Manivannan P. V.

The present article describes the generation of copper nanoparticles in the base fluid using developed micro-electrical discharge machining (micro-EDM) process. Micro-EDM was performed with various operating parameters such as voltage, current, pulse width and duty factor. To prevent agglomeration and coagulation of nanoparticles, polyvinyl alcohol (PVA) and polyethylene glycol (PEG) are used as stabilizers. The characterization of the generated copper nanofluid is done by energy dispersive analysis by X-rays, selected area electron diffraction pattern and transmission electron microscope followed by the study of thermal conductivity and viscosity of nanofluid using KD-2 pro device and falling ball type viscometer. The viscosity measurement enables to determine the dispersion stability of copper nanofluids. The experimental results show that the mean size of generated spherical copper nanoparticles is found to be less than 10 nm. It was observed that the thermal conductivity of copper-de-ionized (DI) water, copper-DI water with PVA and PEG nanofluids are 6%, 14% and 15% are higher than that of pure DI water. Also, it was found that there is a reduction of 96% and 99.9% in the sedimentation velocity of copper nanoparticles in copper-DI water with PVA and PEG nanofluid when compared to copper-DI water nanofluid resulting in excellent dispersion stability of the nanoparticles in copper-DI water with PEG nanofluid rather than PVA nanofluid. © 2014 Taylor & Francis Group, LLC.

Nanoparticles show a practical way of exhibiting enhanced size-dependent properties compared to extremely fine or larger particles of the same material. Nanofluids consist of nanoparticles dispersed in base fluid and are usually used for enhancing thermal conductivity in various systems. This study investigates the dispersion stability and thermal conductivity of copper based nanofluids obtained by generating copper nanoparticles using micro electrical discharge machining (micro-EDM) process in both, de-ionized (DI) water and de-ionized water with polyethylene glycol (PEG) stabilizing agent. Micro-EDM was performed with various operating parameters such as the voltage, current, pulse width and duty factor. The generated nanoparticles in the base fluid were examined by energy dispersive analysis by X-rays (EDAX) and transmission electron microscope (TEM) to evaluate their chemical nature, size and morphology. The size distributions of the copper particles in PEG-based nanofluid were determined resulting in average particle size of around 6 nm. The experimental results show that the dispersion stability of PEG- based copper nanofluid as compared to DI water-based copper nanofluid is improved as discussed in the following sections of the paper. It was also found that the thermal conductivity of copper-water nanofluid and copper-water with PEG nanofluid are higher than that of pure DI water. © 2013 The Authors. Published by Elsevier Ltd.