Recent full scale experiments has detected the presence of low Reynolds number effects in the flow in a ventilated room. This means that one are unable to predict the flow patterns in some geometries for air change rates - or Reynolds numbers - which are relevant for ventilation engineering by a standard model of turbulence. In this paper it is investigated if it is possible to simulate and capture some of the low Reynolds number effects numerically using time averaged momentum equations and low Reynolds number k-e model.
Sandberg and Skaret differentiate between the terms air change efficiency and ventilation effectiveness. Air change efficiency is a measure of how effectively the air present in a room is replaced by fresh air from the ventilation system whereas ventilation effectiveness is a measure of how quickly an air-borne contaminant is removed from the room. The AIVC guide covers ventilation effectiveness and related concepts. It shows the origins of the concepts used, provides proofs of essential formulae, and suggests standard symbols and definitions.
A new simple method is proposed here for the experimental singling out of the air flow patterns in a room. It is based on the use of a series of thermofoil probes, arranged in a lattice, that can be suspended at the ceiling of the room under test.
The concentrations of indoor pollutants should be maintained below recommended values at all occupied locations at any time. A design method based on minimal air change rates may not be satisfactory, since the ventilation effectiveness is determined not only by the nominal air exchange rate but also many other factors, such as the airflow pattern the space, location of contaminant sources, and properties of the contaminants. It is the objective of the present study to investigate numerically the effect of airflow patterns due to the various factors of ventilation effectiveness.
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