Date of Award

Fall 2004

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Mechanical Engineering - (Ph.D.)

Department

Mechanical Engineering

First Advisor

Avraham Harnoy

Second Advisor

Rong-Yaw Chen

Third Advisor

E. S. Geskin

Fourth Advisor

Boris Khusid

Fifth Advisor

John Tavantzis

Abstract

With the proliferation of consumer electronics devices and the increasingly demanding thermal control requirements for such devices, more effective and efficient means of cooling electronics are needed. The feasibility of three alternative approaches to enhancing pure natural convection cooling of electronics is investigated in the current research. The three static or dynamic methods investigated are alternate cross-flow passages, the strategic placement of transversely oscillating plates near the heat sources and a combined method using both the cross-flow passages and the strategically placed oscillating plates. These cooling methods are intended to operate in the regime for which natural convection cooling is inadequate, yet conventional fan driven cooling is inefficient, and, thus, to serve as an intermediary between pure natural convection and forced convective cooling.

Parametric studies of these three cooling methods were carried out through two-dimensional laminar flow numerical simulations. A finite volume program was developed for a simplified model geometry while for more complex geometries and boundary conditions, a finite element package was utilized. The resulting temperature and velocity field data from these studies was used to examine the impact that each cooling method makes on these fields and to determine measures of the cooling effect including average surface temperatures and average and local heat transfer coefficients.

Through comparisons among the results of the parametric studies and to a reference natural convection case the potential cooling effects and the parameter range over which any improvement is possible were estimated. This study provides the information necessary to judge the potential thermal benefits and feasibility of each method.

Based on the results, each of the three methods has the capability to produce a significant cooling effect for viable parameter values with the amount of cooling dependent on the system parameters and the cooling method. Thus each of the three methods has practical potential as a means of enhancing pure natural convection cooling of electronics in a vertically oriented channel arrangement.

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