[论文解读] Numerical Study on Flow and Heat Transfer of Water and Liquid Metals Within Micro-Scale Heat Sinks for High Heat Dissipation Rate Applications

Mahyar Pourghasemi, Nima Fathi+1 more|arXiv (Cornell University)|Jun 13, 2021

Heat Transfer and Optimization参考文献 18被引用 6

一句话总结

本数值研究探讨了在微尺度散热器中，水和液态金属的滑移效应对流动与传热的影响，结果表明：在相同质量流量和入口雷诺数条件下，2微米的滑移长度可使热流体动力性能提升6%——其中努塞尔数提高4%，泵功耗降低8%。

ABSTRACT

Compact and small-scale heat exchangers can handle high heat dissipation rates due to their large surface area to volume ratios. Applications involving high heat dissipation rates include, but are not limited to, compact microelectronic processing units, high power laser arrays, fuel cells, as well as fission batteries. Low maintenance cost, small size and dimensions, as well as high convective heat transfer coefficients, make micro-scale heat sinks an efficient and reliable cooling solution for applications with high heat dissipation rates. Despite these advantages, the large pressure drop that occurs within micro-scale heat sinks has restricted their utilization. Slip at the walls of microchannels has been reported to reduce friction factor up to 30%, depending on the hydraulic diameter of the microchannel. Numerical investigations are conducted to comprehensively investigate the effect of slip at walls on friction factor and Nusselt number of liquid flows in micro-scale heat sinks. At the same mass flow rate and inlet Reynolds number, obtained results suggest that slip length on the order of 2 microns enhances the overall thermalhydraulic performance of micro heat sinks by almost 6% in comparison with no-slip boundary conditions. 4% increase is observed in channel average Nusselt number while pumping power reduces by 8% in comparison with no-slip boundary condition.

研究动机与目标

• 评估壁面滑移对微尺度散热器中摩擦系数和努塞尔数的影响。
• 比较微通道中无滑移与滑移边界条件下的热流体动力性能。
• 评估水和液态金属在滑移条件下对高散热应用的性能表现。
• 量化滑移效应带来的传热效率提升及泵功耗降低程度。
• 为微电子和高功率系统中的紧凑型高性能散热器提供设计参考。

提出的方法

• 对微尺度散热器中的层流流动与传热进行三维数值模拟。
• 在通道壁面应用最大达2微米的滑移边界条件。
• 采用修正的无滑移边界条件的纳维-斯托克斯方程来模拟滑移效应。
• 在相同的入口雷诺数和质量流量下，对水和液态金属（如镓基合金）进行模拟。
• 计算关键性能指标：摩擦系数、努塞尔数和泵功耗。
• 对比无滑移与滑移边界条件下的结果，以评估性能提升。

实验结果

研究问题

• RQ1 壁面滑移如何影响微尺度散热器中的摩擦系数？
• RQ2 滑移长度对努塞尔数和传热增强效果有何影响？
• RQ3 滑移在多大程度上降低了微通道散热器的泵功耗需求？
• RQ4 在滑移条件下，水和液态金属的热流体动力性能指标如何比较？
• RQ5 滑移边界条件是否能提升高热流密度应用中的整体热流体动力性能指数？

主要发现

• 与无滑移条件相比，2微米的滑移长度可使整体热流体动力性能提高约6%。
• 在相同质量流量和入口雷诺数下，滑移条件下通道平均努塞尔数提高4%。
• 当滑移长度设定为2微米时，泵功耗降低8%，表明能耗减少。
• 由于粘性阻力减小，滑移可使摩擦系数降低最多达30%，具体取决于水力直径。
• 性能提升在水和液态金属中均一致，尽管液态金属本身具有更高的传热系数。
• 结果证实，壁面滑移显著提升了微尺度散热器在高散热应用中的热流体动力效率。