Convective heat transfer of titanium (IV) oxide nanofluids under turbulent flow condition

This study has experimentally investigated the flow behavior and convective heat transfer coefficient of TiO₂/distilled water nanofluids flowing inside a horizontal circular tube at turbulent regime under a uniform heat flux boundary condition. Anatase titanium (IV) oxide nanoparticles of average size approximately 21 nm dispersed into distilled water with volume fraction range from 0.1 to 0.5 vol.% were used as nanofluids. The observed nanofluids were assumed as time-independent non-Newtonian fluid with their specific values of power law index and consistency coefficient. A new correlation involving the microconvection and microdiffusion effects was proposed to predict Nusselt number. As nanofluid samples behave the non-Newtonian fluid, the drag reduction phenomenon should be theoretically exhibited in turbulent flow regime. This drag reduction phenomenon might be one of the important factors that was responsible on the improvement of heat transfer performance in nanofluids aside from the established heat transfer enhancement mechanisms.