In this study, a numerical investigation of fluid flow and heat transfer of Al₂O_3-water nanofluids in a pillow plate heat exchanger with a two-phase model is investigated. The flow regime studied in this study is in the laminar flow regime such that the Reynolds numbers are 250, 500, 750, and 1000 and the volume fraction of the nanoparticles remained so that the fluid stayed in Newtonian. The volume fraction of nanoparticles is $\varphi =$ 0, 1, 2, and 3 %. In this study, the effect of the shape of the welding points used in the pillow plate has also been investigated in such a way that three modes of circular welding point, large-diameter elliptic welding point along with the flow and large-diameter elliptic welding point perpendicular to the stream have been investigated. Numerical simulation results show that using nanofluid and increasing Reynolds number improves heat transfer, as well as circular welding point, shows the best heat transfer rate. The shape of the welding points has a direct relationship with the pressure drop and heat transfer, as well as the wake created behind the welding points, which have the highest wake and pressure drop respectively for the elliptic welding points perpendicular to the flow, circular and elliptical parallel to the flow. On the other hand, the addition of nanoparticles increases the friction factor and, on the contrary, increases the Reynolds number, which reduces the friction factor. Finally, the highest Reynolds number, the highest volume fraction of nanoparticles, and the circular welding point state show the highest PEC.

中文翻译：

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使用两相模型的枕板式换热器中纳米流体流动和传热的数值研究：枕板中使用的焊接点形状的影响

在这项研究中，研究了具有两相模型的枕板式换热器中 Al ₂ O _3-水纳米流体的流体流动和传热的数值研究。本研究中研究的流态为层流流态，雷诺数为 250、500、750 和 1000，并且纳米颗粒的体积分数保持不变，因此流体保持牛顿。纳米粒子的体积分数为$\phi =$0、1、2 和 3 %。在这项研究中，还研究了枕板所用焊点形状的影响，采用圆形焊点、大直径椭圆焊点随流焊和大直径椭圆焊三种模式。研究了垂直于流的点。数值模拟结果表明，使用纳米流体和增加雷诺数可以改善传热，并且圆形焊接点显示出最佳的传热率。焊点的形状与压降和传热以及焊点后面产生的尾流有直接关系，垂直于流动的椭圆焊点、圆形焊点和焊点的尾流和压降最高。椭圆平行于流动。另一方面，纳米粒子的添加增加了摩擦系数，相反，增加了雷诺数，从而降低了摩擦系数。最后，最高的雷诺数、最高的纳米粒子体积分数和圆形焊接点状态显示出最高的 PEC。