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Title:Natural and engineered surfaces for enhanced phase change heat transfer
Author(s):Oh, Junho
Director of Research:Miljkovic, Nenad
Doctoral Committee Chair(s):Miljkovic, Nenad
Doctoral Committee Member(s):Jacobi, Anthony M; Braun, Paul V; Cropek, Donald M; Alleyne, Marianne
Department / Program:Mechanical Sci & Engineering
Discipline:Mechanical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(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.
Issue Date:2019-07-12
Type:Text
URI:http://hdl.handle.net/2142/105931
Rights Information:Copyright 2019 Junho Oh
Date Available in IDEALS:2019-11-26
Date Deposited:2019-08


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