Abstract

Studies on thermal enhancement for electronic chips has been gaining prominence as increased transistor density in the chips calls for larger heat dissipation. Various enhancement techniques have been proposed ever since 1981, to enhance the heat dissipation from the chip surface. Micro pin fins have been gaining recognition as a highly favorable surface enhancement due to the design versatility it provides in the form of myriad geometric shapes and fin arrangements as opposed to convention microchannels. The micro pin fins however, present a larger pressure drop over the surface as compared to other conventional methods which reduces the thermal efficiency of the chip surface. To reduce the pressure drop associated with micro pin fins, short micro pin fins were proposed. A short micro pin fin arrangement is similar to micro pin fin arrays, with one change, in that short micro pin fins have a clearance between the fins and the top of the channel. The current study focusses on heat transfer and pressure drop over short micro pin fin arrays.

Experimental studies were conducted over 10 mm × 10 mm with fin heights varying from 200 to 500 µm and clearance over the fins varying from 265 to 900 µm. Distilled water was used as the cooling medium. The heat transfer coefficient and pressure drop characteristics were evaluated at varying fin heights and varying clearance of the surfaces with an aim to identify optimum fin height and clearance parameters. The heat transfer coefficient and pressure drop data obtained from experiments were also evaluated with the correlation proposed by Tullius et al. [17].

Data showed that the highest heat transfer coefficient was observed for fins with the largest fin height. When fin clearance was evaluated for its effect on heat transfer coefficient, a hint of mixing phenomenon leading to enhancement in heat transfer coefficient was observed at higher clearance values. A higher pressure drop was observed at longer fins owing to the increased friction factor at the fin walls. The highest pressure drop of over 100 kPa was observed for a chip gasket combination which consisted of the longest fins with the least amount of clearance. It was also observed that the Nusselt number and Pressure drop correlations proposed by Tullius et al was not able to accurately predict the experimental data. However, the correlation did show the same trend as the experimental data, hence, the present correlation could be modified or used as a basis for new correlations of Nusselt number and friction factor.

Library of Congress Subject Headings

Semiconductors--Thermal properties; Heat-transfer media; Heat--Transmission; Integrated circuits--Cooling

Publication Date

12-1-2015

Document Type

Thesis

Student Type

Graduate

Degree Name

Mechanical Engineering (MS)

Department, Program, or Center

Mechanical Engineering (KGCOE)

Advisor

S.G. Kandlikar

Advisor/Committee Member

Robert Stevens

Advisor/Committee Member

Jason Kolodziej

Comments

Physical copy available from RIT's Wallace Library at TJ263 .B42 2015

Campus

RIT – Main Campus

Plan Codes

MECE-MS

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