Enhancing Condensation Heat Transfer on Three-Dimensional Hybrid Surfaces

Abstract

Given the self-unbridging phenomenon, the confined liquid-film thickness, and the dragging motion observed on the 3D hybrid surfaces, enhanced condensation heat transfer on the 3D hybrid surface over a large subcooling (DT sub) range was achieved. In addition, the obtained heat flux of 655 G 10 kW$m À2 at DT sub $18 K exceeded the values in the literature regarding state-of-the-art micro/ nanostructured surfaces. This suggests that the 3D hybrid surface can be applied to enhance the condensation in various applications.

Ice Dendrite Growth Atop a Frozen Drop under Natural Convection Conditions

“…Note that this model does not include any moving interfaces, such as how the ice dendrites formed in an earlier stage affect the subsequent vapor deposition, and thus the formation of local peaks and depletion zones cannot be described. Similar results have been obtained at the substrates with topological features instead of attached frozen drops [44][45][46][47], where the contribution of gravity is excluded. The role of gravity is quite clear in this work, i.e., it promotes the deposition when it occurs along with gravity, while it hinders or retards the deposition when it occurs against gravity.…”

Robust Micro-Nanostructured Superhydrophobic Surfaces for Long-Term Dropwise Condensation

“…The frequent coalescence-induced jumping of condensate on superhydrophobic surfaces made it difficult to precisely collect and measure the amount of drained water for calculating heat transfer coefficient using latent heat of vapor (Movies S11 and S12 in Supporting Information). Therefore, a heat transfer testing system that could remove noncondensable gas (NCG) and create an ideal condensing condition was designed and assembled based on previous research to directly analyze heat flux and heat transfer coefficient versus surface subcooling. , Condensation heat transfer performance of MNSS, NGSS, MPSS, and plain copper was characterized and compared with previous research (Sections S13–S15, Figures S17–S18 and Movie S13 in Supporting Information). ,,,,, …”

“…Condensation is a ubiquitous phase change phenomenon in nature − and is widely used in industry, such as power generation, water desalination, and heat transfer. − Among all industrial applications, dropwise condensation has lower thermal resistance and higher heat transfer coefficient than filmwise condensation, because vapor condenses directly on a surface instead of through a liquid film. , For instance, heat transfer was enhanced with a heat flux of 655 kW·m –2 by dropwise condensation . Therefore, it is important to enable dropwise condensation on functional surfaces for improving their heat transfer capacity …”

“…Although robust hierarchical micro-nanostructured surfaces, which consisted of micropillars, micropyramids, or microcones with high mechanical durability, were created via a variety of techniques, such as lithography, ,, laser texturing, chemical reaction, , and so forth for long-term dropwise condensation. These approaches served well at the laboratory level, yet are not intended for upscaling in practical applications.…”

“…7,8 For instance, heat transfer was enhanced with a heat flux of 655 kW•m −2 by dropwise condensation. 9 Therefore, it is important to enable dropwise condensation on functional surfaces for improving their heat transfer capacity. 10 It is known that the design of micro-nanostructures and chemistry of materials endows a surface with superhydrophobicity which allows a variety of advanced functions, such as harvesting kinetic energy via droplet impact, 11−14 lab-on-a-chip bioassays, and improved condensation performance.…”