Chilled ceiling effects on the Indoor air quality in a room equipped with displacement ventilation system

Abstract

Over time, many studies have proven the advantages of using chilled ceiling systems as an assistant device for covering the barriers of the stratified air distribution systems. However, previous investigations are still insufficient, especially in analyzing indoor air quality. With the aid of the computational fluid dynamics techniques and Airpak software, we attempted to determine the possible effects of the chilled ceiling on the performance of displacement ventilation by evaluating contaminant removal, ventilation effectiveness, the freshness of air, and air change efficiency. In addition, we tried to find a solution to maintain the stratified form of the contaminant profile, and reduce the impact of the negative buoyant flow caused by the chilled surface. In order to investigate, the study was analyzed with variable exhaust vent location. The results indicated that the indoor air quality indexes had the best operation compared to the other cases when the exhaust vent was placed near the occupants. Actually, by local exhaust vent strategy, the inversion phenomenon caused by chilled surface was minimized and the contaminant concentration was safer at the inhaled zone compared to the other cases. In addition, the chilled ceiling had entirely adverse effects on the mean age of air, contaminant concentration, air change efficiency and ventilation effectiveness. Nevertheless, the disturbance effect was lower when the exhaust vent placed in the vicinity of heat/contaminant sources.

Keywords

• indoor air quality (iaq)
• chilled ceiling (cc)
• displacement ventilation (dv)
• local exhaust vent (lev)