FLOW AND CONVECTIVE HEAT TRANSFER CHARACTERISTICS OF NANOFLUIDS WITH VARIOUS SHAPES OF ALUMINA NANOPARTICLES

摘要

This paper is to investigate flow and convective heat transfer characteristics of nanofluids with various shapes of Al_2O_3 nanoparticles flowing through a uniformly heated circular tube under fully developed laminar flow regime. For the purpose, Al_2O_3 nanofluids of 0.3 Vol.% with sphere, rod, platelet, blade and brick shapes are manufactured by a two-step method. Zeta potential as well as TEM image is experimentally obtained to examine suspension and dispersion characteristics of Al_2O_3 nanofluids with various shapes. To investigate flow characteristics, the pressure drop of Al_2O_3 nanofluids with various shapes are measured. In order to investigate convective heat transfer characteristics, the effective thermal conductivities of Al_2O_3 nanofluids with various shapes, the temperature distribution at the tube surface and the mean temperature of nanofluids at the inlet are measured, respectively. Based on the experimental results, the convective heat transfer coefficient of Al_2O_3 nanofluids with various shapes is compared with that of pure water and the thermal conductivity of Al_2O_3 nanofluids with various shapes. Thus, the effect of nanoparticles shape on the flow and convective heat transfer characteristics flowing through a uniformly heated circular tube under fully developed laminar flow regime is experimentally investigated.