In the current world, demand for Computer Applications have increased exponentially. Since the invention of the first Computer to the current Super-Computers used in IT industries, Technology has developed at such a rapid pace, with still a tremendous scope in further development. This development also calls for high processing and storage of data, resulting in a high increase in Power Density and Heat Generation of Data Servers. An Engineering solution was required for proper heat-dissipation of these servers, with Air-Cooling being a prominent method, used to achieve this objective. It's low cost and easy installation were added advantages. However, its usage has reduced over recent years. Due to the low heat carrying capacity of air, it is not an efficient method in the cooling of high heat-generating servers. There are two methods to remove this heat. Increasing the area of heat transfer is one of the methods, which is not feasible everywhere. To tackle this problem, the liquid immersion cooling method has emerged as a prominent method. Liquid has higher thermal properties like heat capacity, but the limitation is that the liquid must be dielectric to save equipment from short-circuit. This feature also influences the thermal conductivity of the liquids. Generally, dielectric liquids have a low thermal conductivity which affects the thermal performance of the cooling process. The thermal conductivity of the dielectric liquids are drastically increased with the introduction of nanoparticles, which has proven to be the best method.

Nanoparticles are metal and non-metal particles with a size between 1 to 150 nanometers. To keep the dielectric feature of the liquid, the non-metallic nanoparticle can be added to the liquid. Therefore, the Alumina which is one of the materials using as an electrical insulation is used. The mean size of the nanoparticle used in this work is 80 nm and the liquid is mineral oil, which is a low-price liquid for immersion cooling compared to other dielectric liquids. The concentration of nanoparticles was 0 to 5 percent and it is assumed to remain homogeneous. The properties of the mixture were calculated based on the theoretical formula and it was a function of temperature. In this work, we simulated heat transfer and effect of the nanoparticle concentration on the junction temperature of the processors using CFD techniques. The chosen server is an open compute server that has two processors in a row. The junction temperature also was studied for different power conditions of the CPU. The heat transfer coefficient was studied for 3 conditions as follows. No fins, shortfin, and longfin with a different number of blades. 


Numerical Analysis of Oil Immersion Cooling of a Server Using Mineral Oil and Al2o3 Nanofluid

Division / Sponsors: 
Electronic & Photonic Packaging Division (EPPD)

Paper Proceedings: https://asmedigitalcollection.asme.org/InterPACK/InterPACK2020/volume/84041

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