Distribution of cooling airflow in a raised-floor data center

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

What real-world experience says about the UFAD alternative

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.

Air distribution design based on EN ISO 7730 with the help of a computer program

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).

A review of occupant responses to localized air distribution systems

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.

Energy efficient air-conditioning and air distribution system for improved indoor air quality

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.

Potential economical benefits of balancing airflows in an office building

Earlier studies have shown that airflows are not well balanced in office buildings. This maylead to too low ventilation rates in some rooms and too high ventilation rates in others.Several studies have shown that low ventilation rates may lead to a higher prevalence of SBSsymptoms. The reduction of these symptoms may be achieved with improved ventilation.The purpose of this study was to evaluate the benefits of balancing the airflows of the airdistribution system of an office building in Helsinki.

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).

Performance of personalized ventilation in a room with an underfloor air distribution system: transport of contaminants between occupants

Studies have documented that personalized ventilation, which provides clean air at each officeworkplace, is able to improve substantially the quality of air inhaled by occupants. However,the interaction between the airflow generated by personalized ventilation and the airflowpattern outside the workplaces has not been studied in detail. This paper presents a study onthe performance of a personalized ventilation system installed in a full-scale test room with anunderfloor air distribution system.

Personalized ventilation: experimental apparatus to evaluate high induction air terminal devices

The thermal environment in vehicles varies greatly. The interaction of the cabin thermalenvironment, created by the HVAC system, the outdoor conditions as well as the occupants,is rather complex.In this regard, in order to improve occupants comfort, we thought of locally differentiatingthe parameters which influence peoples satisfaction.

Distribution of room air contaminant concentrations as a function of ventilation and air cooling: a numerical investigation

The paper deals with a numerical investigation of the influence of ventilation and airconditioning on the distribution of pollutant concentrations in buildings. The model used is acoupled thermal and airflow model where the room is divided into 18 sub-zones.Temperatures and pressures are determined from the mass and energy conservation equationsin each sub-zone, while airflow rates between two adjacent sub-zones are determined from theBernoulli equation.

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