Date of Award

2010

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

First Advisor

Kizito, John Dr.

Abstract

The overall goal of the present study is to enhance heat transfer rate performance on high heat flux surfaces while maintaining a uniform and low temperature of the substrate. The specific objectives are to determine shapes which maximize heat transport from heater surfaces when using jet impingement cooling method and to model a two phase jet impingement process which incorporates phase change at the impingement substrate. A very high heat flux of up to 10MW/m2 is applied at the bottom of a heated chamber and a jet of air and water are applied separately to a confined control volume. Free stream flow past a heated wedge can be modeled and solved by Falkner-Skan equations when the wedge angle is within a limit. However, when the impingement surface is constrained by walls to create a cavity, the method is no longer valid. A commercially available Computational Fluid Dynamics (CFD) code Fluent® is modified with user defined code to analyze the physical problem numerically. The results show that a newly generated impingement profile, which incorporates a wedge and a concave profile, gives the best performance. Specifically, the heat transfer enhancement level is around 20% higher when compared to a flat surface. The presence of phase change also increases the overall heat removal due to the additional latent heat of vaporization transfer through mass transport. The models developed in the study can be extended to optimize spray cooling schemes.

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