| dc.description.abstract |
The numerical study assessed the heat transfer and pressure drop in an evenly heated square duct with plane and perforated ribs. Working fluid is air with Reynolds number (Re) 10,000-80,000. The pitch ratio (y), the dimensionless spacing between ribs relative to hydraulic diameter, is 0.5, 1.0, and 1.5. Rib inclination angles (θ) from the downstream duct wall range from 30° to 60°. The hole ratio (h) is 0.1 to 0.2, depending on perforation size and hydraulic diameter. In all configurations, the heat transfer improvement is maximum at Re = 10,000 and gradually decreases with rising Re. The thermal performance factors (η) for Re = 10,000 vary between 1.4 and 2.2, depending on configuration. The highest η is found at θ = 60°, y = 0.5, h = 0.2. At Re = 40,000, all configurations have η values over 1. The thermal performance for Re = 80,000 is moderate (η ≈ 1.03) for θ = 60°, y = 0.5, h = 0.2. Other configurations provide lower values that are barely over unity. |
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