共查询到20条相似文献，搜索用时 15 毫秒
1.
Shiva Moradi Mehr Mohammad A. Charsooghi Luca Businaro Mehdi Habibi Ali-Reza Moradi 《American Institute of Chemical Engineers》2023,69(3):e17847
The famous two-balloon experiment involves two identical balloons filled up with air and connected via a hollow tube, and upon onsetting the experiment one of the balloons shrinks and the other expands. Here, we present the liquid version of that experiment. We use superhydrophobic (SHP) substrates to form spherical droplets and connect them with a capillary channel. Different droplet sizes, substrates of different hydrophobicities, and various channel pathways are investigated, and morphometric parameters of the droplets are measured through image processing. In the case of SHP substrates, the pumping is from the smaller droplet to the larger one, similar to the two-balloon experiment. However, if one or both of the droplets are positioned on a normal substrate the curvature radius will indicate the direction of pumping. We interpret the results by considering the Laplace pressures and the surface tension applied by the channel at the connecting points. 相似文献
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本文对固着纯组分液滴的蒸发研究现状进行了综合评述。介绍了固着液滴蒸发的恒接触半径模式、恒接触角模式及混合模式,分析了完全润湿和部分润湿两种固着液滴的蒸发过程及其特点,系统讨论固着液滴的蒸发动力学理论规律,并对固着液滴蒸发的实验研究进行了简要介绍。 相似文献
3.
在微流体研究领域,为了开发低阻力的固-液界面材料,人们关注和研究水滴在超疏水性表面上的运动。在该项研究中,笔者使用超高速摄像技术观察在超疏水性表面上水滴的移动,考察材料表面与水滴的相互作用以及表面的物理和化学特性的影响。这一研究是为了实现超疏水性表面上水滴的可控运动而进行的基础研究。 相似文献
4.
液滴自发聚并在自然和工业中广泛存在,如何高效去除聚并液滴是强化滴状冷凝换热、防结冰等的重要环节。采用数值模拟方法研究了不同半径比液滴在超疏水平壁面和超疏水波浪形壁面上的聚并起跳行为。研究发现,在平壁面上聚并的液滴水平速度与竖直速度差1～2个数量级,液滴的水平方向位移小,聚并后难以有效去除;在波浪形壁面上,由于液桥撞击在斜面上,产生较大的水平分力,聚并后其水平速度保持与竖直速度在同一数量级,水平位移显著增大;并且波浪结构对液滴弹跳过程影响显著,随波浪高宽比的增大液滴水平位移增大且弹跳高度减小,有效促进了液滴的水平运动,且当高宽比为0.21时,促进作用接近峰值。研究结果为聚并液滴的有效去除提供了新参考。 相似文献
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液滴自发聚并在自然和工业中广泛存在,如何高效去除聚并液滴是强化滴状冷凝换热、防结冰等的重要环节。采用数值模拟方法研究了不同半径比液滴在超疏水平壁面和超疏水波浪形壁面上的聚并起跳行为。研究发现,在平壁面上聚并的液滴水平速度与竖直速度差1～2个数量级,液滴的水平方向位移小,聚并后难以有效去除;在波浪形壁面上,由于液桥撞击在斜面上,产生较大的水平分力,聚并后其水平速度保持与竖直速度在同一数量级,水平位移显著增大;并且波浪结构对液滴弹跳过程影响显著,随波浪高宽比的增大液滴水平位移增大且弹跳高度减小,有效促进了液滴的水平运动,且当高宽比为0.21时,促进作用接近峰值。研究结果为聚并液滴的有效去除提供了新参考。 相似文献
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实验研究了超疏水表面上太阳能加热金纳米流体液滴蒸发特性。用高速摄像机和红外摄像机同步触发记录了2 μl不同浓度金纳米流体液滴在超疏水表面的蒸发过程。通过一系列实验,观察对比不同浓度金纳米流体液滴蒸发过程中体积、接触角、接触直径、液滴表面温度以及蒸发速率等动态特性。结合水蒸气扩散模型以及红外温度图分析液滴在超疏水表面上的蒸发过程中蒸发通量变化以及表面温度变化等特性。发现不同浓度纳米流体液滴蒸发速率基本一致;超疏水表面上液滴蒸发以常接触角模式为主,后期呈现混合模式蒸发;液滴蒸发过程中,液滴上半部分蒸发通量大,致使液滴表面温度较低。 相似文献
7.
高羡明;杨汶轩;卢少辉;任晓松;卢方财 《化工学报》2025,76(1):208-220
超疏水表面上的液滴弹跳现象在芯片高效散热、防腐蚀、结冰等领域具有较高的应用价值。为研究双槽道对液滴弹跳性能的影响,设计并制备了由双V槽道构成的W型槽道超疏水表面,试验研究了W型槽道底部间距w、槽道深度h对液滴弹跳速度及能量转化效率的影响,采用数值模拟方式研究了W型槽道的超疏水表面液滴合并弹跳过程中表面能的演化。结果表明,槽宽为0.9 mm的W型槽道所适配的液滴半径为0.5～0.9 mm,此范围内槽道深度h为0.5～0.8 mm、槽道底部间距w为0.5～0.8 mm时对提升液滴合并弹跳的效果更显著;随着液滴半径减小、槽道深度增加、槽道底部间距减小,液滴的合并弹跳速度增加;槽道参数在0.5～0.7 mm内同时增加时,弹跳速度增加,而在0.8 mm时降低。研究结果可为冷凝换热和防腐蚀等领域的表面设计提供参考。 相似文献
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Fluoropolymer transparent thin films were deposited on different substrates by one‐step vacuum evaporation method, which exhibit superhydrophobic property with water contact angle (CA) greater than 150°. Polytetrafluoroethylene (PTFE) film with network structure shows high oleophobicity with oil CA of 138°, whereas polytetrafluoroethylene‐perfluoropropylvinylethers (PFA) film with particle structure is superoleophilicity with oil CA near 0°. It is believed that different conformation of CF2 groups at the surface lead to this different surface activity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
9.
抑制撞击液滴的结冰在实际工程应用中具有重要意义。寻求经济、高效的防/除冰方法是结冰领域的研究热点。针对撞击液滴的结冰问题,首先从动力学特性、结冰特性以及撞击液滴结冰的理论研究等方面进行综述,并对目前关于撞击液滴结冰中存在的一些问题进行分析。然后,基于撞击液滴的反弹特性可从源头上抑制结冰这种思路,提出降低接触时间、增加成核再辉时间的新方法。这些方法的提出有助于从源头上解决撞击液滴的结冰问题,将使“利用撞击液滴的反弹特性抑制结冰”的应用范围极大扩展,积极推动防结冰技术的发展。最后,对利用液滴的反弹特性进行抑制结冰的研究进行展望。 相似文献
10.
王艳;冯致;张正阳;吴昊;张文宇;杨露露;张文硕;禹芹芹;刘维;王进卿;孔明 《化工进展》2025,44(4):1867-1875
针对当前液滴蒸发过程三维形貌测量方法存在的还原精度不足、易受噪声干扰等问题;本文采用Linnik干涉法搭建了一套LED离轴数字全息系统;在光学系统中采用LED光源结合参考光衰减技术以提高光学系统降低相干噪声的性能;算法上采用双曝光法结合加权最小二乘相位解包裹算法矫正相位畸变并减弱相干噪声;提高成像质量。利用该系统研究竖直玻璃表面微尺度无水乙醇液滴的蒸发过程;实现了液滴蒸发过程中的三维形貌还原和动态接触角测量。结果表明;液滴接触角在不同方向上表现出不对称性;尤其在与重力方向成45°角的方向上差异显著;在蒸发过程中重力、表面性质不均匀等均会影响液滴蒸发行为;液滴在不同方向上的蒸发速率具有差异性。本文的研究工作为微尺度液滴三维形貌的动态测量提供了新方法;有望为流体界面科学等领域的研究工作提供重要支持。 相似文献
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Tong Xing Changqing Dong Xiaodong Wang Xiaoying Hu Changrui Liu Haiyang Lv 《Frontiers of Chemical Science and Engineering》2022,16(9):1377
The preparation of environmentally friendly oil/water separation materials remains a great challenge. Freeze-drying of wood after lignin removal yields wood aerogels, which can be used as substrates to prepare fluorine-free environmentally friendly superhydrophobic materials, However, they are more suitable for absorption rather than filtration applications due to their poor strength. A study using cross-sections of pristine wood chips as substrates retains the original strength of wood, but the use of the cross-sectional of wood pieces limits their thickness, strength, and size. In this paper, a degradable fluorine-free superhydrophobic film (max. water contact angle of approximately 164.2°) with self-cleaning and abrasion resistance characteristics was prepared by a one-step method using pristine and activated walnut longitudinal section films as the substrate, with tetraethyl orthosilicate as a precursor and dodecyltriethoxysilane as a modifier. The tensile strength results show that superhydrophobic films with pristine or activated wood substrates maintained the strength of pristine wood and were 2.2 times stronger than the wood aerogel substrate. In addition, after cross-laminating the two samples, the films had the ability to separate oil and water by continuous filtration with high efficiency (98.5%) and flux (approximately 1.3 × 103 L∙m‒2∙h‒1). The method has potential for the large-scale fabrication of degradable superhydrophobic filtration separation membranes. 相似文献
13.
聚二甲基硅氧烷(PDMS),作为一种价格低廉、环境友好的有机硅材料,被广泛作为超疏水修饰剂来使用,并利用其与固化剂混合后可固化成型的特点,用于构建表面结构。综述了PDMS在制备超疏水材料上的研究进展,并对其今后的发展做出了展望。 相似文献
14.
以氧化铝纳米流体液滴为研究对象,本文建立了基于任意拉格朗日-欧拉（ALE）法的液滴蒸发瞬态模型,对液滴蒸发过程中蒸汽浓度、纳米颗粒浓度、温度等进行多物理场耦合,并考虑了Marangoni流对液滴蒸发的影响,同时研究还结合蒸发实验可视化结果,分析了氧化铝纳米流体液滴的瞬态蒸发速率随时间的演化规律,讨论了颗粒体积分数和基板温度对蒸发模式的影响。结果表明,在液滴蒸发过程开始时,纳米流体液滴保持定接触半径蒸发模式,气液界面面积逐渐减小,瞬态蒸发速率也呈逐渐减小的趋势;当颗粒体积分数增大至26%时,瞬态蒸发速率曲线达到驻点;蒸发接近完全时,由于Marangoni流影响了内部流场、强化了内部传热,且液滴在已沉积在基板上的颗粒表面形成液膜,瞬态蒸发速率迅速增大。 相似文献
15.
Mikhil Surendran T. N. C. Anand Shamit Bakshi 《American Institute of Chemical Engineers》2020,66(2):e16845
The behavior of droplets of urea-water-solution (UWS) evaporating under the influence of a hot stream of air was investigated experimentally, under temperatures ranging from 100°C to 400°C. The droplets were suspended on a glass microfiber to minimize the influence of heat conduction, through the fiber, on the evaporation rate of the droplet. The flow rate of air, under all experimental conditions, was measured and these data were used to estimate the average velocity of air around the droplet. Experiments were also conducted on droplets of pure water and the results were compared. The initial mass fraction of urea, in the solution, did not appear to have a significant effect on the evaporation constant, but it did affect a few essential aspects of the evaporation behavior. The evaporation of water droplets was in accordance with the d2 law at all temperatures, whereas the evaporation of UWS droplets was ambient-temperature dependent. 相似文献
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超疏水表面因具有诸多优异特性而展现出良好的应用前景,但在实际应用中容易受到外界机械力损坏或化学侵蚀,赋予超疏水表面自修复性能可以较好地改善表面耐久性,延长其使用寿命。本文针对修复构成超疏水表面的微观结构与低表面能物质展开论述,介绍了在湿度、温度、光等外界因素的引发下超疏水表面对低表面能物质的修复行为与特点,以及以形状记忆聚合物为主制备的超疏水表面对微观结构进行修复的过程。此外,介绍了具有自修复性能的超疏水表面在防腐蚀、油水分离、防覆冰等领域的应用。最后,讨论了通过优化表面结构和化学组成开发自修复超疏水表面的挑战和前景,环保型且无需外界刺激即可迅速对微观结构与低表面能物质进行双重修复的超疏水表面具有重要的研究意义。 相似文献
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超疏水/超双疏材料存在耐久性和稳定性的问题,因此很大程度影响了超疏水/超双疏材料的实际应用。受自然界中荷叶、三叶草等超疏水表面在受到破坏后,表面粗糙结构和表面组成可以恢复直到生物死亡的启发,科研学者通过不断探索研究出修复超疏水/超双疏材料的一些方式。本文从低表面能物质和表面微观结构的自修复角度出发,综述了影响超疏水/超双疏表面的自修复方式。当超疏水/超双疏表面受到物理破坏或者化学破坏时,失去超疏水以及超疏油性能,在温度、相对湿度、机械、UV等诱导条件下,低表面能物质迁移至表面完成自修复过程以及表面微观结构的自修复,从而使超疏水以及超疏油性能得以恢复。价格低廉的环保材料和系统性地研究自修复的机理是将来超疏水/超双疏自修复材料的主要研究方向。 相似文献
18.
Bin-Fang Tsai Yi-Cheng Chen Shih-Fu Ou Kuang-Kuo Wang Yen-Chi Hsu 《International Journal of Applied Ceramic Technology》2019,16(1):211-220
A superhydrophobic surface of titanium was fabricated by anodization in sodium chloride solution followed by immersion in perfluorodecyltriethoxysilane. The surface characteristics of the anodic film (morphology, composition, microstructure, and adhesion) were investigated by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and scratch testing. The anodic film was comprised of TiO2 and TiCl3 with a thickness of 50 nm. The anodized titanium surface exhibited a hierarchical structure, which consisted of a microscale horn structure with a nanoscale strip-overlay. This structure provided superhydrophobicity (water contact angle: 151.9° and sliding angle: 3°) following the immersion process. Furthermore, coverage of the hierarchical structure on the anodized titanium surface was improved by performing surface mechanical attrition treatment (SMAT) to grain-refine titanium surface which was then anodized and it enhanced a slightly increased water contact angle. The thickness (200 nm) of the anodic film on the SMAT-pretreated titanium surface was much higher than that on the titanium surface (50 nm). This resulted from a large number of grain boundaries on the surface serving as a fast diffusion path during anodization. However, the adhesion of the SMAT-and-anodized film was worse than that formed by anodization only. This is due to a large number of pores within the SMAT-and-anodized film. 相似文献
19.
Preparation of superhydrophobic silica‐based surfaces via sol–gel process by adding polyethylene glycol (PEG) polymer into the precursor solution has been developed. Surface roughness of the films was obtained by removing the organic polymer at 500°C and then the hydrophobic groups bonded onto the films were obtained by self‐assembly modification with a monolayer. Characteristic properties of the as‐prepared films were analyzed by contact angle measurements, scanning electron microscopy, atomic force microscopy, UV–vis scanning spectrophotometer, and X‐ray photoelectron spectrophotometer. The experimental parameters were varied by the type of silane species, the R ratio, the hydrolysis time of the precursor solution, the molecular weight of PEG, the pH value of mixing solution, and the different reagents for modification. The results showed that optimum ratio of TEOS/H2O/ethanol in the sol–gel process for precursor solution was set to 1/10/4. The better contact angles of the films can be obtained by the acid catalyst reaction, especially the pH value of mixing solution was adjusted to 0. When the as‐prepared rough films were modified with (tridecafluoro‐1,1,2,2‐tetrahydrooctyl) dimethylchlorosilane (TFCS), the contact angle of the film can be promoted to 150.4°, and the transmittance of the films in the visible light region was greater than 94.5%. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献