Abstract:
This study investigates the influence of eight distinct surfactants on the
stability, rheological characteristics, and thermophysical properties of
hybrid nanofluids (NFs) containing Aluminum oxide (Al2O3) and
Titanium dioxide (TiO2) in a Water-Ethylene Glycol (EG) mixture
(60:40). The objective and novelty of this research is to choose the best
surfactant for long run applications in terms of stability, viscosity, and
thermal conductivity. The results reveal that polyvinylpyrrolidone
(PVP) exhibited the highest stability among all surfactants, surpassing
others in zeta potential and visual stability over 60 days. Additionally,
all the nanofluids exhibited Newtonian behavior. Surfactant addition
increased viscosity, with polyethylene glycol (PEG) showing the highest
enhancement of 37.2% at 30°C. Thermal conductivity increased with
temperature, maximum TC enhancement of 8.3% at 80°C was given by
PEG and oleic acid (OA), but these surfactants were unstable to be used
in any application. In conclusion, PVP emerged as the most suitable
surfactant for Al2O3-TiO2 hybrid nanofluids due to its exceptional
stability, moderate viscosity, and TC enhancement. It enhanced the TC
xvi by 3.6% at 80℃ and contributed 28.9% in viscosity increment at 30℃.
This research contributes to the understanding of surfactant effects on
nanofluid properties, particularly highlighting PVP's potential for long term heat transfer applications.
