Solar air heaters (SAHs) are economical solar energy converters for low- and medium-temperature applications. Even though they are efficient, their use is restricted due to inherently low heat transfer rates. To avoid this limitation, the present work utilizes a numerical analysis to study a new design of the absorber plate with modified wedge-shaped ribs of convex surface. Two-dimensional CFD simulations were conducted in ANSYS Fluent with the RNG K-ε turbulence model to capture the phenomenon of turbulent transport. The major performance parameters—i.e., average Nusselt number ( \(\text{N}\text{u}\) ), friction factor ( \(f\) ), and thermal performance factor ( \(\text{T}\text{P}\text{F}\) )—were analyzed to study the system’s thermo-hydraulic behavior. The simulations were performed for a relative roughness pitch range of 7.14 ≤ P/e ≤ 17.86 and Reynolds numbers between 4000 and 20,000 under a uniform heat flux of 1000 W m−2. The relative roughness height was maintained at a constant value of e/Dh = 0.042. The findings demonstrate that incorporating modified wedge-shaped ribs substantially boosts the thermal performance of the SAH with Nu improves by as much as 3.73 times that of the smooth duct. The gain is, however, also accompanied by fluid friction penalty of approximately 3.13 times. The overall performance is good, even with the existence of this penalty, and the TPF is between 1.26 and 2.28, which proves the effectiveness of the suggested rib construction. Finally, nonlinear regression analysis was utilized to establish correlations between \(\text{N}\text{u}\) and \(f\) as functions of Re and P/e.
