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.
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.
The aim of this paper is to investigate the effect of improved air distribution on symptoms and self-evaluated productivity in a landscape office in which the air was distributed with ventilated cooled beams. The intervention consisted of the improvement of evenness of the air distribution by installing an extra whirl diffuser at the end of every second cooled beam. As a consequence, the draught risk quantified by the draught rating model DR, was reduced to some extend.
The objective of the current investigation was to evaluate the field performance of room air distribution in two rooms of a high-performance (low heating and cooling load) home. Thetwo rooms had similar exterior exposures but had different supply register locations (high sidewall and floor). The impact of normal equipment cycling on the room air distribution performance was also investigated. The performance was evaluated based on room air temperature measurements andthe requirements of ASHRAE Standard 55 (ASHRAE 1992).
For reliable operation of computer equipment in a data center, adequate cooling air must be supplied to the equipment. The distribution of cooling air through the perforated tiles in a raised-floor data center is governed by the fluid mechanics of the underfloor space. The pressure variation in that space is shown to be the cause of nonuniform distribution of airflow. The various factors that influence the distribution are discussed. The effect of floor height and tile open area is illustrated
This article aims at providing an overview of recent field experience, as reported in the literature, about underfloor air distribution systems (UFAD) as an alternative to conventional air distribution.
Klima ADE is a program for fast selection and calculation of air diffusion devices, which isbased on:- Design criteria for the thermal environment are based on EN ISO 7730 (optimaloperative temperature and maximum mean air velocity in occupied zone).
This paper is a review of occupant responses to localized (floor and desk mounted) airdistribution systems. These systems offer personal control, and can produce good ambientconditions, but few studies have examined their effects on actual occupants. A review ofeleven studies suggested these systems can lead to favourable occupant responses, which insome cases exceed those encountered using traditional mixing systems. However, most of thestudies included methodological limitations, which reduce the strength of conclusions that canbe drawn.
The quality of air in the indoor environment is dependent on the nature and source of indoorpollutants and the performance of the ventilation system. Increased dilution in a tropical contextimplies a high energy penalty. This paper presents a novel method of addressing IAQ and energyissues. An innovative energy efficient method and means of air-conditioning for an independentcontrol of temperature and humidity of two different air streams has been developed.
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