Immersion two phase liquid cooling for data center thermal management

• Main Author: Sidharta, Welly
• Other Authors: Fei Duan
• Format: Final Year Project
• Language: English
• Published: 2016
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/68153
• Institution: Nanyang Technological University

The tremendous growth of technology usage in recent years has seen the drastic increase in energy consumption to cool down the data centres. Excess heat generated will have negative implication on the electrical component of the computers. Current preferred method of traditional air cooling consumed a lot of energy and is deemed to be inefficient to remove the excess heat fast enough. Liquid cooling method has been recognized but the incompatibility of commonly available liquid has made this method not economical. As such, two phase immersion cooling method, which allows the liquid to be recycled, is being studied. In this report, a copper block was used to simulate the electrical components. Heat was generated by using heaters. The block was immersed in Novec 7100 dielectric fluid in an enclosed vessel, with an attached condenser. Heat flux was regulated by controlling the voltage input. The heated surface temperatures were estimated from the thermocouples inserted just underneath the test surface. Boiling curve was plotted and heat transfer coefficient was calculated using Newton's Law of cooling. The graphs show increasing trend of heat transfer coefficient at higher heat flux. Bubbles dynamics, which are regarded as important aspects of heat transfer is also studied. High speed camera was installed to capture the boiling phenomena. Analysis was done by replaying the recorded movie at lower frames interval. Results show that increasing heat flux will increase the bubble departure diameter, departure frequency and nucleation site density. Bubble growth rate also increases with heat flux. Comparison with previous studies indicated favourable traits of two phase cooling. However due to the complexity nature of bubbles behaviour in boiling, further research in other areas need to be looked into.