Abstract

In this paper, the effects of the nanoparticles $(\mathrm{NP})$ shape on thermal efficiency, entropy generation $(E_{\mathit{gen}})$ for the application of a ${\mathrm{H}}_2\mathrm{O}$/boehmite alumina nanofluid $(\mathrm{NF})$ in a microheat sink (MHS) are studied. The MHS is composed of a number of microchannels, the walls of which consist of circular pin-fins attached together. A constant heat flux enters the HS from the bottom and heat it up. On the other hand, the nanofluid is responsible for cooling the HS. To study the thermal efficiency and entropy, a simulation using the control volume method has been performed in Fluent software. The effect of the NP size has been reported in this research. The simulation results showed that the average HS temperature strongly depends on the inlet fluid velocity, and an increase in the nanofluid velocity decreases it. Moreover, the addition of NPs reduces the average temperature of the HS, but its impact is smaller than that of the fluid velocity. Adding 5% of the cylindrical nanoparticles reduces the average temperature of the heatsink by 0.72 K. In addition, increasing the velocity and volume fraction of NPs decreases the thermal resistance (${Th}_{\mathit{Res}}$) and increases the pumping power. The addition of 5% platelet-shaped nanoparticles increases the pumping power required by up to 80%. Using cylindrical NPs leads to the best temperature uniformity and least thermal resistance in the HS. Adding NPs decreases entropy generation. Application of blade NPs in high volume fractions, as well as brick NPs in average volume fractions, leads the highest Figure of Merit (FOM).

摘要

在本文中，纳米粒子的作用$(\mathrm{NP})$热效率、熵产生的形状$({乙}_{\mathit{根}})$申请一个${\mathrm{H}}_{\mathrm{2个}}\mathrm{欧}$/勃姆石氧化铝纳米流体$(\mathrm{NF})$在微型散热器 (MHS) 中进行了研究。MHS 由许多微通道组成，其壁由连接在一起的圆形针翅组成。恒定的热通量从底部进入 HS 并将其加热。另一方面，纳米流体负责冷却 H2S。为了研究热效率和熵，在 Fluent 软件中进行了使用控制体积法的模拟。本研究报告了 NP 大小的影响。模拟结果表明，平均 HS 温度在很大程度上取决于入口流体速度，并且纳米流体速度的增加会降低它。此外，添加 NPs 降低了 HS 的平均温度，但其影响小于流体速度的影响。${吨H}_{\mathit{水库}}$) 并增加泵浦功率。添加 5% 的片状纳米颗粒可将所需的泵浦功率提高高达 80%。使用圆柱形 NP 可在 HS 中实现最佳的温度均匀性和最小的热阻。添加 NP 会减少熵的产生。在高体积分数中应用叶片 NP，以及在平均体积分数中应用砖 NP，导致最高的品质因数 (FOM)。