A three-dimensional drift-flux model combined with the deposition boundary conditions for wall surfaces in ventilated rooms are presented to study the particle dispersion in displacement ventilation rooms. Three ventilating air flow rates, 2 ACH, 5 ACH, 8 ACH and several particle sizes, 1, 2.5, 5, 7.5, 10 micron, are investigated. The results show that the particle dispersion characteristics are very different in displacement ventilated rooms with different air supply volume. In rooms with the same air supply volume, large-diameter particles diffuse more widely than small ones.
This paper presents an overview of what is known related to particulate matter indoors. An information for understanding filtration is given along with the way how particles contribute to adverse health effects.
Airborne particulate matter has been implicated as a major contributor to the increased incidence of respiratory disorders among people working in livestock buildings. A clear understanding of particle spatial distribution can provide important information for improvement of ventilation system
design and control strategies. In this study, the dust mass spatial distributions in three different ventilation systems were measured using a multi-point sampler in a full-scale mechanically
ventilated laboratory room under controlled conditions.
This study quantified the daily average concentrations of respirable particulates in rural homes from three Indian districts. Thanks to this data a model is being developed to predict quantitative categories of population exposure based on survey information on housing and fuel characteristics. A better estimation of health risks will be possible.
The deposit of particles lower than 5µm diameter, depends on the airflow path within the room along with the strength of the ventilation.This parameter has to be taken into account to predict particle indoor air quality. For that study, a numerical model
The particle deposition on ceilings causing the soiling of induction outlets is mainly caused by the features of mixed ventilation.This paper offers a solution to the problem. The search for a clean outlet is made easier with the proposed optical and experimental technique that suggest to visualize the soiling patterns of an outlet by photographing deposited sodium chloride crystals. These tracer-particles stem from an atomizer and aerodynamically behave like the particles responsible for the soiling of ceilings in reality.
Mixing ventilation and displacement ventilation were compared in an intervention study inclassrooms. Particles, cat allergen and CO2, were measured in classroom air at different levelsabove the floor, during regular lessons. With mixing ventilation, the particle concentrationtended to decrease with height, with a stronger gradient occurring for larger particles. Withdisplacement ventilation, the particle concentration increased with height, except for particles>25 m. The displacement system thus tended to have a slight upward displacement effect onmost of the particles.
There is increasing evidence of a causal link between airborne particles and ill health and thisstudy examined the exposure to both airborne particles and the gas phase contaminants ofenvironmental tobacco smoke (ETS) in a bar. The work reported here utilized concurrent andcontinuous monitoring using real-time optical scattering personal samplers to recordparticulate (PM10) concentrations at two internal locations. Very high episodes were observedin seating areas compared with the bar area.
The objective of the present study is to apply and test a mathematical model for thedetermination of the strength of various indoor sources of ultra-fine particles (UFP), and thesink effect for such particles. The model is intended for further development in order to createa tool capable of predicting the concentrations of fine and ultra-fine particles in a room. Inputdata to the model are the ventilation rate, emission rates of ultra-fine particles from differentindoor sources and properties describing sink effects. Laboratory measurements of 10 indoorsources (e.g.