Fan Cooling Investigation for High-Speed Electronic Interconnect

Abstract

Quad Small Form-factor Pluggable-Double Density (QSFP-DD) is the smallest high-speed (>14 Tb/s) interconnect system and is widely used in cloud computing and 5G network. However, the high-speed feature comes at the cost of large power dissipation. The QSFP-DD system contributes 400 to 960 W per rack unit, which necessitates its thermal management. The authors, having identified a knowledge gap in the existing literature, humbly hope to pioneer a thermal-hydraulic study for QSFP-DD. The study starts with experiments in a wind tunnel wherein temperature, power, fan speed, and pressure are measured. The experimental data are used to validate computational fluid dynamics (CFD) models. Both lumped fan and multiple reference frame fan models have been studied with comparisons versus experimental data. Subsequently, the focus of CFD study is shifted to the QSFP-DD system’s thermal-hydraulic structures, including variation in fins’ height, quantity, and the grille free area ratio. Finally, the CFD results are processed into an empirical Nusselt number correlation for thermal performance prediction. The study reveals that optimum thermal performance could be achieved by balancing heat sink fin area and pressure drop of the system.