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Wu J, Zou J, Ma H, Wang J, Li C, Yang C, Deng L, Wang M, Yang H. Drop Impact on Submillimeter-Structured Surfaces with Different Wetting Behaviors. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:15022-15030. [PMID: 37813395 DOI: 10.1021/acs.langmuir.3c01841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/11/2023]
Abstract
Droplet impact behaviors are crucial in controlling infectious diseases, inkjet printing, and anti-icing applications. The wettability and microstructure of the material surface are critical factors in this regard. Compared to microstructures, submillimeter structures are more damage-resistant, thereby ensuring droplet impact behaviors' stability. Herein, submillimeter-structured PDMS surfaces with varying wetting properties were prepared to investigate droplet impact behaviors. Experimental results indicate that submillimeter-structured surfaces are more prone to droplet splashing than flat surfaces, which can be suppressed by increasing surface hydrophilicity. An increase in the submillimeter pillar height and a decrease in spacing result in an increased critical Weber number. Additionally, the capillary forces of the superhydrophilic surface lead to droplet impact, accompanied by deposition. This study supports the long-term stable use of the droplet impact effect to achieve fluid separation.
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Affiliation(s)
- Jiangen Wu
- Sino-German College of Intelligent Manufacturing, Shenzhen Technology University, Shenzhen 518118, China
| | - Jun Zou
- Sino-German College of Intelligent Manufacturing, Shenzhen Technology University, Shenzhen 518118, China
| | - Haojun Ma
- Sino-German College of Intelligent Manufacturing, Shenzhen Technology University, Shenzhen 518118, China
| | - Jiayan Wang
- Sino-German College of Intelligent Manufacturing, Shenzhen Technology University, Shenzhen 518118, China
| | - Chunbo Li
- Sino-German College of Intelligent Manufacturing, Shenzhen Technology University, Shenzhen 518118, China
| | - Can Yang
- Sino-German College of Intelligent Manufacturing, Shenzhen Technology University, Shenzhen 518118, China
| | - Leimin Deng
- Wuhan National Research Center for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Meng Wang
- Sino-German College of Intelligent Manufacturing, Shenzhen Technology University, Shenzhen 518118, China
| | - Huan Yang
- Sino-German College of Intelligent Manufacturing, Shenzhen Technology University, Shenzhen 518118, China
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Du J, Li Y, Wang X, Min Q. Inhibiting the Leidenfrost Effect by Superhydrophilic Nickel Foams with Ultrafast Droplet Permeation. ACS APPLIED MATERIALS & INTERFACES 2023; 15:41121-41129. [PMID: 37584594 DOI: 10.1021/acsami.3c08009] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/17/2023]
Abstract
Inhibiting the Leidenfrost effect has drawn extensive attention due to its detrimental impact on heat dissipation in high-temperature industrial applications. Although hierarchical structures have improved the Leidenfrost point to over 1000 °C, the current performance of single-scale structures remains inadequate. Herein, we present a facile high-temperature treatment method to fabricate superhydrophilic nickel foams that demonstrate ultrafast droplet permeation within tens of milliseconds, elevating the Leidenfrost point above 500 °C. Theoretical analysis based on the pressure balance suggests that these remarkable features arise from the superhydrophilic property, high porosity, and large pore diameter of nickel foams that promote capillary wicking and vapor evacuation. Compared to solid nickel surfaces with a Leidenfrost temperature of approximately 235 °C, nickel foams nucleate boiling at high superheat, triggering an order of magnitude higher heat flux. The effects of the pore diameter and surface temperature on droplet permeation behaviors and heat transfer characteristics are also elucidated. The results indicate that droplet permeation is dominated by inertial and capillary forces at low and high superheat, respectively, and moderate pore diameters are more conducive to facilitating droplet permeation. Furthermore, our heat transfer model reveals that pore diameter plays a negligible role in the heat flux at high surface temperatures due to the trade-off between effective thermal conductivity and specific surface area. This work provides a new strategy to address the Leidenfrost effect by metal foams, which may promise great potential in steel forging and nuclear reactor safety.
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Affiliation(s)
- Jiayu Du
- Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China
| | - Yanzhi Li
- Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China
| | - Xiong Wang
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
| | - Qi Min
- Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China
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Wang X, Xu B, Guo S, Zhao Y, Chen Z. Droplet impacting dynamics: Recent progress and future aspects. Adv Colloid Interface Sci 2023; 317:102919. [PMID: 37216871 DOI: 10.1016/j.cis.2023.102919] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 05/02/2023] [Accepted: 05/11/2023] [Indexed: 05/24/2023]
Abstract
Droplet impact behaviours are widely applied in a variety of domains including self-cleaning, painting and coating, corrosion of turbine blades and aircraft, separation and oil repellency, anti-icing, heat transfer and droplet electricity generation, etc. The wetting behaviours and impact dynamics of droplets on solid and liquid surfaces involve complex solid-liquid and liquid-liquid interfacial interactions. The modulation of droplet dynamics by means of specific surface morphology and hydrophobic/hydrophilic patterns, which in turn can be derived to related applications, is one of the current promising interests in the interfacial effect modulating droplet dynamics. This review provides a detailed overview of several scientific aspects of droplet impact behaviours and heat transfer processes influenced by multiple factors. Firstly, the essential wetting theory and the fundamental parameters of impinging droplets are introduced. Secondly, the effects of different parameters on the dynamic behaviours and heat transfer of impinging droplet are discussed. Finally, the potential applications are listed. Existing concerns and challenges are summarized and future perspectives are provided to address poorly understood and conflicting issues.
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Affiliation(s)
- Xin Wang
- School of Energy and Environment, Southeast University, Nanjing, PR China; Department of Mechanical Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, PR China
| | - Bo Xu
- School of Energy and Environment, Southeast University, Nanjing, PR China
| | - Shuai Guo
- School of Energy and Environment, Southeast University, Nanjing, PR China
| | - Yu Zhao
- School of Energy and Environment, Southeast University, Nanjing, PR China
| | - Zhenqian Chen
- School of Energy and Environment, Southeast University, Nanjing, PR China; Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing, PR China; Jiangsu Provincial Key Laboratory of Solar Energy Science and Technology, School of Energy and Environment, Southeast University, Nanjing, PR China.
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Characterization of electrodeposited porous structured composite layers and their unconventional wettability properties. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.130074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Han X, Li J, Tang X, Li W, Zhao H, Yang L, Wang L. Droplet Bouncing: Fundamentals, Regulations, and Applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2200277. [PMID: 35306734 DOI: 10.1002/smll.202200277] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 02/13/2022] [Indexed: 06/14/2023]
Abstract
Droplet impact is a ubiquitous phenomenon in nature, daily life, and industrial processes. It is thus crucial to tune the impact outcomes for various applications. As a special outcome of droplet impact, the bouncing of droplets keeps the form of the droplets after the impact and minimizes the energy loss during the impact, being beneficial in many applications. A unified understanding of droplet bouncing is in high demand for effective development of new techniques to serve applications. This review shows the fundamentals, regulations, and applications of millimeter-sized droplet bouncing on solid surfaces and same/miscible liquids (liquid pool and another droplet). Regulation methods and current applications are summarized, and potential directions are proposed.
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Affiliation(s)
- Xing Han
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, 999077, Hong Kong
| | - Jiaqian Li
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, 999077, Hong Kong
| | - Xin Tang
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, 999077, Hong Kong
| | - Wei Li
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, 999077, Hong Kong
| | - Haibo Zhao
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, 999077, Hong Kong
- Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Ling Yang
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, 999077, Hong Kong
| | - Liqiu Wang
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, 999077, Hong Kong
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Trampolining of Droplets on Hydrophobic Surfaces Using Electrowetting. MICROMACHINES 2022; 13:mi13030345. [PMID: 35334639 PMCID: PMC8953513 DOI: 10.3390/mi13030345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/15/2022] [Accepted: 02/16/2022] [Indexed: 11/25/2022]
Abstract
Droplet detachment from solid surfaces is an essential part of many industrial processes. Electrowetting is a versatile tool for handling droplets in digital microfluidics, not only on plain surface but also in 3-D manner. Here, we report for the first time droplet trampolining using electrowetting. With the information collected by the real-time capacitor sensing system, we are able to synchronize the actuation signal with the spreading of the droplet upon impacting. Since electrowetting is applied each time the droplet impacts the substrate and switched off during recoiling of the droplet, the droplet gains additional momentum upon each impact and is able to jump higher during successive detachment. We have modelled the droplet trampolining behavior with a periodically driven harmonic oscillator, and the experiments showed sound agreement with theoretical predictions. The findings from this study will offer valuable insights to applications that demands vertical transportation of the droplets between chips arranged in parallel, or detachment of droplets from solid surfaces.
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Cheng Y, Wang M, Sun J, Liu M, Du B, Liu Y, Jin Y, Wen R, Lan Z, Zhou X, Ma X, Wang Z. Rapid and Persistent Suction Condensation on Hydrophilic Surfaces for High-Efficiency Water Collection. NANO LETTERS 2021; 21:7411-7418. [PMID: 34176267 DOI: 10.1021/acs.nanolett.1c01928] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Water collection by dew condensation emerges as a sustainable solution to water scarcity. However, the transient condensation process that involves droplet nucleation, growth, and transport imposes conflicting requirements on surface properties. It is challenging to satisfy all benefits for different condensation stages simultaneously. By mimicking the structures and functions of moss Rhacocarpus, here, we report the attainment of dropwise condensation for efficient water collection even on a hydrophilic surface gated by a liquid suction mechanism. The Rhacocarpus-inspired porous surface (RIPS), which possesses a three-level wettability gradient, facilitates a rapid, directional, and persistent droplet suction. Such suction condensation enables a low nucleation barrier, frequent surface refreshing, and well-defined maximum droplet shedding radius simultaneously. Thus, a maximum ∼160% enhancement in water collection performance compared to the hydrophobic surface is achieved. Our work provides new insights and a design route for developing engineered materials for a wide range of water-harvesting and phase-change heat-transfer applications.
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Affiliation(s)
- Yaqi Cheng
- State Key Laboratory of Fine Chemicals, Liaoning Key Laboratory of Clean Utilization of Chemical Resources, Institute of Chemical Engineering, Dalian University of Technology, Dalian 116024, China
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
| | - Mingmei Wang
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
| | - Jing Sun
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
| | - Minjie Liu
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
| | - Bingang Du
- State Key Laboratory of Fine Chemicals, Liaoning Key Laboratory of Clean Utilization of Chemical Resources, Institute of Chemical Engineering, Dalian University of Technology, Dalian 116024, China
| | - Yuanbo Liu
- State Key Laboratory of Fine Chemicals, Liaoning Key Laboratory of Clean Utilization of Chemical Resources, Institute of Chemical Engineering, Dalian University of Technology, Dalian 116024, China
| | - Yuankai Jin
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
| | - Rongfu Wen
- State Key Laboratory of Fine Chemicals, Liaoning Key Laboratory of Clean Utilization of Chemical Resources, Institute of Chemical Engineering, Dalian University of Technology, Dalian 116024, China
| | - Zhong Lan
- State Key Laboratory of Fine Chemicals, Liaoning Key Laboratory of Clean Utilization of Chemical Resources, Institute of Chemical Engineering, Dalian University of Technology, Dalian 116024, China
| | - Xiaofeng Zhou
- Shanghai Key Laboratory of Multidimensional Information Processing, School of Communication and Electronic Engineering, East China Normal University, Shanghai 200241, China
| | - Xuehu Ma
- State Key Laboratory of Fine Chemicals, Liaoning Key Laboratory of Clean Utilization of Chemical Resources, Institute of Chemical Engineering, Dalian University of Technology, Dalian 116024, China
| | - Zuankai Wang
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
- Research Center for Nature-Inspired Engineering, City University of Hong Kong, Hong Kong 999077, China
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