Fundamental studies of hydrophobic thin film durability and degradation mechanisms during dropwise condensation of steam

Ma, Jingcheng

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https://hdl.handle.net/2142/115812 Copy

Description

Title

Fundamental studies of hydrophobic thin film durability and degradation mechanisms during dropwise condensation of steam

Author(s)

Ma, Jingcheng

Issue Date

2022-04-20

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

• Miljkovic, Nenad
• Cahill, David G

Doctoral Committee Chair(s)

Miljkovic, Nenad

Committee Member(s)

• Braun, Paul V
• Jacobi, Anthony M

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)

• Dropwise condensation
• Hydrophobic coatings
• Droplets
• Durability

Abstract

Steam condensation directly affect the energy efficiency of steam power plants that produce 70% of the global electricity baseload. Enhancement in condensation heat transfer has the potential to increase the energy efficiency of these steam power plants by up to 2%, demonstrating a key potential impact on the global energy landscape as well as our carbon footprint. Dropwise condensation on hydrophobic thin films (~100 nm-thick) has the potential to achieve remarkable heat transfer. However, the lack of durability of these thin films has limited applications for a century. Although degradation due to steam condensation has been described as ‘blistering’, no satisfactory insight exists capable of elucidating the driving force for film delamination. This dissertation focuses on designing thin and robust hydrophobic coatings for long-term dropwise condensation. We begin by investigating two mechanisms of coating failure: 1) microscopic condensation-induced blistering, and 2) mesoscopic capillary peeling. We revealed the important role of coating adhesion and pinhole defects on coating’s durability. The findings were leveraged to design, develop, and demonstrate two classes of durable and thin hydrophobic coatings materials: 1) ultra-thin, self-healing dynamic polymer networks that resists pinhole defects, and 2) lipid-like high adhesive coating interfaces, which prevent coating delamination by well-designed van der Waals interaction between the coating and the substrate. The techniques and insights presented here will inform future work on polymeric thin film and enable their durable design for dropwise condensation and a variety of other applications.

Graduation Semester

2022-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Jingcheng Ma

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