Numerical Investigation on the Influence of Contaminant Source Location, Occupant Distribution and Air Distribution on Emergency Ventilation Strategy

Abstract

The purpose of emergency ventilation is to remove pollutants effectively that may be suddenly released indoors. With the occurrence of indoor terrorism attacks and the accidental release of toxic chemicals, people have paid more attention of such emergency events in recent years. The traditional idea of a strategy for emergency ventilation is simply to supply sufficient fresh air into rooms. However, the positioning of a contaminant source, the distribution of occupants and the overall airflow pattern are also important factors. A new concept, integrated accessibility of contaminant source (IACS), has recently been proposed to consider those factors simultaneously. By using this concept as a major index of ventilation efficiency, 84 cases with different combinations of contaminant source and ventilation style in a full-scale room in which the occupant distribution is prescribed have been investigated numerically in this paper. The results show that air exchange rate is not the only dominant parameter, and simply increasing it does not ensure a better ventilation effect. It is also shown that when source location varies, the optimal ventilation strategy might need to differ greatly. From these results some rules are proposed to determine best ventilation strategies for different situations.