An Experimental Study on Some Thermophysical Characteristics of CuO-Water Nanofluid

Abstract

This study presents the effects of the volume fraction of nanoparticles (0.15% ≤ Φ ≤ 0.74%) with ascorbic acid additive on some thermophysical characteristics of water based CuO nanofluids, such as thermal conductivity and viscosity, as well as agglomeration by analyzing microstructure, adhesion and precipitation time. The CuO nanofluids have been prepared and examined for five different volume fractions by using appropriate mixers. The microstructure of the samples, which are prepared with ascorbic acid additive in order to prevent the agglomeration of CuO nanoparticles and to ensure a homogeneous distribution, has been analyzed on the SEM images. In the adhesion experiments, an observational test was performed for 0.23% CuO-water sample. The samples prepared have been kept about 100 hours for observational examination of precipitation similar to the adhesion test. Thermal conductivity measurements have been conducted in a standard experimental set-up and a correlation equation has been proposed based on data acquired. The viscosity measurements have been carried out using a calibrated “falling-piston viscometer” and a correlation equation was also defined for thermal conductivity. The thermal conductivity measurements of the study have been compared to experiments given in the literature and a good agreement has been obtained at low volume fractions (less than 0.5%).