optimal ECEs were obtained for 0.2BSnT-0.8BHfT ceramics, i.e., adiabatic temperature change Δ T = 2.16±0.08 K at 80 °C and 5 MV/m, and Δ T = 3.35±0.09 K at 80 °C and 7 MV/m.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
JOURNAL OF CHEMICAL PHYSICS
·
2016
·Vol. 145
·期 8
·
IF 2.894
Hao Song,Yang Bingchu,Gao Yongli
The presence of grain boundaries is inevitable for chemical vapor deposition (CVD)-grown MoS 2 domains owing to various merging behaviors, which greatly limits its potential applications in novel electronic and optoelectronic devices. It is therefore of great significance to unravel the merging behaviors of the synthesized polygon shape MoS 2 domains. Here we provide systematic investigations of merging behaviors and electrostatic properties of CVD-grown polycrystalline MoS 2 crystals by multiple means. Morphological results exhibit various polygon shape features, ascribed to polycrystalline crystals merged with triangle shape MoS 2 single crystals. The thickness of triangle and polygon shape MoS 2 crystals is identical manifested by Raman intensity and peak position mappings. Three merging behaviors are proposed to illustrate the formation mechanisms of observed various polygon shaped MoS 2 crystals. The combined photoemission electron microscopy and kelvin probe force microscopy results reveal that the surface potential of perfect merged crystals is identical, which has an important implication for fabricating MoS 2 -based devices.
研究领域:
材料科学
·
物理化学
✓ 已验证
DOI
PubMed
高影响因子
ULTRASONICS SONOCHEMISTRY
·
2016
·
IF 4.556
Xiaoming Luo,Juhang Cao,Limin He,Hongping Wang,Haipeng Yan,Yahua Qin
The coalescence process of binary droplets in oil under ultrasonic standing waves was investigated with high-speed photography. Three motion models of binary droplets in coalescence process were illustrated: (1) slight translational oscillation; (2) sinusoidal translational oscillation; (3) migration along with acoustic streaming. To reveal the droplets coalescence mechanisms, the influence of main factors (such as acoustic intensity, droplet size, viscosity and interfacial tension, etc) on the motion and coalescence of binary droplets was studied under ultrasonic standing waves. Results indicate that the shortest coalescence time is achieved when binary droplets show sinusoidal translational oscillation. The corresponding acoustic intensity in this case is the optimum acoustic intensity. Under the optimum acoustic intensity, drop size decrease will bring about coalescence time decrease by enhancing the binary droplets oscillation. Moreover, there is an optimum interfacial tension to achieve the shortest coalescence time.
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
DYES AND PIGMENTS
·
2022
·
IF 5.122
Sheng-Tong Wu,Fan Yang,Chun-Qin Zhao,Lai-Di Xu,Xue-Lian Han,Ping Chen,Shou-Nian Ding
Traditional photonic crystal microspheres have internal pores and can only be fabricated by self-assembly of colloidal nanoparticles . Therefore, their internal vulnerability to contamination and poor structural stability limit their further application. Therefore, we proposed a new method of photonic crystal composite microsphere fabrication by combining polymerisation with the self-assembly process. The droplets composed of colloidal nanoparticles, monomer , and initiator in continuous phase are obtained by a Shirasu porous glass (SPG) membrane emulsification undergo polymerised and self-assembled to obtain organic-inorganic photonic crystal composite microspheres. Since the self-assembled colloidal nanoparticles are immobilized in the polymer cross-linked network, the composite microspheres exhibit high structural stability. Based on this, we fabricated SiO 2 -PHEMA photonic crystal composite microspheres by polymerisation and self-assembly process. Compared with the pure SiO 2 photonic crystal microspheres fabricated by the same method, the composite microspheres exhibit high structural stability, color saturation, and good hydrophobicity due to the self-curling of the material driven by hydrogen bonding during polymerisation. In addition to the potential applications as dyes, biosensors, and in light, these composite microspheres overcome the difficulty of bulk generation of traditional photonic crystal microspheres and have the potential for industrialized mass production.
研究领域:
材料科学
·
化学工程
✓ 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
NEW JOURNAL OF CHEMISTRY
·
2018
·Vol. 42
·期 6
·4337-4343
·
IF 3.201
Guo-Qi Zhang,Yong-Sheng Li,Xiu-Feng Gao
Pioglitazone hydrochloride (PGH) can effectively reduce resistance of cells to insulin, and is a widely used treatment for type 2 diabetes. In this study, we discovered that PGH in acidic media could rapidly induce aggregation of gold nanoparticles (AuNPs) to bring about red-to-purple color change caused by electrostatic adsorption and intermolecular hydrogen bonding. Thus, based on this principle, an automatic method with asynchronous-alternating merging-zone was established to determine the PGH content in medicines. Our method involved the calculation of the absorbance ratio and spectrum scanning for two wavelengths. In particular, the proposed method could solve problems of unmanageable aggregation degree, large manual error, and high testing cost in common AuNPs colorimetry. The approach was rapid in sample throughput (a sample/min) under the premise of consumption of 30 μL reagents (8 nmol L−1 AuNPs) per time, high repeatability (RSD ≤ 1.1%, n = 11) and good addition recovery (99–104%) in 0.5–15 mg L−1 range, which is suitable for analyzing PGH content in diabetic medicines.
研究领域:
分析化学
·
药学
·
纳米技术
✓ 已验证
DOI
高影响因子
MATERIALS CHARACTERIZATION
·
2020
·
IF 3.562
Bo Li,Guofu Xu,Le Fu,Yao Li,Jiwu Huang
Amorphous ZrO 2 -based nanocomposite powder synthesized by sol-gel method is often used as the raw material for preparing advanced ZrO 2 -based ceramics. The crystal growth process of the amorphous ZrO 2 -based nanocomposite powder during heat treatment has a crucial influence on the final microstructure and thus the achieved performance of ZrO 2 -based ceramics. However, the crystal growth process of ZrO 2 nanocrystals (NCs), especially at the early stage, was ambiguous due to the lack of detailed investigation. To illustrate this issue, ZrO 2 -based nanocomposite powder was prepared by sol-gel method, followed by annealing at elevated temperatures. Transmission electron microscopy (TEM) was used to observe the growth process of ZrO 2 NCs. Results showed that tiny ZrO 2 lattice arrays without definite morphology were formed after the completion of nucleation. Nucleation might follow the classic nucleation mechanism of epitaxial growth by utilizing atoms as building blocks. Then, the randomly-oriented ZrO 2 lattice arrays adopt an ordered coalescence mechanism to grow to large ZrO 2 NCs. ZrO 2 lattice arrays acted as building blocks and they grew rapidly by unifying their crystallography orientations. Self-perfecting, including elimination of dislocations and adjustment of lattice spacing, occurred during the growth process. Ordered coalescence of ZrO 2 lattice arrays contributed to the rapid growth of ZrO 2 NCs. This study deepens our fundamental understanding of the growth mechanism of amorphous ZrO 2 -based nanocomposite powder during heat treatment and may offer guidelines for tailoring the final microstructure and performance of ZrO 2 -based ceramics.
研究领域:
材料科学
·
陶瓷
·
纳米技术
·
晶体学
✓ 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）