Geometry-engineered heat sinks for enhanced cooling performance in immersion-cooled servers

초록

This study introduces a novel geometry-engineered dual-CPU heat sink framework for single-phase immersion liquid cooling (SPILC) servers, addressing the limitations of uniform designs that ignore the distinct thermalhydraulic conditions of upstream and downstream CPUs. The originality lies in independently optimizing each CPU's fin height, thickness, and spacing using high-fidelity CFD and Response Surface Methodology, enabling CPU-specific thermal management in SPILC systems. A total of 54 Box-Behnken simulations are conducted to quantify the effects of six geometric variables on average CPU temperature (Ta), inter-CPU temperature difference (Delta T), and pumping power (PP). ANOVA results reveal fin height as the dominant factor across all responses, while fin spacing shows secondary significance and fin thickness has minimal impact. Flow-field analysis demonstrated that tailored geometries greatly enhance coolant penetration, suppress recirculation, and improve temperature uniformity. The optimal configuration (h1 = 19.52 mm, h2 = 25 mm, t1 = 0.90 mm, t2 = 1.50 mm, s1 = 4.83 mm, and s2 = 5 mm) achieves Ta = 51.26 degrees C, Delta T = 0.173 degrees C, and PP = 90.68 & times; 10-5 W, confirming the effectiveness of CPU-specific optimization. A comparative coolant evaluation further shows that oils provide the lowest temperatures while fluorocarbons reduce pumping power, with FC-40 offering the best balance. Overall, this work establishes a new pathway for geometry-adaptive heat sink design in SPILC servers, enabling significantly enhanced thermal performance, uniformity, and energy efficiency.

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