Field survey of occupants thermal comfort in rooms with displacement ventilation

Thermal comfort for 227 occupants in 8 office buildings with displacement ventilation was investigated. The occupants' thermal sensation was close to the predictions by the PMV index. The main conclusion is that draught is the major local discomfort factor for the occupants, mainly at lower leg. The effect of vertical temperature gradients on occupants local discomfort did not appear as evident.

Particle filtration in a ventilated room

Several studies based on analytical models and numerical simulations have shown that it is difficult to control airborne particle movements in a ventilated room. However, more knowledge and information on particle characteristics and particle movements, in combination with new numerical simulation tools, have recently made it easier to estimate particle patterns. In the present paper new information is used to evaluate the role of filtration and ventilation in the particle elimination process.

Design of low-energy cooling systems by using coupled energy simulation and computational fluid dynamics

This paper demonstrates the importance of the combined use of an energy simulation program and a CFD program for an accurate design of two low energy cooling systems : displacement ventilation and a combined chilled ceiling with displacement ventilation.

A simplified model for human induced convective air flows - Model predictions compared to experimental data.

This paper proposes a simple mathematical model for calculation of the convective air flow rate induced by humans. That model has been then compared to a more complex one and to experimental data with satisfactory results.

Displacement ventilation for room air moisture control in hot and humid climate

Few studies dealing with the effect of displacement ventilation on humidity gradient in a hot and humid region have been made . In this paper it is done with a case-study approach (measurements were made in a factory located in the Tropics). The results indicate that the humidity gradient is as significant as the temperature gradient..

Vertical distribution of contaminant concentration in rooms with floor-supply displacement ventilation

The experiment was conducted by means of a scaled-room wtih floor supply ventilation system, it intended to know the vertical distribution of contaminant concentration emitted from a human body. The validity of the models has been proved in so far as the calculated concentrations were almost equal to the measured values.

Design methods and evaluation of thermal comfort for mixing and displacement ventilation

Measurements are made first in a full-scale room ventilated with a mixing ventilation, and later with a displacement ventilation. A new method to design mixing ventilation is established. A comparison shows the thermal comfort obtained with the two systems.

Influence of moving object on air distribution in ventilated rooms

Experiment and CFD simulation show the influence of moving person simulator (of cylinder shape) and thermal manikins on air distribution in ventilated rooms.

Effect of replacement of air systems on kitchen comfort

The impact on thermal comfort of the way of introducing replacement air (to replace air being exhausted by the hood) in a kitchen was analysed using mathematical models and laboratory experiments with a tyhermal mannequin. Results allow to rank systems for replacement air introduction from the most to the least tolerable : displacement ventilation, mixing ventilation with ceiling air diffusers, front-face discharge and backdrop plenum.

Effects of velocity variations in ventilated rooms on comfort, affect and cognitive performance

96 human subjects (18 years age students from a Swedish high school) were submitted in an experimental room furnished as a classroom to different air flows issued from different ventilation systems : displacement with constant air flow rate, alternating between displacement (floor diffusers) and mixing ventilation (ceiling diffusers) with constant flow rate, mixing ventilation with varying flow rate, displacement with constant flow rate and with ceiling fans to generate air motions alternatively on and off.