Investigation on Copper Nanofluid Obtained through Micro Electrical Discharge Machining for Dispersion Stability and Thermal Conductivity

Abstract

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.