Impact of Channels Aspect Ratio on the Heat Transfer in Finned Heat Sinks with Tip Clearance

Micromachines

Elena Martin¹  Alejandro Valeije¹  Francisco Sastre²  Angel Velazquez² 

[1] Departamento de Ingeniería Mecánica, Máquinas y Motores Térmicos y Fluidos, Escuela de Ingeniería Industrial, Campus Marcosende, Universidade de Vigo, 36310 Vigo, Spain;Fluid Mechanics and Aerospace Propulsion Department, Universidad Politécnica de Madrid, Plaza del Cardenal Cisneros 3, 28040 Madrid, Spain;

关键词: heat sink;    tip clearance;    aspect ratio;    heat transfer versus pressure drop;    numerical simulation;    Computational Fluid Dynamics (CFD);   

DOI  :  10.3390/mi13040599

来源: DOAJ

【 摘 要 】

A 3D numerical study is used to analyze the flow topology and performance, in terms of heat transfer efficiency and required pumping power, of heat sink devices with different channel aspect-ratio in the presence of tip-clearance. Seven different channel aspect ratios $AR$, from 0.25 to 1.75, were analyzed. The flow Reynolds numbers $Re$, based on the average velocity evaluated in the device channels region, were in the range of 200 to 1000. Two different behaviors of the global Nusselt were obtained depending on the flow Reynolds number: for $Re<600$, the heat transfer increased with the channels aspect ratio, e.g., for $Re=400$, the global Nusselt number increased by 14% for configuration $AR=1.75$ when compared to configuration $AR=0.25$. For $Re>600$, the maximum Nusselt is obtained for the squared-channel configuration, and, for some configurations, flow destabilization to a unsteady regime appeared. For $Re=700$, Nusselt number reduced when compared with the squared-channel device, 11% and 2% for configurations with $AR=0.25$ and 1.75, respectively. Dimensionless pressure drop decreased with the aspect ratio for all cases. In the context of micro-devices, where the Reynolds number is small, these results indicate that the use of channels with high aspect-ratios is more beneficial, both in terms of thermal and dynamic efficiency.

【 授权许可】

Unknown