Abstract

Rapid advancement of electronics used in domestic, commercial and military applications has necessitated the development of thermal management solutions capable of dissipating large amounts of heat in a reliable and efficient manner. Traditional methods of cooling, including air and liquid cooling, require large fluid flow rates and temperature differences to remove high heat fluxes and are therefore unsuited for many advanced applications. Phase change heat transfer, specifically boiling, is capable of dissipating large heat fluxes with low temperature gradients and hence is an attractive technique for cooling high heat flux applications. However, due to the complex interactions between the fluid dynamics, heat transfer, and surface chemistry, the fundamental physics associated with boiling is not completely understood.

The focus of this work is to get a better understanding of the role played by a nucleating bubble in removing the heat from the substrate. The interfacial forces acting on a bubble, contact line motion, and the thermal interaction with the heater surfaces are some of the important considerations which have not been well understood in literature. The work reported in this dissertation is divided into three parts. In the first part, an analytical study of the effect of evaporation momentum force on bubble growth rate and bubble trajectory was conducted. It was shown that the trajectory of a bubble can be controlled by creating an asymmetric temperature field. This understanding was used to develop a bubble diverter that increased the Critical Heat Flux (CHF) over a horizontal tubular surface by 60% and improved the heat transfer coefficient by 75%. In the second part of the work, additional contact line regions were generated using microgrooves. This enhancement technique increased the CHF with water by 46% over a plain copper surface to 187 W/cm2. Finally, the effect of the heater properties and surface fouling during boiling was evaluated. This included a study on the effect of thermophysical properties of the heater surface on CHF and an investigation of fouling over a heater surface during boiling of seawater.

Library of Congress Subject Headings

Heat sinks (Electronics)--Fluid dynamics; Heat-transfer media--Fluid dynamics; Heat--Transmission; Ebullition

Publication Date

4-2018

Document Type

Dissertation

Student Type

Graduate

Degree Name

Engineering (Ph.D.)

Department, Program, or Center

Engineering (KGCOE)

Advisor

Satish G. Kandlikar

Advisor/Committee Member

Robert Stevens

Advisor/Committee Member

Michael Schertzer

Campus

RIT – Main Campus

Plan Codes

ENGR-PHD

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