Natural and engineered surfaces for enhanced phase change heat transfer

Oh, Junho

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https://hdl.handle.net/2142/105931 Copy

Description

Title

Natural and engineered surfaces for enhanced phase change heat transfer

Author(s)

Oh, Junho

Issue Date

2019-07-12

Director of Research (if dissertation) or Advisor (if thesis)

Miljkovic, Nenad

Doctoral Committee Chair(s)

Miljkovic, Nenad

Committee Member(s)

• Jacobi, Anthony M
• Braun, Paul V
• Cropek, Donald M
• Alleyne, Marianne

Department of Study

Mechanical Sci & Engineering

Discipline

Mechanical Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Condensation
• Phase change heat transfer
• Nanoengineering
• Superhydrophobic

Abstract

Phase change of water is a ubiquitous process that occurs throughout nature and in a wide range of engineering systems. Over the last century, many researchers have studied the effect of surface wettability on the enhancement of phase change heat transfer. Interestingly, interfacial phenomena tailored for the manipulation of water can be found in nature. Many natural plant and insect surfaces have evolved to repel or attract water in order to adapt to external evolutionary pressures and to help them survive. This dissertation focuses on nature-inspired surfaces with desirable wettability characteristics that can enhance phase change heat transfer. We begin by investigating the wettability of natural surfaces to understand why and how hydrophobicity is achieved. We reveal that hydrophobicity of cicada wings, stemming from both chemistry and structure, is governed by life history and reproductive strategy, rather than habitat. We utilize the knowledge of natural surface chemistries to develop hydrophobic materials for environmentally friendly superhydrophobic coatings. Furthermore, we answer a key scientific controversy regarding the wettability of rare earth oxides by conclusively showing that hydrophobicity is driven by hydrocarbon adsorption. The findings were leveraged to design, develop, and demonstrate a novel concepts of condensation heat transfer capable of enhancing performance of state-of-the-art sytems by leveraging thin film condensation and jumping-droplet induced localized hot spot cooling.

Graduation Semester

2019-08

Type of Resource

text

Permalink

http://hdl.handle.net/2142/105931

Copyright and License Information

Copyright 2019 Junho Oh

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