NUMERICAL STUDY OF SOLAR AIR HEATER WITH NOVEL RIB ROUGHNESS

An air heater fueled by solar thermal energy can be made more efficient by incorporating rib roughness to its absorber surface. This alteration increases turbulence and surface area, which enhances the heat transfer. The 2D numerical investigation of a solar-powered air heater having effective surface roughness is the focus of this article. The current work is inspired by the fact that eddies formation near the ribs influences the overall thermohydraulic behavior of regular solar-powered air heaters. Current design of the innovative rib combines two distinct rib geometries. The first half of the rib design is a hyperbolic profile, and the latter half is an airfoil shape. This design prevents the entanglement of small eddies causing heat-transfer enhancement which leads to higher thermal performance. The consequence of different factors such as pitch and height of rib on thermal characteristics and frictional losses is evaluated. In the present study, two distinct roughness height value of 0.5 and 1 mm, along with rib pitches of 10 and 20 mm, are considered to investigate their impact on the thermal efficiency. Comparing the ribbed configuration to the base geometry without ribs, the results showed a noteworthy augmentation in heat transmission performance. For a rib pitch of 10 mm, the Nusselt number exhibited an improvement of 48.73%, indicating a marked augmentation in convective heat transfer. However, the friction factor rose up in parallel with this improvement, which increased by 291.58%, signifying higher flow resistance. Similarly, for a rib pitch of 20 mm, the Nusselt number showed a greater enhancement of 65.22%.