Thermal conductivity measurement and sedimentation detection of aluminum oxide nanofluids by using the 3ω method

Suspensions of nano-sized solid particles in a liquid medium, known as nanofluids 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 (3ω) method for this purpose. The theoretical model for 3ω response of a heater device with de-ionized (DI) water and ethylene glycol (EG) is verified by comparing with experimental measurements. Following this validation, the effective thermal conductivity of Al2O3 nanofluids in DI water and EG are measured at room temperature. In addition, interesting effects in the thermal response due to agglomeration and sedimentation of nanoparticles are observed.