Thermal Conductivity of Nanofluids

Enhanced thermal conductivity of nanofluids compared to that of the base fluid has received attention of many researchers in the last one decade. Experimental data on thermal conductivity of nanofluids using varied nanoparticles in the size range 10-100 nm have been reported. However, there is lot of variance in the data and needs critical analysis. Many models have been proposed by various research groups for predicting the thermal conductivity of nanofluids. Due to complexity of various parameters involved (size, % volume fraction, specific surface area and the type of nano particles, pH of nano fluid, thermal conductivity and viscosity of base fluid) no single model can be used for predicting the thermal conductivity of nanofluids. Inconsistent and conflicting results are reported on the enhanced thermal conductivity of nanofluids. Further, insufficient understanding and inconclusive mechanism behind enhanced thermal conductivity requires further attempt to work in this field. This article critically reviews the available literature on thermal conductivity of nanofluids.