Three-Dimensional Numerical Study on Thermal-Hydraulic Performance of Twisted Mini-Channel Using Al2O3-H2O Nanofluid

Effects of design parameters of the twisted mini-channel, including twist pitch, width, height, and length, are investigated numerically at the Reynolds numbers between 300 and 1500. The Al2O3-H2O nanofluid is used as working fluid, and it is simulated using the mixture two-phase model. The volume fraction of Al2O3 nanoparticles is 1, 2, 3, and 4%. The results show that decreasing of twist pitch and channel length leads to higher values of the Nusselt number. As the Reynolds number is increased, the influence of these factors enhances. The increase of the channel width and height decreases the convective thermal resistance and thus improves the Nusselt number along with a certain penalty in the pressure drops. For all models, by increasing the volume fraction of nanoparticles, the convective thermal resistance is reduced leading to the thermal performance improvement. Finally, two correlations are proposed for the Nusselt number and friction factor, which are useful as a tool to predict the heat transfer and pressure drop characteristics of the twisted mini-channel.