COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2022
·
IF 5.518
Zilu Li,Kefei Zhao,Yue Wang,Zirui Zheng,Chenhui Zhang,Yuxia Gao,Fengpei Du
Impact and spread of droplet on superhydrophobic surface are ubiquitous in inkjet printing , pesticide spraying, paint coating, and other fields. However, due to the extremely water-repellent properties of superhydrophobic surface, droplets frequently splash or roll off, causing great waste and serious environmental problems. Thus, searching for an effective strategy to regulate the droplet splash and spread on superhydrophobic surfaces is of remarkable significance. To address the above issues, herein, we demonstrate the controllable regulation on superhydrophobic lotus leaf surface by tuning the double-chain length of surfactants . The outcomes indicate different regularities for droplet splash in a short time (~10 ms) and spread in a relatively long period (~100 s). It can be concluded that dynamic surface tension of surfactant, diffusion rate of surfactant from the bulk to the interface, and assembly disaggregation rate dominate the impact process, whereas the adsorption kinetic and effectiveness of surfactant along with the spreading driving force determine the wetting transition. Surfactant owning suitable hydrophilic and hydrophobic ratio, fast diffusion rate, and unstable assembly could inhibit droplet splash and improve spreading pronouncedly, thereby enhancing the droplet deposition on superhydrophobic surfaces. This study makes original contribution to screen suitable surfactants from the structural aspects, especially double-chain length, which has not been treated in much detail to date. Our work not only creates a big impetus in illuminating the mechanism of surfactant molecular structure on droplet deposition processes but also greatly expands the applications of surfactant in many fields.
研究领域:
胶体与界面化学
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农业化学
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材料科学
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流体力学
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环境科学
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应用物理
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纳米科技
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING RESEARCH & DESIGN
·
2024
·
IF 3.7
Xiaofei Xu,Xiaolong Li,Zhi Li,Da Zhang
An experimental study of single carbon dioxide (CO 2 ) bubbles ascending in aqueous solutions of carboxymethyl cellulose (CMC) is performed as a means to obtain further understanding of the rising behavior and mass transfer of soluble bubbles in shear-thinning non-Newtonian fluids. High-speed photography and digital image processing technique are employed to quantify the characteristic parameters of the bubble rising process. The rising behavior of single CO 2 bubbles in a Newtonian fluid (tap water) is measured as a reference. It has been found that the rheology of the liquid phase significantly influenced the rising behavior of the bubbles. In CMC aqueous solutions, CO 2 bubbles mostly followed a straight rising path characterized by increasing aspect ratio and decreasing vertical velocity. Increase in initial bubble size led to bubble deformation in less concentrated CMC aqueous solutions which resulted in an irregular rising path. The evolution of bubble equivalent diameter can be mainly divided into two stages: a fast reduction stage followed by a slow one. Meanwhile, the variation of liquid-side mass transfer coefficient k L of CO 2 bubbles in tap water and CMC aqueous solution with different weight percentages is discussed. The mobility of gas-liquid interface is considered to have significant impact on gas-liquid mass transfer. A dimensionless correlation considering the rheology of the liquid phase is proposed to describe the evolution of the motion and deformation of single soluble CO 2 bubbles in infinite stagnant shear-thinning non-Newtonian liquids.
研究领域:
流体力学
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化学工程
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多相流
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传质过程
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非牛顿流体动力学
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气泡动力学
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环境工程
✓ 已验证
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2024
·
IF 4.9
Hui Jiang,Xiaoyan Liu,Ying Xu,Yongying Jia
As a complex component of crude oil, asphaltenes determine the stability of emulsion . However, the mechanism of asphaltenes stabilize emulsion is still insufficient recognition due to the complexity of the molecular structure of asphaltenes. In this paper, the experiments and dissipative particle dynamics simulations were used to study the interfacial properties of asphaltenes. The adsorption of asphaltenes at the oil–water interface was studied by interfacial tension (IFT) experiments. A realistic molecular structure of asphaltene was constructed on the results of the characterization of the asphaltenes. The effects of asphaltenes concentration, temperature, and shear on the formation and stability of emulsion based on this molecular structure were investigated by simulations. The results show that the IFT decreases as asphaltenes concentration increases, while the droplet size of the emulsion decreases and becomes more uniformly distributed. Increasing the temperature enhances the interfacial activity of the asphaltenes, but also promotes its dissolution in the oil phase, which has a negative effect on reducing the IFT value and the stability of the emulsion. As the shear rate increases , the configuration of the emulsion changes from droplets to ellipsoids and rods, and the structure of the interfacial film is disrupted. This work provides useful insights into the mechanisms of asphaltenes concentration, temperature, and shear on the stability of the emulsion.
研究领域:
石油化学
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胶体与界面科学
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流体力学
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分子模拟
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能源工程
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2015
·
IF 4.321
Lu Qi,Xianghai Meng,Rui Zhang,Haiyan Liu,Chunming Xu,Zhichang Liu,Peter A.A. Klusener
Droplet size distribution (DSD) and mean droplet size of chloroaluminate ionic liquid (IL)–heptane dispersion in a stirred vessel were investigated as a model system for the composite ionic liquid/hydrocarbon system applied in the commercial isobutane alkylation process. Focused beam reflectance measurement was used to identify the phase inversion, and particle video microscope (PVM) was employed to measure the DSD of IL-continuous dispersions. The effects of agitation speed and dispersed phase holdup on the DSD and mean droplet size were investigated. Phase inversion was found at a heptane hold-up of just above 0.5. The observed DSDs could be described well by logarithmic normal distributions in spite of variable operating conditions. The DSDs appeared to be more or less independent of the dispersed phase holdup ( ϕ heptane ⩾ 0.3) at the same agitation speed. A semi-empirical correlation based on Shinnar theory was proposed to predict the droplet mean size in the impeller region for the IL-continuous dispersion, and the predicted value agreed well with the experimental data. This work will be a good basis to predict the dispersion behavior under process conditions.
研究领域:
化学工程
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流体力学
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多相系统
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过程工程
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胶体与界面科学
✓ 已验证
DOI
高影响因子
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
·
2024
·
IF 6.4
Boyu Li,Kang Luo,Jian Wu
Thermal energy storage technology utilizing phase change materials (PCMs) is extensively applied in thermal management and energy storage. The inclination angle ( θ ) plays a critical factor in the phase change melting processes in practical implementations. However, the precise experimental velocity fields of liquid PCM and the impact of active regulation technology on the heating wall temperature at various angles remain unclear. Herein, a transparent melting experiment platform was established to measure velocity, and adjust θ and manipulate input electric voltage. Results from Particle Image Velocimetry indicated that the installation angle significantly impacts natural convection in the convection-dominated melting regime. The liquid fraction decreased from 73.5 % (when θ = 90°) to 54.4 % (when θ = 150°) due to reduced thermal energy absorption, as input energy was stored as sensible heat on the copper wall. The electrohydrodynamic (EHD) effect mitigated thermal resistance between the heater and the melt front, increasing melt thickness. EHD flow exhibited limited ability to regulate heating wall temperature under strong natural convection , with a 6.5 % decrease observed under +20 kV conditions. As natural convection rates decreased, the decrease rate of heating wall temperature increased to 10.7 %. The EHD effect demonstrated a heightened capability in enhancing heat transfer melting with increasing θ , leading to an increase in temperature difference from 3.3 °C to 5.3 °C under the +15 kV input voltage. These findings suggest that the electric field is an efficacious method for controlling the heating wall temperature at different inclination angles during the melting process.
研究领域:
热工工程
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储能技术
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流体力学
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传热学
✓ 已验证
DOI
高影响因子
Advanced Science
·
2024
·Vol. 11
·期 38
·2405276
·
IF 14.3
Huangzhe Dai,Chengqian Zhang,Hao Hu,Zhezai Hu,Haonan Sun,Kan Liu,Tiefeng Li,Jianzhong Fu,Peng Zhao,Huayong Yang
The rapid development of ocean exploration and underwater robot technology has put forward new requirements for underwater sensing methods, which can be used for hydrodynamic characteristics perception, underwater target tracking, and even underwater cluster communication. Here, inspired by the specialized undulated surface structure of the seal whisker and its ability to suppress vortex-induced vibration, a multidirectional hydrodynamic sensor based on biomimetic whisker array structure and magnetic 3D self-decoupling theory is introduced. The magnetic-based sensing method enables wireless connectivity between the magnetic functional structures and electronics, simplifying device design and endowing complete watertightness. The 3D self-decoupling capability enables the sensor, like a seal or other organisms, to perceive arbitrary whisker motions caused by the action of water flow without complex calibration and additional sensing units. The whisker sensor is capable of detecting a variety of hydrodynamic information, including the velocity (RMSE < 0.061 m s −1 ) and direction of the steady flow field, the frequency (error < 0.05 Hz) of the dynamic vortex wake, and the orientation (error < 7°) of the vortex wake source, demonstrating its extensive potential for underwater environmental perception and communication, especially in deep sea conditions.
研究领域:
生物医学工程
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海洋生物学
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传感器技术
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流体力学
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仿生学
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水下机器人
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环境感知
✓ 已验证
DOI
高影响因子
FUEL
·
2018
·
IF 4.908
Guoqing Wang,Yuyang Li,Lei Li,Fei Qi
Cellular instability of spherically expanding methanol/air flames was investigated in a constant-volume single-chamber cylindrical combustion vessel at initial temperatures of 373–423 K, initial pressures of 1–10 atm and equivalence ratios of 0.7–2.1. Flame morphology shows that the methanol/air flames suffer from cellular instability, especially at 5–10 atm. Stability analysis was performed to determine the logarithmic growth rate of disturbance, the critical Peclet number and the critical flame radius. The influences of initial temperature, initial pressure and equivalence ratio on cellular instability were analyzed to identify the influential factors. Both experimental results and stability analysis indicate cellular instability monotonically increases with increasing temperature or pressure and non-monotonically varies with increasing equivalence ratio. The reduced critical Peclet number and flame thickness slightly destabilize the flame surface as temperature increases. The almost unchanged critical Peclet number and the greatly reduced flame thickness with increasing pressure make the critical flame radius smaller and the flame surface more unstable at high pressures. The monotonically decreased critical Peclet number and the non-monotonically varied flame thickness result in the non-monotonic variation of cellular instability in methanol/air flames versus equivalence ratio. The critical flame radius consequently increases with increasing equivalence ratio under very rich conditions, while the corresponding flame surface becomes more smooth. The non-monotonic variation of cellular instability versus equivalence ratio is anticipated to exist widely in combustion of heavy fuels .
研究领域:
燃烧学
·
热力学
·
流体力学
·
化学动力学
·
能源工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）