Nanofluids based on vegetal oil with different wt.% of carbon nanotubes (CNT), hexagonal boron nitride (h-BN), and its hybrid (h-BN@CNT) were produced to investigate the effects of these nano-additives on the thermal conductivity and rheological properties of nanofluids. Stable suspensions of these oil/nanostructures were produced without the use of stabilizing agents. The dispersed nanostructures were investigated by SEM, EDS, XRD, and XPS, while the thermal conductivity and rheological characteristics were studied by a transient hot-wire method and steady-state flow tests, respectively. Increases in thermal conductivity of up to 39% were observed for fluids produced with 0.5 wt.% of the hybrid nanomaterials. As for the rheological properties, it was verified that both the base fluid and the h-BN suspensions exhibited Newtonian behavior, while the presence of CNT modified this tendency. This change in behavior is attributed to the hydrophobic character of both CNT and the base oil, while h-BN nanostructures have lip-lip “bonds”, giving it a partial ionic character. However, the combination of these nanostructures was fundamental for the synergistic effect on the increase of thermal conductivity with respect to their counterparts.
Ribeiro, Hélio, Jose Jaime Taha-Tijerina, Ofelia Gomez, Ever Acosta, Gabriel M. Pinto, Lorena R. C. Moraes, Guilhermino J. M. Fechine, Ricardo J. E. Andrade, Jefferson Reinoza, Victoria Padilla, and et al. 2023. "Thermal Transport and Rheological Properties of Hybrid Nanofluids Based on Vegetable Lubricants" Nanomaterials 13, no. 20: 2739. https://doi.org/10.3390/nano13202739
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