Bakthavatchalam Balaji, Habib Khairul, Saidur R, Shahabuddin Syed, Saha Bidyut Baran
Department of Mechanical Engineering, Universiti Teknologi PETRONAS, 32610 Bandar Seri Iskandar, Perak Darul Ridzuan, Malaysia.
Nanotechnology. 2020 Mar 20;31(23):235402. doi: 10.1088/1361-6528/ab79ab. Epub 2020 Feb 25.
Multi-walled carbon nanotubes (MWCNTs) are a contemporary class of nanoparticles that have a prominent thermal, electrical and mechanical properties. There have been numerous studies on the enhancement of thermophysical properties of nanofluids. However, there is only limited research on thermal and stability analysis of MWCNT nanofluids with various kinds of solvents or base fluids, namely propylene glycol, ethanol, ethylene glycol, polyethylene glycol, methanol and water. This paper reports the enhancement of thermophysical properties and stability of MWCNTs with six different base fluids in the presence of sodium dodecyl benzene sulfonate surfactant with a mass concentration of 0.5 wt%. Thermal and dispersion stabilities were determined using a thermogravimetric analyzer (TGA) and Zeta potential, along with a visual inspection method to evaluate the agglomeration or sedimentation of MWCNT nanoparticles over a period of one month. Ultraviolet-visible spectroscopy and Fourier transform infrared spectroscopy were utilized to identify the molecular components and light absorption of the formulated nanofluids at their maximum wavenumber (4500 cm) and wavelength (800 nm). In addition, thermophysical properties such as thermal conductivity, specific heat capacity, viscosity and density with a peak temperature of 200 °C were also experimentally evaluated. The TGA results illustrated that MWCNT/ethylene glycol nanofluid achieved maximum thermal stability at 140 °C and it revealed a maximum zeta potential value of -61.8 mV. Thus, ethylene glycol solution was found to be the best base liquid to homogenize with MWCNTs for acquiring an enhanced thermophysical property and a long-term stability.
多壁碳纳米管（MWCNTs）是一类当代纳米颗粒，具有卓越的热、电和机械性能。关于纳米流体热物理性质增强的研究众多。然而，对于用各种溶剂或基础流体（即丙二醇、乙醇、乙二醇、聚乙二醇、甲醇和水）制备的MWCNT纳米流体的热稳定性和稳定性分析的研究却很有限。本文报道了在质量浓度为0.5 wt%的十二烷基苯磺酸钠表面活性剂存在下，MWCNTs与六种不同基础流体的热物理性质增强和稳定性。使用热重分析仪（TGA）和Zeta电位测定热稳定性和分散稳定性，并采用目视检查方法评估MWCNT纳米颗粒在一个月内的团聚或沉降情况。利用紫外可见光谱和傅里叶变换红外光谱来识别所配制纳米流体在其最大波数（4500 cm）和波长（800 nm）处的分子成分和光吸收。此外，还通过实验评估了热导率、比热容、粘度和密度等热物理性质，峰值温度为200°C。TGA结果表明，MWCNT/乙二醇纳米流体在140°C时达到最大热稳定性，其最大Zeta电位值为-61.8 mV。因此，发现乙二醇溶液是与MWCNTs均匀混合以获得增强热物理性质和长期稳定性的最佳基础液体。
