Nanofluids, which are suspensions of nano-sized solid particles in a liquid medium, show remarkable enhancement in thermal conductivity compared to the base fluid. Nanofluids are a promising candidate for advanced heat transfer applications such as microelectronics cooling. While the thermal conductivity of nanofluids has been measured in the past using conventional techniques such as the transient hot wire method, this work presents the application of the 3-omega (3-ω) method for this purpose. The theoretical model for 3-ω response of a heater device with de-ionized (DI) water is verified by comparing with experimental measurements. Following this validation, the effective thermal conductivity of Al2O3 nanofluids in DI water and ethylene glycol are measured. The measured values are found to be in good agreement with previous works. In addition, interesting effects in the thermal response due to agglomeration and sedimentation of nanoparticles are observed.
RETRACTED: Cross- and in-plane thermal conductivity of AlN thin films measured using differential 3-omega method