Enhancing solar heater performance: A comprehensive study on hybrid nanofluids and angled-rib turbulators for improved heat transfer and reduced irreversibility

Abstract

This research investigates the performance of hybrid nanofluids in solar heating systems, focusing on heat transfer effectiveness and thermodynamic irreversibility. Solar energy is widely favored for its eco-friendly nature, but traditional operating fluids in solar heaters lack sufficient thermal conductivity. To address this issue, modified fluids called nanofluids have been developed. This study proposes a novel approach that combines nanofluids and turbulators to evaluate solar system performance. ANSYS FLUENT 18.0 solver is employed, utilizing the iterative time advancement technique for solving the set of equations. Entropy generation analysis is employed as a promising methodology. Aluminum-oxide nanoparticles are examined for their impact on heat transfer, pressure drop, and entropy generation in a rib channel at Re= 20,000. To enhance heat transfer, the effects of angled-ribs are assessed using the thermal enhancement factor, which considers heat transfer rate and friction factor. Results indicate that triangular-shaped ribs exhibit superior thermal performance. Furthermore, the study investigates the influence of nanofluid volume fraction and heat flux distribution on Nusselt number, pressure drop, thermal performance factor, and entropy generation. Increasing the nanofluid fraction enhances the Nusselt number, pressure drop, and performance evaluation criterion (PEC). Based on the results of a quantitative analysis, it can be concluded that 4% nanoparticle volume fraction results in an increase of 4.6%, 11.63%, and 18.5% in Nusselt number in triangular and rectangular channels without teeth and with teeth, respectively. Additionally, a positive heat flux gradient improves heat transfer and reduces entropy generation, suggesting that adjusting the boundary condition can enhance energy and exergy efficiency. Overall, this study demonstrates the benefits of entropy generation analysis for assessing thermal systems and implementing hybrid nanofluids with turbulators in solar heating, contributing valuable insights to sustainable energy technologies.