Air change rates in a cross-ventilation model were measured from the decay curves of video image signals obtained by the step down method assuming perfect mixing of tracer mists inside the spaces. Wind tunnel test results led to the following conclusions. 1) Ray extinction due to lighting scattering did not affect the measurement accuracy of the air change rates in the two-dimensional model. 2) Tracer mists in a diameter between 0.25 μ m and 2.0 μ m produced the same measurement accuracy.
In order to assess ventilation systems, ventilation and thermal comfort parameters are calculated. Parameters are temperature and ventilation efficiency and PMV I PPD. Two ventilation configurations are set: the supply grille is under the ceiling and tests are performed for 2 exhaust positions. Both are opposite the ceiling: the first one is under the ceiling and the second one is on the floor. In regards with extract position, the ventilation system is better when extract is on the floor. It appears that the air renewal does not influence neither ventilation nor temperature efficiency.
Working spaces in modem buildings are easily formed by interior partitions because these buildings have been designed and constructed as open spaces for flexibility. This could lead to an indoor environment which might be different from the intended design. In this study, the effect of partition on the indoor air quality in a model room has been investigated with different configurations such as the height of' partition and the gap between partition and floor.
An application of the systemic approach is presented for the study of the ventilation of a room in an industrial facility. First, a series of tracer gas experiments was made with a radioactive tracer. Analysis of the Residence Time Distribution (RTD) curves, supported by some CFD, then enabled to build a simple zonal model for the description and quantification of the observed air flow patterns. This model was able to reproduce the experimental RTDs inside the room as well as at the exhaust.
There are many indices to evaluate the ventilation characteristics of the ventilated rooms. These indices are classified into air change efficiency and contaminant removal effectiveness. In order to know how to use many indjces for a good understanding of the characteristics of the concerned ventilation system, the values of various efficiencies under some typical air flow conditions with isothermal condition are compared. The local mean age distributions and local contaminant concentrations are measured with tracer gas technique in a scaled model of the room ventilated mechanically.
The purpose of this study is to find more information of the complicated air flow pattern in the SchOnbrunn palace. The aim is to improve the control of the air infiltration. We have used a passive tracer gas technique, a special case of the constant injection technique, called the homogeneous emission technique. The results gives Air Change Rate's (ACH) of 0,7 to 1,7 in different rooms and parts of the palace. Wind driven ventilation dominates stack driven ventilation. We found a considerable air flow between floors.
The age of the air in a room is normally determined either from a pulse response or from a step change response (up or down). There are a certain number of problems involved in applying these two theoretical models, especially those associated with the duration of the injection, which must either be infinitely short or infinitely long. A hybrid method that consists of injecting a known quantity of tracer for a given time offers the advantages of both methods.
The principles of a new tracer gas technique is described in the paper. The new technique involves pulse injection of tracer gas and has the same advantages as the previously known homogeneous emission technique. It can for example advantageously be used in large buildings and buildings with many rooms and yields information on the distribution of ventilation air within the building. However, contrary to the homogeneous emission technique, yielding the average ventilation performance during an extended time, the new technique allows measurement during short term periods.
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