Entropy generation analysis of turbulent boundary layer flow in different curved diffusers in air-conditioning systems
Department of Mechanical Engineering, Hakim Sabzevari University, Sabzevar, Iran
Accepted: 18 June 2020
Published online: 30 June 2020
Since the ducts are important parts of the engineering facilities and entropy generation decreases the performance of such facilities, it is necessary to study the amount of entropy generation in these geometries in order to reach to maximum efficiency. In addition, the study of turbulent boundary layer flow in curved diffuser has significant importance. Therefore, the current work investigates the effects of curvature and adverse pressure gradient parameter on efficiency and entropy generation due to turbulent and viscosity dissipations in three curved diffusers with curvature ratios of 0.0113, 0.0161 and 0.023 for different adverse pressure gradient parameters of 0.48, 0.56, 0.62, 0.86 and 0.994. Results show that in order to design the curved diffusers to reach the maximum efficiency and minimum total entropy generation in air-conditioning systems, the lowest value of adverse pressure gradient parameter and the highest value of curvature radius should be considered, respectively. The total entropy generation on concave and convex walls decreases with increasing the adverse pressure gradient parameter, while by increasing the curvature radius, it decreases on convex wall and increases on concave wall. Moreover, the rate of increasing the total entropy on convex wall is more than concave wall at constant adverse pressure gradient parameter. Finally, it was found that with decreasing the adverse pressure gradient parameter and increasing the curvature radius, the efficiency increases.
© Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2020