A large number of the studies have indicated that chemical indoor air pollution has become an important environmental factor which influences the population's health. Nitrogenmonoxide and nitrogen dioxide are mainly produced by combustion at high temperatures and are formed by reactions between nitrogen and oxygen. Both nitrogen in the fuel and nitrogen in the air participate in reaction, NO is further oxidized and transferred into N02 in the atmosphere. Nitrogen dioxide is the most toxic of the nitrogen oxides and is the most important from view-point of health.
Source/sink models of volatile organic compound (VOC) emissions from building materials are reviewed and a multi-zone ventilation model is developed to predict concentrations of contaminants in rooms. The source model based on the principles of mass transfer and fluid flow presented by Zhang et al. (1995, 1996) is integrated into the multi-zone ventilation model. The characteristics of the parameters related to voc concentration, i.e. Schmidt number, ventilation rate and air velocity at the free stream are investigated by the sensitivity analysis.
In many new buildings the indoor air quality is affected by emissions of volatile materials. The emission process may be controlled either by diffusion inside the material or evaporation from the surface but it always involves mass transfer across the boundary layer at the surface-air-interface. Experiments at different velocity levels were performed in a full-scale ventilated chamber to investigate the influence of local airflow on the evaporative emission fr-0m a surface.
CFD simulation of airflow and temperature field in a heated room has been described in the paper. The tracking of pollutant particle movement is also presented here. The comparisons between computation and experiment show good and acceptable agreement. It can be concluded that CFD prediction can capture the main features of convective flow and provide satisfactory results. It can be seen that the thermal wall jet created by radiator greatly influences airflow pattern, temperature and pollutant particle distribution in the heated room.
The results of various numerical simulations of wind induced flows through large openings in a room are presented. The study is parametric on the sizes and relative positions of the openings and the wind direction. Various grid densities have been used. Grid independency for the presented results is demonstrated. Validation of the numerical approach is performed using measurements on a test cell with a single opening. The influence of the inflow wind profile is studied. It is shown that different flow patterns are induced within the dwelling when different profiles are assumed.
Condensation on the surfaces of diffuser and cold air dumping are the two major concerns in the application of cold air distribution brought about by the high temperature difference between supply air and room air. Condensation will form if the surface temperature of the diffuser is lower than the dew point temperature of ambient air. The presence of surface condensation can promote growth of unhealthy and smelly mold, and produce unwelcome damage of a structural and/or aesthetic nature. Cold air dumping is a major factor that detracts from thermal comfort in an airconditioned room.
Health effects caused by aerosol air pollutants in the breathing air is a main target for occupational health investigations. The effects of aerosol particles on health usually depend on the dose of particulate matter (PM:) retained at various locations of the respiratory tract. Displacement ventilation has been proved to be an effective ventilation system for the removal of passive pollutants in many buildings. The question is often asked about the performance of non-passive particle removal in a room ventilated by displacement ventilation.
Forced air circulation in a storage room either with freezing/cooling or controlled atmosphere is usually turbulent because a high air change rate is generally required. The interaction between the turbulent air flow and the product layers plays an important role in the performance of the storage room. In this paper, a homogenous model based on the Brinkman-Forchheimer-extended Darcy equation for both fluid and porous layer is described, in association with the standard k-e turbulence model.