Microscale Confinement and Wetting Contrast Enable Enhanced and Tunable Condensation

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, gravityindependent, and durable phase-change heat transfer is required.

Development and prospect of monitoring and prevention methods of icing disaster in China power grid

“…Scholars worldwide have conducted extensive research on icing monitoring and prevention methods in the grids, focusing on the formation mechanism causing ice disaster, key technologies and characteristics, and anti/de-icing approaches development and application. They have successively carried out lots of research on icing mechanism and flashover characteristics of insulators [3][4][5], icing formation mechanism of conductors [6][7][8], influence of hydrophobic surface on conductors and insulators icing [9][10][11][12], anti/de-icing technologies including AC/DC ice melting methods [13,14], and development and implementation of ice melting device [15][16][17]. They also put forward the mathematical models of conductors icing accretion [18][19][20], the probability statistical model of icing accidents [21,22], anti/de-icing mechanism [23][24][25][26], and established natural icing testing stations to investigate the equivalence between the artificial icing and natural icing [27].…”

Bridging-droplet transfer from solid to porous surfaces

“…In an extreme case of a droplet transferring from a nanostructured superhydrophobic substrate to a hydrophilic substrate, nearly the entire droplet volume could transfer without any need to move the substrates (Yan et al. 2022).…”

“…Yan et al. (2022) solved this issue in two different ways. For dispensed droplets, the upper substrate was slowly lowered until it gently contacted the target droplet, at which point the transfer process itself was purely a function of the surface wettabilities.…”

“…The magnitude of each substrate's contact angle hysteresis governs where contact line pinning occurs, which also affects the transfer process (Chen et al 2016). In an extreme case of a droplet transferring from a nanostructured superhydrophobic substrate to a hydrophilic substrate, nearly the entire droplet volume could transfer without any need to move the substrates (Yan et al 2022).…”

“…The ability to transfer a droplet without any relative motion between the substrates is attractive in its simplicity, but raises the question of how to initiate the transfer in the first place. Yan et al (2022) solved this issue in two different ways. For dispensed droplets, the upper substrate was slowly lowered until it gently contacted the target droplet, at which point the transfer process itself was purely a function of the surface wettabilities.…”