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Chu F, Hu Z, Feng Y, Lai NC, Wu X, Wang R. Advanced Anti-Icing Strategies and Technologies by Macrostructured Photothermal Storage Superhydrophobic Surfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2402897. [PMID: 38801015 DOI: 10.1002/adma.202402897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 04/23/2024] [Indexed: 05/29/2024]
Abstract
Water is the source of life and civilization, but water icing causes catastrophic damage to human life and diverse industrial processes. Currently, superhydrophobic surfaces (inspired by the lotus effect) aided anti-icing attracts intensive attention due to their energy-free property. Here, recent advances in anti-icing by design and functionalization of superhydrophobic surfaces are reviewed. The mechanisms and advantages of conventional, macrostructured, and photothermal superhydrophobic surfaces are introduced in turn. Conventional superhydrophobic surfaces, as well as macrostructured ones, easily lose the icephobic property under extreme conditions, while photothermal superhydrophobic surfaces strongly rely on solar illumination. To address the above issues, a potentially smart strategy is found by developing macrostructured photothermal storage superhydrophobic (MPSS) surfaces, which integrate the functions of macrostructured superhydrophobic materials, photothermal materials, and phase change materials (PCMs), and are expected to achieve all-day anti-icing in various fields. Finally, the latest achievements in developing MPSS surfaces, showcasing their immense potential, are highlighted. Besides, the perspectives on the future development of MPSS surfaces are provided and the problems that need to be solved in their practical applications are proposed.
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Affiliation(s)
- Fuqiang Chu
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Zhifeng Hu
- Research Center of Solar Power and Refrigeration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
- Department of Energy and Power Engineering, Tsinghua University, Beijing, 100084, China
| | - Yanhui Feng
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Nien-Chu Lai
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Xiaomin Wu
- Department of Energy and Power Engineering, Tsinghua University, Beijing, 100084, China
| | - Ruzhu Wang
- Research Center of Solar Power and Refrigeration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
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Xia L, Yang Z, Chen F, Liu T, Tian Y, Zhang D. Droplet impacting on pillared hydrophobic surfaces with different solid fractions. J Colloid Interface Sci 2024; 658:61-73. [PMID: 38100977 DOI: 10.1016/j.jcis.2023.12.053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 12/03/2023] [Accepted: 12/08/2023] [Indexed: 12/17/2023]
Abstract
HYPOTHESIS The solid fraction of the substrate is expected to influence the bouncing behavior of an impinging droplet, thereby affecting spreading and contact time. Hence, it should be possible to alter the velocity and pressure distribution of impacting droplet, and also affect the impact velocity for droplet penetration right upon impact. SIMULATIONS We systematically investigate the impact dynamics of water droplets on pillared hydrophobic surfaces with different solid fractions using phase-field simulations. The velocity and pressure distributions of impacting droplets on pillared hydrophobic surfaces with varied Weber numbers and solid fractions are studied. In addition, the influences of the solid fraction on the bouncing behaviors of the impinging droplet, such as the maximum wetting spreading, the maximum impacting depth, and the contact time, are also investigated to further understand the impact event. FINDINGS We show that a three-peak pressure profile appears on the top of the pillared hydrophobic surface during droplet impact by varying the solid fraction of the surface. The first peak is generated by the impact of the droplet itself, while the second peak arises from the droplet recoil impact associated with the dynamic properties of the jet. Moreover, we identify a hitherto unknown third pressure peak related to the hydrodynamic singularity that emerges due to the convergence of the fluid during the droplet rebound. This solid fraction-dependent impacting behavior reveals the intricate interplay between droplet dynamics and the underlying surface characteristics, providing valuable insights into the design and optimization of micro/nano structured hydrophobic surfaces for various applications.
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Affiliation(s)
- Lei Xia
- School of Mechanical Engineering, Tianjin University, Tianjin 300350, China
| | - Zhen Yang
- School of Mechanical Engineering, Tianjin University, Tianjin 300350, China; Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, Tianjin 300350, China
| | - Faze Chen
- School of Mechanical Engineering, Tianjin University, Tianjin 300350, China; Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, Tianjin 300350, China.
| | - Teng Liu
- Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, Tianjin 300350, China; School of Mechanical Engineering, Hebei University of Technology, Tianjin 300130, China
| | - Yanling Tian
- School of Engineering, University of Warwick, Coventry CV4 7DL, UK
| | - Dawei Zhang
- School of Mechanical Engineering, Tianjin University, Tianjin 300350, China; Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, Tianjin 300350, China
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Hu Z, Chu F, Shan H, Wu X, Dong Z, Wang R. Understanding and Utilizing Droplet Impact on Superhydrophobic Surfaces: Phenomena, Mechanisms, Regulations, Applications, and Beyond. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023:e2310177. [PMID: 38069449 DOI: 10.1002/adma.202310177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Revised: 11/13/2023] [Indexed: 12/19/2023]
Abstract
Droplet impact is a ubiquitous liquid behavior that closely tied to human life and production, making indispensable impacts on the big world. Nature-inspired superhydrophobic surfaces provide a powerful platform for regulating droplet impact dynamics. The collision between classic phenomena of droplet impact and the advanced manufacture of superhydrophobic surfaces is lighting up the future. Accurately understanding, predicting, and tailoring droplet dynamic behaviors on superhydrophobic surfaces are progressive steps to integrate the droplet impact into versatile applications and further improve the efficiency. In this review, the progress on phenomena, mechanisms, regulations, and applications of droplet impact on superhydrophobic surfaces, bridging the gap between droplet impact, superhydrophobic surfaces, and engineering applications are comprehensively summarized. It is highlighted that droplet contact and rebound are two focal points, and their fundamentals and dynamic regulations on elaborately designed superhydrophobic surfaces are discussed in detail. For the first time, diverse applications are classified into four categories according to the requirements for droplet contact and rebound. The remaining challenges are also pointed out and future directions to trigger subsequent research on droplet impact from both scientific and applied perspectives are outlined. The review is expected to provide a general framework for understanding and utilizing droplet impact.
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Affiliation(s)
- Zhifeng Hu
- Research Center of Solar Power and Refrigeration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Fuqiang Chu
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - He Shan
- Research Center of Solar Power and Refrigeration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xiaomin Wu
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing, 100084, China
| | - Zhichao Dong
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Sciences, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ruzhu Wang
- Research Center of Solar Power and Refrigeration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
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Peng X, Wang T, Jia F, Sun K, Li Z, Che Z. Singular jets during droplet impact on superhydrophobic surfaces. J Colloid Interface Sci 2023; 651:870-882. [PMID: 37573733 DOI: 10.1016/j.jcis.2023.07.186] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 07/24/2023] [Accepted: 07/28/2023] [Indexed: 08/15/2023]
Abstract
HYPOTHESIS The impact of droplets is prevalent in numerous applications, and jetting during droplet impact is a critical process controlling the dispersal and transport of liquid. New jetting dynamics are expected in different conditions of droplet impact on super-hydrophobic surfaces, such as new jetting phenomena, mechanisms, and regimes. EXPERIMENTS In this experimental study of droplet impact on super-hydrophobic surfaces, the Weber number and the Ohnesorge number are varied in a wide range, and the impact process is analyzed theoretically. FINDINGS We identify a new type of singular jets, i.e., singular jets induced by horizontal inertia (HI singular jets), besides the previously studied singular jets induced by capillary deformation (CD singular jets). For CD singular jets, the formation of the cavity is due to the propagation of capillary waves on the droplet surface; while for HI singular jets, the cavity formation is due to the large horizontal inertia of the toroidal edge during the retraction of the droplet after the maximum spreading. Key steps of the impact process are analyzed quantitatively, including the spreading of the droplet, the formation and the collapse of the spire, the formation and retraction of the cavity, and finally the formation of singular jets. A regime map for the formation of singular jets is obtained, and scaling relationships for the transition conditions between different regimes are analyzed.
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Affiliation(s)
- Xiaoyun Peng
- State Key Laboratory of Engines, Tianjin University, Tianjin, 300350, China
| | - Tianyou Wang
- State Key Laboratory of Engines, Tianjin University, Tianjin, 300350, China; National Industry-Education Platform of Energy Storage, Tianjin University, Tianjin, 300350, China
| | - Feifei Jia
- State Key Laboratory of Engines, Tianjin University, Tianjin, 300350, China
| | - Kai Sun
- State Key Laboratory of Engines, Tianjin University, Tianjin, 300350, China
| | - Zhe Li
- State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin, 300350, China
| | - Zhizhao Che
- State Key Laboratory of Engines, Tianjin University, Tianjin, 300350, China; National Industry-Education Platform of Energy Storage, Tianjin University, Tianjin, 300350, China.
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Lin Y, Wu X, Hu Z, Chu F. Leidenfrost droplet jet engine by bubble ejection. J Colloid Interface Sci 2023; 650:112-120. [PMID: 37399747 DOI: 10.1016/j.jcis.2023.06.174] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 06/19/2023] [Accepted: 06/25/2023] [Indexed: 07/05/2023]
Abstract
HYPOTHESIS Despite the flourishing studies of Leidenfrost droplet motion in its boiling regime, the droplet motion across different boiling regimes has rarely been focused on, where bubbles are generated at the solid-liquid interface. These bubbles are probable to dramatically alter the dynamics of Leidenfrost droplets, creating some intriguing phenomena of droplet motion. EXPERIMENTS Hydrophilic, hydrophobic, and superhydrophobic substrates with a temperature gradient are designed, and Leidenfrost droplets with diverse fluid types, volumes, and velocities travel from the hot end to the cold end of the substrate. The behaviors of droplet motion across different boiling regimes are recorded and depicted in a phase diagram. FINDINGS A special phenomenon of Leidenfrost droplets that resembles a jet engine is witnessed on a hydrophilic substrate with a temperature gradient: the droplet traveling across boiling regimes repulsing itself backward. The mechanism of repulsive motion is the reverse thrust from fierce bubble ejection when droplets meet nucleate boiling regime, which cannot take place on hydrophobic and superhydrophobic substrates. We further demonstrate that conflicting droplet motions can occur in similar conditions, and a model is developed to predict the occurring criteria of this phenomenon for droplets in diverse working conditions, which agrees well with the experimental data.
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Affiliation(s)
- Yukai Lin
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
| | - Xiaomin Wu
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China.
| | - Zhifeng Hu
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
| | - Fuqiang Chu
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China.
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Steerable directional bouncing and contact time reduction of impacting droplets on superhydrophobic stepped surfaces. J Colloid Interface Sci 2023; 629:1032-1044. [DOI: 10.1016/j.jcis.2022.09.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 08/25/2022] [Accepted: 09/04/2022] [Indexed: 11/19/2022]
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Yang K, Liu Q, Lin Z, Liang Y, Liu C. Bouncing dynamics of impact droplets on bioinspired surfaces with mixed wettability and directional transport control. J Colloid Interface Sci 2022; 626:193-207. [DOI: 10.1016/j.jcis.2022.06.158] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 06/09/2022] [Accepted: 06/27/2022] [Indexed: 11/25/2022]
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Hu Z, Ding S, Zhang X, Wu X. Dynamic behavior and maximum width of impact droplets on single-pillar superhydrophobic surfaces. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.129355] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Hu Z, Chu F, Lin Y, Wu X. Contact Time of Droplet Impact on Inclined Ridged Superhydrophobic Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:1540-1549. [PMID: 35072484 DOI: 10.1021/acs.langmuir.1c03001] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Superhydrophobic surfaces decorated with macrostructures have attracted extensive attention due to their excellent performance of reducing the contact time of impacting droplets. In many practical applications, the surface is not perpendicular to the droplet impact direction, but the impacting dynamics in such scenarios still remain mysterious. Here, we experimentally investigate the dynamics of droplet impact on inclined ridged superhydrophobic surfaces and reveal the effect of Wen (the normal Weber number) and α (the inclination angle) on the contact time τ. As Wen increases, τ first decreases rapidly until a platform is reached; if Wen continues to increase, τ further reduces to a lower platform, indicating a three-stage variation of τ in low, middle, and high Wen regions. In the middle and high Wen regions, the contact time is reduced by 30 and 50%, respectively, and is dominated by droplet spreading/retraction in the tangential and lateral directions, respectively. A quantitative analysis demonstrates that τ in the middle and high Wen regions is independent of Wen and α, while the range of middle and high Wen regions is related to α. When α < 30°, increasing α narrows the middle Wen region and enlarges the high Wen region; when α ≥ 30°, the two Wen regions remain unchanged. In addition, droplet sliding is hindered by the friction and is affected by the droplet morphology in the high Wen region. Overall, the synergistic effect of the surface inclination and macrostructures effectively promotes the detachment of impacting droplets on superhydrophobic surfaces, which provides guidance for applications of superhydrophobic surfaces.
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Affiliation(s)
- Zhifeng Hu
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
| | - Fuqiang Chu
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Yukai Lin
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
| | - Xiaomin Wu
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
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Molecular Dynamics Simulation on Behaviors of Water Nanodroplets Impinging on Moving Surfaces. NANOMATERIALS 2022; 12:nano12020247. [PMID: 35055264 PMCID: PMC8780412 DOI: 10.3390/nano12020247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 01/01/2022] [Accepted: 01/07/2022] [Indexed: 12/10/2022]
Abstract
Droplets impinging on solid surfaces is a common phenomenon. However, the motion of surfaces remarkably influences the dynamical behaviors of droplets, and related research is scarce. Dynamical behaviors of water nanodroplets impinging on translation and vibrating solid copper surfaces were investigated via molecular dynamics (MD) simulation. The dynamical characteristics of water nanodroplets with various Weber numbers were studied at five translation velocities, four vibration amplitudes, and five vibration periods of the surface. The results show that when water nanodroplets impinge on translation surfaces, water molecules not only move along the surfaces but also rotate around the centroid of the water nanodroplet at the relative sliding stage. Water nanodroplets spread twice in the direction perpendicular to the relative sliding under a higher surface translation velocity. Additionally, a formula for water nanodroplets velocity in the translation direction was developed. Water nanodroplets with a larger Weber number experience a heavier friction force. For cases wherein water nanodroplets impinge on vibration surfaces, the increase in amplitudes impedes the spread of water nanodroplets, while the vibration periods promote it. Moreover, the short-period vibration makes water nanodroplets bounce off the surface.
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Song M, Zhao H, Wang T, Wang S, Wan J, Qin X, Wang Z. A new scaling number reveals droplet dynamics on vibratory surfaces. J Colloid Interface Sci 2021; 608:2414-2420. [PMID: 34753623 DOI: 10.1016/j.jcis.2021.10.165] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/25/2021] [Accepted: 10/26/2021] [Indexed: 01/08/2023]
Abstract
HYPOTHESIS Droplet spreading on surfaces is a ubiquitous phenomenon in nature and is relevant with a wide range of applications. In practical scenarios, surfaces are usually associated with certain levels of vibration. Although vertical or horizontal modes of vibration have been used to promote droplet dewetting, bouncing from immiscible medium, directional transport, etc., a quantitative understanding of how external vibration mediates the droplet behaviors remains to be revealed. METHODS We studied droplets impacting on stationary and vibratory surfaces, respectively. In analogy to the Weber number We=ρUi2D0/γWe = ρUi2D0/γ, we define the vibration Weber number We*=ρUv2D0/γ to quantitively analyze the vibration-induced dynamic pressure on droplet behaviors on vibratory surfaces, where ρ,γ,D0,UiandUv are liquid density, surface tension, initial droplet diameter, impact velocity of the droplet, and velocity amplitude of vibration, respectively. FINDINGS We demonstrate that the effect of vibration on promoting droplet spreading can be captured by a new scaling number expressed as We*/[We1\2sin(θ/2)], leading to (Dm - Dm0)/Dm0 ∝ We*/[We1\2sin(θ/2)], where θ is the contact angle, and Dm0 and Dm are the maximum diameter of the droplet on stationary and vibratory surfaces, respectively. The scaling number illustrates the relative importance of vibration-induced dynamic pressure compared to inertial force and surface tension. Together with other well-established non-dimensional numbers, this scaling number provides a new dimension and framework for understanding and controlling droplet dynamics. Our findings can also find applications such as improving the power generation efficiency, intensifying the deposition of paint, and enhancing the heat transfer of droplets.
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Affiliation(s)
- Mingkai Song
- School of Mechanical and Aerospace Engineering, Jilin University, Changchun 130025, PR China
| | - Hongwei Zhao
- School of Mechanical and Aerospace Engineering, Jilin University, Changchun 130025, PR China; Key Laboratory of CNC Equipment Reliability, Ministry of Education, Changchun 130025, PR China.
| | - Ting Wang
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, PR China
| | - Shunbo Wang
- School of Mechanical and Aerospace Engineering, Jilin University, Changchun 130025, PR China
| | - Jie Wan
- School of Mechanical and Aerospace Engineering, Jilin University, Changchun 130025, PR China
| | - Xuezhi Qin
- School of Mechanical and Aerospace Engineering, Jilin University, Changchun 130025, PR China; Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, PR China
| | - Zuankai Wang
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, PR China.
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