Mixing Ventilation in a Full Scale Model Room Using a Multi-Orifice Nozzle

A commercial multi-orifice diffuser (OD) is compared under the same experimental conditions to a previously validated innovative lobed diffuser (LD). The OD head is a cylindro-spherical surface pierced with 20 orifices arranged in three rows leading to efficient jet diffusion. The jet analysis reveals that the flow from the closest two orifice-rows to the ceiling attach to it by Coanda effect whereas the orifice jets from the lower orifice-row are directed towards the occupied zone. Thermal comfort analysis reveals less satisfactory conditions for OD than for LD. In the former case, higher velocities in the occupied zone are responsible of a slightly cold sensation. The recorded pressure loss is higher in OD than in LD, whereas no significant difference was observed in terms of sound pressure level in the occupied zone.