Experimental Studies and Analytical Analysis of Thermophysical Properties of Ethylene Glycol–Water-Based Nanofluids Dispersed with Multi-walled Carbon Nanotubes

The present study investigates the thermal conductivity and dynamic viscosity of ethylene glycol–water solutions dispersed with oxidized multi-walled carbon nanotubes. The physico-thermal properties and Mouromtseff number (Mo) were used to evaluate the heat transfer properties of the nanofluids. Ethylene glycol–water mixtures were chosen as base fluids, and the volume fraction of ethylene glycol varied from 100 % to 0 % (pure water). Oxidized multi-walled carbon nanotubes in weight percentages of 0.0625, 0.125, 0.25, and 0.5 were dispersed in ethylene glycol–water mixtures to achieve the best stability. The stability of the nanofluids was monitored by UV–Vis spectroscopy for 2 months. The dispersion of multi-walled carbon nanotubes in the base fluids resulted in a significant improvement in thermal conductivity. To derive correlations for thermal conductivity and dynamic viscosity, 1 500 data points were collected for all possible combinations of temperature, weight percent of multi-walled carbon nanotubes, and ethylene glycol content. The Mouromtseff number (Mo) showed that dilute nanofluids at low concentrations are the most effective heat transfer medium in turbulent flow.