English

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.

The heat sources in a room with upward air supply, can be ideally decomposed into some basic models. Based on searching of the solution of the basic models, then solving the varieties of practical problems, a simplified method for predicting vertical temperature distribution of room air is submitted in this paper. Calculated values of some practical examples agree satisfactorily with experiment results.

The aim of this study was to ascertain the validity of using computational fluid dynamics (CFD) techniques to predict the behaviour of three dimensional gravity induced natural convection buoyant plumes from a vertical heated cylinder in a large quiescent enclosure. The calculated velocity distributions and turbulence quantities over the cylinder were compared to a wide range of experimental measurements. The laminar boundary layer on an isothermal vertical plate was also modelled. The CFX4.

This study is a part of a research project named 'Convective Flows and Vertical Temperature Gradient within Active Displacement Air Distribution'. The project was started in 1996 in order to determine guidelines for air flow rate dimensioning of the system. Aim of this study was to determine the characteristics of the thermal plumes of the heat sources used in the project. The characteristics were determined in order to apply the results to different kinds of plumes, which may occur with active displacement air distribution system.

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.

The paper presents the results of the research on application of the equation describing the increase in the air volume flux in buoyant plume above a point heat source to calculate plumes in rooms with displacement ventilation.The tests carried out in test room have given information about practical defining of the distance from the origin, assuming entrainment coefficient values and possibilities of assuming equal widths of temperature and velocity profiles in order to determine the origin distance.

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.