The use of solar air collectors for room ventilation: a study using two numerical approaches.

Solar energy air-collectors installed on the sun-oriented building facades can be used for improving natural ventilation of adjacent rooms. The basis of the physical process is an unbalanced buoyancy force arising from the temperature difference between ambient and the air inside the room. Although difficult to control due to the variability of the climatic conditions, these devices can be used as means of reducing the need for conventional energy to provide indoor air conditions within acceptable limits required by health and comfort considerations. In this paper, two numerical approaches of different complexity are applied to study the airflow produced by a solar-air collector in a room. These are a simplified model, based on the integral equations of motion and Bernoulli theorem, which provides an insight into the main features of the flow, and a more complex computational fluid dynamics (CFD) model called VORTEX. The simplified model takes into consideration the heat and momentum transfer within the collector and room and the CFD code used has been specifically developed for studying the air movement in rooms, which solves the full elliptic Navier-Stokes equations together with the equations for the k-£ turbulence model. Results for a parametric study of a room with an air collector using both models are presented and discussed.