Stability and thermal conductivity enhancement of aqueous nanofluid based on surfactant-modified TiO₂

Abstract

The surface modified-titania (TiO₂) nanoparticles were prepared by hydrothermal treatment by two kinds of surfactants, CTAB and SDS. The produced nanoparticles were characterized by XRD, FESEM/EDS, TEM and FTIR analysis techniques. The surfactant modified-TiO₂ nanoparticles were dispersed into distilled water to achieve good dispersion stability and enhanced thermal conductivity. The stability of distilled water based nanofluid was checked by sediment photograph capturing. The nanofluid including modified TiO₂ nanofluid with a volume fraction of 1.25% stayed up to two weeks without apparent sedimentation contrary to the unmodified TiO₂ nanofluid. The UV-Vis spectral results revealed that the decrease in the concentration rate was only about 12% and 20% in case of CTAB treated-TiO₂ and for SDS treated-TiO₂, respectively. The results obtained from the Laser diffraction particle size analysis showed the existence of thermodynamically stable clusters. The nanofluids made with CTAB-treated and SDS-treated nanoparticles with volume fraction of 1.25% indicated an improvement in thermal conductivity as 15% and 10%, respectively. The transient thermal conductivity measurement allowed monitoring the stability behavior of the nanofluid.

GRAPHICAL ABSTRACT

Keywords:

• Heat transfer
• nanofluid
• stability
• surface modification
• thermal conductivity
• TiO₂

Acknowledgements

This study is a part of the RafriBat project financially supported by the PARS grant from the Hassan II Academy of Science and Technology, Morocco. M. Ouikhalfan thankfully acknowledges the Scientific and Technological Research Council of Turkey (TUBITAK) for the ‘2216 Research Fellowship Program for International Researchers and providing financial support. Dr. Ahmet SARI would also thank Karadeniz technical Univesrity and King Fahd University of Petroleum and Minerals due to their some analysis feasibilities.

Conflicts of interest

No potential conflict of interest was reported by the authors.