Fahad Mostafa Kamal, Hasan Md Jahid, Ifraj Nowroze Farhan, Chandra Dey Dipta
Department of Mechanical and Production Engineering (MPE), Ahsanullah University of Science and Technology, Dhaka-1208, Bangladesh.
Department of Mechanical and Production Engineering (MPE), Islamic University of Technology (IUT), Board Bazar, Gazipur, 1704, Bangladesh.
Heliyon. 2024 Jul 11;10(14):e34481. doi: 10.1016/j.heliyon.2024.e34481. eCollection 2024 Jul 30.
Helical tube heat exchangers (HTHE) are commonly used as thermal devices in various thermal engineering applications. A comparative investigation was undertaken to examine several helical tube designs in relation to their potential uses with water and nanofluids. Additionally, employing the ternary hybrid nanofluid (THNF) flow in helical-type heat exchangers to assess the heat transfer and frictional loss is a unique concept, as there is currently no research on this specific application. This study involves analyzing three different design configurations, each of which has three different inlet profiles: round, square, and oval shapes. Hence, a numerical analysis has been conducted on nine cases, each including the same pipe length, helix diameter, and pitch distance. The specified range for the Reynolds number under the water and THNF flow condition is 5000-25000. The results are acquired for both fluids, considering the Nusselt number (), friction factor (), outlet temperature ( ), and entropy production ( ). Multi-Criteria Decision Making (MCDM) is employed to provide a thorough assessment of the overall performance of the proposed designs. The results have been shown as graphical representations, streamlines and contours where Nusselt number, friction factor and entropy generation have been evaluated. The Nusselt number has a higher value for the oval cross-section, while it reaches its lowest value for the square cross-section. The highest heat transfer rate is got for Design 1 with the oval-shaped case. The friction factor for a circular cross-section HHTE is 48 % higher than the friction factor for a square cross-section profile. In addition, the square shape at a Reynolds number (Re) of 25000 exhibits 5 % less entropy formation compared to the oval shape geometry at a Reynolds number of 5000. The results of MCDM analysis indicate that Design 1, which features a square section, exhibits superior performance. Conversely, Design 2, which incorporates a circular cross-section, demonstrates poor performance. Among the six ternary hybrid nanofluids, the AlO+CNT+Graphene nanofluid with a water basis exhibits the greatest Nusselt number.
螺旋管换热器（HTHE）在各种热工应用中通常用作热设备。开展了一项对比研究，以考察几种螺旋管设计在水和纳米流体方面的潜在用途。此外，在螺旋式换热器中采用三元混合纳米流体（THNF）流动来评估传热和摩擦损失是一个独特的概念，因为目前尚无针对这一特定应用的研究。本研究涉及分析三种不同的设计构型，每种构型有三种不同的入口轮廓：圆形、方形和椭圆形。因此，对九个案例进行了数值分析，每个案例的管道长度、螺旋直径和螺距距离相同。水和THNF流动条件下雷诺数的指定范围为5000 - 25000。针对两种流体获取了结果，考虑了努塞尔数（）、摩擦系数（）、出口温度（ ）和熵产（ ）。采用多准则决策（MCDM）对所提出设计的整体性能进行全面评估。结果以图形表示、流线和等高线的形式呈现，其中对努塞尔数、摩擦系数和熵产生进行了评估。椭圆形横截面的努塞尔数较高，而方形横截面的努塞尔数最低。设计1的椭圆形案例具有最高的传热速率。圆形横截面HHTE的摩擦系数比方形横截面轮廓的摩擦系数高48%。此外，在雷诺数（Re）为25000时，方形形状的熵形成比雷诺数为5000时的椭圆形形状几何结构少5%。MCDM分析结果表明，具有方形截面的设计1表现出卓越的性能。相反，采用圆形横截面的设计2表现不佳。在六种三元混合纳米流体中，水基的AlO + CNT + 石墨烯纳米流体的努塞尔数最大。
