Thesis
Experimental study of hot spot cooling in micro-scale two phase system with wettability gradient
Washington State University
Master of Science (MS), Washington State University
05/2020
DOI:
https://doi.org/10.7273/000004240
Handle:
https://hdl.handle.net/2376/124784
Abstract
Thermal management is one of the most challenging problems of electronic devices today. As technology becomes increasingly miniaturized, it becomes difficult to keep devices away from overheating due to extremely localized heat dissipation. Two-phase cooling or flow-boiling in micro-spaces utilizes the highly efficient thermal energy transport of phase change from liquid to vapor. However, the excessive consumption of liquid-phase by highly localized heat source causes the two-phase flow maldistribution, leading to a greatly reduced heat transfer coefficient, high-pressure loss, and limited flow rate. In this study, we investigate two-dimensional flow-boiling in a microgap heat sink with different hydrophilic coating on hot-spot and characterize the bubble morphology, heat transfer, and pressure drop. The experiments are carried out on a Stainless Steel plate, having a micro gap depth of 170 [mu]m using deionized water with inlet at room temperature. A partial hydrophilic and a hydrophilic channel surfaces are created on the hot-spot (surface above the heater) to compare the thermal performance with the conventional surface. The relative thermal performance and wettability change between the hydrophilic surfaces are also evaluated. A wide range of heat flux varying from 91.35 KW/m2 to 118.25 KW/m2 and mass flux varying from 1.656 Kg/m2s to 4.97 Kg/m2s are considered to quantify heat transfer coefficient. From the high-speed flow visualizations, it is found that vapor films and slugs are flushed quickly from the hydrophilic surfaces, which improve heat transfer on hydrophilic heat sink compared to the conventional heat sink. It is also evaluated that among the hydrophilic heat sinks, channel hydrophilic heat sink shows better cooling performance and pressure stability as it provides a smooth route for the incoming water to cool the hot spot.
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Details
- Title
- Experimental study of hot spot cooling in micro-scale two phase system with wettability gradient
- Creators
- Anwarul Karim
- Contributors
- Jong Hoon Kim (Advisor) - Washington State University, Engineering and Computer Science (VANC), School of
- Awarding Institution
- Washington State University
- Academic Unit
- Engineering and Computer Science (VANC), School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Identifiers
- 99900896420001842
- Language
- English
- Resource Type
- Thesis