Numerical study of laminar convective heat transfer from a corrugated pipe into an Al2O3–AlN/H2O hybrid nanofluid

Heat transfer in corrugated pipes carrying hybrid nanofluid is investigated. A saw-tooth corrugated pipe is considered. The nanofluid comprises of colloidal mixture of Aluminum Oxide and Aluminum Nitride nanoparticles, mixed as suspension in water. The heat transfer from the hot pipe surface (at 2000 W/m2) into the nanofluid is computed at different flow Reynolds numbers for laminar flow, at varying volumetric nanoparticle concentrations (1%–6%). The effects on the heat transfer and pumping power requirement with increasing Reynolds number and nanoparticle concentrations are studied. The effects of changing the corrugation configurations, such as the corrugation height and the placement eccentricity of the individual corrugation elements, on the heat transfer and pumping power are also examined. Results indicate that the pipe corrugations considerably enhance the heat transfer compared to the corresponding straight pipe case. With increasing Reynolds number and nanoparticle concentration, the heat transmission enhances, and the pumping power is correspondingly increased. The corrugation height and placement eccentricity significantly affect the heat transfer as well as the requirement of the pumping power. The average Nusselt number and pumping power both increase linearly with increasing corrugation height and the corrugation placement eccentricity.