Experimental and meta-heuristic optimization for the highest thermo-hydraulic performance of a solar air heater with a V-notch pattern of hemispherical protrusions on absorber surfaces

Abstract

Thermo-hydraulic performances of a new solar air heater with single V-notch patterns of hemispherical protrusions on the absorber plate are investigated experimentally for different relative protrusion heights (hp/Dh = 0.027–0.069), relative pitch (pp/hp = 6–14), attack angle (αap = 15°-75°), and Reynolds number (Re =3600–21,700). Three meta-heuristic algorithms, i.e., Ant colony optimization (ACO), Whale optimization algorithm (WOA), and Grass-hopper optimization algorithm (GOA), were used for single and multi-objective optimizations. Experimental results provide the maximum Nusselt number (Nu) as 127.07 at hp/Dh = 0.050, pp/hp = 10, αap = 600, and Re =21,700, whereas the minimum friction factor (f) becomes 0.0165 at hp/Dh = 0.027, pp/hp = 10, αap = 450, and Re =21,700. The highest normalized Nusselt number (Nu/Nus) is found to be 2.56 for hp/Dh = 0.050, pp/hp = 10, αap = 600, and Re =7200, and the maximum normalized friction factor (f/fs) is observed as 4.30 at hp/Dh = 0.050, pp/hp = 10, αap = 450, and Re =7200. The highest thermo-hydraulic performance parameter (THPP) was to be 1.60 at pp/hp = 10, hp/Dh = 0.050, αap = 600, and Re =7200. Empirical correlations were developed. In single objective optimization for Nu, WOA provided the best results. For f, WOA gives a minimum value. The WOA metaheuristic algorithm outperformed the other algorithms.