Improving heat transfer in parabolic trough collectors using hybrid nanofluids and concentric tube designs
摘要
This study aims to enhance the thermal performance of a parabolic trough collector (PTC) by integrating a concentric tube design, hybrid nanofluids, and optimized fin structures. The outer tube contains a hybrid nanofluid composed of Al2O3, CuO, and GO at 1% volumetric concentration in a 50:50 water–Syltherm 800 mixtures. The inner tube, on the other hand, employs pure water, Syltherm 800, or their 50:50 blends. Solar irradiation is simulated using Tonatiuh 2.2.4, with flow rates ranging from 0.15 to 0.6 kg s-1. Fins of various shapes are installed on the inner tube’s external surface to disrupt boundary layers and enhance turbulence. The study demonstrates that this configuration significantly increases outlet temperatures, reaching 435 K for the outer tube and 393 K for the inner tube at a flow rate of 0.15 kg s-1. It also achieves high thermal efficiencies of 78.32% and 70.23%, respectively. Optimized nanofluid selection and fin geometry reduce entropy generation by 25.43% in the outer tube and 12.22% in the inner tube, indicating decreased thermodynamic irreversibility and more uniform temperature distribution. These findings confirm that the combination of hybrid nanofluids, concentric tube configuration, and strategic fin placement substantially improves heat transfer, fluid dynamics, and overall PTC efficiency. They also provide valuable guidance for designing high-performance and sustainable solar thermal systems.