Bibliographic Review of Velocity Fields in the Vicinity of Local Exhaust Hood Openings

Braconnier, Robert

doi:10.1080/15298668891379585

Cited by 25 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The imposed velocity decreases exponentially with the horizontal distance from the edges of the hood. ACGIH has reported simple formulas that have been used for many years in practical applications (Bracconier, 1988). These are denoted by…”

Section: Suction Induced Flowmentioning

confidence: 99%

Personalized displacement ventilation as an energy-efficient solution for airborne disease transmission control in offices

Heij

Gkantonas²,

Mastorakos³

2023

Front. Mech. Eng.

View full text Add to dashboard Cite

There is evidence to suggest that airborne droplets play an important role in the transmission of respiratory diseases. The highest risk of exposure to these pathogens is in indoor environments, where airflow control has been recognized as one of the most effective engineering means to combat its spread. However, this can contribute to a significant increase in energy costs, as conventional ventilation is often not designed to remove contaminants efficiently. In this study, Computational Fluid Dynamics simulations were used to analyze how a novel ventilation approach, called Personalized Displacement Ventilation (PerDiVent), can simultaneously reduce both pathogenic airborne transmission and reduce energy costs in an open office. In addition, thermal comfort and noise were investigated to assess the practicality of the concept. PerDiVent was found to reduce the risk of cross infection by a factor of 1.08–2.0 compared to mixing ventilation in the worst and best case scenarios analyzed, and lead to savings in mechanical power of at least 30%. Furthermore, there is great potential to further improve the system and to increase the stated numbers substantially with relatively simple alterations to the design. Tools that can be used to great advantage for such optimization are also proposed in this work. These include a simple integral model and analytical metrics to estimate the reduction in cross-infection risk and energy savings as a function of PerDiVent’s effectiveness in removing contaminants. Finally, the system has a modular and highly flexible arrangement, which makes it suitable for retrofitting purposes in various indoor environments and integration with current ventilation systems. The concept shows great promise for the future, where ventilation is required to create healthier and more sustainable environments.

show abstract

Section: Suction Induced Flowmentioning

confidence: 99%

Personalized displacement ventilation as an energy-efficient solution for airborne disease transmission control in offices

Heij

Gkantonas²,

Mastorakos³

2023

Front. Mech. Eng.

View full text Add to dashboard Cite

show abstract

“…(7) The velocities along the centerline axis of a local exhaust hood were usually measured to characterize the capture velocity. Garrison (8) and Braconnier (9) have provided a review on the centerline velocity gradients for plain and flanged local exhaust inlets. Garrison (10,11) has also presented graphic data and fitted equations obtained from the centerline velocity measurements.…”

Section: Introductionmentioning

confidence: 99%

Effects of Flange Size on Dividing Streamlines of Exterior Hoods in Cross Drafts

Huang

Liu

Chen

et al. 2004

Journal of Occupational and Environmental Hygiene

View full text Add to dashboard Cite

Effects of flange size on the flow patterns of an exterior circular hood subject to the influence of various uniform cross drafts were studied in an apparatus consisting of hood-model/wind-tunnel assembly. The cross draft to suction velocity ratio covered the range from 0.056 to 0.792. The flange width to hood diameter ratio spanned from 1.2 to 3.0. The hood equipped without flange was also probed. A two-component laser Doppler anemometer was used to measure the velocity field on the symmetry plane. The streamline patterns were obtained from the measured velocity data. The cross draft caused a capture envelope. The boundary of the envelope was described by a dividing streamline. It was found that the flange width presented complex effects on the capture envelope and the dividing streamline. Corresponding to a cross draft to suction velocity ratio, a critical flange width existed. If the flange width was smaller than the critical value, the dividing streamline would terminate at the downstream tip of the flange. The behaviors of the capture envelope and the dividing streamline of the hood in cross draft under different flange widths are presented and discussed.

show abstract

“…Performance of the hood in a quiescent environment generally depends on how large the bell-shaped capture zone can extend to conduct an effective capture of the pollutants. The velocity distribution along the centerline axis (7)(8)(9)(10) of a local hood is usually measured in order to characterize the "capture capability. "…”

Section: Introductionmentioning

confidence: 99%

Development and Characterization of a Wake-Controlled Exterior Hood

Huang¹,

Liu²,

Lin³

et al. 2004

Journal of Occupational and Environmental Hygiene

View full text Add to dashboard Cite

A wake-controlled exterior hood was developed to overcome the negative influence of cross draft on an exterior hood and avoid the operation inconvenience caused by the enclosure of an airflow capture booth. This new type of local exterior hood used the hood suction flow to stabilize the dynamic vortex shedding that was induced when a crossflow passed over a blockage plate, and therefore formed a hydrodynamics-stabilized local isolation area for efficient removing of the contaminant. The development process was performed in a test section of an open-circuit wind tunnel. The blockage plate and the exterior hood model were placed in a wind-tunnel test section so that the crossflow could be freely supplied by the airstream of the wind tunnel. The laser light sheet flow visualization method and the laser Doppler velocimeter were employed to reveal the characteristics of the flow field. Primary influential parameters were factored out of the measured velocity results so that a design procedure was proposed. Experiments using hot-wire type alcohol sensors to measure the toluene vapor concentration distributions showed that the capture efficiency of this type of actively controlled hood was remarkably higher than that of an uncontrolled hood.

show abstract

Bibliographic Review of Velocity Fields in the Vicinity of Local Exhaust Hood Openings

Cited by 25 publications

References 0 publications

Personalized displacement ventilation as an energy-efficient solution for airborne disease transmission control in offices

Personalized displacement ventilation as an energy-efficient solution for airborne disease transmission control in offices

Effects of Flange Size on Dividing Streamlines of Exterior Hoods in Cross Drafts

Development and Characterization of a Wake-Controlled Exterior Hood

Contact Info

Product

Resources

About