air distribution

The air distribution characteristics formed by an "air curtain" ventilation approach are investigated in detail. The airflow visualization and full-scale experimental results of air distribution in an occupied zone are reported in this paper. The Coanda effect of air curtain ventilation and the spreading airflow over the floor in a room are demonstrated. Additionally, the "air lake" or "air pool" phenomenon created by air curtain ventilation resembles displaced air movement to some extent.

Nowadays, the ceiling slot diffuser is very popular in offices. However one of the problems, for the producer and designer of linear diffusers, is to determine and specify correctly the throw-length data, in order to achieve optimal air movement in the occupied zone. Here, experimental studies were conducted to identify the variation characteristics in jet behaviour for ceiling slot diffusers. Nine cases, covering different aspect ratios, were measured under isothermal conditions in two test rooms using traversing measurement systems.

This paper introduces a concept of robustness of an air distribution method, which is defined as being capable of meeting the ventilation requirements during varying operational conditions. The robustness performance may be particularly important when the system allows individual control of the supply air parameters. As a preliminary example, plenum-based (ductless) air distribution methods are studied using computational fluid dynamics.

This study evaluated and optimized the thermal environment inside an air-conditioned train stationbuilding using the computational fluid dynamics (CFD) method. The impacts of some air-conditioningdesign parameters such as supply air temperature, velocity, altitude and incidence angle on indoorthermal environment were discussed. The primary air-conditioning design scheme was optimized.

In this paper air distribution solutions aiming to lower air velocities and good temperature control arestudied by measurements in 6 schools and temperature simulations. Air velocity measurementsshowed good performance of duct and ceiling diffusers which provided maximum velocities less than0.2 m/s and can be highly recommended for classrooms. The wall diffusers were clearly not suitable forclassrooms due to high velocities up to 0.43 m/s.

This paper deals with the study of natural ventilation in a building under tropical climates. Roomair distribution is analyzed with a statistical approach. The building is a cube with two opposing outdoor large openings. The cube is modeled using the RNG k-e model. A dimensionless velocity coefficient for different wind directions is evaluated for each indoor cell of the grid. Cumulative distribution function of this coefficient is calculated at different height to point out the influence of the wind direction.

Underfloor air distribution (UFAD) strategy is gaining popularity during the last years, howeverresearches about the performance of such systems still need to be deepened.One of the appreciated features of this technology is the use of an underfloor plenum below a raised floor. This plenum is used to distribute the conditioned air in the rooms and makes possible to avoid large air ducts to be installed.

We present in this paper an advanced formulation of zonal models for calculating room airtemperature and airflow distributions. It is based on a new way of sub-dividing the room usings the Octree method. It allows us to obtain a partitioning based on airflow patterns. The behaviour of the room is represented by the connection of SPARK calculation objects according to its partitioning. The SPARKs objects represent sub-zones of the room or interfaces between sub-zones. We developed an automatic generator of zonal models.

For underfloor air distribution (UFAD) systems, more rapid mixing of the supply air with ambient airis desirable for better thermal comfort, and swirling air diffusers are usually used. In order to rigorously simulate the flow characteristics of such diffusers, we used the multi-grid technique and validated it with experimental results. In this paper, the technique is used to compare the square diffuser and the swirling diffuser.

The accumulation of heat, contaminant and water vapour into the upper part of rooms is utilized in stratification and zoning room air conditioning strategies. For the zoning strategy the plume penetration through the supply air jet is an essential parameter in modelling the temperature, concentration and humidity in the lower and upper zones of the room. This paper presents an analytical method for modelling the plume penetration for an air distribution method based on horizontal inclined jets of industrial grilles.