Flow and heat transfer performances of nanofluids inside small hydraulic diameter flat tube

An experimental system was built to study flow and convective heat transfer features of the nanofluid flowing in a small hydraulic diameter flat tube. The convective heat transfer coefficient and the friction factor of the sample Cu-water nanofluid were measured. The experimental results showed that the nanofluid has larger heat transfer coefficient than pure water under the same Reynolds number and showed that the heat transfer feature of the nanofluid increases with the volume fraction of nanoparticles. The friction factor of the sample nanofluid with the low volume fraction of nanoparticles was almost not changed compared with that of pure water.