Particle Evolution In Different Ventilation Rooms

The most important environment in relation to our health is the indoor environment. The main purpose of HVAC systems is to provide a healthy and comfortable environment for the occupants of the space. But more and more concern is focusing on the indoor particle pollution and its effect on human health in the current days.The typical contaminants in buildings are presence in the form of gases and particles. Ventilation plays a key role in the dilution and removal of contaminants within indoors. But most ventilation and air conditioning systems are designed without much concern about how separating particles behave in ventilation air flow, and many epidemiological studies showed that air pollution related health problems have extensive relation to inhalable particles. For office and other similar work-related environments, hospitals, schools etc, the main source of pollutants is often outdoor air. In the present paper, the characteristics and evolution of particle size distributions in different ventilation rooms.Based on the aerosol particle dynamic equation and the monitoring date of Chengdu's outdoor particle concentration, the FLUENT code is employed to simulate the particle motion and deposition in Mixing Ventilation (MV) and Under-Floor Air Distribution (UFAD) rooms, and the characteristics of rooms airflow, temperature and particle concentration are evaluated and estimated. The numerical results show that the variation of indoor particle concentration is directly influenced by outdoor particle concentration; and compared to MV rooms, the supply air within UFAD rooms is much cleaner, especially at the work area and respiratory district, and more in line with the requirements of human comfort.In addition, the results of the simulations about particle movement, diffusion and deposition in different ventilation rooms and different height indicate that: first, particle pollution on human health effects is relevant to pollution sources location, particularly pollution sources located in official surface. Second, the amounts of particle deposition on persons in MV rooms are more than UFAD rooms, whereas particle depositions on floors are reverse, but if being able to ensure to clean depositions in UFAD rooms regularly, UFAD is better than MV at restraining and eliminating particle contaminants which at different locations. Meanwhile, the time evolution of fine particle in MV and UFAD rooms under typical conditions is analyzed.