Farklı kanal kesitlerine sahip hava ısıtıcı güneş kolektörlerinin CFD yöntemi ile ısıl ve hidrolik performanslarının incelenmesi

In this study, two different designs of air heating solar collector ducts were analyzed using Computational Fluid Dynamics. A conventional rectangular duct of 800mm width and 20mm height with flat absorber plate and a proposed duct with fins installed below flat absorber plate were compared within the frame of thermal and hydrodynamic properties. Fins had 1mm thickness, were 50mm apart from each other and were compressed between absorber and back plates. Modeling and steady state analysis were carried out using ANSYS Fluent 15.0 software. Two ducts were modeled in three dimensions with 760mm deep entrance region and 1600mm deep test region. Working fluid was air, duct and fin materials were aluminum. The effect of fins on air and absorber plate mean temperatures, heat distribution, heat transfer coefficient, Nusselt number, pressure drop, friction factor and performance enhancement ratio was investigated for Reynolds number ranging from 3000 to 10000 and constant heat flux of 1000 W/m2. It was found that increasing Reynolds number increases the thermal performance of the ducts by increasing heat transfer coefficient; and increases pressure drop. When finned duct was compared with flat duct, higher air mean temperature, lower absorber plate temperature, therefore better heat distribution; however more pressure drop was observed. Thermo hydraulic performance of finned duct was determined by calculating overall enhancement ratio in order to discuss the overall effect fins. Although average heat transfer coefficient was increased with the addition of fins, reduction of flow hydraulic diameter due to fins caused reduction in Nusselt number.