On the effect of distributed cooling in natural ventilation

• Published in: Journal of fluid mechanics Vol. 600; pp. 1 - 17
• Main Authors: LIVERMORE, S. R., WOODS, A. W.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 10.04.2008
• Subjects: Air conditioning. Ventilation; Applied sciences; Building technical equipments; Buildings; Buildings. Public works; Cooling; Energy; Energy. Thermal use of fuels; Environmental engineering; Exact sciences and technology; Fluid mechanics; Heating, air conditioning and ventilation; Temperature control; Ventilation; Ventilation. Air conditioning; Air flow; Buildings; Instrumentation; Natural convection; Plume; Experimental study; Heat transfer; Natural ventilation
• ISSN: 0022-1120; 1469-7645
• DOI: 10.1017/S0022112007009809

We examine the natural ventilation flows which develop when a low-level heat source interacts with a distributed zone of cooling at high level in an enclosed space. We develop some new analogue laboratory experiments in which we use a saline plume to model a localized heat source and a heated plate to model a distributed source of cooling. The experiments show that in a building with a low-level point source of heating, a two-layer steady stratification develops in which the depth of the lower layer decreases as the intensity of the cooling at the ceiling increases. We develop a theoretical model which accounts for the penetrative entrainment across the interface associated with the convection in the upper layer. We show that this becomes more dominant as the cooling increases and eventually the room becomes well-mixed. We discuss the role of such distributed cooling on the design of natural ventilation and its ability to provide sufficient flow and adequate temperature control.