Entropy generation analysis in a 180-degree return bend pipe using nanofluid

Abstract

Heat transfer and entropy generation analysis for 180-degree return bend has been carried out numerically using Al2O3-water nanofluid. The governing differential equations for mass, momentum and energy are solved in a staggered grid arrangement employing finite volume technique. A constant temperature boundary condition has been applied to the bend portion of the pipe. Reynolds number based on the hydraulic diameter of the duct and nanofluid volume fraction have varies from 200 to 1800 and 0 to 5%, respectively. Both the thermal and frictional entropy generations are quantified to access the total entropy generation. The frictional entropy generation is found to be lower than the thermal entropy generation. The ratio of the thermal and total entropy generation rates has been presented in term of Bejan number. Bejan number at low Reynolds number has been close to 1 due to the dominance of the thermal entropy generation.