Photonically enhanced and controlled pool boiling heat transfer

Date of Award

2012

Degree Name

M.S. in Chemical Engineering

Department

Department of Chemical and Materials Engineering

Advisor/Chair

Advisor: Robert J. Wilkens

Abstract

The high cooling requirements from modern day electronic devices have given rise to a need for alternative heat dissipation methods. State of the art liquid to vapor phase change cooling schemes provide a cooling rate orders of magnitude higher than current single phase systems. Boiling studies have long been performed with the goal to enhance critical boiling parameters such as heat transfer coefficient (HTC) and critical heat flux (CHF) by altering surface morphology. More recently, the desire for active control of boiling processes has been realized due to transient and dynamic changes in system cooling requirements. A means of controlling the boiling process by manipulating surface energy through light excitation can provide the necessary adaptive heat transfer properties. In this study, photonically controlled pool boiling studies are conducted on copper, titanium dioxide, and carbon nanotube (CNT) samples. A significant variance in both HTC and CHF upon light excitation is observed in all samples, with different physical and chemical mechanisms for the change in surface energy. Copper boiling samples were induced to a 35% decrease in CHF condition after several minutes using photonic energy via formation of hydrophobic nanoclusters of copper oxide. Photoactive titanium dioxide and CNT experiments showed a 16.8% decrease and 14.5% increase in HTC, respectively, upon light exposure. Small scale contact angle tests, scanning electron microscopy (SEM), and x-ray photoelectron spectroscopy (XPS) on irradiated samples provide an insight into surface changes due to boiling and ultraviolet (UV) light exposure. In addition to photonically enhanced and controlled heat transfer experiments, a new technique for measuring liquid-solid contact during boiling using electrochemical impedance spectroscopy (EIS) is discussed.

Keywords

Photocatalysis Research, Electronic apparatus and appliances Cooling Research, Heat Transmission Research

Rights Statement

Copyright © 2012, author

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