Experimental and numerical investigation on heat transfer and pressure drop of SiO2 and Al2O3 oil-based nanofluid characteristics through the different helical tubes under constant heat fluxes

In the present paper, a numerical and experimental study has been performed to investigate the heat transfer and pressure drop properties of Al2O3 and SiO2/Base oil nanofluid flow in a helical tube under constant heat fluxes. The nanofluids were prepared by using SN-300 base oil as a working fluid for 0.05%, 0.1%, 0.3%, and 0.5% mass concentrations. The experiments were carried out with two constant heat fluxes of 3950 W/m2 and 5280 W/m2 at 30, 40, 50, and 60 degrees C. The impact of various parameters, including flow Reynolds number, fluid temperature, two different nanoparticles, and various weight concentrations, on the heat transfer factor and pressure drop of the flow, are investigated. To examine the impact of different geometries on the heat transfer rate, simulations were conducted over four different helical tubes by changing the pitch circle diameter and steps. The results indicated that the heat transfer factor and pressure drop were increased by utilizing nanofluid instead of the base fluid. In addition, in the same mass concentration, the Al2O3 nanofluid increased the heat transfer coefficient more than the SiO2 nanofluid. The maximum heat transfer rate corresponds to 0.5% mass concentrations of Al2O3 and SiO2 nanofluids, which are 41.4% and 27.3% more than base oil, respectively. The helical tube compared to the straight tube increased heat transfer by 19.5%. Moreover, heat transfer was improved by 6% and 16.5%, respectively, by reducing helical pitch and pitch circle diameter.

Automated summary

In this study, the heat transfer and pressure drop properties of Al2O3 and SiO2/Base oil nanofluid flow in a helical tube were investigated numerically and experimentally. The impact of various parameters, including flow Reynolds number, fluid temperature, nanoparticles, and weight concentrations, on the heat transfer factor and pressure drop was analyzed. The results showed that nanofluid enhanced the heat transfer factor and pressure drop compared to the base fluid. The Al2O3 nanofluid exhibited higher heat transfer coefficient than the SiO2 nanofluid. The maximum heat transfer rate was achieved with 0.5% mass concentrations of Al2O3 and SiO2 nanofluids. The helical tube geometry improved heat transfer by 19.5%, and reducing helical pitch and pitch circle diameter further enhanced the heat transfer.