3D Numerical Analysis of Two-Phase Immersion Cooling for Electronic Components

This paper presents a three-dimensional numerical analysis, using ANSYS Fluent, of a two-phase immersion cooling solution for high-powered processor designs. The primary electronic component, a CPU package, is modeled as a bare 5cm × 5cm flat plate heat source. The remainder of the model is based on the structure of typical two-phase immersion-cooled servers. Two arrangements are investigated, both fully immersing the heat-producing components in liquid coolant. The first has two vertically mounted heat sources to achieve higher packing density of the server, while the second only has a single heat source. This study considers 3M Novec7000 as the phase change coolant, which is a dielectric with a low (34°C) boiling temperature. We validate our numerical model against published results. Our simulations show: (1) when the two heat sources are in series, the upper source runs significantly hotter than the lower source because bubbles from lower source reduce the coolant contact area on the upper source. (2) Novec7000 can support cooling a 5cm × 5cm heat source in a vertical orientation with power as high as 225W (heat flux 9W/cm
²
). However, if two such sockets are thermally coupled, the power of the upper socket must be lower than 185W. If socket power exceeds that limit, a heat transfer enhancement layer should be applied to the coupled sockets to increase cooling area and reduce heat flux.