Thermal Performance of Surface Characterization for Two-Phase Immersion Cooling using HFE-7200

The recent advancements in AI have led to increased heat generation in CPUs and GPUs used in data center servers. Traditional air-cooling methods used in existing data centers are becoming increasingly inadequate to effectively manage the rising heat loads, prompting extensive research into immersion cooling. While numerous studies have explored thermal performance enhancement through surface modification in two-phase immersion cooling, this research has largely been confined to pool boiling chambers, which do not accurately reflect actual server environments. In this study, we fabricated surface-modified samples using copper foam and sintered copper microporous coating (MPC) with varying thicknesses. We evaluated thermal performance within a chamber that simulates real server immersion cooling conditions. Experimental results showed that, compared to a smooth surface, the surface-modified samples achieved up to a 705% improvement in heat transfer coefficient and a 78% increase in critical heat flux (CHF). Both surface modification methods exhibited a trend where increased thickness led to decreased heat transfer coefficient but increased CHF. The sintered copper MPC was more effective in enhancing the heat transfer coefficient, while copper foam was more effective in increasing CHF. Furthermore, visualization analysis was conducted to identify the mechanism behind the thermal performance improvements due to surface modification. This study analyzes the impact of surface modification techniques and thickness variations under realistic two-phase immersion cooling conditions. It offers practical insights for their application in two-phase immersion-cooled server systems.