Investigations on performance of single-phase immersion cooling system

Abstract

Cooling of data centers is crucial from the point of view of energy consumption and zero downtime of data centers. The present study examines the heat transfer behavior for a single-phase immersion cooling system for dielectric fluid (FC40) and dielectric oil (PAO-6) in a 1 U server. Thermal resistance and the temperature of the server are considered to study the system's thermal performance at various system parameters. Parameters varied are inlet/outlet configuration, bypass of the fluid (a gap between the heat sink and the fluid tank), imposed suction fans, fin pitch of the heat sink, fluid flowrate, fluid inlet temperature, and heat load. T-type configuration of inlet/outlet outperforms Z-type configuration. The performance of the system is reduced monotonically with the increase in the gap spacing between the heat sink and tank due to the increased bypass of fluid. The suction created downstream of the heat sink by deploying two fans in series improves the performance appreciably. The effect of the fin pitch of the heat sink on the performance of the system is different for both fluids. For PAO-6, the fin pitch of 2.2 mm yields better performance than the dense pitch of 1.2 mm whereas FC-40 shows the opposite trend. Thermal resistance considerably decreases for PAO-6 with an increase in fluid flowrate from 1 to 3 LPM. Thermal resistance decreases whereas the temperature of the server increases when the fluid inlet temperature increases from 15 to 35 °C. A similar effect is reported when the heat load is increased from 200 to 600 W. Numerical investigations are also carried out for studying to explain the flow field and temperature distribution in case of bypass of fluid.