ABSTRACT

Active and passive techniques have been utilized together to enhance heat transfer in this study. The ferronanofluid, magnetic field, and dimpled tube have not been utilized together in the literature so far. Regarding this issue, this investigation is the first experimental study to specify the effect of use of these three effects simultaneously. The concept of this study is to determine the thermo-hydraulic performance of Fe₃O₄/H₂O flow inside a dimpled tube under magnetic field effect. Constant and uniform heat flux of 4500 W/m² has been applied on the surface of the tube. The work aims to gain data in the range of laminar flow (1131≤ Re≤2102) in the dimpled tube. Dimple geometry with pitch ratio of P/d = 3.75, magnetic field (B = 0.03 ≤ T ≤ 0.16), and nanoparticle volume fraction of 1.0% are the base variables. The results showed that Nusselt number increases with increasing Reynolds number and magnetic field intensity. The highest increase in Nusselt number is obtained as 115.31% compared with the distilled water flow in the smooth tube for the case of magnetic field intensity of 0.3 T. The highest Performance Evaluation Criteria value is also determined as 1.44 for the case of ferronanofluid flow in dimpled tube at Re = 1131 in absence of magnetic field.

摘要

在这项研究中，主动和被动技术一起被用来增强传热。迄今为止，文献中尚未同时使用铁纳米流体、磁场和凹陷管。关于这个问题，本调查是第一个同时指定使用这三种效果的实验研究。本研究的概念是确定在磁场作用下凹陷管内Fe ₃ O ₄ /H _{2 O 流动的热工水力性能。}管表面施加了4500 W/m ²的恒定且均匀的热通量 。该工作旨在获得层流范围内的数据（1131≤Re≤2102) 在波纹管中。螺距比为P/d =  3.75、磁场 ( B =  0.03  ≤ T ≤  0.16) 和纳米粒子体积分数为 1.0 %的凹坑几何形状是基本变量。结果表明，努塞尔数随着雷诺数和磁场强度的增加而增加。在磁场强度为0.3 T的情况下，与光管中的蒸馏水流相比， 努塞尔数的最高增加为115.31 %。对于在没有磁场的情况下，Re =  1131的凹坑管中亚铁纳米流体流动的情况，最高性能评估标准值也确定为 1.44 。