The air solar collectors: Comparative study, introduction of baffles to favor the heat transfer

Concerning the solar air collectors, various techniques favorise and increase the heat transfer coefficient between the caloporting fluid (air) and the absorber; such as the fixation of small wings to the absorber, the manner in which the air flows vis à vis the absorber, the shape of the collector itself and those of its inlets and outlets. Studies achieved at the University of Valenciennes–France, Laboratory of Aerodynamic, Energetic and Environmental (current naming), were especially interested in another factor: the creation of turbulence in the air channels by using obstacles or baffles. The efficiency reached 80% for an air flow rate of 50 m3/h/m2, allowing a temperature increase of 70 °C to be achieved. All the configurations of baffles are subjected to visualizations of air flow, measurement of pressure drop and instantaneous energetic efficiency. The best configuration is the one that permits extending the trajectory of the air flow and increases the speed of the air within the collector and therefore the heat transfer.