Thermal conductivity and photothermal conversion performance of ethylene glycol-based nanofluids containing multiwalled carbon nanotubes

Abstract

In this study, the successful hydroxyl functionalization of carbon nanotubes (MWCNT-OH) was prepared by chemical treatments and characterized by Raman and FTIR spectra. MWCNT-OH was successfully dispersed into ethylene glycol (EG) with the Tween-80 surfactant by an ultrasonication method to prepare nanofluids. Thermal conductivity of nanofluid was investigated, and a maximum thermal conductivity enhancement about 24% at 50°C was obtained with nanofluid containing 0.64 vol.% MWCNT concentration. The photothermal conversion performance of nanofluid was also investigated by measuring the change of the temperature under lighting from a solar simulator. The measurement results showed that the highest photothermal conversion was obtained about 4.2% after a 30 min lighting with nanofluid containing 0.48 vol.% CNT concentration compared to ethylene glycol. These obtained results have propose a potential application of CNTs in nanofluids for solar absorption.