Advancing in Data Centers Thermal Management: Experimental Assessment of Two-Phase Liquid Cooling Technology

Abstract In response to the exponential growth of online platforms and the rise of web-based Artificial Intelligence (AI), the demand for computational power and the expansion of data centers have surged significantly. This trend necessitates advanced cooling strategies and heightened energy efficiency to address the increasing power densities of Information Technology (IT) equipment and the consequent rise in energy consumption. Consequently, there is a significant pivot towards efficient cooling mechanisms that emphasize thermal management and energy efficiency. Against this backdrop, our study thoroughly evaluates a two-phase direct-to-chip liquid cooling system’s ability to effectively manage and dissipate heat in high-density rack environments. Central to our research is the deployment of a highly efficient Refrigerant-to-Liquid (R2L) Coolant Distribution Unit (CDU) across multi-racks, which face high thermal demands. This innovative system, featuring an in-row pumped two-phase CDU with a cooling capacity of 160 kW, is intricately integrated with row and rack manifolds and server cooling loops to ensure optimal cooling performance. To accurately simulate the thermal loads encountered in real-world data center operations, the study employs Thermal Testing Vehicles (TTVs). These 3U TTVs are equipped with 2.5 kW heaters, covering an extensive area of 2500 mm2, thereby effectively replicating server thermal loads up to 10 kW. The investigation starts with a detailed description of the system’s design and continues with the commissioning process. This process includes extensive hydraulic and thermal testing, along with a comprehensive assessment of the impact of pressure drops across the system, focusing on supply manifolds, cooling loops, dry breaks, and return manifolds, utilizing Cooling Loops (CLs) each containing four Cold Plates (CPs). The study culminates in the analysis of experimental data from heating the TTVs, focusing on the efficiency of two-phase cooling in transferring heat from the TTVs to chilled water using R134a refrigerant as the performance benchmark. Future directions include exploring eco-friendly cooling practices by investigating alternative green refrigerants with low Global Warming Potential (GWP) to replace R134a, aligning with global sustainability goals and the imperative to reduce greenhouse gas emissions. The observed maximum values were calculated at a specific volumetric flow rate of 0.48 LPM/kW and a Tcase as low as 56.4 °C was achieved. These results demonstrate the system’s capability to significantly enhance thermal management in data centers, tackle the challenges presented by high-power density chips, and encourage broader adoption of two-phase cooling technologies as a sustainable strategy for thermal regulation in the face of increasing computational demands.