This study investigates the influence of combining multiple exhaust air positions on ventilation effectiveness in mechanically ventilated spaces using a slot diffuser for the supply air distribution in a single main vortex covering the whole room. By systematically testing different paired exhaust configurations, the analysis examines their impact on air change effectiveness (ACE) and contamination removal effectiveness (CRE). The results show that the ventilation effectiveness of combined exhaust configurations generally falls between the values of the individual positions, observed across tested scenarios. To simplify the analysis under a one-vortex airflow characteristic, the ACE of combined exhaust positions can be reasonably approximated by averaging the ACE values of the individual exhaust locations. CRE includes the position of the contamination source. Close distance between the source and the exhaust in line of the airflow pattern increase the CRE.
Brockmann et al. (Tue,) studied this question.