The Study on Improving CFD Simulation Accuracy for Heat Sink Design Optimization in Single-Phase Immersion Cooling System

Data center sustainability has becoming one top priority in the industry nowadays, mainly driven by cooling efficiency challenge of data center high heat flux components such as high thermal design power (TDP) microprocessors in high density rack server as well as the related regulation and enforcement of sustainability locally and worldwide. Power usage effectiveness (PUE) is one of mainstream indicators for environmentally sustainable data center. Lower PUE highly matters in the existing data center reconstruction or new built data center. Recent research and engineering practice in ecosystem has proved the feasibility of immersion cooling technology for hyper scale data center deployment to achieve PUE 1.1 or lower. However, ramping up immersion cooling solutions for massive production scaling in the industry still need address the challenges from the phase of design, validation to deployment and maintenance. Parameters setting of thermal simulation utility for immersion cooling system design accuracy is one pain point nowadays as mainstream setting parameters are with best known methods of air cooling, which accumulated for decades. Deviating significantly from the principles of air cooling system design, immersion cooling hinges on the manipulation of liquid density variations to induce fluid circulation, but weakened by gravitational effects. This paradigm shift necessitates a meticulous reassessment of parameter configurations and the meticulous selection of thermal simulation tools tailored specifically for immersion cooling scenarios. In this study, the commercial version of Foltherm XT, a computational fluid dynamics (CFD) utility, is used with optimal parameters setting for thermal simulation of immersion cooling system design. Intel immersion cooling engineering system (aka. Open IP immersion cooling reference system) is used for engineering validation to prove the accuracy of immersion cooling thermal simulations with optimal parameters. Validation results have concluded the coolant flow field is dominated by laminar flow where FC-40 of 3M Fluorinert Electronic liquid used to cool high density servers with Intel Xeon scalable processors, and less than 2.5% deviation between simulation and engineering validation eventually achieved. To demonstrate the value and benefit of this study on high CFD simulation accuracy for immersion cooling, an advanced heat sink design optimal for single immersion cooling system is introduced with the conclusion drawn that heat sink in louver design way hit the sweetest spot of performance, cost and capacity for single-phase immersion cooling system, where its thermal resistance has achieved 7% lower than typical 1U air heat sink (44+2 fins and 0.3 mm fin thickness) widely used nowadays.