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Numerical Investigation of Upper‐Room UVGI Disinfection Efficacy in an Environmental Chamber with a Ceiling Fan
Author(s) -
Zhu Shengwei,
Srebric Jelena,
Rudnick Stephen N.,
Vincent Richard L.,
Nardell Edward A.
Publication year - 2013
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/php.12039
Subject(s) - ceiling (cloud) , computational fluid dynamics , environmental science , environmental engineering , mechanics , meteorology , physics
This study investigated the disinfection efficacy of the upper‐room ultraviolet germicidal irradiation ( UR ‐ UVGI ) system with ceiling fans. The investigation used the steady‐state computational fluid dynamics ( CFD ) simulations to solve the rotation of ceiling fan with a rotating reference frame. Two ambient air exchange rates, 2 and 6 air changes per hour (ACH), and four downward fan rotational speeds, 0, 80, 150 and 235 rpm were considered. In addition, the passive scalar concentration simulations incorporated ultraviolet ( UV ) dose by two methods: one based on the total exposure time and average UV fluence rate, and another based on SVE 3* (New Scale for Ventilation Efficiency 3), originally defined to evaluate the mean age of the air from an air supply opening. Overall, the CFD results enabled the evaluation of UR ‐ UVGI disinfection efficacy using different indices, including the fraction of remaining microorganisms, equivalent air exchange rate, UR ‐ UVGI effectiveness and tuberculosis infection probability by the Wells–Riley equation. The results indicated that air exchange rate was the decisive factor for determining UR ‐ UVGI performance in disinfecting indoor air. Using a ceiling fan could also improve the performance in general. Furthermore, the results clarified the mechanism for the ceiling fan to influence UR ‐ UVGI disinfection efficacy.