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displacement ventilation

Validation of a CFD model for several displacement ventilation geometries

Fläkt Woods, which manufactures a wide range of ventilation equipment, has undertaken a programme of experimental verification of the concepts of new displacement ventilation equipment, as well as validation of a CFD (Computational Fluid Dynamics) package

CFD Simulation of Air Distribution in Displacement Ventilated Rooms with a Moving Object

Numerical experiments by computational fluid dynamics (CFD) simulation were done toinvestigate air distribution in displacement ventilated rooms with a moving person, which affects thermal stratification of indoor air required for controlling and maintaining good air quality and high efficient ventilation performance. The distributions of indoor air and ventilation effectiveness obtained by the simulation were compared with the experiments using a full-scale room model.

Numerical Study of Particle Dispersion in Displacement Ventilated Rooms

A three-dimensional drift-flux model combined with the deposition boundary conditions for wall surfaces in ventilated rooms are presented to study the particle dispersion in displacement ventilation rooms. Three ventilating air flow rates, 2 ACH, 5 ACH, 8 ACH and several particle sizes, 1, 2.5, 5, 7.5, 10 micron, are investigated. The results show that the particle dispersion characteristics are very different in displacement ventilated rooms with different air supply volume. In rooms with the same air supply volume, large-diameter particles diffuse more widely than small ones.

Thermal comfort of seated occupants in rooms with personalized ventilation combined with mixing or displacement ventilation

The performance of two personalized ventilation systems combined with mixing or displacement ventilation was studied under different conditions in regard to thermal comfort of seated occupants. The cooling performance of personalized ventilation was found to be independent of room air distribution. Differences between the personalized air terminal devices were identified in terms of
the cooling distribution over the manikins body. The personalized ventilation supplying air from the

Displacement ventilation

Advantages and drawbacks of a Displacement Ventilation system are presented in this paper, in comparison with the traditional "mixing" ventilation cooling systems.

Indoor air quality on displacement ventilation in the tropics a chamber study

This paper presents the indoor air quality performance of a displacement ventilation system ina thermal chamber. This study consists of two sets of experiments. In the first experiment, thethermal chamber was operated under displacement ventilation (DV) mode with the relativehumidity (RH) set at about 65% while the ambient temperature (AT) at 1.3 m height variedfrom 22 to 26C. In the second experiment, all the conditions are the same except that theventilation strategy is changed to mixing ventilation (MV).

Design methods for air distribution systems and comparison between mixing ventilation and displacement ventilation

The paper will discuss design models for the air distribution system in an office with twopersons. The comparisons are made between mixing ventilation and displacement ventilationand they are based on a maximum velocity assumption and a restricted vertical temperaturegradient in the room. The comparison is extended by considering both the local discomfortcaused by draught rating (DR) and the percentage of dissatisfied due to the temperaturegradient (PD).

Mixing and displacement ventilation compared in classrooms; distribution of particles, cat allergen and CO2

Mixing ventilation and displacement ventilation were compared in an intervention study inclassrooms. Particles, cat allergen and CO2, were measured in classroom air at different levelsabove the floor, during regular lessons. With mixing ventilation, the particle concentrationtended to decrease with height, with a stronger gradient occurring for larger particles. Withdisplacement ventilation, the particle concentration increased with height, except for particles>25 m. The displacement system thus tended to have a slight upward displacement effect onmost of the particles.

The influence on ventilation efficiency in typical dwelling with floor-based displacement ventilation

The characteristics of the climate in Taiwan are high temperature and humidity. In order to solvethese basic problems in dwellings, a meteorological station was established in Fulong(northeastern part of Taiwan) to document the detailed microclimatic information of indoor andambient environments during 4 years. According to the hydrodynamics and thermal mechanics,the new ventilation strategy was developed with the thermal mass cooling-down systemconstructed as the porous floor in a full-scale climate chamber.

Relative influence of boundary conditions on the indoor air quality of a displacement ventilated room

In the indoor air quality (IAQ) assessment of ventilated enclosures it is useful to know therelative influence of key boundary conditions on the personal exposure and ventilationeffectiveness, for instance as a source of information on where to allocate the greatest effortin the design phase. CFD is used to predict ventilation effectiveness and personal exposure tocontaminant sources in a displacement ventilated room subject to variation of several keyboundary conditions.

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