Energy efficient ventilation: Stratification in exhaust-driven mechanical displacement ventilation

Abstract

Upflow displacement ventilation is designed to provide fresh, pre-conditioned air throughout a space, while maintaining the natural tendency of hot air to rise to the top of the space. In principle this can reduce the cooling load in comparison with systems which use a high level source of pre-conditioned air combined with mixing ventilation. One of the questions concerning upflow displacement ventilation is the distribution and concentration of contaminants which may accumulate within the space through the interaction of the ventilation flow and the occupants/activity in the building. We develop a simplified fluid model to explore this feature of displacement ventilation in more detail, and test the model with some new laboratory experiments.