Abstract

The effects of using copper oxide-thermal oil on convective heat transfer and pressure drop in a downward flow in an inclined microfin tube are investigated experimentally in this research project. The flow regime and wall temperature are laminar and constant, respectively. The effects of nanofluid, Graetz number, Prandtl number, negative and positive inclination angles, on convective heat transfer augment moderately as nanoparticles mass concentration increases. Correlations are advisable to anticipate Nusselt number and Darcy friction factor in upward and downward single-phase flow in microfin tube under constant wall temperature and laminar flow in inclined plain and finned tubes. The maximum aberration is lower than 21% which is acceptable to predict experimental data. In this paper, we found that the heat ratio matches the pumping ratio. It turns out that, if the increment of pressure drop is more than heat transfer enhancement, it will not be appropriate to use CuO-thermal oil, negative inclination angles and microfin tube. The maximum FOM was 64%, which, was calculated with 1.5% nanoparticles mass concentration and inclination angle 60º at Prandtl number 349 in microfin tube.

Keywords: Nanofluid; Pressure drop; Convective heat transfer; Upward and downward flow; Friction factor; Laminar flow