Hybrid nanofluid based on CuO nanoparticles and single-walled Carbon nanotubes: Optimization, thermal, and electrical properties

The purpose of this study is to use the thermal and electrical conductivities of copper oxide nanoparticles and carbon nanotubes for the preparation of high-performance nanofluids for achieving better heat transfer properties. These nanofluids consist of a water/Ethylene Glycol solution containing single-wall carbon nanotubes (SWCNTs) and copper oxide nanoparticles (CuONPs). The effects of such independent variables as CuONPs and SWCNT concentrations, Ethylene Glycol ratio and solution pH were optimized to enhance the Thermal conductivity by the response surface method. The experimental results revealed that adding small amounts of nanoparticles to water/Ethylene Glycol mixtures would improve the thermal and electrical conductivity of nanofluids. The morphology of the nanoparticles was investigated by Scanning and Transmission Electron Microscopy (SEM and TEM) and Energy-Dispersive X-ray Spectroscopy (EDS). For the first time, the electrical conductivity of nanofluids was investigated by electrical impedance spectroscopy. The combined effects of both nanoparticles and nanotubes on thermal and electrical properties of the base fluid were compared to the influence of each on the same base fluid. The electrical and thermal conductivities could be enhanced by 18000 % and 157 % by addition of 0.41 % wt of SWCNT and 1.15 % wt of CuONPs to a 44:56 Ethylene Glycol-water mixture.