Strong enhancement in thermal conductivity of ethylene glycol-based nanofluids by amorphous and crystalline Al2O3 nanoparticles

Abstract

In the present work, the temperature and concentration dependence of thermal conductivity (TC) enhancement in ethylene glycol (EG)-based amorphous and crystalline Al2O3 nanofluids have been investigated at temperatures ranging from 0 to 100 °C. In our prior study, nanometer-sized particles of amorphous-, γ-, and α-Al2O3 were prepared via a simple sol-gel process with annealing at different temperatures and characterized by various techniques. Building upon the earlier study, we probe here the crystallinity, microstructure, and morphology of the obtained α-Al2O3 nanoparticles (NPs) by using X-ray powder diffraction with Rietveld full-profile refinement, scanning electron microscopy, and high-resolution transmission electron microscopy, respectively. In this study, we achieved a 74% enhancement in TC at higher temperature (100 °C) of base fluid EG by incorporating 1.0 vol. % of amorphous-Al2O3, whereas 52% and 37% enhancement is accomplished by adding γ- and α-Al2O3 NPs, respectively. The amorphous phase of NPs appears to have good TC enhancement in nanofluids as compared to crystalline Al2O3. In a nutshell, these results are demonstrating the potential consequences of Al2O3 NPs for applications of next-generation efficient energy transfer in nanofluids.

Multiphase TiO2nanostructures: a review of efficient synthesis, growth mechanism, probing capabilities, and applications in bio-safety and health

“…A thermal treatment (annealing or calcination) is normally needed to transform the gel into the nal required SMON. [97][98][99][100][101][102][103][104][105][106][107] The sol-gel processing of multiphase TiO 2 nanostructures is an interesting approach with a high level of control of the shape based on the controlled hydrolysis and condensation of the appropriate precursors. The sol-gel method is valuable for a high-throughput production of multiphase TiO 2 nanostructures and much work has been carried out to date on this process, mainly involving the grain nanostructures.…”

“…TiO 2 nanostructures have been widely explored owing to their extensive applications across a myriad of areas, particularly in photocatalysis, including those for the decomposition of organic/ inorganic dyes, 16,23,[36][37][38][39][40] hydrogen production from water, [41][42][43][44] removal of pollutants and plastics from the environment, [45][46][47][48] dye-sensitized solar cells, 49 sensors, 50 sunscreens, [51][52][53][54] paints, 55,56 rechargeable batteries, [57][58][59] supercapacitors, 60 food colouring, [61][62][63][64] environmental remediation and biomedical elds. 95,96 Over the past few decades, extensive research effort has been dedicated to the engineering of TiO 2 nanostructures synthesized via chemical routes, such as sol-gel, [97][98][99][100][101][102][103][104][105][106][107] hydrothermal, [108]…”

Moringa oleifera Leaf Extract-Mediated Green Synthesis of Nanostructured Alkaline Earth Oxide (MgO) and Its Physicochemical Properties

“…Metal oxides are widely employed as catalysts, optical devices, sensors, thermal conductivity enhancers, and energy conversion devices [1][2][3][4][5][6][7][8][9][10]. Engineered nanomaterials have unique properties which can be tailored with shape and size, and morphology leads to outstanding properties which are limited to bulk materials.…”

Simple One-Step Leaf Extract-Assisted Preparation of α-Fe2O3 Nanoparticles, Physicochemical Properties, and Its Sunlight-Driven Photocatalytic Activity on Methylene Blue Dye Degradation

“…Generally, metal oxides are widely employed as catalysts, optical devices, sensors, thermal conductivity enhancers, energy conversion devices, biomedical imaging, paints, optoelectronic devices, and nanodrug delivery [24][25][26][27][28][29][30][31][32][33][34]. Engineered nanomaterials have unique properties, and their shape, size, and morphology can be tailored leading to outstanding properties which are limited to bulk materials.…”