1
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Di Novo NG, Bagolini A, Pugno NM. Single Condensation Droplet Self-Ejection from Divergent Structures with Uniform Wettability. ACS NANO 2024; 18:8626-8640. [PMID: 38417167 DOI: 10.1021/acsnano.3c05981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/01/2024]
Abstract
Coalescence-induced condensation droplet jumping has been extensively studied for anti-icing, condensation heat transfer, water harvesting, and self-cleaning. Another phenomenon that is gaining attention for potential enhancements is the self-ejection of individual droplets. However, the mechanism underlying this process remains elusive due to cases in which the abrupt detachment of an interface establishes an initial Laplace pressure difference. In this study, we investigate the self-ejection of individual droplets from uniformly hydrophobic microstructures with divergent geometries. We design, fabricate, and test arrays of truncated, nanostructured, and hydrophobic microcones arranged in a square pattern. High-speed microscopy reveals the dynamics of a single condensation droplet between four cones: after cycles of growth and stopped self-propulsion, the suspended droplet self-ejects without abrupt detachments. Through analytical modeling of the droplet in a conical pore as an approximation, we describe the slow isopressure growth phases and the rapid transients driven by surface energy release once a dynamic configuration is reached. Microcones with uniform wettability, in addition to being easier to fabricate, have the potential to enable the self-ejection of all nucleated droplets with a designed size, promising significant improvements in the aforementioned applications and others.
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Affiliation(s)
- Nicolò Giuseppe Di Novo
- Laboratory of Bioinspired, Bionic, Nano, Meta, Materials & Mechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123 Trento, Italy
- Center for Sensors and Devices, Fondazione Bruno Kessler, Via Sommarive 18, 38123 Trento, Italy
| | - Alvise Bagolini
- Center for Sensors and Devices, Fondazione Bruno Kessler, Via Sommarive 18, 38123 Trento, Italy
| | - Nicola Maria Pugno
- Laboratory of Bioinspired, Bionic, Nano, Meta, Materials & Mechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123 Trento, Italy
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
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2
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Holder D, Peter A, Kirsch M, Cáceres S, Weber R, Onuseit V, Kulenovic R, Starflinger J, Graf T. Enhancing heat transfer at low temperatures by laser functionalization of the inner surface of metal pipes. Sci Rep 2024; 14:2557. [PMID: 38297142 PMCID: PMC10830557 DOI: 10.1038/s41598-024-53062-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 01/27/2024] [Indexed: 02/02/2024] Open
Abstract
The latent heat transfer during vapour condensation in the condenser section of passive heat transport devices such as the two-phase closed thermosiphon is limited by film condensation. Dropwise condensation provides an increase of the heat transfer coefficient by up to one order of magnitude and can be achieved with a water-repellant surface. The inner surface of pipes made from stainless steel was functionalized by laser surface texturing with ultrashort laser pulses and subsequent storage in a liquid containing long-chained hydrocarbons. The pipes were separated into half-pipes by wire eroding to enable laser texturing of the inner surface, and were then joined by electron beam welding after laser texturing. As a result, superhydrophobic and water-repellent surfaces with a contact angle of 153° were obtained on the inner surface of the pipes with a length of up to 1 m. The functionalized pipes were used in the condenser section of a two-phase closed thermosiphon to demonstrate a heat transfer rate of 0.92 kW at 45 °C, which is approximately three times the heat transfer rate of 0.31 kW of a smooth reference pipe.
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Affiliation(s)
- Daniel Holder
- Institut für Strahlwerkzeuge (IFSW), University of Stuttgart, Pfaffenwaldring 43, Stuttgart, Germany.
- ARENA2036 Research Campus, Pfaffenwaldring 19, Stuttgart, Germany.
| | - Alexander Peter
- Institut für Strahlwerkzeuge (IFSW), University of Stuttgart, Pfaffenwaldring 43, Stuttgart, Germany
| | - Marc Kirsch
- Institut für Kernenergetik und Energiesysteme (IKE), University of Stuttgart, Pfaffenwaldring 31, Stuttgart, Germany
| | - Sergio Cáceres
- Institut für Kernenergetik und Energiesysteme (IKE), University of Stuttgart, Pfaffenwaldring 31, Stuttgart, Germany
| | - Rudolf Weber
- Institut für Strahlwerkzeuge (IFSW), University of Stuttgart, Pfaffenwaldring 43, Stuttgart, Germany
| | - Volkher Onuseit
- Institut für Strahlwerkzeuge (IFSW), University of Stuttgart, Pfaffenwaldring 43, Stuttgart, Germany
| | - Rudi Kulenovic
- Institut für Kernenergetik und Energiesysteme (IKE), University of Stuttgart, Pfaffenwaldring 31, Stuttgart, Germany
| | - Jörg Starflinger
- Institut für Kernenergetik und Energiesysteme (IKE), University of Stuttgart, Pfaffenwaldring 31, Stuttgart, Germany
| | - Thomas Graf
- Institut für Strahlwerkzeuge (IFSW), University of Stuttgart, Pfaffenwaldring 43, Stuttgart, Germany
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3
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Donati M, Regulagadda K, Lam CWE, Milionis A, Sharma CS, Poulikakos D. Metal Surface Engineering for Extreme Sustenance of Jumping Droplet Condensation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:1257-1265. [PMID: 38156900 PMCID: PMC10795172 DOI: 10.1021/acs.langmuir.3c02713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 12/11/2023] [Accepted: 12/12/2023] [Indexed: 01/03/2024]
Abstract
Water vapor condensation on metallic surfaces is critical to a broad range of applications, ranging from power generation to the chemical and pharmaceutical industries. Enhancing simultaneously the heat transfer efficiency, scalability, and durability of a condenser surface remains a persistent challenge. Coalescence-induced condensing droplet jumping is a capillarity-driven mechanism of self-ejection of microscopic condensate droplets from a surface. This mechanism is highly desired due to the fact that it continuously frees up the surface for new condensate to form directly on the surface, enhancing heat transfer without requiring the presence of the gravitational field. However, this condensate ejection mechanism typically requires the fabrication of surface nanotextures coated by an ultrathin (<10 nm) conformal hydrophobic coating (hydrophobic self-assembled monolayers such as silanes), which results in poor durability. Here, we present a scalable approach for the fabrication of a hierarchically structured superhydrophobic surface on aluminum substrates, which is able to withstand adverse conditions characterized by condensation of superheated steam shear flow at pressure and temperature up to ≈1.42 bar and ≈111 °C, respectively, and velocities in the range ≈3-9 m/s. The synergetic function of micro- and nanotextures, combined with a chemically grafted, robust ultrathin (≈4.0 nm) poly-1H,1H,2H,2H-perfluorodecyl acrylate (pPFDA) coating, which is 1 order of magnitude thinner than the current state of the art, allows the sustenance of long-term coalescence-induced condensate jumping drop condensation for at least 72 h. This yields unprecedented, up to an order of magnitude higher heat transfer coefficients compared to filmwise condensation under the same conditions and significantly outperforms the current state of the art in terms of both durability and performance establishing a new milestone.
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Affiliation(s)
- Matteo Donati
- Laboratory
of Thermodynamics in Emerging Technologies, Department of Mechanical
and Process Engineering, ETH Zurich, Sonneggstrasse 3, 8092 Zurich, Switzerland
| | - Kartik Regulagadda
- Laboratory
of Thermodynamics in Emerging Technologies, Department of Mechanical
and Process Engineering, ETH Zurich, Sonneggstrasse 3, 8092 Zurich, Switzerland
| | - Cheuk Wing Edmond Lam
- Laboratory
of Thermodynamics in Emerging Technologies, Department of Mechanical
and Process Engineering, ETH Zurich, Sonneggstrasse 3, 8092 Zurich, Switzerland
| | - Athanasios Milionis
- Laboratory
of Thermodynamics in Emerging Technologies, Department of Mechanical
and Process Engineering, ETH Zurich, Sonneggstrasse 3, 8092 Zurich, Switzerland
| | - Chander Shekhar Sharma
- Thermofluidics
Research Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Ropar, Rupnagar 140001, Punjab, India
| | - Dimos Poulikakos
- Laboratory
of Thermodynamics in Emerging Technologies, Department of Mechanical
and Process Engineering, ETH Zurich, Sonneggstrasse 3, 8092 Zurich, Switzerland
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4
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Bahal S, Sharma CS. Modeling Dropwise Condensation on Hydrophobic Microgrooved Surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:18486-18498. [PMID: 38058150 DOI: 10.1021/acs.langmuir.3c02788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/08/2023]
Abstract
Dropwise condensation heat transfer on water-repellent surfaces is inherently linked to the mode of droplet departure from the surface. When a microgrooved hydrophobic surface is exposed to condensation, multiple spontaneous droplet removal pathways for surface renewal are manifested. We present numerical modeling of dropwise condensation on a microgrooved hydrophobic surface. Our model is an extension of the well-established one-dimensional modeling approach involving estimation of overall condensation heat transfer through the integration of individual droplet contributions. The model presented here accounts for all the surface renewal mechanisms observed on the microgrooved hydrophobic surface: growth and coalescence of condensate droplets within the microgroove and on the ridges, imbibition of the microgrooves with condensate, bulge formation, spontaneous dewetting of the microgrooves, and shedding of large drops through gravity. The modeling results show that the microgrooves trigger condensate shedding from the surface much earlier compared to a planar hydrophobic surface. As a result, the microgrooved hydrophobic surface maintains a much lower area coverage and attains a significantly higher condensation heat flux compared to a planar surface. The model also enables isolation of the relative contributions of the four mechanisms, wherein it is observed that the spontaneous dewetting transition of microgrooves dominates the other mechanisms in terms of the overall surface renewal rate. This is in contrast to the planar hydrophobic surface where droplet shedding under gravity is the main surface renewal mechanism. Finally, we also evaluate the effect of microgroove geometry on the condensation heat transfer performance. The model predicts that hydrophobic microgrooves with depth of ∼200 μm and narrow widths below ∼100 μm can yield enhanced thermal performance.
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Affiliation(s)
- Simrandeep Bahal
- Thermofluidics Research Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Ropar, Rupnagar, 140 001 Punjab, India
| | - Chander Shekhar Sharma
- Thermofluidics Research Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Ropar, Rupnagar, 140 001 Punjab, India
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5
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Rezaee B, Mahlouji Taheri M, Pakzad H, Fakhri M, Moosavi A, Aryanpour M. Enhancement of Dropwise Condensation Heat Transfer through a Sprayable Superhydrophobic Coating. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023. [PMID: 37267064 DOI: 10.1021/acs.langmuir.3c00947] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Improving the shedding rate of condensed droplets has many applications in industries and daily problems, including increasing heat transfer and self-cleaning properties. One way to achieve this goal is by enhancement of the wetting properties of surfaces. In this research, the hierarchical superhydrophobic coating over aluminum has been applied using a relatively cost-effective method, spraying, which is also applicable to any metal surface used as a condenser. According to the results obtained from the experimental tests, the fabricated surface is highly superhydrophobic, with a contact angle of 158° and contact angle hysteresis of less than 5°. The results show that the presented surface increases the heat transfer coefficient by 20.6% at the subcooling temperature of 25.5 °C when the surface temperature and relative humidity are 70 °C and 98%, respectively. In addition, this coated surface showed great potential at lower surface temperatures by increasing the water condensation rate as much as 50.5% at the subcooling temperature of 12 °C, when the surface temperature and relative humidity are 11.25 °C and 70%, respectively. Therefore, it is found that for the fabricated superhydrophobic paint in the present study, the effectiveness of the dropwise condensation mode profoundly depends on surface temperatures besides subcooling temperatures. In other words, a surface with lower temperatures shows better performance for the same subcooling temperatures. In addition, various types of durability tests are carried out. The results reveal that this coating has good durability against high surface temperatures, submerged conditions for 30 days, imposing hot steam for 150 h, corrosion, and organic solvents. Hence, it is suitable for industrial applications.
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Affiliation(s)
- Behzad Rezaee
- Center of Excellence in Energy Conversion (CEEC), School of Mechanical Engineering, Sharif University of Technology, Azadi Avenue, P.O. Box 11365-9567, Tehran P932+FM4, Iran
| | - Mahmoud Mahlouji Taheri
- Center of Excellence in Energy Conversion (CEEC), School of Mechanical Engineering, Sharif University of Technology, Azadi Avenue, P.O. Box 11365-9567, Tehran P932+FM4, Iran
| | - Hossein Pakzad
- Center of Excellence in Energy Conversion (CEEC), School of Mechanical Engineering, Sharif University of Technology, Azadi Avenue, P.O. Box 11365-9567, Tehran P932+FM4, Iran
| | - Mohammadali Fakhri
- Center of Excellence in Energy Conversion (CEEC), School of Mechanical Engineering, Sharif University of Technology, Azadi Avenue, P.O. Box 11365-9567, Tehran P932+FM4, Iran
| | - Ali Moosavi
- Center of Excellence in Energy Conversion (CEEC), School of Mechanical Engineering, Sharif University of Technology, Azadi Avenue, P.O. Box 11365-9567, Tehran P932+FM4, Iran
| | - Masoud Aryanpour
- Center of Excellence in Energy Conversion (CEEC), School of Mechanical Engineering, Sharif University of Technology, Azadi Avenue, P.O. Box 11365-9567, Tehran P932+FM4, Iran
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6
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Song YY, Zhang X, Yang JL, Zhang ZQ, Cheng GG, Liu Y, Lv GJ, Yu ZP. Ultrafast sorption of micro-oil droplets within water by superhydrophobic-superoleophilic conical micro-arrays. Sep Purif Technol 2023. [DOI: 10.1016/j.seppur.2023.123651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
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7
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Wong HY, Wong LW, Tsang CS, Yan Z, Zhang X, Zhao J, Ly TH. Superhydrophobic Surface Designing for Efficient Atmospheric Water Harvesting Aided by Intelligent Computer Vision. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37200621 DOI: 10.1021/acsami.3c03436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Atmospheric water harvesting (AWH) is a possible solution for the current water crisis on the Earth, and the key process of AWH has been widely applied in commercial dehumidifiers. To improve the energy efficiency of the AWH process, applying a superhydrophobic surface to trigger coalescence-induced jumping could be a promising technique that has attracted extensive interest. While most previous studies focused on optimizing the geometric parameters such as nanoscale surface roughness (<1 μm) or microscale structures (10 μm to a few hundred μm range), which might enhance AWH, here, we report a simple and low-cost approach for superhydrophobic surface engineering, through alkaline oxidation of copper. The prepared medium-sized microflower structures (3-5 μm) by our method could fill the gap of the conventional nano- and microstructures, simultaneously act as the preferable nucleation sites and the promoter for the condensed droplet mobility including droplet coalescence and departure, and eventually benefit the entire AWH performances. Moreover, our AWH structure has been optimized with the aid of machine learning computer vision techniques for droplet dynamic analysis on a micrometer scale. Overall, the alkaline surface oxidation and medium-scale microstructures could provide excellent opportunities for superhydrophobic surfaces for future AWH.
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Affiliation(s)
- Hok Yin Wong
- Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
| | - Lok Wing Wong
- Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen 518000, China
| | - Chi Sing Tsang
- Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen 518000, China
| | - Zhangyuan Yan
- Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen 518000, China
| | - Xuming Zhang
- Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
| | - Jiong Zhao
- Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen 518000, China
| | - Thuc Hue Ly
- Department of Chemistry and Center of Super-Diamond & Advanced Films (COSDAF), City University of Hong Kong, Kowloon, Hong Kong, China
- Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong, China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen 518000, China
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8
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Salmean C, Qiu H. Flow Boiling Heat Transfer Enhancement Using Tuned Geometrical Contact-Line Pinning. ACS APPLIED MATERIALS & INTERFACES 2023; 15:23844-23859. [PMID: 37130321 DOI: 10.1021/acsami.2c21813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Wettability patterning is a promising method to manipulate bubble dynamics in microscale boiling systems, allowing the transfer of large heat fluxes at low wall temperatures. Herein, we experimentally investigate the enhancement of flow boiling through exploitation of contact-line pinning using superbiphilic wettability patterns with a range of geometries and orientations. We compare the boiling performance on symmetrical (i.e., circular, square, and diamond-shaped) and asymmetrical (i.e., triangular) superhydrophobic patches and also create rings and chevrons through insertion of self-similar, recursive superhydrophilic cut-outs. Two main principles for boiling heat transfer enhancement are demonstrated: first, the ease of bubble departure from the superhydrophobic patches is shown to depend upon the interaction between the local contact angle and the bubble's tilt due to hydrodynamic drag; second, we find that ring-shaped superhydrophobic patches may trap droplets inside the forming bubbles, thus supplementing the heat transfer coefficient and critical heat flux through latent heat. Through application of these principles, the heat transfer coefficient and critical heat flux of heterogeneous surfaces was enhanced over the homogeneous analogues by 62% and 24%, respectively. Finally, we establish and validate a general model to estimate the ease of bubble departure through the use of geometric arguments.
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Affiliation(s)
- Christopher Salmean
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR 999077, P.R. China
| | - Huihe Qiu
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR 999077, P.R. China
- Sustainable Energy and Environment Thrust, The Hong Kong University of Science and Technology (Guangzhou), Nansha, Guangzhou 511453, P.R. China
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9
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Lambley H, Graeber G, Vogt R, Gaugler LC, Baumann E, Schutzius TM, Poulikakos D. Freezing-induced wetting transitions on superhydrophobic surfaces. NATURE PHYSICS 2023; 19:649-655. [PMID: 37205127 PMCID: PMC10185467 DOI: 10.1038/s41567-023-01946-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 01/05/2023] [Indexed: 05/21/2023]
Abstract
Supercooled droplet freezing on surfaces occurs frequently in nature and industry, often adversely affecting the efficiency and reliability of technological processes. The ability of superhydrophobic surfaces to rapidly shed water and reduce ice adhesion make them promising candidates for resistance to icing. However, the effect of supercooled droplet freezing-with its inherent rapid local heating and explosive vaporization-on the evolution of droplet-substrate interactions, and the resulting implications for the design of icephobic surfaces, are little explored. Here we investigate the freezing of supercooled droplets resting on engineered textured surfaces. On the basis of investigations in which freezing is induced by evacuation of the atmosphere, we determine the surface properties required to promote ice self-expulsion and, simultaneously, identify two mechanisms through which repellency falters. We elucidate these outcomes by balancing (anti-)wetting surface forces with those triggered by recalescent freezing phenomena and demonstrate rationally designed textures to promote ice expulsion. Finally, we consider the complementary case of freezing at atmospheric pressure and subzero temperature, where we observe bottom-up ice suffusion within the surface texture. We then assemble a rational framework for the phenomenology of ice adhesion of supercooled droplets throughout freezing, informing ice-repellent surface design across the phase diagram.
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Affiliation(s)
- Henry Lambley
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Gustav Graeber
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Raphael Vogt
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Leon C. Gaugler
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Enea Baumann
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Thomas M. Schutzius
- Laboratory for Multiphase Thermofluidics and Surface Nanoengineering, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Dimos Poulikakos
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
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10
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Matsuo M, Hashishita H, Tanaka S, Nakata S. Sequentially Selective Coalescence of Binary Self-Propelled Droplets upon Collective Motion. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:2073-2079. [PMID: 36692295 DOI: 10.1021/acs.langmuir.2c03344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Subsequent synthesis and detection using droplets as microreactors have shown promise in the development of novel materials and drugs because microreactors enable small-scale synthesis and detection of covalent/non-covalent intermolecular interactions. Self-organization exhibited by autonomous droplets under non-equilibrium conditions is beneficial for manipulating the sequentiality and selectivity of droplet coalescence because expensive equipment or elaborate techniques are not required with the autonomy of droplets. However, to our knowledge, selective coalescence caused by the collective motion of self-propelled droplets has not been demonstrated in inanimate systems. Here, we report sequentially selective coalescence based on the dynamic collective pattern of self-propelled droplets composed of ethyl salicylate (ES) or butyl salicylate (BS). When ES and BS droplets were placed on an aqueous sodium dodecyl sulfate (SDS) solution, the collective motion of droplets resulted in three stages of selective coalescence on the time development. Initially, coalescence was observed only between different types of self-propelled droplets. Subsequently, the formed droplets selectively coalesced with ES droplets. Finally, mature droplets merged with BS droplets. The sequentially selective coalescence was discussed from the dynamic pattern formation of swarming droplets and the collapse of the SDS monolayer at the o/w interface caused by the difference in Laplace pressure and the interfacial instability at the contact point between droplets. Thus, this study formulates a strategy of sequentially selective coalescence of droplets via the collective motion of non-identical self-propelled droplets, promoting a new type of powerful and efficient automation technology based on an autonomous inanimate manner of spatiotemporal pattern formation under non-equilibrium conditions for the droplet manipulation.
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Affiliation(s)
- Muneyuki Matsuo
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Hiromi Hashishita
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Shinpei Tanaka
- Graduate School of Advanced Science and Engineering, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Satoshi Nakata
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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11
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Stendardo L, Milionis A, Kokkoris G, Stamatopoulos C, Sharma CS, Kumar R, Donati M, Poulikakos D. Out-of-Plane Biphilic Surface Structuring for Enhanced Capillary-Driven Dropwise Condensation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:1585-1592. [PMID: 36645348 PMCID: PMC9893811 DOI: 10.1021/acs.langmuir.2c03029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 12/30/2022] [Indexed: 06/17/2023]
Abstract
Rapid and sustained condensate droplet departure from a surface is key toward achieving high heat-transfer rates in condensation, a physical process critical to a broad range of industrial and societal applications. Despite the progress in enhancing condensation heat transfer through inducing its dropwise mode with hydrophobic materials, sophisticated surface engineering methods that can lead to further enhancement of heat transfer are still highly desirable. Here, by employing a three-dimensional, multiphase computational approach, we present an effective out-of-plane biphilic surface topography, which reveals an unexplored capillarity-driven departure mechanism of condensate droplets. This texture consists of biphilic diverging microcavities wherein a matrix of small hydrophilic spots is placed at their bottom, that is, among the pyramid-shaped, superhydrophobic microtextures forming the cavities. We show that an optimal combination of the hydrophilic spots and the angles of the pyramidal structures can achieve high deformational stretching of the droplets, eventually realizing an impressive "slingshot-like" droplet ejection process from the texture. Such a droplet departure mechanism has the potential to reduce the droplet ejection volume and thus enhance the overall condensation efficiency, compared to coalescence-initiated droplet jumping from other state-of-the-art surfaces. Simulations have shown that optimal pyramid-shaped biphilic microstructures can provoke droplet self-ejection at low volumes, up to 56% lower than superhydrophobic straight pillars, revealing a promising new surface microtexture design strategy toward enhancing the condensation heat-transfer efficiency and water harvesting capabilities.
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Affiliation(s)
- Luca Stendardo
- Laboratory
of Thermodynamics in Emerging Technologies (LTNT), ETH Zurich, Sonneggstrasse
3, Zurich 8092, Switzerland
| | - Athanasios Milionis
- Laboratory
of Thermodynamics in Emerging Technologies (LTNT), ETH Zurich, Sonneggstrasse
3, Zurich 8092, Switzerland
| | - George Kokkoris
- Institute
of Nanoscience and Nanotechnology, NCSR
Demokritos, Agia Paraskevi 15341, Greece
- School
of Chemical Engineering, National Technical
University of Athens, Heroon Polytechniou 9, Zografou, Athens 15780, Greece
| | - Christos Stamatopoulos
- Laboratory
of Thermodynamics in Emerging Technologies (LTNT), ETH Zurich, Sonneggstrasse
3, Zurich 8092, Switzerland
| | - Chander Shekhar Sharma
- Thermofluidics
Research Lab, Department of Mechanical Engineering, Indian Institute of Technology Ropar, Rupnagar, Punjab 140001 India
| | - Raushan Kumar
- Thermofluidics
Research Lab, Department of Mechanical Engineering, Indian Institute of Technology Ropar, Rupnagar, Punjab 140001 India
| | - Matteo Donati
- Laboratory
of Thermodynamics in Emerging Technologies (LTNT), ETH Zurich, Sonneggstrasse
3, Zurich 8092, Switzerland
| | - Dimos Poulikakos
- Laboratory
of Thermodynamics in Emerging Technologies (LTNT), ETH Zurich, Sonneggstrasse
3, Zurich 8092, Switzerland
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12
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Chu C, Zhao Y, Hao P, Lv C. Wetting state transitions of individual condensed droplets on pillared textured surfaces. SOFT MATTER 2023; 19:670-678. [PMID: 36597934 DOI: 10.1039/d2sm01271e] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The ability to realize the self-removal of condensed droplets from a surface is of critical importance for science and applications such as water harvesting and thermal engineering. Despite the enormous interest in micro/nanotextured superhydrophobic materials for high-efficiency condensation, a clear picture of the wetting state transition of condensed droplets is missing, particularly, on a single-droplet level of the order of micrometers. Herein, by varying a substantial parameter space of the contact angle and the geometry of the pillared textures, we have quantified the wetting transition of individual droplets during condensation. We found that a droplet is finally either spontaneously removed from the textures due to a Laplace pressure difference or wets the textures; four different wetting state transition modes have been identified numerically and they are classified in a phase diagram. Simple theories have been constructed to correlate the critical conditions of the wetting state transition to the wettability and geometry of the textures, and they were verified experimentally. We found that the self-removal of condensed droplets benefits from the contact angle and the height of the pillars. These findings not only enhance our fundamental understanding of the wetting state transition of condensed droplets but also allow the rational design of micro/nanotextured water-repellent materials for anti-fogging and anti-wetting.
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Affiliation(s)
- Chenlei Chu
- Department of Engineering Mechanics, AML, Tsinghua University, 100084 Beijing, China.
- Beijing Institute of Spacecraft Environment Engineering, 100094 Beijing, China
| | - Yinggang Zhao
- Department of Engineering Mechanics, AML, Tsinghua University, 100084 Beijing, China.
| | - Pengfei Hao
- Department of Engineering Mechanics, AML, Tsinghua University, 100084 Beijing, China.
- Tsinghua University (School of Materials Science and Engineering)-AVIC Aerodynamics Research Institute Joint Research Center for Advanced Materials and Anti-Icing, Tsinghua University, 100084 Beijing, China
| | - Cunjing Lv
- Department of Engineering Mechanics, AML, Tsinghua University, 100084 Beijing, China.
- Center for Nano and Micro Mechanics, Tsinghua University, 100084 Beijing, China
- State Key Laboratory of Tribology in Advanced Equipment (SKLT), Tsinghua University, 100084 Beijing, China
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13
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Balachandran A, Parayilkalapurackal H, Rajpoot S, Lone S. Bioinspired Green Fabricating Design of Multidimensional Surfaces for Atmospheric Water Harvesting. ACS APPLIED BIO MATERIALS 2023; 6:44-63. [PMID: 36580351 DOI: 10.1021/acsabm.2c00804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Across the globe, the quest for clean water is escalating for both households as well as agricultural exigencies. With the industrial revolution and swift population growth, the contamination of natural water bodies has impacted the lives of more than two billion people around the world. A spectrum of water-saving solutions has been examined. Nonetheless, most of them are either energy-inefficient or limited to only a particular region. Thus, the pursuit of clean and potable drinking water is an assignment that invites collective discourse from scientists, policymakers, and innovators. In this connection, the presence of moisture in the atmosphere is considered one of the major sources of potential freshwater. Thus, fishing in atmospheric water is a mammoth opportunity. Atmospheric water harvesting (AWH) by some plants and animals in nature (particularly in deserts or arid regions) at low humidity serves as an inspiration for crafting state-of-the-art water harvesting structures and surfaces to buffer the menace of acute water scarcity. Though a lot of research articles and reviews have been reported on bioinspired structures with applications in water and energy harvesting, the area is still open for significant improvisation. This work will address the multidimensional-based AWH ability of natural surfaces or fabricated structures without the involvement of toxic chemicals. Moreover, the review will discuss the availability of clean technologies for emulating fascinating natural surfaces on an industrial scale. In the end, the current challenges and the future scope of bioinspired water harvesters will be discussed for pushing greener technologies to confront climate change.
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Affiliation(s)
- Akshay Balachandran
- Department of Chemistry, National Institute of Technology (NIT), Srinagar 190006, India.,iDREAM (Interdisciplinary Division for Renewable Energy & Advanced Materials), National Institute of Technology (NIT), Srinagar 190006, India
| | - Hariprasad Parayilkalapurackal
- iDREAM (Interdisciplinary Division for Renewable Energy & Advanced Materials), National Institute of Technology (NIT), Srinagar 190006, India.,Department of Physics, National Institute of Technology (NIT), Srinagar 190006, India
| | - Surbhi Rajpoot
- Department of Physics, National Institute of Technology (NIT), Srinagar 190006, India
| | - Saifullah Lone
- Department of Chemistry, National Institute of Technology (NIT), Srinagar 190006, India.,iDREAM (Interdisciplinary Division for Renewable Energy & Advanced Materials), National Institute of Technology (NIT), Srinagar 190006, India
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14
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Tripathy A, Regulagadda K, Lam CWE, Donati MA, Milionis A, Sharma CS, Mitridis E, Schutzius TM, Poulikakos D. Ultrathin Durable Organic Hydrophobic Coatings Enhancing Dropwise Condensation Heat Transfer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:11296-11303. [PMID: 36037308 PMCID: PMC9494938 DOI: 10.1021/acs.langmuir.2c01477] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 08/17/2022] [Indexed: 06/15/2023]
Abstract
Organic hydrophobic layers targeting sustained dropwise condensation are highly desirable but suffer from poor chemical and mechanical stability, combined with low thermal conductivity. The requirement of such layers to remain ultrathin to minimize their inherent thermal resistance competes against durability considerations. Here, we investigate the long-term durability and enhanced heat-transfer performance of perfluorodecanethiol (PFDT) coatings compared to alternative organic coatings, namely, perfluorodecyltriethoxysilane (PFDTS) and perfluorodecyl acrylate (PFDA), the latter fabricated with initiated chemical vapor deposition (iCVD), in condensation heat transfer and under the challenging operating conditions of intense flow (up to 9 m s-1) of superheated steam (111 °C) at high pressures (1.42 bar). We find that the thiol coating clearly outperforms the silane coating in terms of both heat transfer and durability. In addition, despite being only a monolayer, it clearly also outperforms the iCVD-fabricated PFDA coating in terms of durability. Remarkably, the thiol layer exhibited dropwise condensation for at least 63 h (>2× times more than the PFDA coating, which survived for 30 h), without any visible deterioration, showcasing its hydrolytic stability. The cost of thiol functionalization per area was also the lowest as compared to all of the other surface hydrophobic treatments used in this study, thus making it the most efficient option for practical applications on copper substrates.
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Affiliation(s)
- Abinash Tripathy
- Laboratory
of Thermodynamics in Emerging Technologies, Department of Mechanical
and Process Engineering, ETH Zurich, Sonneggstrasse 3, CH-8092 Zurich, Switzerland
| | - Kartik Regulagadda
- Laboratory
of Thermodynamics in Emerging Technologies, Department of Mechanical
and Process Engineering, ETH Zurich, Sonneggstrasse 3, CH-8092 Zurich, Switzerland
| | - Cheuk Wing Edmond Lam
- Laboratory
of Thermodynamics in Emerging Technologies, Department of Mechanical
and Process Engineering, ETH Zurich, Sonneggstrasse 3, CH-8092 Zurich, Switzerland
| | - Matteo A. Donati
- Laboratory
of Thermodynamics in Emerging Technologies, Department of Mechanical
and Process Engineering, ETH Zurich, Sonneggstrasse 3, CH-8092 Zurich, Switzerland
| | - Athanasios Milionis
- Laboratory
of Thermodynamics in Emerging Technologies, Department of Mechanical
and Process Engineering, ETH Zurich, Sonneggstrasse 3, CH-8092 Zurich, Switzerland
| | - Chander Shekhar Sharma
- Thermofluidics
Research Lab, Department of Mechanical Engineering, Indian Institute of Technology Ropar, Rupnagar, Punjab 140 001, India
| | - Efstratios Mitridis
- Laboratory
of Thermodynamics in Emerging Technologies, Department of Mechanical
and Process Engineering, ETH Zurich, Sonneggstrasse 3, CH-8092 Zurich, Switzerland
| | - Thomas M. Schutzius
- Laboratory
of Thermodynamics in Emerging Technologies, Department of Mechanical
and Process Engineering, ETH Zurich, Sonneggstrasse 3, CH-8092 Zurich, Switzerland
| | - Dimos Poulikakos
- Laboratory
of Thermodynamics in Emerging Technologies, Department of Mechanical
and Process Engineering, ETH Zurich, Sonneggstrasse 3, CH-8092 Zurich, Switzerland
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15
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Dai X, Wang M, Zhang J, Xin G, Wang X. Vapor Condensation on Bioinspired Hierarchical Nanostructured Surfaces with Hybrid Wettabilities. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:11099-11108. [PMID: 36037002 DOI: 10.1021/acs.langmuir.2c01796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Vapor condensation on bioinspired hierarchical nanostructured surfaces with hybrid wettabilities has been investigated using molecular dynamics simulations. A series of hierarchical surfaces consisting of nanocylinder arrays with hydrophilic top and hydrophobic nanopillar arrays are constructed. The results manifest that the condensed nanodroplets undergo three states in the whole water vapor condensation process, and the total condensed atom number on surfaces increases with the increase of nanocylinder diameter (D), which indicates that the introduction of hydrophilic nanocylinders is conducive to improving the condensation performance compared with that on the hydrophobic surface patterned with homogeneous nanopillars. However, the nucleation sites on hierarchical nanostructured surfaces are covered by the condensed nanodroplets at the end of condensation, which suppresses the further enhancement of condensation performance. To solve these problems, we add a collection region close to the edge of the nanostructured surface. It is noticed that the condensed nanodroplets can roll into the collection regions gradually during the condensation process, which keeps the nucleation sites on nanostructured surfaces exposed effectively, especially for the cases of 20 Å ≤ D ≤ 40 Å. Moreover, the cluster number, the total condensed atom number, and the condensation enhancement efficiency on hierarchical nanostructured surfaces with collection regions at 20 Å ≤ D ≤ 40 Å are higher obviously compared with those on surfaces without collection regions. Our study demonstrates that the bioinspired hierarchical nanostructured surface with the collection region is beneficial to boost the vapor condensation performance, which can bring new insights into water vapor condensation.
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Affiliation(s)
- Xingbo Dai
- Institute of Thermal Science and Technology, Shandong University, Jinan 250061, China
| | - Man Wang
- School of Mechanical Engineering, Shandong University, Jinan 250061, China
| | - Jingzhi Zhang
- School of Energy and Power Engineering, Shandong University, Jinan 250061, China
- Shenzhen Research Institute of Shandong University, Shenzhen 518057, China
| | - Gongming Xin
- School of Energy and Power Engineering, Shandong University, Jinan 250061, China
- Shenzhen Research Institute of Shandong University, Shenzhen 518057, China
| | - Xinyu Wang
- Institute of Thermal Science and Technology, Shandong University, Jinan 250061, China
- Shenzhen Research Institute of Shandong University, Shenzhen 518057, China
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16
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Hou B, Wu C, Liu H, Sun R, Li X, Liu C, Wu J, Chen M. Shape approximation of sessile droplet by the equivalence between vertical capillary force and hydrostatic pressure. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.130203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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17
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Wang X, Xu B, Chen Z, Del Col D, Li D, Zhang L, Mou X, Liu Q, Yang Y, Cao Q. Review of droplet dynamics and dropwise condensation enhancement: Theory, experiments and applications. Adv Colloid Interface Sci 2022; 305:102684. [PMID: 35525088 DOI: 10.1016/j.cis.2022.102684] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 03/21/2022] [Accepted: 04/23/2022] [Indexed: 02/06/2023]
Abstract
Droplet dynamics and condensation phenomena are widespread in nature and industrial applications, and the fundamentals of various technological applications. Currently, with the rapid development of interfacial materials, microfluidics, micro/nano fabrication technology, as well as the intersection of fluid mechanics, interfacial mechanics, heat and mass transfer, thermodynamics and reaction kinetics and other disciplines, the preparation and design of various novel functional surfaces have contributed to the local modulation of droplets (including nucleation, jumping and directional migration) and the improvement of condensation heat transfer, further deepening the understanding of relevant mechanisms. The wetting and dynamic characteristics of droplets involve complex solid-liquid interfacial interactions, so that the local modulation of microdroplets and the extension of enhanced condensation heat transfer by means of complex micro/nano structures and hydrophilic/hydrophobic properties is one of the current hot topics in heat and mass transfer research. This work presents a detailed review of several scientific issues related to the droplet dynamics and dropwise condensation heat transfer under the influence of multiple factors (including fluid property, surface structure, wettability, temperature external field, etc.). Firstly, the basic theory of droplet wetting on the solid wall is introduced, and the mechanism of solid-liquid interfacial interaction involving droplet jumping and directional migration on the functional surfaces under the various influencing factors is discussed. Optimizing the surface structure for the local modulation of droplets is of guidance for condensation heat transfer. Secondly, we summarize the existing theoretical models of dropwise condensation applicable to various functional surfaces and briefly outline the current numerical models for simulating dropwise condensation at different scales, as well as the fabricating techniques of coatings and functional surfaces for enhancing heat transfer. Finally, the relevant problems and challenges are summarized and future research is discussed.
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Affiliation(s)
- Xin Wang
- School of Energy and Environment, Southeast University, Nanjing, PR China
| | - Bo Xu
- 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.
| | - Davide Del Col
- Department of Industrial Engineering, University of Padua, Italy
| | - Dong Li
- School of Energy and Power Engineering, Zhengzhou University of Light Industry, Zhengzhou, PR China
| | - Leigang Zhang
- School of Energy and Mechanical Engineering, Nanjing Normal University, Nanjing, PR China
| | - Xinzhu Mou
- School of Energy and Environment, Southeast University, Nanjing, PR China
| | - Qiusheng Liu
- Key Laboratory of Microgravity, Institute of Mechanics, Chinese Academy of Sciences, Beijing, PR China
| | - Yang Yang
- Engineering and technology center for space applications, Chinese academy of sciences, Beijing, PR China
| | - Qian Cao
- Engineering and technology center for space applications, Chinese academy of sciences, Beijing, PR China
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18
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Yan X, Chen F, Zhao C, Wang X, Li L, Khodakarami S, Fazle Rabbi K, Li J, Hoque MJ, Chen F, Feng J, Miljkovic N. Microscale Confinement and Wetting Contrast Enable Enhanced and Tunable Condensation. ACS NANO 2022; 16:9510-9522. [PMID: 35696260 DOI: 10.1021/acsnano.2c02669] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Dropwise condensation represents the upper limit of thermal transport efficiency for liquid-to-vapor phase transition. A century of research has focused on promoting dropwise condensation by attempting to overcome limitations associated with thermal resistance and poor surface-modifier durability. Here, we show that condensation in a microscale gap formed by surfaces having a wetting contrast can overcome these limitations. Spontaneous out-of-plane condensate transfer between the contrasting parallel surfaces decouples the nanoscale nucleation behavior, droplet growth dynamics, and shedding processes to enable minimization of thermal resistance and elimination of surface modification. Experiments on pure steam combined with theoretical analysis and numerical simulation confirm the breaking of intrinsic limits to classical condensation and demonstrate a gap-dependent heat-transfer coefficient with up to 240% enhancement compared to dropwise condensation. Our study presents a promising mechanism and technology for compact energy and water applications where high, tunable, gravity-independent, and durable phase-change heat transfer is required.
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Affiliation(s)
- Xiao Yan
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Feipeng Chen
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Chongyan Zhao
- Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China
| | - Xiong Wang
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Longnan Li
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Siavash Khodakarami
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Kazi Fazle Rabbi
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Jiaqi Li
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Muhammad Jahidul Hoque
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Feng Chen
- Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China
| | - Jie Feng
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Nenad Miljkovic
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
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19
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Liu C, Zhao M, Lu D, Sun Y, Song L, Zheng Y. Laplace Pressure Difference Enhances Droplet Coalescence Jumping on Superhydrophobic Structures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:6923-6933. [PMID: 35451848 DOI: 10.1021/acs.langmuir.2c00412] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Coalescence-induced droplet jumping has great prospects in many applications. Nevertheless, the applications are vastly limited by a low jumping velocity. Conventional methods to enhance the droplet coalescence jumping velocity are enabled by protruding structures with superhydrophobic surfaces. However, the jumping velocity improvement is limited by the height of protruding structures. Here, we present rationally designed limitation structures with superhydrophobic surfaces to achieve a dimensionless jumping velocity, Vj* ≈ 0.64. The mechanism of enhancing the jumping velocity is demonstrated through the study of numerical simulations and geometric parameters of limitation structures, providing guidelines for optimized structures. Experimental and numerical results indicate that the mechanism consists of the combined action of the velocity vectors' redirection and the Laplace pressure difference within deformed droplets trapped in limitation structures. On the basis of previous research on the mechanisms of protruding structures and our study, we successfully exploited those mechanisms to further improve the jumping velocity by combining the limitation structure with the protruding structure. Experimentally, we attained a dimensionless jumping velocity of Vj* ≈ 0.74 with an energy conversion efficiency of η ≈ 48%, breaking the jumping velocity limit. This work not only demonstrates a new mechanism for achieving a high jumping velocity and energy conversion efficiency but also sheds lights on the effect of limitation structures on coalescence hydrodynamics and elucidates a method to further enhance the jumping velocity based on protruding structures.
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Affiliation(s)
- Chuntian Liu
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
| | - Meirong Zhao
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
| | - Dunqiang Lu
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
| | - Yukai Sun
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
| | - Le Song
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
| | - Yelong Zheng
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
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20
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Abstract
Condensation frosting is a type of icing encountered ubiquitously in our daily lives. Understanding the dynamics of condensation frosting is essential in developing effective technologies to suppress frost accretions that compromise heat transfer and system integrity. Here, we present an experimental study on ice dendrite growth atop a single frozen drop, an important step affecting the subsequent frosting process, and the properties of fully-developed frost layers. We evaluate the effect of natural convection by comparing the growth dynamics of ice dendrites on the surface of a frozen drop with three different orientations with respect to gravity. The results show that both the average deposition rate and its spatial variations are profoundly altered by surface orientations. Such behavior is confirmed by a numerical simulation, showing how gravity-assisted (hindered) vapor diffusion yields the deposition outcomes. These findings benefit the optimization of anti-/de- frosting technologies and the rational design of heat exchangers.
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21
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Zhang Y, Zhang Z, Yang J, Yue Y, Zhang H. A Review of Recent Advances in Superhydrophobic Surfaces and Their Applications in Drag Reduction and Heat Transfer. NANOMATERIALS 2021; 12:nano12010044. [PMID: 35009994 PMCID: PMC8746732 DOI: 10.3390/nano12010044] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 12/20/2021] [Accepted: 12/20/2021] [Indexed: 11/16/2022]
Abstract
Inspired by the superhydrophobic properties of some plants and animals with special structures, such as self-cleaning, water repellent, and drag reduction, the research on the basic theory and practical applications of superhydrophobic surfaces is increasing. In this paper, the characteristics of superhydrophobic surfaces and the preparation methods of superhydrophobic surfaces are briefly reviewed. The mechanisms of drag reduction on superhydrophobic surfaces and the effects of parameters such as flow rate, fluid viscosity, wettability, and surface morphology on drag reduction are discussed, as well as the applications of superhydrophobic surfaces in boiling heat transfer and condensation heat transfer. Finally, the limitations of adapting superhydrophobic surfaces to industrial applications are discussed. The possibility of applying superhydrophobic surfaces to highly viscous fluids for heat transfer to reduce flow resistance and improve heat transfer efficiency is introduced as a topic for further research in the future.
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Affiliation(s)
- Yu Zhang
- Technical Institute of Physics and Chemistry of CAS, Beijing 100190, China; (Y.Z.); (Z.Z.); (Y.Y.); (H.Z.)
- University of Chinese Academy of Sciences, Beijing 100049, China
- Key Laboratory of Food & Pharmaceutical Quality Processing Storage and Transportation Equipment and Energy-Saving Technology, China National Light Industry, Beijing 100190, China
| | - Zhentao Zhang
- Technical Institute of Physics and Chemistry of CAS, Beijing 100190, China; (Y.Z.); (Z.Z.); (Y.Y.); (H.Z.)
- Key Laboratory of Food & Pharmaceutical Quality Processing Storage and Transportation Equipment and Energy-Saving Technology, China National Light Industry, Beijing 100190, China
| | - Junling Yang
- Technical Institute of Physics and Chemistry of CAS, Beijing 100190, China; (Y.Z.); (Z.Z.); (Y.Y.); (H.Z.)
- Key Laboratory of Food & Pharmaceutical Quality Processing Storage and Transportation Equipment and Energy-Saving Technology, China National Light Industry, Beijing 100190, China
- Correspondence:
| | - Yunkai Yue
- Technical Institute of Physics and Chemistry of CAS, Beijing 100190, China; (Y.Z.); (Z.Z.); (Y.Y.); (H.Z.)
- University of Chinese Academy of Sciences, Beijing 100049, China
- Key Laboratory of Food & Pharmaceutical Quality Processing Storage and Transportation Equipment and Energy-Saving Technology, China National Light Industry, Beijing 100190, China
| | - Huafu Zhang
- Technical Institute of Physics and Chemistry of CAS, Beijing 100190, China; (Y.Z.); (Z.Z.); (Y.Y.); (H.Z.)
- Key Laboratory of Food & Pharmaceutical Quality Processing Storage and Transportation Equipment and Energy-Saving Technology, China National Light Industry, Beijing 100190, China
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22
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Tang Y, Yang X, Li Y, Lu Y, Zhu D. Robust Micro-Nanostructured Superhydrophobic Surfaces for Long-Term Dropwise Condensation. NANO LETTERS 2021; 21:9824-9833. [PMID: 34472863 DOI: 10.1021/acs.nanolett.1c01584] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Design of hierarchical micromorphology represents an important strategy for developing functional surfaces but has yet to be achieved for promising long-term dropwise condensation. Herein, micropapillaes overlaid with nanograss were created to enhance dropwise condensation. By analyzing the nucleation and evolution of the condensate droplets, we elucidated that these hierarchical micro-nanostructures topologized tapered gaps, which produced upward pressure, to achieve spontaneous dislodging of condensate microdroplet out of gaps, and then to trigger microdroplet navigation before finally departing from the surface by coalescence-induced jumping. The high mobility of condensate delayed flooding and contributed to a very high heat transfer coefficient of 218 kW·m-2·K-1. Moreover, these micropapillaes served as forts that protected the nanograss from being destroyed, resulting in improved mechanical and chemical robustness. Our work proposed new examples of topology creation for long-term dropwise condensation heat transfer and shed light on application integration of such promising functional surfaces.
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Affiliation(s)
- Yu Tang
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Xiaolong Yang
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Yimin Li
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Yao Lu
- Department of Chemistry, Queen Mary University of London, London E1 4NS, United Kingdom
| | - Di Zhu
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
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23
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Chang CM, Lin YH, Reshetnyak V. Dynamics of water condensation on a switchable surface originated from molecular orientations. Phys Rev E 2021; 104:034701. [PMID: 34654192 DOI: 10.1103/physreve.104.034701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 08/18/2021] [Indexed: 11/07/2022]
Abstract
In heat transfer systems, how water condenses on the surface is critical to the energy efficiency of the system. With fixed surface wettability, hydrophilic surfaces enhance the nucleation rate but result in filmwise condensation due to pinning effect, which impedes the heat transfer between water vapor and surface during droplet growth. A hydrophilic surface with high drop mobility is realized with static tailored wettability surfaces, while tunable surfaces have potential in more comprehensive manipulation in condensation with different scale in time and scale. However, the mechanism has rarely been investigated and elucidated. In this paper, we investigate water condensation on a tunable surface originated from surface tension distribution control. The surface tension distribution under applied electric field is modeled and tested. We demonstrate that the surface tension manipulated by liquid crystal orientation alters the nucleation site density. Also, the periodic surface tension distribution aligns condensed water drops and decelerates the radius growth of droplets. The mechanism of active water condensation manipulation can be further applied to other tunable surfaces for various applications such as atmospheric water generator, heat transfer systems, and desalination systems.
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Affiliation(s)
- Chia-Ming Chang
- Department of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
| | - Yi-Hsin Lin
- Department of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
| | - Victor Reshetnyak
- Theoretical Physics Department, Taras Shevchenko National University of Kyiv, Kyiv 01601, Ukraine
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24
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Tripathy A, Lam CWE, Davila D, Donati M, Milionis A, Sharma CS, Poulikakos D. Ultrathin Lubricant-Infused Vertical Graphene Nanoscaffolds for High-Performance Dropwise Condensation. ACS NANO 2021; 15:14305-14315. [PMID: 34399576 DOI: 10.1021/acsnano.1c02932] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Lubricant-infused surfaces (LIS) are highly efficient in repelling water and constitute a very promising family of materials for condensation processes occurring in a broad range of energy applications. However, the performance of LIS in such processes is limited by the inherent thermal resistance imposed by the thickness of the lubricant and supporting surface structure, as well as by the gradual depletion of the lubricant over time. Here, we present an ultrathin (∼70 nm) and conductive LIS architecture, obtained by infusing lubricant into a vertically grown graphene nanoscaffold on copper. The ultrathin nature of the scaffold, combined with the high in-plane thermal conductivity of graphene, drastically minimize earlier limitations, effectively doubling the heat transfer performance compared to a state-of-the-art CuO LIS surface. We show that the effect of the thermal resistance to the heat transfer performance of a LIS surface, although often overlooked, can be so detrimental that a simple nanostructured CuO surface can outperform a CuO LIS surface, despite filmwise condensation on the former. The present vertical graphene LIS is also found to be resistant to lubricant depletion, maintaining stable dropwise condensation for at least 24 h with no significant change of advancing contact angle and contact angle hysteresis. The lubricant consumed by the vertical graphene LIS is 52.6% less than that of the existing state-of-the-art CuO LIS, also making the fabrication process more economical.
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Affiliation(s)
- Abinash Tripathy
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Sonneggstrasse 3, 8092 Zurich, Switzerland
| | - Cheuk Wing Edmond Lam
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Sonneggstrasse 3, 8092 Zurich, Switzerland
| | - Diana Davila
- IBM Research, Saeumerstrasse 4, 8803 Rueschlikon, Switzerland
| | - Matteo Donati
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Sonneggstrasse 3, 8092 Zurich, Switzerland
| | - Athanasios Milionis
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Sonneggstrasse 3, 8092 Zurich, Switzerland
| | - Chander Shekhar Sharma
- Thermofluidics Research Lab, Department of Mechanical Engineering, Indian Institute of Technology Ropar, Rupnagar, Punjab 140001, India
| | - Dimos Poulikakos
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Sonneggstrasse 3, 8092 Zurich, Switzerland
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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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26
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Zheng SF, Gross U, Wang XD. Dropwise condensation: From fundamentals of wetting, nucleation, and droplet mobility to performance improvement by advanced functional surfaces. Adv Colloid Interface Sci 2021; 295:102503. [PMID: 34411880 DOI: 10.1016/j.cis.2021.102503] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 08/02/2021] [Accepted: 08/03/2021] [Indexed: 01/22/2023]
Abstract
As a ubiquitous vapor-liquid phase-change process, dropwise condensation has attracted tremendous research attention owing to its remarkable efficiency of energy transfer and transformative industrial potential. In recent years, advanced functional surfaces, profiting from great progress in modifying micro/nanoscale features and surface chemistry on surfaces, have led to exciting advances in both heat transfer enhancement and fundamental understanding of dropwise condensation. In this review, we discuss the development of some key components for achieving performance improvement of dropwise condensation, including surface wettability, nucleation, droplet mobility, and growth, and discuss how they can be elaborately controlled as desired using surface design. We also present an overview of dropwise condensation heat transfer enhancement on advanced functional surfaces along with the underlying mechanisms, such as jumping condensation on nanostructured superhydrophobic surfaces, and new condensation characteristics (e.g., Laplace pressure-driven droplet motion, hierarchical condensation, and sucking flow condensation) on hierarchically structured surfaces. Finally, the durability, cost, and scalability of specific functional surfaces are focused on for future industrial applications. The existing challenges, alternative strategies, as well as future perspectives, are essential in the fundamental and applied aspects for the practical implementation of dropwise condensation.
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27
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Dewetting transition of water on nanostructured and wettability patterned surfaces: A molecular dynamics study. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.116869] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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28
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Baba S, Sawada K, Tanaka K, Okamoto A. Condensation Behavior of Hierarchical Nano/Microstructured Surfaces Inspired by Euphorbia myrsinites. ACS APPLIED MATERIALS & INTERFACES 2021; 13:32332-32342. [PMID: 34190527 DOI: 10.1021/acsami.1c01400] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In nature, many extant species exhibit functionalized surface structures during evolution. In particular, wettability affects the functionalization of the surface, and nano/microstructures have been found to enable functions, such as droplet jumping, thereby making self-cleaning, antifog, antibacterial, and antireflection surfaces. Important efforts are underway to understand the surface structure of plant leaves and establish rational design tools for the development of new engineering materials. In this study, we focused on the hierarchical nano/microstructure of the leaves of Euphorbia myrsinites (hereinafter, E. myrsinites), which has a hierarchical shape with microsized papillae, covered with nanosized protruding wax, and observed the condensation behavior on the leaf surface. Si is vertically etched via reactive ion etching (RIE) to artificially mimic the hierarchical nano/microstructures on the leaves of E. myrsinites. We made four types of artificial hierarchical structures, with micropillars having pillar diameters of 5.6 and 16 μm (pillar spacing of 20 and 40 μm, respectively) and heights of 6.5 and 19.5 μm, and nanopillars formed on the surface. The optical observation with a microscope revealed a very high density of condensed droplets on the artificial surface and a stable jumping behavior of droplets of 10 μm or more. Furthermore, in the samples with a micropillar diameter of 5.6 μm and a micropillar height of 19.5 μm, the droplets that had jumped and fallen thereupon bounced off, thereby preventing reattachment. As a result, no droplets of 35 μm or more could exist even after 10 min. In addition, it was clear that a small underlying droplet of less than 10 μm was generated at the bottom of the relatively large secondary droplet existing on the large micropillar of 16 μm, and a frequent coalescence of the droplets occurred. This study revealed the phenomenon of condensation on the surface of plants as well as made it possible to improve the heat exchange process by significantly promoting the heat transfer of condensation using artificial surfaces.
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Affiliation(s)
- Soumei Baba
- Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology (AIST), 1-2-1 Namiki, Tsukuba-shi, Ibaraki 305-8564, Japan
| | - Kenichiro Sawada
- Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-0233, Japan
| | - Kohsuke Tanaka
- Japan Aerospace Exploration Agency (JAXA), 2-1-1 Sengen, Tsukuba-shi, Ibaraki 305-8505, Japan
| | - Atsushi Okamoto
- Japan Aerospace Exploration Agency (JAXA), 2-1-1 Sengen, Tsukuba-shi, Ibaraki 305-8505, Japan
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29
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Xu Y, Zhang G, Luo Z, Qi X, Ma W, Xu C, Liu C, Yao W. Investigation of Dropwise Condensation on a Super-Aligned Carbon Nanotube Mesh-Coated Surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:2629-2638. [PMID: 33586440 DOI: 10.1021/acs.langmuir.0c03263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Enhanced vapor condensation is a critical issue for improving the efficiency of energy conversion, thermal management, water recovery, and treatment. Low-energy surfaces incorporating micro/nanoscale roughness have been reported to significantly promote vapor condensation. In this research, the mesh structures of super-aligned carbon nanotube (SACNT) films were prepared by crossing monolayer SACNT films on a copper substrate. Then, the sustaining dropwise condensation was achieved on the SACNT mesh-coated surface. The SACNT mesh-coated surface could obviously enhance the coalescence and sweeping departure of the condensing droplets. Additionally, the measured overall heat transfer coefficient (HTC) of the SACNT mesh-coated surface demonstrated a 36% enhancement compared to that on the bare copper surface. The parallel stacking of SACNT films with different groove structures was also studied, and a 15% enhancement in the HTC was shown as compared with the bare copper surface. Furthermore, we developed a morphology-based model to theoretically analyze the condensation-enhancement mechanism on a SACNT mesh-coated surface. The SACNT surfaces also have advantages of low cost, durability, flexibility, and extensibility. Our findings revealed that the SACNT films could be readily used as vapor condensation-strengthening surfaces, further extending their potential applications to industrial equipment.
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Affiliation(s)
- Yantong Xu
- Department of Space Science Research, Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology, Beijing 100094, China
- Beijing Institute of Spacecraft Environment Engineering, Beijing 100094, China
| | - Guang Zhang
- Department of Space Science Research, Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology, Beijing 100094, China
| | - Zhiling Luo
- Tsinghua-Foxconn Nanotechnology Research Center and Department of Physics, Tsinghua University, Beijing 100084, China
| | - Xin Qi
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China
| | - Weigang Ma
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China
| | - Changjian Xu
- State Key Laboratory of Engine Combustion, School of Mechanical Engineering, Tianjin University, Tianjin 300350, China
| | - Changhong Liu
- Tsinghua-Foxconn Nanotechnology Research Center and Department of Physics, Tsinghua University, Beijing 100084, China
| | - Wei Yao
- Department of Space Science Research, Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology, Beijing 100094, China
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30
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Zhang C, Wang D, Yang J, Zhang W, Sun Q, Yu F, Fan Y, Li Y, Chen L, Deng X. Charge Density Gradient Propelled Ultrafast Sweeping Removal of Dropwise Condensates. J Phys Chem B 2021; 125:1936-1943. [DOI: 10.1021/acs.jpcb.0c10285] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Chenglin Zhang
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Dehui Wang
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Jinlong Yang
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Wenluan Zhang
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China
- School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Qiangqiang Sun
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, 610031 Chengdu, China
| | - Fanfei Yu
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Yue Fan
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Yong Li
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Longquan Chen
- School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Xu Deng
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China
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31
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Liu C, Zhao M, Zheng Y, Cheng L, Zhang J, Tee CATH. Coalescence-Induced Droplet Jumping. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:983-1000. [PMID: 33443436 DOI: 10.1021/acs.langmuir.0c02758] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
When two or more droplets coalesce on a superhydrophobic surface, the merged droplet can jump spontaneously from the surface without requiring any external energy. This phenomenon is defined as coalescence-induced droplet jumping and has received significant attention due to its potential applications in a variety of self-cleaning, anti-icing, antifrosting, and condensation heat-transfer enhancement uses. This article reviews the research and applications of coalescence-induced droplet jumping behavior in recent years, including the influence of droplet parameters on coalescence-induced droplet jumping, such as the droplet size, number, and initial velocity, to name a few. The main structure types and influence mechanism of the superhydrophobic substrates for coalescence-induced droplet jumping are described, and the potential application areas of coalescence-induced droplet jumping are summarized and forecasted.
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Affiliation(s)
- Chuntian Liu
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
| | - Meirong Zhao
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
| | - Yelong Zheng
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
| | - Luya Cheng
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
| | - Jiale Zhang
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
| | - Clarence Augustine T H Tee
- Department of Electrical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia
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32
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Du B, Cheng Y, Yang S, Xu W, Lan Z, Wen R, Ma X. Preferential Vapor Nucleation on Hierarchical Tapered Nanowire Bunches. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:774-784. [PMID: 33382946 DOI: 10.1021/acs.langmuir.0c03125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Controlling vapor nucleation on micro-/nanostructured surfaces is critical to achieving exciting droplet dynamics and condensation enhancement. However, the underlying mechanism of nucleation phenomena remains unclear because of its nature of nanoscale and transience, especially for the complex-structured surfaces. Manipulating vapor nucleation via the rational surface design of micro-/nanostructures is extremely challenging. Here, we fabricate hierarchical surfaces comprising tapered nanowire bunches and crisscross microgrooves. Nanosteps are formed around the top of the nanowire bunches, where the nanowires all around agglomerate densely because of surface tension. The theoretical analysis and molecular dynamics simulation show that nanostep morphologies that are around the top of the nanowire bunches can enable a lower energy barrier and a higher nucleation capability than those of the sparsely packed nanowires at the center and bottom of the nanowire bunches. Vapor condensation experiments demonstrate that the nucleation preferentially occurs around the top of the nanowire bunches. The results provide guidelines to design micro-/nanostructures for promoting vapor nucleation and droplet removal in condensation.
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Affiliation(s)
- 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, PR China
| | - 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, PR China
| | - Siyan Yang
- 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, PR China
| | - Wei Xu
- 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, PR 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, PR 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, PR 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, PR China
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33
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Xiao Y, Guo Z. Recent advances in biomimetic surfaces inspired by creatures for fog harvesting. NEW J CHEM 2021. [DOI: 10.1039/d1nj03675k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In this review, the recent advances in artificial surfaces for fog harvesting are introduced with emphasis on the surfaces and their mechanisms used to enhance water capture and transportation, providing prospects for coping with water shortages.
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Affiliation(s)
- Yisu Xiao
- Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University, Wuhan 430000, People's Republic of China
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, People's Republic of China
| | - Zhiguang Guo
- Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University, Wuhan 430000, People's Republic of China
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, People's Republic of China
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34
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Yan X, Qin Y, Chen F, Zhao G, Sett S, Hoque MJ, Rabbi KF, Zhang X, Wang Z, Li L, Chen F, Feng J, Miljkovic N. Laplace Pressure Driven Single-Droplet Jumping on Structured Surfaces. ACS NANO 2020; 14:12796-12809. [PMID: 33052666 DOI: 10.1021/acsnano.0c03487] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Droplet transport on, and shedding from, surfaces is ubiquitous in nature and is a key phenomenon governing applications including biofluidics, self-cleaning, anti-icing, water harvesting, and electronics thermal management. Conventional methods to achieve spontaneous droplet shedding enabled by surface-droplet interactions suffer from low droplet transport velocities and energy conversion efficiencies. Here, by spatially confining the growing droplet and enabling relaxation via rationally designed grooves, we achieve single-droplet jumping of micrometer and millimeter droplets with dimensionless jumping velocities v* approaching 0.95, significantly higher than conventional passive approaches such as coalescence-induced droplet jumping (v* ≈ 0.2-0.3). The mechanisms governing single-droplet jumping are elucidated through the study of groove geometry and local pinning, providing guidelines for optimized surface design. We show that rational design of grooves enables flexible control of droplet-jumping velocity, direction, and size via tailoring of local pinning and Laplace pressure differences. We successfully exploit this previously unobserved mechanism as a means for rapid removal of droplets during steam condensation. Our study demonstrates a passive method for fast, efficient, directional, and surface-pinning-tolerant transport and shedding of droplets having micrometer to millimeter length scales.
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Affiliation(s)
- Xiao Yan
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Yimeng Qin
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Feipeng Chen
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Guanlei Zhao
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Soumyadip Sett
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Muhammad Jahidul Hoque
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Kazi Fazle Rabbi
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Xueqian Zhang
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Zi Wang
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Longnan Li
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Feng Chen
- Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China
| | - Jie Feng
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Nenad Miljkovic
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
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35
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Stamatopoulos C, Milionis A, Ackerl N, Donati M, Leudet de la Vallée P, Rudolf von Rohr P, Poulikakos D. Droplet Self-Propulsion on Superhydrophobic Microtracks. ACS NANO 2020; 14:12895-12904. [PMID: 32806052 DOI: 10.1021/acsnano.0c03849] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Liquid transport (continuous or segmented) in microfluidic platforms typically requires pumping devices or external fields working collaboratively with special fluid properties to enable fluid motion. Natural liquid adhesion on surfaces deters motion and promotes the possibility of liquid or surface contamination. Despite progress, significant advancements are needed before devices for passive liquid propulsion, without the input of external energy and unwanted contamination, become a reality in applications. Here we present an unexplored and facile approach based on the Laplace pressure imbalance, manifesting itself through targeted track texturing, driving passively droplet motion, while maintaining the limited contact of the Cassie-Baxter state on superhydrophobic surfaces. The track topography resembles out-of-plane, backgammon-board, slowly converging microridges decorated with nanotexturing. This design naturally deforms asymmetrically the menisci formed at the bottom of a droplet contacting such tracks and causes a Laplace pressure imbalance that drives droplet motion. We investigate this effect over a range of opening track angles and develop a model to explain and quantify the underlying mechanism of droplet self-propulsion. We further implement the developed topography for applications relevant to microfluidic platform functionalities. We demonstrate control of the rebound angle of vertically impacting droplets, achieve horizontal self-transport to distances up to 65 times the droplet diameter, show significant uphill motion against gravity, and illustrate a self-driven droplet-merging process.
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36
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Wang R, Wu F, Xing D, Yu F, Gao X. Density Maximization of One-Step Electrodeposited Copper Nanocones and Dropwise Condensation Heat-Transfer Performance Evaluation. ACS APPLIED MATERIALS & INTERFACES 2020; 12:24512-24520. [PMID: 32363858 DOI: 10.1021/acsami.0c05224] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Currently, it is still a great challenge to obtain copper-based high-efficient dropwise condensation heat transfer (CHT) interfaces via template-free electrodepositing technologies. Here, we report that the density of template-free electrodeposited copper nanocones can maximally reach 1.5 × 106/mm2 by the synergistic control of substrate surface roughness, poly(ethylene glycol) (PEG) molecular weight, and PEG concentration. After thiol modification, the densely packed copper nanocone samples can present low-adhesive superhydrophobicity and condensate microdrop self-jumping function at ambient environment. Condensation heat and mass transfer characterizations show that the CHT coefficient of copper surfaces can maximally enhance 98% for 20 °C vapor and 51% for 40 °C vapor by in situ growth of superhydrophobic densely packed copper nanocones. Although the dropwise condensation mode can change from the jumping mode to the mixed jumping and sweeping mode and the shedding-off mode along with the increase of surface subcooling and vapor temperature, the CHT performance of the nanosample is still superior to that of the contrast flat hydrophobic surface during the whole testing range of surface subcooling. As vapor temperature increases to 80 °C, the CHT performance of the nanosample is inferior to that of the contrast sample. The CHT enhancement under low-temperature vapor should be ascribed to the enhancement of small-drop mass transfer ability caused by low-adhesive superhydrophobicity nature of nanosample surfaces. Their performance degradation mainly results from increased drop-drop drag force along with the increase of surface subcooling and vapor temperature. In sharp contrast, the CHT deterioration under high-temperature vapor should be ascribed to larger drop-surface adhesion and drop-drop drag force. The former is caused by vapor penetration, whereas the latter is caused by the dramatically increased nucleation density and growth rate of condensates. These findings would help design and develop copper-based high-efficiency condensation heat transfer interfaces.
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Affiliation(s)
- Rui Wang
- Functional Materials and Interfaces Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, P. R. China
| | - Feifei Wu
- Functional Materials and Interfaces Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, P. R. China
| | - Dandan Xing
- Functional Materials and Interfaces Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, P. R. China
- School of Nano-Tech and Nano-Bionics, University of Science and Technology of China, Hefei 230026, P. R. China
| | - Fanfei Yu
- Functional Materials and Interfaces Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, P. R. China
| | - Xuefeng Gao
- Functional Materials and Interfaces Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, P. R. China
- School of Nano-Tech and Nano-Bionics, University of Science and Technology of China, Hefei 230026, P. R. China
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37
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Zhao G, Zou G, Wang W, Geng R, Yan X, He Z, Liu L, Zhou X, Lv J, Wang J. Rationally designed surface microstructural features for enhanced droplet jumping and anti-frosting performance. SOFT MATTER 2020; 16:4462-4476. [PMID: 32323690 DOI: 10.1039/d0sm00436g] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The accretion of frost on heat exchanging surfaces through the freezing of condensed water in cold and humid environments significantly reduces the operating efficiency of air-source heat pumps, refrigerators and other cryogenic equipment. The construction of hierarchical micro-nanostructured SHSs, with the ability to timely remove condensed water before freezing via self-propelled droplet jumping, serves as a promising anti-frosting strategy. However, the actual relationship between microstructural features and water removal capability through droplet jumping is still not clear, hindering the further optimization of anti-frosting SHSs. Herein, a series of aluminum SHSs with different micro-cone arrays is designed and fabricated via ultrafast laser processing and chemical etching. The effect of microstructural features on water removal capability is elucidated by statistically analyzing the condensation process. As compared to nanostructured SHSs with the micro-cone size ranging from 10 to 40 μm, the water removal through droplet jumping is remarkably enhanced from 3.42 g m-2 to as much as 13.91 g m-2 over 10 minutes of condensation experiments due to the effective transition of condensed microdroplets from the initial high-adhesion partial wetting (PW) state to low-adhesion Cassie state, leading to significantly reduced water accumulation and improved anti-frosting performance. However, a further increase in the micro-cone size decreased the water removal amount due to greater droplet adhesion to the surface, which results in higher chances for immobile coalescence and the formation of large droplets. Herein, by rationally tuning the size scale of the structured micro-cones, the optimal SHSs display the least water accumulation and render excellent frosting delay of over 90 minutes under simulated harsh operating conditions.
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Affiliation(s)
- Guanlei Zhao
- Department of Mechanical Engineering, State Key Laboratory of Tribology, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Ministry of Education of PR China, Tsinghua University, Beijing 100084, China. and Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
| | - Guisheng Zou
- Department of Mechanical Engineering, State Key Laboratory of Tribology, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Ministry of Education of PR China, Tsinghua University, Beijing 100084, China.
| | - Wengan Wang
- Department of Mechanical Engineering, State Key Laboratory of Tribology, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Ministry of Education of PR China, Tsinghua University, Beijing 100084, China.
| | - Ruikun Geng
- Department of Mechanical Engineering, State Key Laboratory of Tribology, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Ministry of Education of PR China, Tsinghua University, Beijing 100084, China.
| | - Xiao Yan
- Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, 10084, China
| | - Zhiyuan He
- Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
| | - Lei Liu
- Department of Mechanical Engineering, State Key Laboratory of Tribology, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Ministry of Education of PR China, Tsinghua University, Beijing 100084, China.
| | - Xin Zhou
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Jianyong Lv
- Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
| | - Jianjun Wang
- Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and School of Future Technology, University of Chinese Academy of Sciences, Beijing 100190, China
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38
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Evolution of microstructures on stainless steel induced by ultra-short pulsed laser ablation. SN APPLIED SCIENCES 2020. [DOI: 10.1007/s42452-020-2447-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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39
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Zhao G, Zou G, Wang W, Geng R, Yan X, He Z, Liu L, Zhou X, Lv J, Wang J. Competing Effects between Condensation and Self-Removal of Water Droplets Determine Antifrosting Performance of Superhydrophobic Surfaces. ACS APPLIED MATERIALS & INTERFACES 2020; 12:7805-7814. [PMID: 31972085 DOI: 10.1021/acsami.9b21704] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Preventing condensation frosting is crucial for air conditioning units, refrigeration systems, and other cryogenic equipment. Coalescence-induced self-propelled jumping of condensed microdroplets on superhydrophobic surfaces serves as a favorable strategy against condensation frosting. In previous reports, efforts were dedicated to enhance the efficiency of self-propelled jumping by constructing appropriate surface structures on superhydrophobic surfaces. However, the incorporation of surface structures results in larger area available for condensation to occur, leading to an increase in total amount of condensed water on the surface and partially counteracts the effect of promoted jumping on removing condensed water from the surface. In this paper, we focus on the competing effects between condensing and self-propelled jumping on promoting and preventing water accumulation, respectively. A series of micro- and nanostructured superhydrophobic surfaces are designed and prepared. The condensation process and self-propelled jumping behavior of microdroplets on the surfaces are investigated. Thousands of jumping events are statistically analyzed to acquire a comprehensive understanding of antifrosting potential of superhydrophobic surfaces with self-propelled jumping of condensed microdroplets. Further frosting experiments shows that the surface with the lowest amount of accumulated water exhibits the best antifrosting performance, which validates our design strategy. This work offers new insights into the rational design and fabrication of antifrosting materials.
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Affiliation(s)
- Guanlei Zhao
- Department of Mechanical Engineering, State Key Laboratory of Tribology, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Ministry of Education of PR China , Tsinghua University , Beijing 100084 , China
- Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190 , China
| | - Guisheng Zou
- Department of Mechanical Engineering, State Key Laboratory of Tribology, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Ministry of Education of PR China , Tsinghua University , Beijing 100084 , China
| | - Wengan Wang
- Department of Mechanical Engineering, State Key Laboratory of Tribology, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Ministry of Education of PR China , Tsinghua University , Beijing 100084 , China
| | - Ruikun Geng
- Department of Mechanical Engineering, State Key Laboratory of Tribology, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Ministry of Education of PR China , Tsinghua University , Beijing 100084 , China
| | - Xiao Yan
- Institute of Nuclear and New Energy Technology , Tsinghua University , Beijing , 10084 , China
| | - Zhiyuan He
- Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190 , China
| | - Lei Liu
- Department of Mechanical Engineering, State Key Laboratory of Tribology, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Ministry of Education of PR China , Tsinghua University , Beijing 100084 , China
| | - Xin Zhou
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Jianyong Lv
- Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190 , China
| | - Jianjun Wang
- Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190 , China
- School of Future Technology , University of Chinese Academy of Sciences , Beijing 100190 , China
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40
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Yin C, Wang T, Che Z, Jia M, Sun K. Critical and Optimal Wall Conditions for Coalescence-Induced Droplet Jumping on Textured Superhydrophobic Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:16201-16209. [PMID: 31738548 DOI: 10.1021/acs.langmuir.9b02885] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The effectiveness of coalescence-induced jumping of microdroplets on superhydrophobic surfaces is critical to a wide range of applications such as self-cleaning surfaces, anti-icing/frosting, water harvesting, phase-change heat transfer, and hotspot cooling. Introducing textures on the surfaces can readily enlarge the effective contact angle, while an overlarge texture spacing may unfavorably lead to droplet penetration into the gaps in droplet coalescence processes. To clarify the effect of surface textures on the droplet jumping dynamics, we simulated the coalescence of droplets on textured superhydrophobic surfaces with various surface wettability and texture spacings and theoretically derived the critical conditions of jumping and the optimal condition of maximum jumping velocity. The results show that the nonmonotonic emergence of "nonjumping"-"jumping"-"nonjumping" with decreasing solid fraction is synergistically controlled by the surface adhesion and the effective impinging pressure. At a large solid fraction, the transition from "nonjumping" to "jumping" is caused by the reduction of the dimensionless surface adhesion energy below a critical value, which is determined to be 0.035 for Oh = 0.02 and 0.01 for Oh = 0.12. At a small solid fraction, the transition from "jumping" to "nonjumping" is dominated by the reduction of the dimensionless effective impinging pressure, the critical value of which is identified to be 0.14 and is independent of Oh. Moreover, jumping velocity maximizes when wetting critically transits from the Cassie-Baxter (CB) state to the partial-wetting state, and a penetration index is proposed from the wetting theory to predict such transition, which shows good agreement with both present simulations and previous experiments. The present findings are helpful for the design of superhydrophobic surfaces that pursue robust and efficient jumping of droplets.
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Affiliation(s)
- Cuicui Yin
- State Key Laboratory of Engines , Tianjin University , Tianjin 300072 , China
| | - Tianyou Wang
- State Key Laboratory of Engines , Tianjin University , Tianjin 300072 , China
| | - Zhizhao Che
- State Key Laboratory of Engines , Tianjin University , Tianjin 300072 , China
| | - Ming Jia
- School of Energy and Power Engineering , Dalian University of Technology , Dalian 116024 , China
| | - Kai Sun
- State Key Laboratory of Engines , Tianjin University , Tianjin 300072 , China
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41
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Yan P, Li X, Li H, Shao Y, Zhang H, Gao X. Hydrodynamics and mechanism of hydrophobic foam column tray: Contact angle hysteresis effect. AIChE J 2019. [DOI: 10.1002/aic.16793] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Peng Yan
- School of Chemical Engineering and Technology, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) Tianjin University Tianjin China
- Intensified Reaction & Separation Systems, Process & Energy Department Delft University of Technology Delft The Netherlands
| | - Xingang Li
- School of Chemical Engineering and Technology, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) Tianjin University Tianjin China
- National Engineering Research Center of Distillation Technology Tianjin China
| | - Hong Li
- School of Chemical Engineering and Technology, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) Tianjin University Tianjin China
- National Engineering Research Center of Distillation Technology Tianjin China
| | - Yuanyuan Shao
- School of Chemical Engineering and Technology, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) Tianjin University Tianjin China
| | - Hui Zhang
- School of Chemical Engineering and Technology, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) Tianjin University Tianjin China
- Particle Technology Research Center, Department of Chemical & Biochemical Engineering The University of Western Ontario London Ontario Canada
| | - Xin Gao
- School of Chemical Engineering and Technology, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) Tianjin University Tianjin China
- National Engineering Research Center of Distillation Technology Tianjin China
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Sharma CS, Lam CWE, Milionis A, Eghlidi H, Poulikakos D. Self-Sustained Cascading Coalescence in Surface Condensation. ACS APPLIED MATERIALS & INTERFACES 2019; 11:27435-27442. [PMID: 31271531 PMCID: PMC6703749 DOI: 10.1021/acsami.9b07673] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 07/04/2019] [Indexed: 06/09/2023]
Abstract
Sustained dropwise condensation of water requires rapid shedding of condensed droplets from the surface. Here, we elucidate a microfluidic mechanism that spontaneously sweeps condensed microscale droplets without the need for the traditional droplet removal pathways such as use of superhydrophobicity for droplet rolling and jumping and utilization of wettability gradients for directional droplet transport among others. The mechanism involves self-generated, directional, cascading coalescence sequences of condensed microscale droplets along standard hydrophobic microgrooves. Each sequence appears like a spontaneous zipping process, can sweep droplets along the microgroove at speeds of up to ∼1 m/s, and can extend for lengths more than 100 times the microgroove width. We investigate this phenomenon through high-speed in situ microscale condensation observations and demonstrate that it is enabled by rapid oscillations of a condensate meniscus formed locally in a filled microgroove and pinned on its edges. Such oscillations are in turn spontaneously initiated by coalescence of an individual droplet growing on the ridge with the microgroove meniscus. We quantify the coalescence cascades by characterizing the size distribution of the swept droplets and propose a simple analytical model to explain the results. We also demonstrate that, as condensation proceeds on the hydrophobic microgrooved surface, the coalescence cascades recur spontaneously through repetitive dewetting of the microgrooves. Lastly, we identify surface design rules for consistent realization of the cascades. The hydrophobic microgrooved textures required for the activation of this mechanism can be realized through conventional, scalable surface fabrication methods on a broad range of materials (we demonstrate with aluminum and silicon), thus promising direct application in a host of phase-change processes.
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43
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Yan X, Chen F, Sett S, Chavan S, Li H, Feng L, Li L, Zhao F, Zhao C, Huang Z, Miljkovic N. Hierarchical Condensation. ACS NANO 2019; 13:8169-8184. [PMID: 31265236 DOI: 10.1021/acsnano.9b03275] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
With the recent advances in surface fabrication technologies, condensation heat transfer has seen a renaissance. Hydrophobic and superhydrophobic surfaces have all been employed as a means to enhance condensate shedding, enabling micrometric droplet departure length scales. One of the main bottlenecks for achieving higher condensation efficiencies is the difficulty of shedding sub-10 μm droplets due to the increasing role played by surface adhesion and viscous limitations at nanometric length scales. To enable ultraefficient droplet shedding, we demonstrate hierarchical condensation on rationally designed copper oxide microhill structures covered with nanoscale features that enable large (∼100 μm) condensate droplets on top of the microstructures to coexist with smaller (<1 μm) droplets beneath. We use high-speed optical microscopy and focal plane shift imaging to show that hierarchical condensation is capable of efficiently removing sub-10-μm condensate droplets via both coalescence and divergent-track-assisted droplet self-transport toward the large suspended Cassie-Baxter (CB) state droplets, which eventually shed via classical gravitational shedding and thereby avoid vapor side limitations encountered with droplet jumping. Interestingly, experimental growth rate analysis showed that the presence of large CB droplets accelerates individual underlying droplet growth by ∼21% when compared to identically sized droplets not residing beneath CB droplets. Furthermore, the steady droplet shedding mechanism shifted the droplet size distribution toward smaller sizes, with ∼70% of observable underlying droplets having radii of ≤5 μm compared to ∼30% for droplets growing without shading. To elucidate the overall heat transfer performance, an analytical model was developed to show hierarchical condensation has the potential to break the limits of minimum droplet departure size governed by finite surface adhesion and viscous effects through the tailoring of structure length scale, coalescence, and self-transport. More importantly, abrasive wear tests showed that hierarchical condensation has good durability against mechanical damage to the surface. Our study not only demonstrates the potential of hierarchical condensation as a means to break the limitations of droplet jumping, it develops rational design guidelines for micro/nanostructured surfaces to enable excellent heat transfer performance as well as extended durability.
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Affiliation(s)
- Xiao Yan
- Department of Mechanical Science and Engineering , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Feng Chen
- Institute of Nuclear and New Energy Technology, Tsinghua University , Beijing 100084 , China
| | - Soumyadip Sett
- Department of Mechanical Science and Engineering , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Shreyas Chavan
- Department of Mechanical Science and Engineering , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Hang Li
- Department of Mechanical Science and Engineering , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Lezhou Feng
- Department of Mechanical Science and Engineering , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Longnan Li
- Department of Mechanical Science and Engineering , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Fulong Zhao
- Institute of Nuclear and New Energy Technology, Tsinghua University , Beijing 100084 , China
| | - Chongyan Zhao
- Institute of Nuclear and New Energy Technology, Tsinghua University , Beijing 100084 , China
| | - Zhiyong Huang
- Institute of Nuclear and New Energy Technology, Tsinghua University , Beijing 100084 , China
| | - Nenad Miljkovic
- Department of Mechanical Science and Engineering , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Department of Electrical and Computer Engineering , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Frederick Seitz Materials Research Laboratory , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- International Institute for Carbon Neutral Energy Research (WPI-I2CNER) , Kyushu University , 744 Moto-oka , Nishi-ku , Fukuoka 819-0395 , Japan
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Stamatopoulos C, Bleuler P, Pfeiffer M, Hedtke S, Rudolf von Rohr P, Franck CM. Influence of Surface Wettability on Discharges from Water Drops in Electric Fields. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:4876-4885. [PMID: 30884239 DOI: 10.1021/acs.langmuir.9b00374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
It is known that electrified droplets deform and may become unstable when the electric field they are exposed to reaches a certain critical value. These instabilities are accompanied by electric discharges due to the local enhancement of the electric field caused by the deformed droplets. Here we report and highlight an interesting aspect of the behavior of unstable water droplets and discharge generation: by implementing wettability engineering, we can manipulate these discharges. We demonstrate that wettability strongly influences the shape of a droplet that is exposed to an electric field. The difference in shape is directly related to differences in the critical value of the applied electric field at which inception of discharge occurs. Using theoretical models, we can predict and sufficiently support our observations. Thus, by tailoring the wettability of the surface, we can control droplet's behavior from expediting the discharge inception to completely restricting it.
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Walker C, Mitridis E, Kreiner T, Eghlidi H, Schutzius TM, Poulikakos D. Transparent Metasurfaces Counteracting Fogging by Harnessing Sunlight. NANO LETTERS 2019; 19:1595-1604. [PMID: 30689389 DOI: 10.1021/acs.nanolett.8b04481] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Surface fogging is a common phenomenon that can have significant and detrimental effects on surface transparency and visibility. It affects the performance in a wide range of applications including windows, windshields, electronic displays, cameras, mirrors, and eyewear. A host of ongoing research is aimed at combating this problem by understanding and developing stable and effective antifogging coatings that are capable of handling a wide range of environmental challenges "passively" without consumption of electrical energy. Here we introduce an alternative approach employing sunlight to go beyond state-of-the-art techniques, such as superhydrophilic and superhydrophobic coatings, by rationally engineering solar absorbing metasurfaces that maintain transparency, while upon illumination induce localized heating to significantly delay the onset of surface fogging or decrease defogging time. For the same environmental conditions, we demonstrate that our metasurfaces are able to reduce defogging time by up to 4-fold and under supersaturated conditions inhibit the nucleation of condensate outperforming conventional state-of-the-art approaches in terms of visibility retention. Our research illustrates a durable and environmentally sustainable approach to passive antifogging and defogging for transparent surfaces. This work opens up the opportunity for large-scale manufacturing that can be applied to a range of materials, including polymers and other flexible substrates.
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Affiliation(s)
- Christopher Walker
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering , ETH Zurich , Sonneggstrasse 3 , CH-8092 Zurich , Switzerland
| | - Efstratios Mitridis
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering , ETH Zurich , Sonneggstrasse 3 , CH-8092 Zurich , Switzerland
| | - Thomas Kreiner
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering , ETH Zurich , Sonneggstrasse 3 , CH-8092 Zurich , Switzerland
| | - Hadi Eghlidi
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering , ETH Zurich , Sonneggstrasse 3 , CH-8092 Zurich , Switzerland
| | - Thomas M Schutzius
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering , ETH Zurich , Sonneggstrasse 3 , CH-8092 Zurich , Switzerland
| | - Dimos Poulikakos
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering , ETH Zurich , Sonneggstrasse 3 , CH-8092 Zurich , Switzerland
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Ahlers M, Buck-Emden A, Bart HJ. Is dropwise condensation feasible? A review on surface modifications for continuous dropwise condensation and a profitability analysis. J Adv Res 2019; 16:1-13. [PMID: 30899584 PMCID: PMC6413338 DOI: 10.1016/j.jare.2018.11.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 11/27/2018] [Accepted: 11/28/2018] [Indexed: 11/03/2022] Open
Abstract
The interest in surface treatments promoting dropwise condensation has grown exponentially in the past decades. Savings in the operating and maintenance costs of steam processes involving phase changes are promised. Numerous surface preparation methods allow the formation of droplets during condensation. However, stable dropwise condensation has been hardly realized in industrial applications. This review aims to highlight the surface preparation techniques that promote dropwise condensation. It emphasizes on their durability and the resulting stability of dropwise condensation. Furthermore, the possibilities of implementation at an industrial level are discussed, apart from evaluating the economic feasibility through a case study. Despite years of research and numerous surface design possibilities, dropwise condensation cannot be maintained: coating deterioration and fluctuating process conditions commonly lead to surface flooding within hours or weeks. A more profound understanding of the mechanisms of dropwise condensation and innovative design concepts for self-renewing heat transfer surfaces may diminish encountered challenges.
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Affiliation(s)
| | | | - Hans-Jörg Bart
- Thermische Verfahrenstechnik, TU Kaiserslautern, Chair of Separation Science and Technology, Gebäude 44, Raum 476, Gottlieb-Daimler Straße, 67663 Kaiserslautern, Germany
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