English

This paper introduces the infrastructure of Microflo CFO modelling system in conjunction with the virtual simulation environment. The theoretical basis is described and particularly the graphical user interfaces for pre and post processing are described in detail. Features of the Microflo system are further demonstrated through its application in the design projects.

Cheap 3D models for visualization of room ventilation applications are now available. VRML (Virtual Reality Modelling Language) is found to be a good format to describe buildings, rooms and furniture. A 3D model in VRML can be placed on an World Wide Web www page and others can see the model in "Walk Through" mode. Use of VRML is described with examples as for instance in planning of measurements and as a basis for geometry in CFD calculations. The advantage of 3D and VRML is that it is much easier to see, find and correct problems than using traditional drawings.

Future information age technology will demand cleaner and more cleanrooms for the manufacture, assembly and repair of electronic components. Many special processes can be very sensitive to trace contaminants which are not removed by conventional air conditioning, filtering and distribution. High efficiency particulate air filters, high velocity streamline air flows, relatively dry air, clean ducts and plenums, cooling, noise reduction and perhaps disinfection are needed.

The concept of air exchange efficiency of ventilation, a quantity entirely determined by the spatial distribution of the local mean age of air, is discussed. A divergence-type conservation equation for the local mean age of air is derived. This equation is solved numerically for a room ventilated by the desk displacement ventilation concept, using a CFO-routine. The CFO-calculated mean-age-of-air pattern is compared with mean age results from tracer experiments in a corresponding laboratory configuration.

The occupants of buildings are exposed to a range of aerosol contaminants, of both indoor and outdoor origin; at present, filtered mechanical ventilation is the only effective means of airborne particulate control in polluted urban areas. Significant energy costs may be incurred, however, through the large pressure drops associated with membrane filtration. An alternative to filtration might be the enhancement of aerosol deposition on a protruding surface which is parallel to the incoming airflow direction, but which does not significantly retard the airflow.

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.

Microbial monitoring of the indoor environment can be performed in several ways and with the aid of different techniques. Knowing the limitations of the chosen system is of vital importance for the correct evaluation and interpretation of the results. The number of Colony Forming Units (CFU) detected by one method can not be directly compared with results from another method. The paper presents an evaluation of commonly used instruments for the collection and counting of airborne viable particles.

Displacement ventilation is acknowledged to be an efficient system for the removal of contaminants and excess heat from occupied zones of rooms, this system is aiming at supplying clean undiluted supply-air directly to the zone of occupation. Air flow rate, temperature and the design of the supply device strongly influence the parameters that determine thermal comfort. In the paper, one kind of displacement ventilation systems - ohair air supplying system is investigated.

The purpose of the work described in this paper is to develop a mathematical model of downdraft exhaust hoods in order that ways of improving these hoods efficiency can be examined. In this initial study the model developed is twodimensional. The flow has been assumed to be ideal and the complex potential considered. By use of conformal mappings the airflow in the vicinity of a bench, which is extracting air and also has air being blown down from above, is modelled. Various ratios of extraction to downdraft are considered in order to investigate the most efficient method of operation.

When a fume cupboard is placed in a room with a ventilation duct, the air movement inside and around the fume cupboard is fully three-dimensional turbulent flow. However, in order to understand the fluid flow away from the fume cupboard a much simpler model can be used. This leads to a steady 20 model, with the computational domain including only the sash of the fume cupboard, the room and the entrance into the ventilation duct. In this paper we have used both the k-E turbulence model and the wall function technique to calculate the steady 20 turbulent fluid flow.