Abstract

In this research, the effect of magnetic nano-fluids (Fe₃O₄) on the heat transfer enhancement in a pipe with laminar flows (Re numbers of 171, 228 and 285) were examined. Different heats (15.75 and 20.6 W) were applied to an acrylic pipe to analyse the effect of magnetic nano-fluids for transferring the heat and reducing the wall temperature on a non-metal material pipe. Variations of nano-particles (volume percentage) were used in the nano-fluids solution: 2, 3 and 4%, respectively. The magnetic nano-fluids (Fe₃O₄) were prepared from 32.5 g of FeCl₃.6H₂O (ferric chloride) and 12.7 g of FeCl₂.4 H₂O (ferrous chloride) by using a co-precipitation method. The material characterisations using XRD and FE-SEM confirmed that Fe₃O₄ single phase occurred and shown that the average size diameters of the nano-particles are within a range of 20-40 nm. The experimental results suggested that the cooling capability can be enhanced by adding magnetic nano-particles controlled by permanent magnet and increasing the heat transfer in the magnetic nano-fluids system. The aggregation of the magnetic nano-particles following the magnetic field applied from the permanent magnet increases the convection heat transfer from the heating source to the nano-fluids, and thus reducing the wall temperature of the acrylic pipe.

中文翻译：

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磁性纳米流体（Fe 3 O 4）对层流管中传热增强的影响

摘要

在这项研究中，研究了磁性纳米流体（Fe ₃ O ₄）对层流管道（Re值为171、228和285）中传热增强的影响。将不同的热量（15.75和20.6 W）应用于丙烯酸管，以分析磁性纳米流体在非金属材料管上传递热量和降低壁温的效果。纳米流体溶液中使用的纳米颗粒（体积百分比）的变化分别为2％，3％和4％。由32.5 g FeCl ₃ .6H ₂ O（氯化铁）和12.7 g FeCl ₂ .4 H ₂制备磁性纳米流体（Fe ₃ O ₄）。O（氯化亚铁）采用共沉淀法。使用XRD和FE-SEM进行的材料表征证实了Fe ₃ O ₄单相的出现，并且表明纳米粒子的平均粒径在20-40nm的范围内。实验结果表明，可以通过添加永磁体控制的磁性纳米颗粒并增加磁性纳米流体系统中的热传递来增强冷却能力。磁性纳米粒子的聚集遵循从永磁体施加的磁场，从而增加了从加热源到纳米流体的对流传热，从而降低了丙烯酸管的壁温。