Effect of windexchanger duct cross-section area and geometry on the room airflow distribution

In this work, the effect of duct cross-section area and geometry, square and rectangular, of a windexchanger (WE) on the room airflow distribution is studied for a room with a window, at windward or leeward. Airflow distribution inside a room produced by natural ventilation is an important bioclimatic architecture strategy for thermal comfort in hot climates. Ten different WE types at different wind directions, resulting in 18 cases, are experimentally evaluated using scale models in a water channel and velocity measurements at the vertical central plane obtained by stereo-particle image velocimetry. The homogeneity index, the area percentage with a significant flow speed, the normalized turbulent kinetic energy and the normalized ventilation flow rate are used as evaluation parameters. It is demonstrated that in general by increasing the duct cross-section area of a given windexchanger, the windexchanger performance improves, the exceptions are when the openings of the WE have mixed functions, i.e. injection and extraction. Nevertheless, more important than the areas ratios are the configuration of the WE and the location of the window. The WEs show a better performance when all their openings have an opposite function to that of the window.