Structured surface enhanced flow boiling

Nithin Vinod Upot, -

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https://hdl.handle.net/2142/117536 Copy

Description

Title

Structured surface enhanced flow boiling

Author(s)

Nithin Vinod Upot, -

Issue Date

2022-10-11

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

• Miljkovic, Nenad
• Jacobi, Anthony

Doctoral Committee Chair(s)

Miljkovic, Nenad

Committee Member(s)

• Elbel, Stefan
• Banerjee , Arijit

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)

• Boiling
• Structures: Scalable

Abstract

Flow boiling is prevalant in a variety of industrial sectors such as thermal management of electronics, automotive and off-road vehicles, distillation, chemical synthesis, desalination, thermoelectric power generation, refrigeration, and cryogenics since it offers the dual advantage of near-isothermal operation, and ultra-efficient energy transfer. Although the flow boiling heat transfer coefficient, a characteristic measure of the efficiency of heat transfer, is higher when compared to other modes of thermal exchange such as single phase flow, a vast amount of work has been done in the recent past to further enhance two-phase heat transfer coefficients via surface-structuring techniques. However, the majority of such studies suffer from limitations of being difficult to scale, not being characterized for durability, being difficult to manufacture on typical heat exchanger materials or having typically been studied with water as the working fluid. To address these gaps, this dissertation focuses on development of scalable fabrication methods to enhance effective heat transfer coefficients for metal-based heat exchangers with refrigerants as the working fluid. We begin by fabricating internal micron scale and nanoscale structures on the internal surface of an aluminum tube and demonstrate enhancements in heat transfer coefficients for the microstructured surface. Building on these findings, we extend the microstructuring techniques to copper and stainless-steel to examine surface-structuring enabled heat transfer coefficient enhancements. We then evaluate enhancements on existing enhanced tubes by microstructuring finned aluminum tubes through crystallographic chemical etching and demonstrate improvements in thermal performance. Finally, predictive mechanisms for heat transfer coefficients are examined and an artificial neural network is developed for high-accuracy HTC prediction. The insights presented in this thesis help in potential applicability of the demonstrated microstructuring techniques to full-scale heat exchangers.

Graduation Semester

2022-12

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Nithin Vinod Upot

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