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tracer gas

Evaluating age from arbitrary forms of injection functions of tracer.

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 homogeneous tracer pulse technique for measurement of ventilation and air distribution in buildings.

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.

A Scale Model Study on Contaminant Removal Effectiveness of Industrial Facility

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.

Prediction of Gas and Pollutant Distributions in a Ventilated Cell in Case of Fire

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.

Test Room and Measurement System for Active Displacement Air Distribution

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.

Detailed Experimental Data of Room Airflow with Displacement Ventilation

This paper presents a set of detailed experimental data of room airflow with displacement ventilation. These data were obtained from a new environmental test facility at the Massachusetts Institute of Technology (MIT). The measurements were conducted for three typical room configurations: a small office, a large office with partition, and a classroom. The experiment measured the distributions of air velocity, air velocity fluctuation, and air temperature by omnidirectional hot-sphere anemometers and contaminant concentrations by tracer gas at 54 points in the room.

Comparison of Natural and Mechanical Ventilation Performance in Similar Houses

The ventilation performance in 59 terraced houses of similar construction was investigated using a passive tracer gas technique. Some thirty houses were ventilated through the original natural ventilation, while eight were equipped with an additional bathroom fan and 20 were retrofitted with a mechanical supply and exhaust ventilation system. All measurements were made simultaneously in March. The ventilation performance was computed using both single-zone and two zone approaches.

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