Effect of Dimpled Rib with Arc Pattern on Hydrothermal Characteristics of Al2O3-H2O Nanofluid Flow in a Square Duct

Abstract

The present work is concerned with the experimental analysis of the thermal and hydraulic performance of Al2O3−H2O nanofluid flow in dimpled rib with arc pattern in a square duct. The Alumina nanofluid consists of nanoparticles having a size of 30 nm. Reynolds number Renum studied in the square duct range from 5000 to 26,000. The nanoparticle volume fraction (ϕnp) ranges from 1.5% to 4.5%, the ratio of dimpled-arc-rib-height to print-diameter HAD/Pd ranges from 0.533 to 1.133, the ratio of the dimpled-rib-pitch to rib height PAD/HAD range from 3.71 to 6.71 and dimpled arc angle (αAD) range from 35° to 65°. The Al2O3−H2O-based nanofluid flow values of Nusselt number Nurs and friction factor frs are higher in comparison to pure water. The dimpled ribs in the arc pattern significantly improved the thermal-hydraulic performance of the investigated test section. The nanoparticle concentration of 4.5%, the ratio of dimpled arc rib height to print diameter of 0.933, the relative dimpled arc rib height of 4.64 and the dimpled arc angle of 55° deliver the maximum magnitude of the heat transfer rate. The maximum value of the thermal-hydraulic performance parameters was found to be 1.23 for Al2O3−H2O-based nanofluid flow in a dimpled rib with arc pattern square duct for the range of parameters investigated. Correlations of Nurs, frs and ηrs have been developed for the selected range of operating and geometric parameters.