Optimizing Heat Transfer Performance of Solar Air Heaters: Influence of Hexagonal Inline and Staggered Ribs with Different Blockage Ratios in Trapezoidal Ducts

Demand for energy supply is growing daily; dependency on fossil fuels is unreliable as the fossil fuels become depleted. Sustainable energy is the leading energy source for meeting global demands. Solar air heaters are one of the uses of sustainable energy. This experimental study examined the THP of a solar air heater that uses a hexagonal rib on the plate that absorbs. This study examines the effects of rib height ratio (e/Dh = 0.1109, 0.1479, and 0.1849), rib pitch (P = 60 mm, 80 mm, and 100 mm), and attack angle (α = 90° and 120°) on the transmission of heat enhancement within a trapezoidal duct for the Re of 5000-30000. To enhance the plate area and interplay of heat, trapezoidal ducts were selected. The experimental work shows that the Reynolds number leads the Nusselt number to rise for different blockage ratios. For 120° staggered ribs, with the ultimate blockage ratio, e/Dh=0.1849 performs better than all other ribs. The maximum heat transfer is higher by as much as 56% over a smooth duct, but there is more friction. The 120° rib orientation, particularly in staggered configurations, outperformed the 90° orientation. With the lowest Reynolds number, the 120° staggered rib exhibits a maximum thermal performance of 1.92, which is 29.7 percent better than the similar 90° orientation's 1.48. More thermal performance with controllable pressure losses is possible with a greater blockage ratio and a high angle of attack. In general, the absorber with hexagonal ribs improves thermal efficiency, which is a great and affordable way to make solar air heaters work better.