Numerical study on the forced convection heat transfer of nanofluids in micro-channels

The objective of this numerical study is to examine the three-dimensional heat transfer of laminar single-phase flow in 215 m wide and 821 m deep rectangular micro-channels. The FLUENT computational fluid dynamics software is used to conduct simulations with saturated pure water and various water-based nanofluids, including Al₂O₃, CuO, and TiO₂ nanoparticles. The accuracy of the previous correlations for nanofluid viscosity is assessed using the predicted friction factor data for those correlations in a comparison with experimental friction factor data. The computational model shows relatively good accuracy in capturing the heat transfer coefficient data measured for pure water and water-Al₂O₃ nanofluids. The local heat transfer coefficient increases as both the nanoparticle concentrations and total heat transfer rate increase, but it has a very weak dependence on the type of nanoparticle. The reason for this trend is the higher thermal conductivity that yields a higher heat transfer coefficient, especially for laminar flow. The uneven distribution of the local heat transfer rate caused by the axial heat conduction inside the solid block is observed along the micro-channel.