Stack-Driven Ventilation in Two Interconnected Rooms Sharing a Single Opening and Connected to the Exterior by a Lower Vent

Abstract

This paper describes the transient ventilation of two interconnected rooms. One of them has a negative buoyancy source located at ceiling level, similar to an overhead split type air-conditioning system with ductless distribution, whereas the other has a vent at floor level. The flow evolution from short-and longterm analytical models was determined and confirmed with scale-model salt bath experiments. The shortterm model predicts the depth of the dense-layer 'first front' until it reaches the ceiling of the first room, and the long-term model predicts the density evolution of the fluid until it reaches a steady value. The advance of the first front depends on the location of the interior opening but is independent of the size of the exterior vent. The long-term density evolution depends on both parameters. As the interior opening is lowered, the volume implicated in the dynamics decreases and the dense fluid density increases at a higher rate. Furthermore, increasing the size of the exterior vent causes a turbulent exchange flow to develop through that vent, which inhibits the increase of the average density by introducing ambient fluid to the rooms.

Buoyancy-Driven Ventilation in the Interior-Most Flats of an Apartment Building with Different Corridor Vent Opening Condition

“…In order to avoid a tall stack, it has been proposed that upper floors should be provided with a mechanical ventilation system, whereas the lower floors should be naturally ventilated. Tovar and Garrido [9] simulated the transient airflow behaviour of two interconnected rooms, sharing a single opening. The exterior vent opening is provided at the floor level of a room whereas, near the roof of the other room, cold air is stacked.…”

The Impact of Air Pressure Conditions on the Performance of Single Room Ventilation Units in Multi-Story Buildings

“…The pressure difference in buildings with natural ventilation is caused mainly by the wind and the stack effect. There are numerous studies on both the stack effect [30][31][32][33][34] and the wind-induced pressure [35][36][37] in different building types with variable height, geometry and location. Wind conditions depend on the location and surroundings of the building.…”