Microscopic Hierarchical Condensation

Fazle Rabbi, Kazi

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https://hdl.handle.net/2142/109751 Copy

Description

Title

Microscopic Hierarchical Condensation

Author(s)

Fazle Rabbi, Kazi

Issue Date

2021

Keyword(s)

• Condensation Heat
• Thermoelectric Power Generation

Abstract

The attainment of ultra-high condensation heat transfer has been a decades-old pursuit due to its potential to enhance the efficiency of thermoelectric power generation, high heat flux thermal management, water harvesting and distillation. To enhance condensation by enabling ultra-efficient droplet removal, we demonstrate condensation on rationally designed hierarchical superhydrophobic surfaces consisting of hill-like microstructures covered with nanostructures that enable large (∼100 μm) spherical condensate droplets on top of the microstructures to coexist with underlying smaller (<10 μm) shadow droplets. Termed hierarchical condensation, the approach combines the spontaneous coalescence of the larger suspended Cassie–Baxter droplets with its shadow droplets residing beneath. We use high-speed optical microscopy and focal plane shift imaging to show that hierarchical condensation is capable of efficiently removing the sub-10-μm condensate droplets via both coalescence and divergent-track-assisted droplet self-transport toward the large suspended Cassie–Baxter state droplets. In addition, experimental growth rate analysis showed that the presence of the large CB droplets accelerates individual underlying shadow droplet growth by ∼21% when compared to identically sized droplets not residing beneath Cassie–Baxter droplets.

Type of Resource

Image

Language

eng

Permalink

http://hdl.handle.net/2142/109751

Copyright and License Information

Copyright 2021 Kazi Fazle Rabbi

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