Cabaleiro David, Hamze Samah, Fal Jacek, Marcos Marco A, Estellé Patrice, Żyła Gaweł
Departamento de Física Aplicada, Facultade de Ciencias, Universidade de Vigo, 36310 Vigo, Spain.
Laboratoire de Génie Civil et Génie Mécanique, LGCGM, Université Rennes, 35000 Rennes, France.
Nanomaterials (Basel). 2020 Jun 15;10(6):1168. doi: 10.3390/nano10061168.
This paper presents the preparation and thermal/physical characterization of phase change materials (PCMs) based on poly(ethylene glycol) 400 g·mol and nano-enhanced by either carbon black (CB), a raw graphite/diamond nanomixture (G/D-r), a purified graphite/diamond nanomixture (G/D-p) or nano-Diamond nanopowders with purity grades of 87% or 97% (nD87 and nD97, respectively). Differential scanning calorimetry and oscillatory rheology experiments were used to provide an insight into the thermal and mechanical changes taking place during solid-liquid phase transitions of the carbon-based suspensions. PEG400-based samples loaded with 1.0 wt.% of raw graphite/diamond nanomixture (G/D-r) exhibited the lowest sub-cooling effect (with a reduction of ~2 K regarding neat PEG400). The influences that the type of carbon-based nanoadditive and nanoparticle loading (0.50 and 1.0 wt.%) have on dynamic viscosity, thermal conductivity, density and surface tension were also investigated in the temperature range from 288 to 318 K. Non-linear rheological experiments showed that all dispersions exhibited a non-Newtonian pseudo-plastic behavior, which was more noticeable in the case of carbon black nanofluids at low shear rates. The highest enhancements in thermal conductivity were observed for graphite/diamond nanomixtures (3.3-3.6%), while nano-diamond suspensions showed the largest modifications in density (0.64-0.66%). Reductions in surface tension were measured for the two nano-diamond nanopowders (nD87 and nD97), while slight increases (within experimental uncertainties) were observed for dispersions prepared using the other three carbon-based nanopowders. Finally, a good agreement was observed between the experimental surface tension measurements performed using a Du Noüy ring tensiometer and a drop-shape analyzer.
本文介绍了基于聚乙二醇400 g·mol且通过炭黑（CB）、原始石墨/金刚石纳米混合物（G/D-r）、纯化石墨/金刚石纳米混合物（G/D-p）或纯度分别为87%和97%的纳米金刚石粉末（分别为nD87和nD97）进行纳米增强的相变材料（PCM）的制备及其热/物理特性表征。采用差示扫描量热法和振荡流变学实验来深入了解碳基悬浮液固-液相转变过程中发生的热和机械变化。负载1.0 wt.%原始石墨/金刚石纳米混合物（G/D-r）的基于PEG400的样品表现出最低的过冷效应（相对于纯PEG400，过冷度降低了约2 K）。还研究了碳基纳米添加剂类型和纳米颗粒负载量（0.50和1.0 wt.%）在288至318 K温度范围内对动态粘度、热导率、密度和表面张力的影响。非线性流变学实验表明，所有分散体均表现出非牛顿假塑性行为，在低剪切速率下炭黑纳米流体的这种行为更为明显。石墨/金刚石纳米混合物的热导率增强最高（3.3 - 3.6%），而纳米金刚石悬浮液的密度变化最大（0.64 - 0.66%）。两种纳米金刚石粉末（nD87和nD97）的表面张力降低，而使用其他三种碳基纳米粉末制备的分散体表面张力略有增加（在实验不确定度范围内）。最后，使用杜诺伊环张力计和滴形分析仪进行的实验表面张力测量结果之间观察到了良好的一致性。
