Honeycomb-shaped artificial roughness in solar air heaters: CFD-experimental insights into thermo-hydraulic performance

This research paper presents numerical and experimental investigations to examine the effectiveness of a honeycomb pattern as a form of the geometry of artificial roughness in solar air heaters. Utilizing Computational Fluid Dynamics (CFD) through three-dimensional simulations, the study explores how Thermo-Hydraulic Performance Parameter (THPP) is affected by variations in honeycomb geometry. The research examines various parameters, including the angle of attack (& Oslash;), relative roughness pitch (P/e), and relative roughness height (e/D) within the respective ranges of (90 degrees-120 degrees), (8-12), and (0.03-0.05). The system's performance is evaluated across various flow scenarios, covering Reynolds numbers from (3000) to (21,000). Incorporating the honeycomb design into an absorber is observed to improve the heat transfer rates. The system achieves a maximum Nu of (140.65) at (e/D) of 0.04, (P/e) of 10, (& Oslash;) of 120 degrees, and Re of (21,000). The maximum FF of (0.039) was obtained at (e/D) of 0.05, (P/e) of 9, and (& Oslash;) of 120 degrees at a Reynolds number of (6000). The system exhibited a THPP of (1.7) at a Reynolds number of (6000). This Maximum THPP was associated with specific parameters, including (e/D) of 0.04, (P/e) of 10, and (& Oslash;) of 120 degrees.