ASHRAE Journal - November 2023 - 48
TECHNICAL FEATURE
CFD Analysis of Room
Air Distribution: Effect
On Upper-Room UVGI
System Performance
BY KISHOR KHANKARI, PH.D., FELLOW ASHRAE; WILLIAM P. BAHNFLETH, PH.D., P.E., PRESIDENTIAL MEMBER/FELLOW ASHRAE
Airflow patterns can affect the performance of upper-room ultraviolet germicidal
irradiation (UVGI) systems. Using computational fluid dynamics (CFD) analyses, this
study systematically evaluated the impact of the air supply and return layout on the
effectiveness of the upper-room UVGI system for an overhead mixing system.
Upper-room (UR) ultraviolet germicidal irradiation
with UV-C light has been used successfully in schools to
reduce the incidence of a variety of airborne childhood
diseases, and in health-care facilities it has been used to
inactivate tuberculosis (TB) bacteria in isolation rooms
and TB wards and to reduce transmission of nosocomial
infections.1-3 The COVID-19 pandemic has created a
renewed interest in all types of UVGI systems to control
the transmission of the SARS-CoV-2 virus, but especially
UR-UVGI. Wall- or ceiling-mounted UV-C fixtures
equipped with mercury vapor or amalgam lamps
are used to generate a UV-C field, usually at 254 nm
wavelength in the upper part of a room above the
occupied zone. Microbial susceptibility to UV-C depends
on a microbial rate constant and UV-C dose, which is the
product of UV-C fluence (the flux of germicidal energy
from all directions at a point in space) and the residence
time of microbes in the UV-C field. These are the most
important factors that affect the efficacy of upper-room
UVGI systems, as shown by Equation 1.4,5
S = exp(-kD)
Where S is the surviving fraction of a microbial
population, k is the UV rate constant for a given
microorganism (m2/J) and D is the germicidal UV
dose (J/m2).
The sources of infectious aerosols are often located
within the breathing zone of occupants at about 4 ft
to 6 ft (1.2 m to 1.8 m) above the floor, while the UV-C
inactivation field is located near the ceiling. Therefore,
once the UV-C fixtures of a certain UV-C output are
Kishor Khankari, Ph.D., is the president at AnSight LLC in Ann Arbor, Mich. William P. Bahnfleth, Ph.D., P.E., is a professor at the Pennsylvania State University, in University Park, Penn.
48
ASHRAE JOURNAL ashrae.org N OVEMBER 2 0 2 3
(1)
http://www.ashrae.org
ASHRAE Journal - November 2023
Table of Contents for the Digital Edition of ASHRAE Journal - November 2023
Table of Contents
ASHRAE Journal - November 2023 - Intro
ASHRAE Journal - November 2023 - Cover1
ASHRAE Journal - November 2023 - Cover2
ASHRAE Journal - November 2023 - 1
ASHRAE Journal - November 2023 - Table of Contents
ASHRAE Journal - November 2023 - 3
ASHRAE Journal - November 2023 - 4
ASHRAE Journal - November 2023 - 5
ASHRAE Journal - November 2023 - 6
ASHRAE Journal - November 2023 - 7
ASHRAE Journal - November 2023 - 8
ASHRAE Journal - November 2023 - 9
ASHRAE Journal - November 2023 - 10
ASHRAE Journal - November 2023 - 11
ASHRAE Journal - November 2023 - 12
ASHRAE Journal - November 2023 - 13
ASHRAE Journal - November 2023 - 14
ASHRAE Journal - November 2023 - 15
ASHRAE Journal - November 2023 - 16
ASHRAE Journal - November 2023 - 17
ASHRAE Journal - November 2023 - 18
ASHRAE Journal - November 2023 - 19
ASHRAE Journal - November 2023 - 20
ASHRAE Journal - November 2023 - 21
ASHRAE Journal - November 2023 - 22
ASHRAE Journal - November 2023 - 23
ASHRAE Journal - November 2023 - 24
ASHRAE Journal - November 2023 - 25
ASHRAE Journal - November 2023 - 26
ASHRAE Journal - November 2023 - 27
ASHRAE Journal - November 2023 - 28
ASHRAE Journal - November 2023 - 29
ASHRAE Journal - November 2023 - 30
ASHRAE Journal - November 2023 - 31
ASHRAE Journal - November 2023 - 32
ASHRAE Journal - November 2023 - 33
ASHRAE Journal - November 2023 - 34
ASHRAE Journal - November 2023 - 35
ASHRAE Journal - November 2023 - 36
ASHRAE Journal - November 2023 - 37
ASHRAE Journal - November 2023 - 38
ASHRAE Journal - November 2023 - 39
ASHRAE Journal - November 2023 - 40
ASHRAE Journal - November 2023 - 41
ASHRAE Journal - November 2023 - 42
ASHRAE Journal - November 2023 - 43
ASHRAE Journal - November 2023 - 44
ASHRAE Journal - November 2023 - 45
ASHRAE Journal - November 2023 - 46
ASHRAE Journal - November 2023 - 47
ASHRAE Journal - November 2023 - 48
ASHRAE Journal - November 2023 - 49
ASHRAE Journal - November 2023 - 50
ASHRAE Journal - November 2023 - 51
ASHRAE Journal - November 2023 - 52
ASHRAE Journal - November 2023 - 53
ASHRAE Journal - November 2023 - 54
ASHRAE Journal - November 2023 - 55
ASHRAE Journal - November 2023 - 56
ASHRAE Journal - November 2023 - 57
ASHRAE Journal - November 2023 - 58
ASHRAE Journal - November 2023 - 59
ASHRAE Journal - November 2023 - 60
ASHRAE Journal - November 2023 - 61
ASHRAE Journal - November 2023 - 62
ASHRAE Journal - November 2023 - 63
ASHRAE Journal - November 2023 - 64
ASHRAE Journal - November 2023 - 65
ASHRAE Journal - November 2023 - 66
ASHRAE Journal - November 2023 - 67
ASHRAE Journal - November 2023 - 68
ASHRAE Journal - November 2023 - 69
ASHRAE Journal - November 2023 - 70
ASHRAE Journal - November 2023 - 71
ASHRAE Journal - November 2023 - 72
ASHRAE Journal - November 2023 - Cover3
ASHRAE Journal - November 2023 - Cover4
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2024november_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2024november
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_BDMHLG
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_WJDGRY
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ATMAHK
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_VHQRAW
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_XGMDXI
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_YELQLJ
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_QJLWMC
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_MCDEBX
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_WNYSQY
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_XATVOD
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_FJSHSS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_CCBZDS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_XDEFVG
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2023november_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2023november
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_VHGNBL
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_WPKBNJ
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_UUVCDE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_RTGDEW
https://www.nxtbook.com/nxtbooks/ashrae/ashraemexico_2023
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_LKRFXS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_AZSOFG
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ERCDBH
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_QWDFRV
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_JHGVDF
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_OPUYHG
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SREIBM
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_LRTGLK
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_OKRFGH
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2022november_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2022november
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_TZSERA
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_LVRUIX
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_RPTVYZ
https://www.nxtbook.com/nxtbooks/ashrae/mini_pub_catalog
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_XIYTGD
https://www.nxtbook.com/nxtbooks/ashrae/ashraemexico_2022
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_RFGDOB
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_PABXNU
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_REMKLS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_PICVBT
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_AOYTVW
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_JQOPLS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_IOYTBC
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SGAJJF
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_IGHYER
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_PDRKLS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2021november
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2021november_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_XCODFR
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_QSLFGO
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ILKVNM
https://www.nxtbook.com/nxtbooks/ashrae/ashraemexico_2021
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_OPDJKD
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_VJKSRY
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SDHUTC
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_JPPKRR
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SDLTTH
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_CKLLES
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SLDOX
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_HJETUK
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_OLUHGE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2020october
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2020october_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ZERDGH
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_QVMNEO
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_RTPOKE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_BBATRE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_STUBMW
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_TPEMPE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_JNMKDS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_FBTTPA
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_WQMMNE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_TVBRYN
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_showguide2020
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_KTUZMA
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ABEDGD
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201910
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201909
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2019septmeber_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2019september
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201908
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201907
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201906
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201905
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201904
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2019april
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201903
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2019march
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201902
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201901
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_showguide2019
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2018december
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2018november
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2018fall_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2018fall
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2018october
https://www.nxtbook.com/nxtbooks/ashrae/ashraemexico_2018
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201810
https://www.nxtbook.com/nxtbooks/ashrae/ashraeinsights_201806
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201805
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201804
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201803
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201712
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201711
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201710
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2017fall_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2017fall
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201709
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201705
https://www.nxtbook.com/nxtbooks/ashrae/ashrae_meetinginsert_201610
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2016fall_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2016fall
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_acrexindia
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2015summer_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2015summer
https://www.nxtbook.com/nxtbooks/amca/2014summer2
https://www.nxtbook.com/nxtbooks/amca/2014summer
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_acma_2014summer
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201311
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201309
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_acmasupp_2013fall
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201305
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201303
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2013winter
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201211
https://www.nxtbook.com/nxtbooks/ashrae/achr_expo_mexico2012
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201209
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201208_v3
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201208_v2
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2012summer
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201205
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201203
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2012winter
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201111_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201109_v2
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2011summer
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201105
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201103
https://www.nxtbookmedia.com