Microchannel-elevated micromembrane for sustainable phase-separation condensation

Shan, Li; Guo, Zongqi; Monga, Deepak; Boylan, Dylan; Dai, Xianming

doi:10.1016/j.joule.2022.11.010

Cited by 19 publications

(5 citation statements)

References 38 publications

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“…The filmwise condensation, in the end, may be related to the oxidation process of copper, which degrades the wettability of PDMS coating. , It should be noted that even after degradation, the wetting properties of the coating can be restored by applying a bit of PDMS oil (Figure S8, Supporting Information). Moreover, as a perspective of future impacts, although PDMS brush coating is grafted on the flat substrate here, it may also be used to modify the structured surface to further enhance condensation …”

Section: Resultsmentioning

confidence: 99%

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Durable, Ultrathin, and Antifouling Polymer Brush Coating for Efficient Condensation Heat Transfer

Li,

Lam,

Donati

et al. 2023

ACS Appl. Mater. Interfaces

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Heat exchangers are made of metals because of their high heat conductivity and mechanical stability. Metal surfaces are inherently hydrophilic, leading to inefficient filmwise condensation. It is still a challenge to coat these metal surfaces with a durable, robust, and thin hydrophobic layer, which is required for efficient dropwise condensation. Here, we report the nonstructured and ultrathin (∼6 nm) polydimethylsiloxane (PDMS) brushes on copper that sustain high-performing dropwise condensation in high supersaturation. Due to the flexible hydrophobic siloxane polymer chains, the coating has low resistance to drop sliding and excellent chemical stability. The PDMS brushes can sustain dropwise condensation for up to ∼8 h during exposure to 111 °C saturated steam flowing at 3 m•s −1 , with a 5−7 times higher heat transfer coefficient compared to filmwise condensation. The surface is selfcleaning and can reduce the level of bacterial attachment by 99%. This low-cost, facile, fluorine-free, and scalable method is suitable for a great variety of heat transfer applications.

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Section: Resultsmentioning

confidence: 99%

“…Moreover, as a perspective of future impacts, although PDMS brush coating is grafted on the flat substrate here, it may also be used to modify the structured surface to further enhance condensation. 70 2.4. Antifouling Test.…”

Section: Condensation Heat Transfer Performance At High Pressure To Q...mentioning

confidence: 99%

Durable, Ultrathin, and Antifouling Polymer Brush Coating for Efficient Condensation Heat Transfer

Li,

Lam,

Donati

et al. 2023

ACS Appl. Mater. Interfaces

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“…In Figure 3a 1 , the vapor condenses on the hydrophilic surface to form a continuous liquid film, which introduces a new thermal resistance between the condensing plate and vapor, resulting in a sharp decrease in the heat transfer efficiency of condensation. [37] Therefore, dropwise condensation, in which microdroplets generated during condensation on hydrophobic surfaces grow and merge in the form of discrete droplets, has been extensively studied [38][39][40][41][42] (Figure 3a 2 ). The large droplets after condensation are more likely to break away from the surface under external forces (such as gravity), which significantly improves the condensation efficiency.…”

Section: The Vapor Collecting Performance Of Wettability Patterned Co...mentioning

confidence: 99%

Bio‐inspired Thermal Diode with Anti‐Gravity Unidirectional Heat Transfer and Switchable Functionality for Intelligent Thermal Management

Zhang,

et al. 2024

Adv Materials Technologies

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Phase‐change thermal diodes with asymmetric and adjustable heat transfer capacity exhibit great application prospects in spacecraft heat management and solar energy storage. Current heat modulation strategies mainly depend on the anisotropic assistance from gravity and the rectification ratio can hardly be adjusted due to the immobilized inner structures. Here, a novel bioinspired thermal diode vapor chamber has been carried out with magnetic microgroove cones array sealed between two copper plates, where the evaporating plate with porous copper foam can reserve water and the condensing plate with patterned wettability can coagulate vapor into droplets at designated spot. With microgroove cones rooting from the evaporating plate and their tips contacting the condensing plate, these cones can directionally and rapidly transport condensed liquid from the condensing plate to evaporating plate under the unbalanced strong capillarity while prohibiting water flowing backward. This eventually leads to unidirectional liquid‐vapor circulation and anti‐gravitational directional heat transferring with a rectification ratio as high as 7.4. Such flowing of liquid can also be regulated by magnetically controlling the bending of cones to realize switched ON–OFF of thermal diode and achieve further modulation of heat management. This bioinspired thermal diode vapor chamber provides new ideas for intelligent thermal management systems.

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“…Recently, 2-tier hierarchical superhydrophobic surfaces combining well-designed microscale and nanoscale structures have emerged. [46,47] Compared with 1-tier surfaces, 2tier surfaces with hierarchical structures obtain great heat transfer performance over a wider subcooling range. Mou et al [47] fabricated hierarchical micro/nano porous structures on copper tubes, realizing droplet jumping at a subcooling degree up to ≈20 K and achieving great heat transfer enhancement at up to ≈7 K subcooling, with the heat transfer coefficient being ≈105 kW m −2 K −1 under the pressure of ≈8 kPa and at a subcooling of ≈4 K. Such 2-tier surface design strategy also applys to conditions with high concentrations of a non-condensable gas.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, 2‐tier hierarchical superhydrophobic surfaces combining well‐designed microscale and nanoscale structures have emerged. [ 46,47 ] Compared with 1‐tier surfaces, 2‐tier surfaces with hierarchical structures obtain great heat transfer performance over a wider subcooling range. Mou et al.…”

Section: Introductionmentioning

confidence: 99%

A Multiscale Strategy for Constructing Finned Microporous Superhydrophobic Surface for Highly‐Efficient Condensation Heat Transfer Enhancement Enabled by Lifespan Regulation of Droplets

Zhang

Fan

2023

Adv Funct Materials

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Spontaneous droplet jumping on micro‐/nano‐structured superhydrophobic surfaces has been exploited as an efficient means for enhancing steam condensation heat transfer. However, the good performance of such surfaces quickly decays with raising the degree of subcooling, due to the mismatch between the characteristic length scales and droplet sizes when they grow up. Herein, a novel strategy for multiscale droplet regulation is proposed by combining sub‐millimeter fin structure with a hierarchical microporous superhydrophobic surface. A superior condensation heat transfer performance is attained on such hierarchical superhydrophobic finned tube (F‐SHB), in comparison to the baseline case of superhydrophobic non‐finned (SHB) tube under well‐controlled test conditions. Although the droplet jumping is not as vigorous as that on the SHB tube, the finned geometry of the F‐SHB tube leads to a condensation heat transfer enhancement even under high degrees of subcooling up to 36 K, because of the accelerated departure of large droplets by imposing Laplace force gradient in the presence of V‐shaped sub‐millimeter fins. This multiscale enhancement strategy is shown to enable a cascading regulation over the entire lifespan of condensate droplets. The fabrication of F‐SHB tubes is facile and easy to be scaled up, showing great potential in practical steam condensation applications.

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Microchannel-elevated micromembrane for sustainable phase-separation condensation

Cited by 19 publications

References 38 publications

Durable, Ultrathin, and Antifouling Polymer Brush Coating for Efficient Condensation Heat Transfer

Durable, Ultrathin, and Antifouling Polymer Brush Coating for Efficient Condensation Heat Transfer

Bio‐inspired Thermal Diode with Anti‐Gravity Unidirectional Heat Transfer and Switchable Functionality for Intelligent Thermal Management

A Multiscale Strategy for Constructing Finned Microporous Superhydrophobic Surface for Highly‐Efficient Condensation Heat Transfer Enhancement Enabled by Lifespan Regulation of Droplets

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