In conjunction with IEA Annex 18, DCV-systems, a test on an auditorium in a school in Tyreso south of Stockholm has been carried out. The auditorium has 450 seats on a slightly sloped floor and a ventilation system with low impulse air supply devices placed at the lower (front) part of the auditorium. The system is intended to act as a displacement ventilation system during operation with heat load from people. The flow rate is governed by a CO2 sensor in the exhaust air device. In non-operational state, and if heating is necessary, the system operated with recirculation of air.
The paper presents a criterion to assess the performance of mechanical exhaust hoods for dome stic kitchens and a procedure to experimentally test them; an analysis of the relevant parameters which affect their performance is made, the test results are shown, and finally these are compared with the results of a numerical fluid dynamic code. Experiments were performed using the tracer gas technique, and attention has been drawn rather on the hood efficiency in the removal of pollutants than on the IAQ in the test room.
A test room which was built at a scale 1:5 to the original one has been used to investigate air-conditioned rooms. The original room was specified by the international project IEA ANNEX 20. A lot of experiments were made on different inlet geometries and air change rates. Velocities and turbulent quantities were measured not only in the inlet plan but also in the room itselfby means of hot wire anemometry. The ammonia absorption method according to Kruckels has been applied to determine the heat transfer coefficients at the walls. Qualitative results were obtained by laser light sheets.
The efficiency of removing excess heat by employing mixing ventilation is based on the properties of jets. Therefore the behaviour of jets in enclosures is important. A correct supply design is essential otherwise the jet will separate from theceiling and drop into the occupied zone. This will give rise to unacceptable high velocities. the basic properties of jets in ideal situations like an infinite space are well known. However, in a room the jet interacts with the room air and the room surfaces.
A new miniature mechanical ventilation system with both supply and extract air and an air-to-air heat exchanger has been developed in Great Britain and Denmark. The system which is intented to ventilate a single room has the dimensions of a shoe box and can be placed/installed on the inside wall in an existing air vent. The system can operate with two air flows, 40 or 70 m³/h. At the low speed the noise is insignificant, intended to be "not disturbingN in sleeping rooms.
An even distribution of room air can improve indoor air quality, lower energy costs, and create thermally comfortable environments. This paper investigates the influence of the design of plaque diffusers on the efficiency of supply air. For better comfort and more accurate observations, the isothermal flow investigation was made in a small scale chamber with the air supply and exhaust on opposite walls. The supply air was spread radially and symmetrically over the vertical inlet wall. Plaques of different sizes, both solid and perforated were tested.
Cooling ceilings are more and more proposed, in order to eliminate excess heat in office buildings without consuming much energy in air transport. On the other hand, piston ventilation is proposed to efficiently eliminate contaminants. These two systems may however interact and experiments were planned to look at these interactions. Measurements of the age of air and air change efficiency were performed, together with more classical temperature and air velocity measurements, on various ventilation systems installed in the test chamber of Sulzer Infra, in Winterthur.
Ventilation of buildings is necessary, both to insure adequate indoor air quality and to protect the building itself against condensation and mould growth. On the other hand, ventilation rates must not lead to excessive energy consumption. French regulation doesn't appreciate directly the indoor air quality but fixes requirements for the value of exhaust stale air in service rooms ; furthermore heat losses related to cross ventilation due to wind effects are also taken into account.
A combined thermal and ventilation model has been used to investigate the seasonal variation of air infiltration rates and ventilation heat losses in modern industrial buildings. The model was initially compared to measurements of ventilation rates, temperatures and heating loads in such a building, and was found to agree well. The model was then used to predict infiltration rates, temperatures, ventilation heat losses and space heating loads for a standard heating season for that building.
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