The effects of supply temperature and vertical location of inlet air on particle dispersion in a displacement ventilated (DV) room were numerically modeled with validation by experimental data from the literature. The results indicate that the temperature and vertical location of inlet supply air did not greatly affect the air distribution in the upper parts of a DV room, but could signiflcantly influence the airflow pattern in the lower parts of the room, thus affecting the indoor air quality with contaminant sources located at the lower level, such as particles from working activities in an offlce. The numerical results also show that the inlet location would slightly influence the relative ventilation efflciency for the same air supply volume, but particle concentration in the breathing zone would be slightly lower with a low horizontal wall slot than a rectangular diffuser. Comparison of the results for two different supply temperatures in a DV room shows that, although lower supply temperature means less incoming air volume, since the indoor flow is mainly driven by buoyancy, lower supply temperature air could more efflciently remove passive sources (such as particles released from work activities in an offlce). However, in the breathing zone it gives higher concentration as compared to higher supply air temperature. To obtain good indoor air quality, low supply air temperature should be avoided because concentration in the breathing zone has a stronger and more direct impact on human health.
The impact of thermal conditions of the ground on ventilation in the interior courtyard and rooms of enclosed building is very important to improve the air quality in courtyard. The computational fluid dynamics( CFD) model was used to investigate the flow field of a certain courtyard and analyze the static differential pressure between the two sides of the vent and ventilation conditions of the courtyard. The results indicate that thermal effects not only changed the air flow pattern of the interior courtyard but also obviously increased the flow velocity of the upper space of the courtyard. For the most of courtyard rooms,the absolute value of static differential pressure increases as the thermal intensity of the ground increases. In all wind directions,the air exchange rate of the courtyard increases with the higher thermal intensity of the ground which makes a greater influence on the increasing of the ventilation rate of the roof opening than that on the gate opening.
