Airflow performance characteristics of ventilators in hybrid ventilation systems

Part of the task in the design of ventilation systems involves selection and specification of system components - components sizes and expected performance characteristics or criteria to achieve specific ventilation objectives for anticipated environmental conditions. Careful selection of these components is required to ensure that they are able to react to changes in environmental conditions.

Characterization of airflows at the exit of registers using laser doppler velocimetry (LDV)

This paper reports the results of fluid flow measurements carried out at the exit of sidewall registers. Time-averaged mean velocity and turbulence (local root mean square velocity fluctuation) profiles were measured at the exit plane of two commonly used 8 in. 4 in. (203 mm 102 mm) sidewall registers.

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

Modelling microclimate in urban environments and assessing its influence on the performance of surrounding buildings

An energy balance over an urban area and over a rural one, reveals that the first case is always more complex than the last one. The urban context is able to change all the energy transferences mainly due to its own layout. Thus, analysing all the energy transferences one by one, we can find how they affect in a different way depending on the surroundings, among other influences.

Impact of ventilation strategies on particle deposition in a ventilated room: an experimental and numerical study

The deposit of particles lower than 5µm diameter, depends on the airflow path within the room along with the strength of the ventilation.This parameter has to be taken into account to predict particle indoor air quality. For that study, a numerical model

Natural ventilation in dense residential areas: studying alternatives

The provision of adequate naturally generated airflow is a vital component of energy-efficienthealthy buildings. Increasing densification in cities of today acts as a dominant influence onthe wind regime, diverting and obstructing natural wind flow to unpredictable levels.Localized air movement is often inadequate and vastly different from regional magnitudes anddirections and cannot be used as the basis of design.

Flow Network Model based on Power Balance as Applied to Cross-Ventilation

This paper reviews the flow network model based on power balance as applied to wind-induced cross ventilation in a residential building. The characteristics of wind-induced cross-ventilation with open windows in buildings are different from those of air infiltration through cracks in walls. The features of the velocity and pressure distributions are apparently different. In cross-ventilation, it seems that a kind of stream tube is formed through the building.

Impact of airflow interaction on inhaled air quality and transport of contaminants in rooms with personalized and total volume ventilation

The impact of airflow interaction on inhaled air quality and transport of contaminants betweenoccupants was studied in regard to pollution from floor covering, human bioeffluents andexhaled air, with combinations of two personalized ventilation systems (PV) with mixing anddisplacement ventilation. In total, 80 l/s of clean air supplied at 20C was distributed betweenthe ventilation systems at different combinations of personalized airflow rate. Two breathingthermal manikins were used to simulate occupants in a full-scale test room.

CFD simulation of airflow characteristics of swirling floor diffusers

Air supply diffusers used in air-conditioning systems can be classified as ceiling diffusers,side-wall diffusers, floor diffusers, jet nozzles and low velocity displacement diffusers. Fixedor adjustable slats are usually used to control airflow directions. Recently, swirling vanes areused in floor diffusers to create a swirling out-flow jet, so that more rapid mixing withambient air can be achieved.

The impact of a uniformly distributed thermal load on mixed flow

The influence of uniformly distributed cooling load is investigated on the air velocity in theoccupied zone. The experiments have been carried out in a scaled test room of 6 6 2 mwith a scale factor 1:1.5. The room is equipped with nine vortex inlets. The inlets areuniformly distributed; every inlet supplies a cubical volume to remove the maximum possiblecooling load with a minimum airflow rate. The air supply rates based on floor area are set to30 m/(h m2). The cooling load generated by mannequins is uniformly distributed and variesbetween 0 and 180 W/m2.