Natural and engineered surfaces for enhanced phase change heat transfer

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.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2019

Author dc:creator

• Oh, Junho

Contributors dc:contributor

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

• Condensation
• Phase change heat transfer
• Nanoengineering
• Superhydrophobic

Statement dc:rights

• Copyright 2019 Junho Oh

Language dc:language

en

Handle dc:identifier

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

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/105931