Experimental study on convection heat transfer of nanocolloidal dispersion in a turbulent flow

Abstract

This paper reports measurements of the convective heat transfer of nanocolloidal dispersion in a turbulent flow. The convective heat transfer coefficient of the sample SiO2-water colloids with two different particle sizes of 7 nm and 40 nm flow inside a tube was measured. There is no anomalous enhancement on thermal conductivity but an anomalous size effect on viscosity of the sample nanocolloidal dispersion. The experimental result shows that the convective heat transfer coefficient of the dispersion increases with the flow velocity but decrease with the volume fraction and size of nanoparticles. For heat transfer coefficient at 3% volume fraction of nanoparticles, there is a 33% decrease compared with the base fluid. The experimental result of Nusselt number is very close to the theory value of Dittus-Boelter correlation. The effect of viscosity and interaction of particle-liquid and particle-particle are considered to play an important role in the heat transfer of nanocolloidal dispersion.