Enhanced heat transfer with nanostructured coatings in two-phase immersion cooling

In recent years, there is a significant growing trend in the amount of data stored in company servers. This results in the need for data centers to run continuously all year-round, creating overheating issues where conventional method of air cooling could no longer sustain. Single phase liquid cooli...

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Main Author: Yeo, Jie Wei
Other Authors: Fei Duan
Format: Final Year Project
Language:English
Published: 2017
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Online Access:http://hdl.handle.net/10356/70793
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-707932023-03-04T18:36:48Z Enhanced heat transfer with nanostructured coatings in two-phase immersion cooling Yeo, Jie Wei Fei Duan School of Mechanical and Aerospace Engineering DRNTU::Engineering::Mechanical engineering In recent years, there is a significant growing trend in the amount of data stored in company servers. This results in the need for data centers to run continuously all year-round, creating overheating issues where conventional method of air cooling could no longer sustain. Single phase liquid cooling was introduced as an alternative but was still insufficient to overcome the heat generated. This led to the proposal of two phase liquid cooling, where the liquid is boiled to vapour and condensed back to liquid using available pool boiling. Using fluid with a low boiling point, the saturation point of the liquid is easily achieved by pool boiling. This helps to cool the hot surfaces with the constant vaporisation and condensation of the liquid at saturation point. Novec 7100 was selected due to its dielectric property, which is suitable for usage on servers and electronics. In this report, heat generated from the exposed surface causes the formation of bubbles in the liquid that contacts the surface. Heat is then transferred to the bubbles. The exposed surface was orientated vertically, providing a good path for the bubbles to travel. This causes the bubbles to rise rapidly which in turn cools the surface. Addition of nanotube structure to the exposed surface was also evaluated in this report. Thus, this report serves to summarize the enhancements evaluated to improve the cooling efficiency which includes using subcooled conditions and surfaces with in-built structures. Heat flux and heat transfer coefficient were obtained and compared. Results from the experiment showed that normal plain copper surface can reach a critical heat flux (CHF) of 37 W/cm2. A linear increase in CHF was being observed at subcooled conditions. At subcooled conditions of 15°C, a 46% higher heat flux as compared to saturated conditions was observed. Copper surfaces with titanium nanotubes posed an issue as the heat flux did not increase proportionally. It was suspected that the disproportionality of the heat flux increase is contributed because of using two different material. Hence, the study was repeated using a titanium block with nanotube to evaluate the effect of nanotube enhancement. The results indicated a lower heat flux as compared to the plain copper surface. This indicates that copper is far superior than titanium in terms of heat transfer. However, due to lack of time future studies can focus on nanotube as well as the effects and properties of the bubble departure. Bachelor of Engineering (Mechanical Engineering) 2017-05-11T06:14:22Z 2017-05-11T06:14:22Z 2017 Final Year Project (FYP) http://hdl.handle.net/10356/70793 en Nanyang Technological University 67 p. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic DRNTU::Engineering::Mechanical engineering
spellingShingle DRNTU::Engineering::Mechanical engineering
Yeo, Jie Wei
Enhanced heat transfer with nanostructured coatings in two-phase immersion cooling
description In recent years, there is a significant growing trend in the amount of data stored in company servers. This results in the need for data centers to run continuously all year-round, creating overheating issues where conventional method of air cooling could no longer sustain. Single phase liquid cooling was introduced as an alternative but was still insufficient to overcome the heat generated. This led to the proposal of two phase liquid cooling, where the liquid is boiled to vapour and condensed back to liquid using available pool boiling. Using fluid with a low boiling point, the saturation point of the liquid is easily achieved by pool boiling. This helps to cool the hot surfaces with the constant vaporisation and condensation of the liquid at saturation point. Novec 7100 was selected due to its dielectric property, which is suitable for usage on servers and electronics. In this report, heat generated from the exposed surface causes the formation of bubbles in the liquid that contacts the surface. Heat is then transferred to the bubbles. The exposed surface was orientated vertically, providing a good path for the bubbles to travel. This causes the bubbles to rise rapidly which in turn cools the surface. Addition of nanotube structure to the exposed surface was also evaluated in this report. Thus, this report serves to summarize the enhancements evaluated to improve the cooling efficiency which includes using subcooled conditions and surfaces with in-built structures. Heat flux and heat transfer coefficient were obtained and compared. Results from the experiment showed that normal plain copper surface can reach a critical heat flux (CHF) of 37 W/cm2. A linear increase in CHF was being observed at subcooled conditions. At subcooled conditions of 15°C, a 46% higher heat flux as compared to saturated conditions was observed. Copper surfaces with titanium nanotubes posed an issue as the heat flux did not increase proportionally. It was suspected that the disproportionality of the heat flux increase is contributed because of using two different material. Hence, the study was repeated using a titanium block with nanotube to evaluate the effect of nanotube enhancement. The results indicated a lower heat flux as compared to the plain copper surface. This indicates that copper is far superior than titanium in terms of heat transfer. However, due to lack of time future studies can focus on nanotube as well as the effects and properties of the bubble departure.
author2 Fei Duan
author_facet Fei Duan
Yeo, Jie Wei
format Final Year Project
author Yeo, Jie Wei
author_sort Yeo, Jie Wei
title Enhanced heat transfer with nanostructured coatings in two-phase immersion cooling
title_short Enhanced heat transfer with nanostructured coatings in two-phase immersion cooling
title_full Enhanced heat transfer with nanostructured coatings in two-phase immersion cooling
title_fullStr Enhanced heat transfer with nanostructured coatings in two-phase immersion cooling
title_full_unstemmed Enhanced heat transfer with nanostructured coatings in two-phase immersion cooling
title_sort enhanced heat transfer with nanostructured coatings in two-phase immersion cooling
publishDate 2017
url http://hdl.handle.net/10356/70793
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