Numerical Simulation Of Air Contamination Dispersal In A Room

Because of bad ventilation and a large amount of construction materials which contain contaminant were used, it have increased the indoor air pollutant levels significantly and deteriorated the indoor air quality. So it is significant to study the air contaminant distribution when a room has different ventilation rate and different contaminant source.This thesis using CFD software PHOENICS study the air contaminant distribution in an office, and examines the impact of ventilation rate, ventilation system and contaminant source on the indoor contaminant concentrations.It has been found that ventilation system greatly influence the air contaminant distribution. The ceiling diffuser with low outlet is the best one in the four ventilation system, when the ventilation rate is same. Increasing ventilation rate can reduce contaminant concentration, but the effect of ventilation rate to the concentration is limited, and the reduction of concentration is not in proportion to the increased ventilation rate. The contaminant source emission rate has greatly influence on the air contaminant concentration. When the emission rate is reduced, at the same ventilation rate, the air contaminant concentration reduced greatly.When the contaminant source is wet material, the emission rate and air contaminant concentration are time-dependent. The contaminant concentrations reach a peak in about 0.5 hour. After that, the concentrations begin to decay. Since the VOCs concentrations in the chamber were non-uniform, the time required for different areas' concentration to reach the threshold value was different. At the breathing level (z=1.2m), the time differences between areas having the highest and lowest concentrations were approximately 5 hours.At last, the mass balance model and experiment way was used to validate the numerical simulation results.