A comparative experimental performance evaluation of solar air collector having absorber plate with convex oval-trench dimple

Abstract

The purpose of this research is to examine how convex oval-trench dimples placed staggered on a solar air collector's absorber improved vortex heat transfer. At air mass flow rates of 0.013, 0.027, and 0.036 kg/s, convex oval-trench dimple absorbers with relative roughness heights, e/D=0.2 and e/D=0.4, as well as a flat plate absorber, were evaluated for back-pass and frontpass applications. The oval-trench dimpled absorber plates in the back-pass and front-pass achieved the maximum energy efficiency of 37.5% and 50.6%, respectively, with e/D=0.4 and 0.036 kg/s. The increase in the number of Nu in e/D=0.4 was 26% and 31% more than that of the flat plate for the examined parameter ranges of back-pass and front-pass, respectively. (e/D=0.4)/(flat plate) and (e/D=0.4)/(e/D=0.2) increased by an average of 28% and 24% in back-pass for (Nuotd /Nu0)/(fotd / f0), respectively. In front-pass, (e/D=0.4)/(flat plate) and (e/D=0.4)/(e/D=0.2) improved by 35% and 25%, respectively. The collector with a relative roughness height of 0.4 has the optimal structure for this examination of collectors with an ovaltrench dimple. The results indicated that collectors with convex oval-trench dimples outperform flat plates in terms of surface area expansion and turbulence generation, which boosts thermal efficiency substantially. In addition, when the experiment results were compared, the front-pass implementation outperformed the back-pass approach. As a result, thermal systems may benefit from utilizing the convex oval-trench dimple.