Possible explanations of the deviations in the thermal conductivity measurements

K. Han, M. Lee, J. Koo, M.A. Kedzierski
Kyung Hee University, KR

Keywords: nanofluids


Nanofluids were invented to enhance thermal conductivity of the working fluid near the wall region, where the conduction is the only mechanism to dissipate heat and it limits the heat transfer rate from a body to fluid. Many research groups have reported thermal conductivity measurements of homemade nanofluids, although there were large deviations between them, without investigating the causes. This presentation explains the apparent deviations between measurement results in terms of the fundamental non-equilibrium nature of nanofluids. Recently, Hong et al. [1] and Han et al. [2] performed critical studies on the transient hot-wire method, which has been commonly used by many research groups due to its simplicity and short response time. They reported that the proper selection of the temperature history range is crucial to avoid the impact of natural convection on the thermal conductivity estimation, and the temperature dependence of nanofluid thermal conductivity enhancement observed by other research groups might be misleading due to the failure to prevent it.