A study on high temperature thermal conductivity measurement of nanofluid using 2-phase model

The effective thermal conductivity of 2-phase material such as un-bonded silica sands saturated with a nanofluid was measured at high temperature using the transient thermal probe method. The nanofluid used in this study was the water based mixture of 0.1vol% Al2O3 nanoparticles of 47nm. The convection problem of fluid was prevented with this measurement method because fluid was confined within the very small pore spaces. From the prediction model for un-bonded sands, the thermal conductivities of the saturating nanofluid at high temperatures could be determined with the measured effective thermal conductivities of 2-phase material. As a results, increase in the thermal conductivity ratios of the nanofluid to pure water when temperatures were varied from 30 .deg. C to 80 .deg. C were within the range of 4.87∼5.48%.