Impact of the Narrowing System at Different Locations and ‎Heights on the Performance of a Plane Solar Collector

This paper presents a numerical study of a solar air collector aiming at analyzing the influence of several geometrical parameters on the heat transfer mechanisms with minimum losses. The laminar airflow in the collector undergoes a sudden or gradual narrowing at the absorber in its path. The finite volume method is used to solve the conservative equations of the fluid flow in the system. The results for these two narrowing models, at different positions and heights, show an improvement in heat transfer and a reduction in friction, especially in the case of gradual narrowing. Both narrowing models reduce the recirculation zones and thus increase the fluid velocity (1.25 to 2.50 times the reference velocity), leading to a gain in pressure drop compared to the perpendicular shoulder case. This solution also increased system efficiency (22.41% to 50.12% for the inclined shoulder case, 21.83% to 48.86% for the perpendicular case, and 20.81% to 38.66% for the simple case).