Self-propelled water droplet movement on a laser-etched radial gradient copper surface

Sommers, Andrew D.; Panth, Mohan; Eid, Khalid

doi:10.1016/j.applthermaleng.2020.115226

Cited by 9 publications

(17 citation statements)

References 54 publications

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“…Thus, using a surface coating (hydrophilic vs. hydrophobic vs. baseline) should be carefully chosen and based on the specific application and geometry. More recent and encouraging efforts in this area have focused on patterned (or hybrid) wettability [70][71][72][73] and wettability gradients [74][75][76] for the passive manipulation and/or removal of droplets. Such approaches thus allow the favorable aspects of both types of surface wettability modification to be more fully realized.…”

Section: Thermophysical Propertiesmentioning

confidence: 99%

Evaporator Frosting in Refrigerating Appliances: Fundamentals and Applications

et al. 2021

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Modern refrigerators are equipped with fan-supplied evaporators often tailor-made to mitigate the impacts of frost accretion, not only in terms of frost blocking, which depletes the cooling capacity and therefore the refrigerator coefficient of performance (COP), but also to allow optimal defrosting, thereby avoiding the undesired consequences of condensate retention and additional thermal loads. Evaporator design for frosting conditions can be done either empirically through trial-and-error approaches or using simulation models suitable to predict the distribution of the frost mass along the finned coil. Albeit the former is mandatory for robustness verification prior to product approval, it has been advocated that the latter speeds up the design process and reduces the costs of the engineering undertaking. Therefore, this article is aimed at summarizing the required foundations for the design of efficient evaporators and defrosting systems with minimized performance impacts due to frosting. The thermodynamics, and the heat and mass transfer principles involved in the frost nucleation, growth, and densification phenomena are presented. The thermophysical properties of frost, such as density and thermal conductivity, are discussed, and their relationship with refrigeration operating conditions are established. A first-principles model is presented to predict the growth of the frost layer on the evaporator surface as a function of geometric and operating conditions. The relation between the microscopic properties of frost and their macroscopic effects on the evaporator thermo-hydraulic performance is established and confirmed with experimental evidence. Furthermore, different defrost strategies are compared, and the concept of optimal defrost is formulated. Finally, the results are used to analyze the efficiency of the defrost operation based on the net cooling capacity of the refrigeration system for different duty cycles and evaporator geometries.

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Section: Thermophysical Propertiesmentioning

confidence: 99%

Evaporator Frosting in Refrigerating Appliances: Fundamentals and Applications

et al. 2021

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“…9 Gradients could offer a means for improved drainage performance on surfaces used in moist air-cooling heat exchangers leading to improved efficiency. 9,10 Gradients have also been suggested as having biomedical applications as no external power supply is needed to transport droplets, and they do not pose side effects. 11 Such applications include the investigation of biomolecular interactions and cell motility.…”

Section: ■ Introductionmentioning

confidence: 99%

“…They have been cited as having potential application in thermal management applications such as heating, ventilation, air-conditioning, and refrigeration systems (HVAC&R). For example, refrigeration evaporators condense water vapor during operation, which can reduce their efficiency and promote biofouling . Gradients could offer a means for improved drainage performance on surfaces used in moist air-cooling heat exchangers leading to improved efficiency. , Gradients have also been suggested as having biomedical applications as no external power supply is needed to transport droplets, and they do not pose side effects .…”

Section: Introductionmentioning

confidence: 99%

“…For example, refrigeration evaporators condense water vapor during operation, which can reduce their efficiency and promote biofouling . Gradients could offer a means for improved drainage performance on surfaces used in moist air-cooling heat exchangers leading to improved efficiency. , Gradients have also been suggested as having biomedical applications as no external power supply is needed to transport droplets, and they do not pose side effects . Such applications include the investigation of biomolecular interactions and cell motility. , Other applications which have been noted include micropump needles and biochips …”

Section: Introductionmentioning

confidence: 99%

“…Number of publications on passive wetting gradients vs year of publication. The papers listed here correspond to refs − , , − , , − .…”

Section: Introductionmentioning

confidence: 99%

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Survey of Micro/Nanofabricated Chemical, Topographical, and Compound Passive Wetting Gradient Surfaces

et al. 2021

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Surface wetting gradients are desirable due to their ability to passively transport liquid droplets without the aid of gravity. Such surfaces can be prepared through topographical or chemical methods or a compound approach involving both methods. By altering the surface free energy across a surface, a droplet that contacts such a surface will experience an actuation force toward the hydrophilic region. Such transport properties make these surfaces attractive for a range of applications from thermal management to microfluidics to the investigation of biomolecular interactions. This paper reviews passive wetting gradients that have been demonstrated over the last three decades, focusing on the types of surfaces that have been developed to date along with the materials that have been used. The corresponding wetting ranges and physical lengths over which droplet mobility has been achieved on these various types of gradient surfaces are compared to guide future developments.

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Rapid surface texturing to achieve robust superhydrophobicity, controllable droplet impact, and anti-frosting performances

Dai,

Chen,

Pan

et al. 2023

Friction

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Robust superhydrophobic surfaces with excellent capacities of repelling water and anti-frosting are of importance for many mechanical components. In this work, wear-resistant superhydrophobic surfaces were fabricated by curing a mixture of polyurethane acrylate (PUA) coating and 1H,1H,2H,2H-Perfluorodecyltrichlorosilane (HFTCS) on titanium alloy (TC4) surfaces decorated with micropillars pattern, thus, composite functional surfaces with PUA coating in the valleys around the micropillars pattern of TC4 were achieved. Apparent contact angle on fabricated surfaces could reach 167°. Influences of the geometric parameters of micropillars pattern on the apparent contact angle were investigated, and the corresponding wear-resistant property was compared. Droplet impact and anti-frosting performances on the prepared surfaces were highlighted. An optimized design of surface texture with robust superhydrophobicity, controllable droplet impact, and anti-frosting performances was proposed. This design principle is of promising prospects for fabricating superhydrophobic surfaces in traditional mechanical systems.

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Self-propelled water droplet movement on a laser-etched radial gradient copper surface

Cited by 9 publications

References 54 publications

Evaporator Frosting in Refrigerating Appliances: Fundamentals and Applications

Evaporator Frosting in Refrigerating Appliances: Fundamentals and Applications

Survey of Micro/Nanofabricated Chemical, Topographical, and Compound Passive Wetting Gradient Surfaces

Rapid surface texturing to achieve robust superhydrophobicity, controllable droplet impact, and anti-frosting performances

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