Effective Thermal Conductivity and Viscosity of Nanofluids

This paper presents a model to determine the effective thermal conductivity (ETC) of nanofluids. The model was developed by considering the geometrical structure of dispersed nanoparticles in base fluids. For the experimental investigation, nanofluids were prepared by suspending aluminum oxide (Φ80 nm) and titanium oxide (Φ15 nm and Φ10×40 nm) nanoparticles in deionized (DI) water and taken through longtime (8–10 hours) sonication for proper mixture of nanoparticles. Cetyltrimethylammoniumbromide (CTAB) surfactant was used to ensure better stability and dispersion of nanoparticles in the base fluids. The thermal conductivity and viscosity of the nanofluids were measured and compared with the predictions by various models. The present model gives better prediction of the effective thermal conductivity of nanofluids compared to existing models.