In tube convection heat transfer enhancement: SiO2 aqua based nanofluids.

In this paper, an experimental investigation is carried out on internal convective heat transfer of SiO 2 /water nanofluids in a copper tube for a fully turbulent regime. Nusselt number and convective heat transfer coefficients of nanofluid at three different volumetric concentration (0.001%, 0.003%, 0.007%) of nanoparticles were estimated. Local convective heat transfer coefficient at different locations along the tube at varying Reynolds number was also observed. With volumetric concentration of 0.001% of SiO 2 nanoparticles, maximum enhancement observed was 8–9%. Whereas at 0.007% volumetric concentration of SiO 2 nanoparticles, a 27% enhancement in convective heat transfer coefficient was observed. The decrease in the heat transfer rate was observed in axial direction. Particle migration, chaotic movement of the nanoparticles and fluctuations in the fluid and increased thermal conductivity of the nanofluid are considered the possible reasons for this enhancement. • Internal convective heat transfer of SiO 2 /water nanofluid • Heat transfer coefficient at 0.001, 0.003 and 0.007 vol% of nanoparticles • Local convective heat transfer at different locations along the tube • Average and local Nusselt number at different locations along the tube • 0.007% SiO 2 nanofluid shows almost 27% enhancement in heat transfer. [ABSTRACT FROM AUTHOR]