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.
Effective ventilation systems for a factory where various kinds of contaminant are discharged from many point sources are investigated in this study. Two ventilation systems are examined by scale model experiment using tracer gas. One system supplies fresh air and exhausts indoor air through the ceiling; the other has the inlet in the floor and outlet in the ceiling. Each system has a hanging wall installed at the ceiling, a device for immediate removal of the contaminant before it diffuses into the whole space.
Previous full scale experiments gave us a global and qualitative understanding of the gas circulation in a ventilated room in case of fire. In order to go thoroughly in the knowledge of these phenomena, we have built a scale model to perform more precise temperature measurements and more complete tracer gas experiments. The results show the existence of two zones when the air inlet is near the floor. At the opposite, when it is near the ceiling the room can be considered as a one single zone.
A test room and measurement system were developed for the full-scale measurements of the active displacement air distribution. The room represents a 3-meter wide module of a larger hall. The requirements for the room included minimisation of the errors caused by air leaks, thermal conductance and flow obstacles. The measurement of the flow pattern is carried out with ultrasonic and thermal anemometers. Automated traversing system was built to move the sensors in the vertical symmetry plane of the room.
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