Investigation of the thermophysical properties of ethylene glycol based nanofluids containing decorated carbon nanotubes with silver and copper nanoparticles by passing time

In this study, functionalized carbon nanotubes decorated with silver and copper nanoparticles (fCNTs-Ag, fCNTs-Cu) with mass ratios of 2% and 4% have been used to prepare ethylene glycol (EG) based nanofluids with different concentrations (0.1, 0.25 and 0.5 wt.%). The main goal of this research is the investigation of the effect of passing time on the thermal conductivity and stability of EG-based nanofluids. The thermal conductivity of samples was measured by a Decagon KD2 Pro thermal analyzer device for 90 days. The results showed that in all samples, the thermal conductivity of nanofluids was increased with increasing the concentration of nanoadditives. In addition, it was surprisingly observed that the thermal conductivity of samples was exponentially increased by passing time. The stability of the samples was investigated using UV-vis spectroscopy for 60 days. It was observed that the stability of nanofluids containing fCNTs-Cu is higher than the stability of nanofluids containing fCNTs-Ag.