Item – Theses Canada

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OCLC number
1334505523
Link(s) to full text
LAC copy
Author
Feng, Chen.
Title
Fabrication of Thermal Management Devices using Thermal Spray Technology.
Degree
Ph.D. -- University of Toronto, 2019.
Publisher
[Toronto, Ontario] : University of Toronto, 2019
Description
1 online resource
Abstract
Thermal spray coating processes have been employed to create a composite finned heat sink and a flat vapor chamber featuring structured porous coating wicks, for thermal management application. Three composite heat sinks in the shape of a disk, a cylinder, and a cylinder with vertically projecting fins were made by applying a thin (0.4 - 0.7 mm) zinc layer onto ABS polymer cores using wire-arc spraying. An analytical model of the heat conduction in an annular fin was developed, and the model was found to agree well with the temperature distribution along the disk-shaped heat sink measured using an infra-red camera. The calculated temperatures at the base of the heat sink also agreed with measured values as heater power was varied. The model was used to examine the effect of fin radius and coating thickness on fin efficiency. A flat copper vapor chamber was fabricated by depositing structured porous coatings on the evaporator using flame spraying. The porous copper coatings act as wicks of the vapor chamber for liquid transport due to the capillary effect. Channels to enhance liquid flow were made in the porous copper coatings. Coated samples were made with porosity varying from 2 to 44 %, and groove width ranging from 0.16 to 0.53 mm. The capillary performance of the coatings was evaluated experimentally by measuring the rate-of-rise of ethanol in the coatings. The capillary performance parameter ∆Pcap∙k increases with coating porosity and channel size. The rate of ethanol evaporation on the vertically placed coated samples was investigated. Increasing the effective porosity of the coating enhanced the maximum mass flow rate through it. The flat vapor chamber charged with water operated successfully, and in the heat spreader test it achieved an overall thermal resistance of 0.13 K/W at a maximum heating power of 162 W. The structured porous wicks demonstrated a greater capillary performance than sintered powder wicks, which extends the heat flux up to 140 W/cm2 without reaching the capillary limit. The effective radial conductivity ranges from 1200 to 7000 W/m∙K, depending on the applied power.
Other link(s)
tspace.library.utoronto.ca
hdl.handle.net
Subject
Analytical modelling
Heat transfer
Thermal management devices
Thermal spraying