Numerical analysis of solar air collector provided with rows of rectangular fins

The most promising collector must achieve the best thermal efficiency and fill out high requirements of low weight, low power consumption, ease of manufacturing, and low cost. In this study; a novel efficiently optimized flat plate solar air collector is modeled with a selective absorber and three rows of rectangular fins installed beneath the structure that provides 81% of thermal efficiency and 0.5 W of pumping power. A three dimensional CFD model of a flat plate solar air collector is developed and solved in steady-state conditions. We propose a suitable approach for assessing and optimizing a 1.28 m2 surface collector’s performance with forced convection flow. Results indicate that additional fin rows (from 35 rows to 142 rows) and fins relative height (0.5 to 0.8) with a nonselective absorber increase the thermal performance from 63% to 80%, and additional turbulent flow causes an increase of pump power from 1.8 W to 16 W. The adoption of a selective absorber contributes to efficiency 5% higher than that of a collector with 35 rows of fin for a volume flow of 85.33 m3/hm2. In contrast, the gain achieved by adding 142 rows of fin (l’/L=0.006) remains the most important, where it leads to an effective efficiency of 79.2% for a volume flow rate of 85.33 m3/hm2. Thus, it has been proposed to combine the selective absorber with the addition of rectangular fins in the new design.