A great deal of the literature on general ventilation expresses the adequacy of the volumetric flow rate of air in terms of the number of room air changes per hour. Although the concept of air change rate has very little relevance to the control of contaminants as it relates to the size of the room and not to the scale of the problem, the overall amount of air entering and leaving a workplace is of fundamental importance in assessing the quality of the working environment.
The present study deals with indoor air quality and is mainly based on an experimental work. The experimental set up is a full scale test cell with a ventilation system which comprises a fixed air supply and a mobile extract. A source of pollutant continuously supplies tracer gas at the centre of the cell. We carried out 12 tests under steady state and with various conditions. The test parameters were the exhaust location, the fresh air now rate and the supply air temperature.
The paper presents a comparison between the results of experimental tests airflow pattern forming in a room with displacement ventilation and numerical calculation. The heat source in the room was a heating plate. Quasi-laminar diffusers supplied the air with the ventilation change rate from l to 7 h-1. Temperature and velocity distributions in the plume and in its surroundings as well as the tracer gas concentrations in the background were measured. The airflow in the room was also predicted by means of CFD, using the standard k-E turbulence model and standard log-law wall-functions.
This paper is based on a dual approach (experimental and numerical) in order to predict the indoor air quality for small ventilated enclosures. The experimental part employs a ventilated test room and a tracer gas technique (constant method as gas injection) to estimate the diffusion of a pollutant. The gas used is the sulphur hexafluoride (F6S). The numerical approach is a CFD simulation, adding a convection - diffusion equation (to determine the local mass fraction of the pollutant) to the equations normally used to solve a turbulent flow.
The New Zealand Building Code has kept with tradition in allowing residential building ventilationdesigns based entirely on openable window areas. Working against this tradition, however, is a trend inNew Zealand towards more airtight construction and declining reliance on open windows. Contributingto this trend are changing patterns of occupancy with fewer people at home during the working week,along with developing concerns for personal security.
The air quality in a subway-train was studied to suggest optimal design criteria and operationconditions based on the ventilation demand by passengers. The C02 emitted from thepassengers was the tracer for this study. The C02 bioeffluent from a human body was firstlyquantified and used for the data analysis. Then the C02 concentration was monitored in asubway-train being operated.
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