Abstract

We report the method of tuning the thermal conductivity through the composition of multiwall carbon nanotube (MWCNT) dispersed ethylene glycol based nanofluids. The structure and properties of the MWCNTs were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy and thermogravimetric analysis. A parallel plate thermal conductivity (PPTC) set up was fabricated and used for measurement of thermal conductivity of the nanofluids. We have prepared ethylene glycol based nanofluids containing 0.05, 0.1, 0.15, 0.20, 0.25 and 0.35 wt% of MWCNTs. The thermal conductivities of these fluids were measured by keeping them between the two (parallel) plates, referred as the hot and the cold plates, of the sample holder in the PPTC apparatus. The lower plate was water-cooled and the upper plate was heated. The temperature of the hot plate was varied between 35 and 80 °C. The thermal conductivity of the fluids was calculated using the one-dimensional heat conduction equation. According to our observation, an efficient heat transfer occurs through the nanofluids with an optimum concentration of 0.20 wt% of CNTs. Our work demonstrates the importance of the composition of the nanofluids and their structural defects in heat transfer.

Graphic Abstract

中文翻译：

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组合物在增强碳纳米管-乙二醇基纳米流体传热行为中的作用

摘要

我们报告了通过多壁碳纳米管（MWCNT）分散的乙二醇基纳米流体的组成来调节热导率的方法。通过扫描电子显微镜，透射电子显微镜，X射线衍射，拉曼光谱和热重分析对MWCNT的结构和性能进行了表征。制备了平行板热导率（PPTC）装置，并将其用于测量纳米流体的热导率。我们已经制备了包含0.05、0.1、0.15、0.20、0.25和0.35重量％的MWCNT的基于乙二醇的纳米流体。通过将这些流体保持在PPTC设备中样品架的两个（平行）板（称为热板和冷板）之间来测量它们的热导率。将下板水冷，并将上板加热。热板的温度在35至80°C之间变化。使用一维热传导方程计算流体的热导率。根据我们的观察，通过纳米流体的有效传热发生在CNT的最佳浓度为0.20 wt％的位置。我们的工作证明了纳米流体的组成及其在传热中的结构缺陷的重要性。

图形摘要