A Theoretical Investigation on Thermal Entrance Region Heat Transfer in a Conduit Filled with Nanofluids

A theoretical analysis has been made to explore thermal entrance region heat transfer in nanofluids. The numerical model used in this paper is based on the Buongiorno model for convective heat transfer in nanofluids with modifications to fully account for the effects of nanoparticles volume fraction distributions on the continuity, momentum and energy equations. Numerical investigations have been conducted for developing laminar forced convection flows in a circular tube subject to a uniform wall heat flux. From the results, it has been concluded that, for certain cases of aluminawater nanofluids and titania-water nanofluids, in most entrance region, anomalous heat transfer enhancement (that exceeding the rate expected from the increase in thermal conductivity) is possible, whereas, close to the edge of the entrance, no anomalous heat transfer enhancement is observed.