Experimental Investigation of a Liquid Immersion Cooled Electronics Module using Two-Phase Heat Transfer for Thermal Management
Type of DegreeDissertation
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As society’s demand for constant connectivity to one another grows, both from an economic and social perspective, the requirements on high performance data centers throughout the world will as well. The expeditious transfer of data over reliable and efficient networks is as much a problem that must be addressed from a thermal management perspective as it is from a computer science one. The speed at which data is transferred is directly related to the amount and density of heat that a processing element emits. System reliability is tied to the operating temperature at which these high performance computing devices are maintained. The need for energy efficiency of any design will only continue to grow as worldwide consumption increases in the face of dwindling global power resources. With these macro-scale issues in mind, the current study proposes a thermal management solution for near and far-term high performance electronic devices which addresses all three of these concerns. The proposed system is a small form factor, power dense cartridge which houses heated elements meant to simulate the heat output of electronic components typically found in servers or other high performance computing systems. These elements are immersed in a low boiling point dielectric fluid where, when powered to an adequate heat flux, cools the devices through two-phase heat transfer. The combination of latent and convective heat transfer from boiling results in incredibly high heat transfer coefficients, translating to lower operating temperatures and greater system reliability. In allowing the heated elements to boil in a pool of dielectric fluid, power dissipations of over 300 W have been achieved at an operating temperature of 77°C using the bare silicon surface. By introducing boiling surface enhancements, microporous and microfinned surfaces, operating temperatures at the maximum power dissipation decrease by roughly 18°C. By pumping dielectric fluid through the cartridge, power dissipations over 700 W have been achieved at a surface temperature of only 71°C. At this latter power dissipation, the cartridge, which is only 300 mm x 150 mm x 38 mm (L x W x H), has eight times the volumetric power dissipation capabilities of a similar system that uses air cooling techniques. Particle Image Velocimetry (PIV) measurements, both in the single and two-phase, have been taken to ascertain flow distribution characteristics as well as assist in the development of ways in which to divert flow over critical areas of interest within a densely packed electronics enclosure.