Numerical simulation and irreversibility analysis of nanofluid flow within a solar absorber duct equipped with a novel turbulator

Abstract

This research presents an innovative alteration to the solar collector's design by integrating a 4-lobed tube with helical tape. The choice of a working fluid, a combination of water and alumina nanoparticles, is purposeful, aiming to reduce irreversibility. Extensive numerical simulations, along with thorough benchmark verification, meticulously assess the system's performance, demonstrating strong alignment with established benchmarks.This study delves into the interaction among pivotal parameters—D* (diameter ratio), Re (Reynolds number), and N (revolution number)—and their impact on essential performance metrics, encompassing ηII (second law performance), Xd (exergy drop), and Φx (exergy drop ratio). With the elevation of all three parameters, the intensified swirl flow facilitates improved heat absorption by the nanofluid, resulting in reduced entropy generation and subsequently, a decrease in exergy drop. More precisely, the increments in Re, N, and D* lead to significant reductions in the value of Xd, with approximately 52.1 %, 4.02 %, and 5.03 %, respectively. When N = 4, D*=0.02, the amount of ηII for Re = 2e4 is 8.38 times greater than that of Re = 4e3. Increasing D* and N leads to substantial improvements in ηII, with approximately 50.02 % and 30.15 % enhancements, respectively. The highest ηII, reaching 0.582, is attained when D*=0.048, N = 7, and Re = 2e4.

Keywords

• Helical tape
• Irreversibility
• Nanofluid flow
• Thermal efficiency
• Solar irradiation
• Finite volume method