Airborne pollutant spatial distribution, emission, and ventilation effectiveness for mechanically ventilated livestock buildings

The spatial distribution of pollutants indoors has not been adequately addressed in the literature primarily due to tedium, high experimental cost, and lack of funding. Yet, this information is essential in the design of pollutant control measures and ventilation systems in buildings. The spatial distributions of particles and gases, as well as the emission and effectiveness of ventilation systems, were studied by conducting field and laboratory experiments and computational fluid dynamics (CFD) simulation.; The results of experiments in a mechanically ventilated swine building showed that the spatial distribution of particulate matter (PM) and ammonia (NH3) concentrations differed in winter and summer due to the different airflow patterns. The PM concentration was more likely to vary crosswise in winter and lengthwise in summer within the building. The concentration of NH3, on the other hand, tended to vary more lengthwise in winter and was distributed almost uniformly in summer. These results are important in the strategic location of samplers in the building.; Laboratory experiments were conducted to determine how the type of ventilation system and the levels of ventilation rate affect the spatial distribution of pollutants. Carbon dioxide (CO2) was used as a tracer gas to represent the transport of other gases. The type of ventilation system had a significant effect on the spatial distribution of both particles and CO 2. The ventilation rate, on the other hand, had no substantial effect on the spatial distribution of both pollutants. In addition, increased in ventilation rate decreased the removal effectiveness for PM possibly due to resuspension of particles. Increasing the ventilation rate, however, resulted in increased contaminant removal effectiveness for CO2.; CFD simulation was used to predict the spatial distribution of particles less than 10 mum in diameter (PM10) in the swine building. Results showed that the magnitude of the predicted concentrations was significantly higher than the measured concentrations which could be attributed to the assumption of the particle generation rate. Thus, the CFD will be useful as a simulation tool in the future if the particle variables (e.g., particle generation rate, particle velocity) in the model can be properly quantified.