Computational and Experimental Analysis of Thermohydraulic Enhancement in Solar Air Heaters

A novel compound roughness configuration, consisting of repeated chamfer rib–semicircular groove elements, is proposed to enhance the thermohydraulic performance of solar air heaters. Computational fluid dynamics (CFD) simulations were performed to optimize key geometric parameters (which will break the viscous sublayer and enhance heat transfer), including roughness height, chamfer angle, groove position, and groove depth under turbulent flow conditions ([Formula: see text]). The geometry that has been taken for optimization is repeated chamfer rib–semicircular groove roughness. The groove position was optimized, and it is kept exactly at the reattachment point. Providing a semicircular groove instead of a V-groove resulted in greater heat transfer enhancement, as more turbulence is created. Also, it resulted in a lower friction factor. Thus, the performance index for the semicircular groove is higher than that for the V-groove. CFD investigations reported a heat transfer enhancement of 3.6-fold and a friction factor ratio of 2.4-fold, whereas experimental studies reported a heat transfer enhancement of 3.5-fold and a friction factor ratio of 3-fold. As per the experimental results, the performance index obtained is 2.5, which is high compared to those of other geometries.