Enhanced water capture induced with electrowetting-on-dielectric (EWOD) approach

Yan, Run; McClure, Thomas S.; Jasim, Ibrahem; Koppula, Akshay; Wang, Sheng; Almasri, Mahmoud; Chen, Chung‐Lung

doi:10.1063/1.5053703

Cited by 22 publications

(11 citation statements)

References 29 publications

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“…These improved properties have more potential applications in the electric wetting devices.Polymers 2020, 12, 574 2 of 11 complex, and the experimental conditions are usually at high temperature and high pressure [6,7]. In order to make full use of the advantages of inorganic and polymer dielectric materials, some researchers have proposed a two-layer structure with a composite of an organic hydrophobic layer on the surface and an inorganic layer with a high dielectric constant on the bottom [6,8]. However, the manufacturing process of this structural design is more complicated.…”

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confidence: 99%

Designing Micro Bulge Structure with Uniform PS Microspheres for Boosted Dielectric Hydrophobic Blend Films

et al. 2020

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In this paper, homogeneous polystyrene (PS) microspheres with controllable sizes of 40 nm, 80 nm, and 120 nm were synthesized by controlling the temperature of solvothermal method. In order to explore the effect of PS microspheres on dielectric-hydrophobic properties of the composite films, the composite films containing polystyrene, Polydimethylsiloxane, and P(VDF-TrFE) with high dielectric and hydrophobicity were successfully prepared by a simple and feasible solution blending method. The dielectric constant and hydrophobicity of composite films were boosted by increasing the mass fraction of PS content and decreasing the size of PS due to the enhanced interfacial polarization and the uniform surface micro bulge structure. Meanwhile, the composite films maintain a low loss tangent. Typically, the dielectric constant with 5 wt.% 40 nm PS reached to 29 at 100Hz, which is 4 times that of PDMS/P(VDF-TrFE) (mass ratio: 2/3). Otherwise, the largest the contact angle of 126° in the same composition was remarkably larger than the pure PDMS/P(VDF-TrFE) (110°). These improved properties have more potential applications in the electric wetting devices.

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confidence: 99%

Designing Micro Bulge Structure with Uniform PS Microspheres for Boosted Dielectric Hydrophobic Blend Films

et al. 2020

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“…[ 13,33 ] A series of follow‐up studies confirmed these basic original observations regarding the evolution of the drop distribution for straight interdigitated electrodes. [ 35–39 ]…”

Section: Introductionmentioning

confidence: 99%

Electrowetting‐Controlled Dropwise Condensation with Patterned Electrodes: Physical Principles, Modeling, and Application Perspectives

Hoek

Dey

Mugele

2020

Adv Materials Inter

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Patterning the wettability of solid surfaces is a successful strategy to control the dropwise condensation of vapor onto partially wetting solid surfaces. The condensation of water vapor onto electrowetting‐functionalized surfaces is studied with structured co‐planar electrodes. A detailed analysis of the experimental distribution of millions of drops reveals that despite the presence of contact angle hysteresis and the occurrence of random drop coalescence events, the preferential drop positions closely follow the numerically calculated local minima of the electrostatic energy for variable drop size. Even subtle transitions between competing preferred locations are properly reproduced by the model. Based on this quantitative understanding of the condensation patterns, a series of important follow‐up steps that need to be taken to demonstrate a reliable performance gain in various applications focusing in particular on enhanced heat transfer is discussed.

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“…Ke et al [30] numerically studied droplet dynamics and condensation enhancement on microstructure surfaces using electrowetting to form different wettability patterns. Inspired by this study, Yan et al [79] proposed an active approach to achieve a similar objective via EWOD for water harvesting studies. Most recently, researchers have examined the electrowetting impact on condensation in terms of condensation patterns [80] and droplet shedding characteristics [81].…”

Section: Discussionmentioning

confidence: 99%

“…The contact angle variation of the EWOD devices was measured under charged (40 V DC) and uncharged conditions. The 40 V DC was chosen for safety reasons, as previous research [79] identified the safety range of applied voltage as 0-70 V DC.…”

Section: Contact Angle Measurementmentioning

confidence: 99%

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Water harvesting and condensation heat transfer enhancement induced with electrowetting-on-dielectric

Yan¹

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As demand for the world's natural resources continues to rise, energy saving has become an urgent topic. Water harvesting and condensation heat transfer enhancement represent two vital energy-saving objectives. Many researchers have focused on alternating surface wettability by employing advanced materials or complex surface structures to achieve such goals; however, most of these approaches operate in a passive manner. In terms of active methods, electrowetting-on-dielectric (EWOD) has become a popular option owing to its excellent contact angle reversibility, switching speed, and long-term reliability in altering surface wettability. This dissertation presents a study of the EWOD effect on water harvesting and condensation heat transfer. It describes experimental and analytical studies concerning various characteristics such as EWOD-induced droplet dynamics, water capture capability, and heat transfer performance. It also quantifies water harvesting and condensation heat transfer enhancement. This dissertation is divided into four main studies, each of which considers different aspects of the effects of EWOD on water harvesting and condensation heat transfer. The first part of this dissertation (Chapter 2) describes microfabrication technologies to obtain EWOD devices, including low-pressure chemical vapor deposition, photolithography, sputtering deposition, and lift-off and spin coating. Mask designs with different electrode configurations and a device microfabrication protocol are also described. The second part of this dissertation (Chapter 3) presents an experimental investigation of EWOD-induced water harvesting enhancement. EWOD devices were tested in a high-humidity environment under mist flow. Compared with an uncharged EWOD device, the water capture capability of charged devices improved significantly. These results are of great importance, as they indicate strong potential for improvement in water-harvesting applications. The third part of this dissertation (Chapter 4) describes a visualization study of EWOD-regulated condensation droplet distribution. Side-by-side experiments were performed to compare charged and uncharged devices. Charged devices exhibited a regulated droplet distribution, faster droplet growth, more dispersed droplet distribution, and more large droplets. These experimental results introduced a novel approach to actively influence droplet distribution on microfabricated condensing surfaces and showed promise for improving the condensation heat transfer rate via EWOD. The fourth part of this dissertation (Chapter 5) discusses the EWOD effect on the condensation heat transfer coefficient and heat flux. The heat transfer coefficient and heat flux were compared on uncharged and charged (40V DC) EWOD devices. Experimental results demonstrated a positive effect of EWOD on condensation heat transfer. This approach could be incorporated into many industrial applications (e.g., heat exchanger fin surfaces, condensing surfaces of waste heat recovery systems, and components of electronic cooling packages) requiring high-efficiency heat dissipation. In summary, this work makes valuable contributions to the field of water harvesting and condensation heat transfer, proposing a new approach to research in these areas. Findings also detail a new tool to achieve water harvesting and condensation heat transfer enhancement via an active EWOD method.

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Enhanced water capture induced with electrowetting-on-dielectric (EWOD) approach

Cited by 22 publications

References 29 publications

Designing Micro Bulge Structure with Uniform PS Microspheres for Boosted Dielectric Hydrophobic Blend Films

Designing Micro Bulge Structure with Uniform PS Microspheres for Boosted Dielectric Hydrophobic Blend Films

Electrowetting‐Controlled Dropwise Condensation with Patterned Electrodes: Physical Principles, Modeling, and Application Perspectives

Water harvesting and condensation heat transfer enhancement induced with electrowetting-on-dielectric

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