Measurement of the Thermal Performance of a Single-Phase Immersion Cooled Server at Elevated Temperatures for Prolonged Time

Abstract

Fully immersion of servers in electrically nonconductive (dielectric) fluid has recently become a promising technique for minimizing cooling energy consumption in data centers. The improved thermal properties of these dielectric fluids facilitate considerable savings in both upfront and operating cost over traditional air-cooling. This technology provides an opportunity for accommodating increased power densities. It also minimizes the common operational issues of air cooling technique like overheating and temperature swing in the system, fan failures, dust, air quality, and corrosion. This paper presents various data about the thermal performance of a fully single-phase dielectric fluid immersed server over wide temperature ranges (environment temperatures) from 25°C to 55°C for prolonged periods in an environmental chamber. This work explores the effects of high temperatures on the performance of a server and other components like pump, along with potential issues associated with extreme climatic conditions. The experimental data serves as a means to determine failure criteria for the server and pump by subjecting the system to accelerated thermal aging conditions i.e. around 55°C, consequently simulating the most extreme environmental condition that the server may encounter. Connector seals are inspected for expected degradation upon temperature cycling typically at such extreme conditions. Throttling limit for the server and pump power draw for different temperatures was determined to assess pump performance. Determining the relations between component behavior and operating temperature provides an accurate measure of lifetime of a server. The scope of this paper can be expanded by reviewing the effects of low temperatures on server and component performance. Changes to various performance parameters like power draw of pump and server at the higher and the lower operating temperatures and an understanding of issues like condensation can be used to quantify upper and lower limits for pump and server performance.