Abstract

In this study, nanofluid jet impingement cooling performance with single and multiple jets are analyzed under the impacts of using double porous layers with finite element method (FEM). The numerical study is performed by using different values of pertinent parameters as: Re number ($100\le \text{Re}\le 300$), permeability of the porous zones (${10}^{-4}\le \text{Da}1\le {10}^{-1}$ and ${10}^{-4}\le \text{Da}2\le {10}^{-1}$), second porous layer height ($0.1H\le \mathrm{d}2\le 0.5H$), distance between the porous layers ($0.1H\le \mathrm{h}\le 0.5H$), solid volume fraction ($0\le \varphi \le 3\%$), and particle diameter ($20\text{nm}\le dp\le 80\text{nm}$). Discrepancies between the single and multiple jet configurations become higher for Re numbers while at Re = 300, the average heat transfer (HT) is 31% for multiple jet case. The presence of the double porous layers significantly affects the convective HT performance and the highest impact is observed by varying the permeability of the porous layers. When the lowest and highest permeability of the lower layer are compared, there is 119% variation in the average Nu for multi-jet (MJ) case and this value is 84.5% for single jet (SJ) case. When varying the permeability of the upper porous layer, the highest HT rate is achieved at Darcy number of ${10}^{-3}$ while 32% higher Nu is obtained for MJ case as compared to SJ case. There is slight impact of the distance between the porous layers on the fluid flow and HT while varying the height of the upper layer results in 8.9% variation in the average Nu number. Inclusion of the nanoparticle (NP) further improves the average Nu by about 11% for single and multiple jet cases at the highest solid volume fraction while the impact of NP size is slight.

摘要

在这项研究中，在使用有限元法（FEM）的双多孔层的影响下，分析了单射流和多射流的纳米流体射流冲击冷却性能。数值研究是通过使用不同的相关参数值来进行的： Re number ($100\le \text{关于}\le 300$), 多孔层的渗透率 (${10}^{-4}\le \text{大}1\le {10}^{-1}$和${10}^{-4}\le \text{大}2\le {10}^{-1}$), 第二多孔层高度 ($0.1H\le \mathrm{d}2\le 0.5H$），多孔层之间的距离（$0.1H\le \mathrm{H}\le 0.5H$), 固体体积分数 ($0\le \phi \le 3\%$) 和粒径 ($20\text{纳米}\le dp\le 80\text{纳米}$）。对于 Re 数，单喷射和多喷射配置之间的差异变得更大，而在 Re = 300 时，多喷射情况下的平均传热 (HT) 为 31%。双多孔层的存在显着影响对流 HT 性能，通过改变多孔层的渗透率观察到最大的影响。当比较下层的最低和最高渗透率时，多射流（MJ）情况下的平均 Nu 变化为 119%，而单射流（SJ）情况下该值为 84.5%。当改变上部多孔层的渗透率时，最高的 HT 速率在达西数达到${10}^{-3}$与 SJ 病例相比，MJ 病例的 Nu 高出 32%。多孔层之间的距离对流体流动和 HT 有轻微影响，而改变上层高度会导致平均 Nu 数变化 8.9%。纳米颗粒 (NP) 的加入进一步提高了单个和多个射流情况下最高固体体积分数的平均 Nu 约 11%，而 NP 尺寸的影响很小。