Experimental Investigation of Exhaled Aerosol Transport Under Two Ventilation Systems

A. C. K. Lai, S. L. Wong

    Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

    20 Citations (Scopus)

    Abstract

    Although the importance and implications of studying expiratory droplet concentration distribution in indoor environments are obvious, experimental measurements are very scarce and incomplete. In the work described herein, spatial and temporal aerosol concentrations generated by a modeled expiratory process were studied experimentally. Two heated manikins were placed inside a chamber with either a displacement ventilation system or a ceiling supply and ceiling return ventilation system. One of the manikins emitted 0.05 micrometer monodisperse polystyrene microspheres mimicking the generation of expiratory droplets. Flow characteristics were measured by a hot-film anemometry system before and after the momentary emission of aerosols at three locations. The temporal concentration profiles at eight locations were also measured. The results show that a high-speed air jet easily penetrates the boundary layer of the manikin regardless of the ventilation system used. Transient ventilation effectiveness was also evaluated and compared for both ventilation systems. The results show that the ventilation effectiveness of displacement ventilation is always higher than that of ceiling-type ventilation. Experimental observation also suggests that the presumption of complete mixing must be applied cautiously.
    Original languageEnglish
    Pages (from-to)444-452
    JournalAerosol Science and Technology
    Volume44
    Issue number6
    DOIs
    Publication statusPublished - Jun 2010

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