Enhancing Solar Air Heater Heat Transfer Performance: The Impact of Hexagonal 90° and 120° Inline Ribs with Varying Blockage Ratios in Trapezoidal Ducts
Abstract
An experimental investigation was carried out to evaluate the thermo-hydraulic performance of a solar air heater (SAH) equipped with a hexagonal ribbed absorber plate. The study examines the effects of geometric parameters—blockage ratio (e/Dh = 0.1109, 0.1479, and 0.1849), rib pitch (P = 60 mm, 80 mm, and 100 mm), and angle RIDWWDFNĮ DQGRQKHDWWUDQVIHUDQGIORZG\QDPLFV within a trapezoidal duct, over a Reynolds number range of 5000 to 30,000. Trapezoidal ducts were selected for their ability to enhance surface area and flow interaction. For Reynolds numbers ranging from 5000 to 30,000, the Nusselt number for Į LQOLQHULEVLQFUHDVHGE\–ZKLOHWKHĮ inline ribs exhibited a higher enhancement of 40–60%. This improvement in heat transfer was accompanied by an increase LQIORZUHVLVWDQFH7KHIULFWLRQIDFWRUIRUĮ ULEVZDV about 1.5–WLPHVKLJKHUWKDQWKHVPRRWKGXFWZKHUHDVIRUĮ ULEVLWLQFUHDVHGE\QHDUO\–3.0 times. Considering both parameters, the thermo-hydraulic performance factor 73)ZDVIRXQGWREHVXSHULRUIRUWKHĮ FRQILJXUDWLRQ UDQJLQJIURPWRFRPSDUHGWRWRIRUWKHĮ FDVH7KLVVXJJHVWVWKDWKLJKHUDQJOHVDQGEORFNDJHUDWLRV enhance turbulence and mixing, improving heat transfer with manageable pressure losses. Overall, the hexagonal ribbed absorber significantly improves thermal efficiency, offering a promising and cost-effective solution for enhancing solar air heater performance while supporting energy efficiency and environmental sustainability.
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