Abstract

This full-scale experiment studies the efficiency of a mechanical smoke exhaust system by using hot smoke testing. The mechanical smoke exhaust system consisted of an air-conditioning system in a ceiling and its linear return diffusers were used as a smoke vent. To measure the efficiency of the system, the study included measurements of the smoke descending rate, the diffusion of heat into the room, and the visibility. Simultaneously, the diffusions of the smoke scenes were recorded and visually inspected. In accordance with Taiwan’s regulatory body, the smoke exhaust flow rate was set at 1.0 CMM/m² as a reference. It was found that if the location of the smoke vent was established improperly, smoke turbulence was formed. The feasibility was assessed when the smoke exhaust flow rate was adjusted to 0.8 and 0.5 CMM/m². Finally, the effect of the total area ratio of the diffuser opening on the efficiency of the new system was studied by adjusting the area ratio to 2.5, 5, 10 and 15%. The experimental results proved that the global ceiling, used as a smoke vent, could exhaust smoke most effectively.

Key words: Visibility, smoke exhaust system, full-scale experiment, smoke descending rate.