Abstract
The work is focused on the estimation of convective heat transfer and friction factor of vacuum pump oil/Fe3O4 magnetic nanofluids flow in a tube under laminar flow at high Prandtl numbers experimentally. The thermophysical properties also studied experimentally at different particle concentrations and temperatures. The Fe3O4 nanoparticles were synthesized using the chemical reaction method and characterized using X-ray powder diffraction (XRD) and vibrating sample magnetometer (VSM) techniques. The experiments were conducted at mass flow rate from 0.04 kg/s to 0.208 kg/s, volume concentration from 0.05% to 0.5%, Prandtl numbers from 440 to 2534 and Graetz numbers from 500 to 3000. The results reveal that, the thermal conductivity and viscosity enhancements are 9% and 1.75-times for 0.5 vol. % of nanofluid at a temperature of 60 degrees C, respectively, compared with base fluid data. The heat transfer enhancement is 13.1% and 17.8%, the Nusselt number enhancement is 8.95% and 13.48% for 0.5 vol. % of nanofluid at mass flow rates of 0.0416 kg/s and 0.208 kg/s, respectively, compared with base fluid data with a friction factor penalty of 1.21-times. The correlations of Nusselt number and friction factor were proposed based on the experimental data at high Prandtl numbers.