‫تقرير نهائي لمشروع بحث‬
Research project final report /
Rapport final du projet de recherche
1
4102 ‫برنامج دعم البحوث العلمية‬
Grant Program for Scientific Research in Lebanon – 2012
Programme de subvention à la recherche scientifique au Liban – 2012
‫مستند إداري‬
Administrative Document
--------
Administrative information / ‫المعلومات اإلداري‬
:‫المرجع‬
Project Title - )‫عنوان المشروع (عربي وأجنبي‬
‫تحسين نظام التوزيع الهوائي لتعطيل الميكروبات والجراثيم المعدي بواسط األشع فوق البنفسجي في‬
‫القسم األعلى من الغرف‬
Optimize Air Distribution System to Inactivate Airborne Microorganisms using
Upper-room Ultraviolet Germicidal Irradiation
Principal Investigator - ‫الباحث الرئيسي‬
College Hall/Provost
Office
P.O.Box 11-0236 / Riad
El-Solh / Beirut 1107 2020
Lebanon
farah@aub.edu.lb
‫العنوان‬
Address
‫العنوان االلكتروني‬
e-mail
00961-1350000 ext 2513
Nesreen Ghaddar
‫رقم الهاتف‬
Telephone
‫االسم والشهرة‬
Name &
surname
American University of
Beirut
‫المؤسسة‬
Institution
Qatar Chair in Energy
Studies and Professor of
Mechanical Engineering
‫الوظيفة‬
Post
Co-investigators - ‫الباحثون المشاركون‬
‫العنوان االلكتروني‬
‫المؤسسة‬
e-mail
Institution
Ka04@aub.edu.lb American University of Beirut
‫االسم والشهرة‬
Name and surname
Kamel Ghali
garaj@aub.edu.lb American University of Beirut
Georges Araj
2
4102 ‫برنامج دعم البحوث العلمية‬
Grant Program for Scientific Research in Lebanon – 2012
Programme de subvention à la recherche scientifique au Liban – 2012
.1
Duration and starting date of the research / ‫المدة التعاقدي للمشروع وتاريخ بدء البحث‬
Two years
Duration (year) / ‫المدة التعاقدية للمشروع‬
May 1, 2012 - May 31, 2014
Starting date of the research /‫وتاريخ بدء البحث‬
Scientific Information / ‫العلمي‬
‫ المعلومات‬.2
ّ
Objectives - ‫الهدف‬
(mandatory field to fill 5-8 lines) – )‫ أسطر‬8-5 : ‫( معلومات إلزامية‬
The aim of this work is to study and enhance the performance of Upper-Room (UR)
Ultra-Violet Germicidal Irradiation (UVGI) systems in providing acceptable biological air
quality and then reducing cross-infection in spaces conditioned by two localized air
distribution systems recirculating a fraction of return air: Chilled Ceiling
(CC)/Displacement Ventilation (DV) system with vertical localizing air flow and Zonal
localizing systems for horizontal air localization. The contribution of the UR-UVGI in
enhancing the energy efficiency of both air distribution systems will be evaluated as well.
Achievements - ‫أالنجازات المحقق‬
(mandatory field to fill 5-8 lines) – )‫ أسطر‬8-5 : ‫( معلومات إلزامية‬
•
Upper room UVGI system has been installed in two experimental rooms available
at AUB: 1) CC/DV room with vertical air localization and 2) room with cassette-type
unit for zonal localizing air flow.
•
An experimental setup for bacteria generation and air sampling has been built in
the CC/DV room to measure using steady-state method the UR-UVGI efficacy and
validate bacteria concentrations obtained from simulations.
•
Two 3-D detailed CFD models have been developed and experimentally validated
to simulate the pathogen dispersion in both CC/DV system (for vertical air localization)
and zonal localizing air distribution system (horizontal localization). The CFD models
have been integrated with developed supplementary programs to simulate the UV
inactivation of bacteria, use of the return air, and bacteria deposition on indoor surfaces.
•
A simplified model has been developed to predict airborne pathogen dispersion in
upper-room UVGI spaces conditioned by CC/mixed DV systems. The model has been
validated by experimentation and CFD simulations.
•
A parametric study have been performed to identify the critical air return mixing
ratio to be used in CC/DV system in presence of UVGI to minimize energy consumption
without comprising indoor air quality in terms of CO2 and airborne bacteria concentration
levels in the localized zones. An energy simulation was also conducted to compare the
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4102 ‫برنامج دعم البحوث العلمية‬
Grant Program for Scientific Research in Lebanon – 2012
Programme de subvention à la recherche scientifique au Liban – 2012
economic edge of both UR-UVGI and in-duct UVGI systems.
Perspectives - ‫آفاق البحث‬
(mandatory field to fill 5-8 lines) – )‫ أسطر‬8-5 : ‫( معلومات إلزامية‬
•
The study considered the opportunity to magnify the energy efficiency of localized
air-conditioning systems using UGVI systems. The power consumption of UV devices
may be optimized through occupancy-based control technologies.
•
The experimentally validated simplified model can be used as a design tool that
determines the optimal return air mixing ratio for maximum energy efficiency and good
indoor air quality in CC/DV spaces. The model can be extended to include bacteria
deposition on surfaces for more accurate predictions of bacterial concentrations in spaces
conditioned by CC/DV.
•
Future work may consider modeling the bacteria growth in biologically
contaminated localized air-conditioning systems to determine accurate boundary condition
at the supply.
•
The evaluation criteria for good air quality may be expanded to comprehend the
concentration levels of volatile organic compounds (VOC) and other indoor air
contaminants in addition to CO2 and airborne bacteria.
Publications & Communications - ‫المنشورات والمساهمات في المؤتمرات‬
A. The following journal paper has been accepted for publication
M. Kanaan, N. Ghaddar, K. Ghali, G. Araj. New Airborne Pathogen Transport Model
for upper-room UVGI spaces Conditioned by Chilled Ceiling and Mixed
Displacement Ventilation: Enhancing Air Quality and Energy Performance. Energy
Conversion and Management, accepted for Publication, may 2014.
Energy Conversion and Management Journal Impact Factor is 3.07.
B. The following paper has been submitted to the ASHRAE International Conference
on Efficient Building Design: Materials and HVAC Equipment Technologies,
which will take place Oct. 2-3, 2014, in Beirut, Lebanon.:
M. Kanaan, N. Ghaddar, K. Ghali. G. Araj. CFD Investigation of the Performance of
Localized Air-Conditioning with Upper- Room Ultraviolet Germicidal Irradiation in
Reducing Cross-Infection.
C. The following journal paper is in preparation:
M. Kanaan, N. Ghaddar, K. Ghali. Localized Air-Conditioning with Upper-Room
UVGI Systems: Reduction of Cross-Contamination. In preparation.
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4102 ‫برنامج دعم البحوث العلمية‬
Grant Program for Scientific Research in Lebanon – 2012
Programme de subvention à la recherche scientifique au Liban – 2012
Abstract - ‫موجز عن نتائج البحث‬
(mandatory field to fill 5-8 lines) – )‫ أسطر‬8-5 : ‫( معلومات إلزامية‬
The main goal of the study is to evaluate the effect of using maximum fractions of return
air on energy efficiency of localized air-conditioning systems. In fact, increasing the
return air mixing ratio results in reducing energy consumption, but it is always
constrained by indoor air quality (IAQ) requirements for CO2 (maximum 700ppm) and
bacteria concentrations (no more than 500CFU/m3) at the breathing level. The use of
UVGI (upper-room type and in-duct type) will enhance the biological air quality at
relatively low cost. However, the in-duct type consumes more energy since effective
disinfection using this type requires high UV output level due to short exposure time to
UV in the supply duct. The performance of upper-room UVGI system in providing
healthy indoor air quality in spaces with mixed localized air-conditioning systems is
evaluated using CFD modeling, mathematical modeling, and experimentation. The energy
efficiency of the systems is assessed as well. The work has come up with the following
conclusions:
1.
The simplified model for airborne bacteria transport in CC/DV conditioned
was validated by experimentation.
2.
The bacteria concentration predicted by the simplified model agreed well with
experimentally-validated CFD results.
3.
The bacteria concentration requirement is more stringent than that of CO2, and
then the use of UVGI allows maintaining acceptable bacteria concentration in the
breathing zone without any necessary decrease in the mixing ratio.
4.
The upper-room UVGI achieved a disinfection rate of 25% at the breathing level
in CC/DV system operating with 100% fresh air, while 89% killing rate was achieved at
the room exhaust. The air in the upper room is effectively disinfected due to high UV
dose it receives due to the intense UV field and significant residence time in the upper
recirculation zone. Therefore, relatively high fractions of return air can be used to
maximize energy savings without violating the requirement of healthy air quality.
5.
Using the return mixing ratio dictated by the WHO standard for bacteria
concentrations without the use of UGVI, the CC/DV system consumes up to 27% less
energy than the 100% fresh air system. When the CC/DV uses higher fractions of return
air permitted by the presence of UVGI, energy savings can reach 35% in case of upper
room UVGI; while no more than 12% saving can be achieved when using in-duct UVGI.
6.
The CFD simulations showed that localized air flow may not prevent crossinfection within one environmental zone, especially in extreme cases such as the case of
high density of infected occupants. CFD results showed that this issue may be resolved
using UR-UVGI that can significantly reduce the bacterial concentration at the breathing
level in localized air-conditioned spaces.
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4102 ‫برنامج دعم البحوث العلمية‬
Grant Program for Scientific Research in Lebanon – 2012
Programme de subvention à la recherche scientifique au Liban – 2012
‫توقيع الباحث‬
6
4102 ‫برنامج دعم البحوث العلمية‬
Grant Program for Scientific Research in Lebanon – 2012
Programme de subvention à la recherche scientifique au Liban – 2012
Final report /
Rapport Final
Warning / Avertissement
1. The final report must be limited to results directly related to the research project
supported by the Council excluding any other activity carried out by the investigator
otherwise the report will be rejected.
2. Appendices may be added or attached to the report.
1. Le rapport final doit être limité aux résultats directement liés au projet de recherche
soutenu par le Conseil à l'exclusion de toute autre activité menée par le chercheur
sous peine de rejet.
2. Des annexes peuvent être ajoutées ou attachées au rapport.
1.
Principal investigator / Chercheur principal
Name and surname /
Nom et prénoms
Nesreen Ghaddar
Institution of affiliation /
Institution d'affiliation
American University of Beirut
2.
Title of the project as proposed in the original application /
Titre du projet tel qu'il a été proposé dans la demande originale
(English and French / Anglais et Français)
Optimize Air Distribution System to Inactivate Airborne Microorganisms
using Upper-room Ultraviolet Germicidal Irradiation
‫تحسين نظام التوزيع الهوائي لتعطيل الميكروبات والجراثيم المعدية بواسطة األشعة فوق البنفسجية في القسم‬
‫األعلى من الغرفة‬
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4102 ‫برنامج دعم البحوث العلمية‬
Grant Program for Scientific Research in Lebanon – 2012
Programme de subvention à la recherche scientifique au Liban – 2012
3. Purpose of the project / Objectifs du projet
(1page)
A. Project objectives and outcomes as stated in the submitted proposal and degree of
success in achieving the project outcomes
The aim of this work is to study and enhance the performance of Upper-Room (UR) UltraViolet Germicidal Irradiation (UVGI) systems in providing acceptable biological air quality
and then reducing cross-infection in spaces conditioned by two localized air distribution
systems: Chilled Ceiling (CC)/Displacement Ventilation (DV) system with vertical localizing
air flow and Zonal localizing systems for horizontal air localization. The study considers the
economic viability of both systems when using a fraction of the return air and investigates the
ability of UVGI to maintain healthy air quality in the localized zones. Computational Fluid
Dynamics (CFD) models are developed to simulate the pathogen dispersion and air
disinfection with UV in both localized air distribution systems. Experimentally validated
mathematical models are used to predict the UV fields in the conditioned spaces and are
incorporated in the CFD codes. The developed CFD models are also validated using
experimental air flow and thermal data. A simplified model is also developed to predict the
vertical distribution of airborne bacteria in UR-UVGI spaces conditioned by CC/mixed DV
systems. The simplified model predictions of bacterial concentrations, with and without the
use of UVGI, inside the space are compared with CFD results and then validated by
experimentation. The validated model is used to perform a parametric study to determine the
return air mixing ratio that minimizes the energy consumption of the system while meeting
ASHRAE standard for good indoor air quality (700 ppm CO2 at the breathing level) and
permissible bacteria concentration level recommended by WHO for no more than
500CFU/m3 in the breathing zone. Additional CFD simulations of the zonal localizing air
flow are performed to investigate the effect of the UV output and fresh air intake delivered to
the space on the UV disinfection rate
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4102 ‫برنامج دعم البحوث العلمية‬
Grant Program for Scientific Research in Lebanon – 2012
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4. Expected outputs / Résultats attendus
1 page max / 1 page au maximum
This work aims at evaluating the positive impact of upper-room UVGI on indoor air quality
and energy efficiency in localized air-conditioning systems using the return air. The study
considers two air distribution systems: the CC/DV system used for vertical air localization
and zonal localizing air-conditioning system for horizontal air localization. In order for this
goal to be achieved, the following deliverables should be done:
1. To determine the indoor airborne germ distribution in spaces conditioned by the two
HVAC systems with and without the use of upper-room UVGI. This deliverable will
be achieved using CFD models validated using experimental airflow and thermal data.
The developed CFD models will use the Eulerian approach to simulate the airborne
bacteria transport and should be able to simulate the recirculation of a fraction of the
return air, deposition of microorganisms on indoor surfaces, and spatial UV
distribution and associated inactivation of bacteria
2. To build the experimental setups needed to determine accurate supply conditions to be
used in the simulations and validate the developed models. Experiments will include
measuring indoor air velocities and temperatures, UV irradiance levels, and bacteria
concentrations before and after UV exposure. Measurements will be taken at different
heights and positions in the experimental rooms.
3. To provide a simple predictive tool that can determine, at low computational cost, the
maximal return air mixing ratio to be used to minimize the energy consumption and at
the same time maintain good air quality in the localized breathing zone. Due to the
stratified air flow in CC/DV systems, a simplified multi-layer model will be developed
and experimentally validated to predict the vertical distribution of bacteria in upperroom UVGI spaces conditioned by CC/mixed DV and determine which of the two
concerned air quality requirements (maximum of 700 ppm CO2 or maximum of 500
CFU/m3bacteria in the breathing zone) is more restrictive. The model should also
determine convenient values of the used return ratios.
4. To evaluate the energy savings achieved from using maximum fractions of return air
in presence of UVGI and compare the system energy consumption for both upperroom and in-duct types of UVGI.
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Grant Program for Scientific Research in Lebanon – 2012
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Résultats obtenus / Obtained results
5 to 10 pages / 5 à 10 pages
Appendices can be added a the end of this document / Des annexes peuvent être ajoutées à la
fin de ce document
1. Upper-room UVGI system was installed in two experimental rooms at AUB: the
CC/DV room and room with cassette-type unit for zonal localizing air flow. The UV
fixtures contain each 18W UCV lamps and are mounted at minimal height of 2.3 m.
Louvers are composed of 1 mm thick iron sheets. Reflectors are made of highly
reflective stainless Steel of thickness 0.7 mm. The UV fields in the CC/DV room was
measured using actinometrical cells that were uniformly distributed at 1 m from the
floor to measure the UV irradiance in at the eye level, and at heights 2.2 m and 2.4 m
to measure the UV field in the upper irradiated zone. The average UV irradiance when
one and two lamps were ON were respectively 0.0008W/m2 and 0.0017W/m2 in the
occupied zone ; whereas the values 0.2106W/m2 and 0.3111W/m2 were measured in
the UV zone. These experimental data was compared with the predictive model of Wu
et al. (2011) and results showed reasonable agreement with maximal error of 9% for
the upper UV field and 14% for the values obtained for the occupied zone.
2. Experimental air flow and thermal data measured in the test rooms were used to
determine accurate supply conditions to be used in the simulations and validate their
predictions. An anemometer system (Model IFA 300 16 channels, accuracy 0.15%)
equipped with a xyz traverse table was used to mount the probes in order to measure
air velocity at different points. Temperature was measured using a type T
thermocouple (±0.3°C) linked to the anemometer system. The air flow measurements
agreed well with the CFD values with relative errors 8-11% ; whereas, 3-5% error was
identified in the temperature value comparison.
3. The three specific user-defined functions were successfully developed in C++ and
interpreted/compiled on ANSYS 14.0 (CFD software). These supplementary
programs enabled the CFD code to simulate the recirculation of a fraction of the
return air, deposition of microorganisms on indoor surfaces, and spatial UV
distribution and associated inactivation of bacteria. Figs.1-3 show samples of CFD
results generated by ANSYS 14.0.
Fig. 1: Contour plots of the (a) themal field, (b) Carbone dioxide concentration, and (c)air velocity field in the CC/DV
room for 100% fresh air case (supply flowrate: 0.1 kg/s, supply air temperature: 20.4°C, chilled ceiling temperature:
18°C, CO2 generation rate: 4×0.6 L/min, heat output 4×100W)
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4102 ‫برنامج دعم البحوث العلمية‬
Grant Program for Scientific Research in Lebanon – 2012
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5 to 10 pages / 5 à 10 pages
Appendices can be added a the end of this document / Des annexes peuvent être ajoutées à la
fin de ce document
Fig. 2: Contour plots of bacteria concentration a 100% fresh air case for the same conditions mentioned above with
bacteria emission rate of 2×700CFU/m3 of S.aureus (a) without the use of UV and (b) with the use of UV
Fig. 3: Contour plots of air (a) velocity and (b) temperature in the room with horizontal air localization (supply flow
rate 0.1 m3/s, air supply temperature 16°C, heat output 4×100W)
4. The experimental setup for bacteria generation and air sampling in the CC/DV room
was built to measure using steady-state method the UR-UVGI efficacy. The room was
equipped with a mechanical ventilation system that delivers high efficiency
particulate air (HEPA)-filtered outside air through the supply system. The room
conditions were the same as mentioned in part 3. A suspension of S. marcescens
(108CFU/mL) will be introduced into the room 1.05 m above the floor from via a sixjet atomizer (Model 9306A, TSI, Inc., USA) at a flow rate 12 L/min and pressure
138KPa. Air samples were collected at the supply diffuser, exhaust grill (at height 2.5
m), and at the breathing level of a seated adult 1.05 m from the floor. Two
experiments were conducted: the first without operating the UVGI system and the
second with the two UV lamps operated. The results of bacteria enumeration revealed
a disinfection rate of 25% at the breathing level and 90% at the exhaust for 100%
fresh air operation of CC/DV.
5. The simplified model of bacteria dispersion in UVGI spaces conditioned with upperroom UVGI was developed and validated by experimentation. The values of bacterial
concentration obtained from the simplified multi-layer model applied on the current
experimental setup were compared with the measured values. Results displayed in
Fig. 5 show good agreement with a maximal error of 19%.
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4102 ‫برنامج دعم البحوث العلمية‬
Grant Program for Scientific Research in Lebanon – 2012
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Fig. 4: Comparative plot of bacteria concentrations predicted by the model and those obtained by measurements (a)
without use of UV and (b) with use of UV
6. The values of bacterial concentrations obtained from the simplified model were
evaluated as average values for each layer outside the plume for all layers and was
compared with bacterial concentrations predicted by the detailed 3-D CFD model
averaged over each corresponding layer in the simplified model. Fig. 4 compares the
multi-layer model and detailed CFD simulation predictions of bacteria concentrations
as a function of height for room air (a) without use of UV and (b) while using UV.
The model results are in good agreement with CFD results with a maximum error of
34.2 CFU/m3 in the exhaust air when UV is not used and 10.4 CFU/m3 when UV is
used.
Fig. 5: Plots of the results using the multi-layer model and the CFD simulation predictions of bacteria concentrations
as a function of height for room air (a) without use of UV and (b) with use of UV
7. The validated simplified model was demonstrated using a case study (CC/DV room)
to determine the critical return ratio providing good indoor quality with maximal
energy efficiency. The energy performance of the whole system for different return
air mixing ratios and UVGI types was simulated for three typical days during the
cooling season in Beirut. Results shown in Fig. 6 shows that the high fractions of
return air in the presence of UVGI, energy savings can reach 35% in case of upper
room UVGI, while no more than 12% saving can be achieved when using in-duct
UVGI.
Fig. 6: Comparison of the system electrical consumption for different mixing ratios and UVGI setups
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Grant Program for Scientific Research in Lebanon – 2012
Programme de subvention à la recherche scientifique au Liban – 2012
Summary table of expected and obtained results / Tableau récapitulatif des résultats attendus
et des résultats obtenus
Table 1. Project stated outcomes and their extent of completion.
No.
Outcome/goal
Extent of completion
1.
Install the upper room UVGI
Three 18 W UV fixtures were installed in the
system in the two experimental room with cassette-type unit and two 18 W UV
rooms available at AUB: 1)
fixtures were installed in the CC/DV room at
CC/DV room and 2) room with height 2.3 m.
cassette-type unit for zonal
localizing air flow.
This outcome has been completed
2.
Take UV irradiance
The UV irradiance was measured by actinometry.
measurements to determine the Actinometrical cells were placed evenly at
UV distribution in both rooms
different heights in both lower occupied zone and
upper irradiated zone of each room. The
experimental data was used to validate the
mathematical predictive model of Wu et. al (2011)
that was used to compute the spatial distribution of
UV irradiance.
Results showed reasonable agreement between
the model predictions and measurements with
maximal error of 14%.
Outcome has been completed.
3.
A set of air flow and thermal measurements were taken in
Take air velocity and
several locations and heights to:
temperature measurements at
determine accurate supply conditions to be used in the
different locations in both
simulations
experimental rooms
- validate the developed CFD model.
The
air
temperature
and
velocity
measurements agreed well with the CFD values
with respective maximum relative errors of 5%
and 8%.
Outcome complete
4.
The Eulerian method was implemented to simulate using
Develop a 3-D detailed CFD
CFD (software: ANSYS 14) the transport of airborne
model to simulate the pathogen
bacteria in spaces conditioned by CC/DV and those with
dispersion in both CC/DV
zonal localized air flow. Three supplementary programs
system (for vertical air
were developed and integrated with the CFD code as userlocalization) and zonal
defined functions to perform the following:
1. Add the UV inactivation as sink term in each
localizing air distribution
computational cell.
system (horizontal localization)
2.
3.
Simulate the use of return air
Impose the “trap” boundary condition on walls to
simulate the bacteria deposition on surfaces (only for
zonal localizing air flow)
The contour plots of velocity, temperature, and species
were generated by the CFD software.
5.
Validate the developed CFDUV model using published
experimental data.
In order to validate the developed CFD-UV model, the
bacteria concentration was predicted for the setup
described in the published work of Miller and Macher
(2000) in which they experimentally measured bacteria
concentration and investigated the efficacy of
germicidal lamps in inactivating different types of
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4102 ‫برنامج دعم البحوث العلمية‬
Grant Program for Scientific Research in Lebanon – 2012
Programme de subvention à la recherche scientifique au Liban – 2012
6.
Develop a simplified model for
airborne pathogen transport in
upper-room UVGI spaces
conditioned by
CC/mixed DV
7.
Build the experimental setup
for bacteria generation and air
sampling in the CC/DV room to
measure using steady-state
method the UR-UVGI efficacy.
Moreover, perform experiments
to validate the simplified
model.
Experimentally evaluate the
UVGI efficacy
8.
9.
Validate the simplified model
by experimentation
10.
Compare the CFD predictions
of bacteria concentrations in
CC/DV spaces with and
without upper-room UVGI.
11.
Perform a parametric study
using the simplified model to
determine the optimum return
air mixing ratio for enhancing
energy performance and indoor
air quality.
12. Study the energy efficiency of
the mixed CC/DV system when
airborne bacteria.
Comparison showed agreement with maximum
error of 8%.
A mathematical model was developed based on
Kanaan et al. (2010) mutli-layer model for contaminant
transport in CC/DV rooms and Noakes et al.(2004)
mutli-zone model for evaluating the upper room UGVI
efficacy.
Outcome complete
The CC/DV room was equipped with: a HEPA filter
in the supply duct for safety and environmental
control,
a six-jet atomizer for injecting bacteria
solution (108-109 CFU/ml), and constant flow air
sampling pumps for air sampling through glass
impingers.
Outcome complete
Experiments using S. marcescens with and without
operating the UV device were conducted. Bacteria
were enumerated after incubation. The number of
bacteria colony forming units obtained after the UV
exposure was compared to that obtained before the use
of UV to determine the UVGI efficacy.
Results revealed a disinfection rate of 25% at the
breathing level and 90% at the exhaust for 100%
fresh air operation of CC/DV.
Air samples were collected at the supply, breathing
level, and room exhaust. Measured bacteria
concentrations were also compared with those
predicted by the simplified model.
Results showed a good agreement with a maximum
error of 19%.
The values of bacterial concentration obtained from the
simplified model were evaluated as average values for
each the room air layer and was compared with
bacterial concentrations predicted by the detailed 3-D
CFD model averaged over each corresponding layer in
the simplified model.
The model results are in good agreement with CFD
results with a maximum error of 34.2 CFU/m3 in
the exhaust air when UV is not used and 10.4
CFU/m3 when UV is used.
The validated model was used as a simple predictive
tool that determines, at low computational cost, the
vertical distribution of airborne bacteria in CC/DV
spaces with given return ratio and UV output
Outcome complete.
Energy simulations of a case study of CC/DV space
were performed with different return air mixing ratios
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using upper-room and in-duct
UVGI
5.
and UVGI types (upper-room and in-duct).
Results showed that the high fractions of return air
in the presence of UVGI, energy savings can reach
35% in case of upper room UVGI, while no more
than 12% saving can be achieved when using induct UVGI
Possible encountered difficulties / Difficultés éventuelles rencontrées
Several challenges have been faced throughout this work:
1. To write special programs in C++ (user-defined functions : udf) to be interpreted or
compiled on ANSYS required learning some of the language syntax. Moreover, since
udf’s access data from a ANSYS/FLUENT solver, we needed to learn the basics of
grid structure and terminology. The most challenging programming task was to
develop a compiled udf to compute the specified mass fraction of bacteria on walls to
include its deposition on the indoor surfaces. The corresponding udf should capture
the boundary layer at the wall and fluid properties in neighbouring computational
cells and others.
2. A problem of convergence was faced in the steady-state simulation of the zonal
localizing air flow. This was due to the turbulent interaction between the buoyancydriven flows from the four heat sources and the downward supply jets from the
cassette-type cooling unit leading to unstable solution at steady-state. Therefore,
transient, and not steady-state, simulations were performed with relatively small time
step.
3. It was not clear how to find an equivalent concentration value in CFU/m3 (adopted
unit in WHO standard) to the bacteria molar fraction given by the CFD software. The
molar fraction was then multiplied by the bacteria density in kg/m3 and then divided
by the mass of one bacterium. Our CFU conversion assumed that each colony forming
unit arises from a single viable bacterium which is quite conservative in assessing the
cleanliness of air.
4. The Lagrangian approach was preferred over the Eulerian approach to simulate the
bacteria transport and inactivation using UV since each individual microorganism can
be tracked. This tracking model helps to determine the residence time of each particle
and then make accurate predictions of the total UV dose that it has received by the
time it leaves the simulated space. However, the simulation of recirculating the return
air is not feasible in the Lagrangian method since particles cannot be tracked anymore
or returned back into the computational domain after escaping from it. Consequently,
the CFD simulations used the Eulerian approach to simulate the bacteria transport and
special udf to simulate the use of return air.
5. Scientific publications )articles in peer review journals, books,
communications, etc …) / Publications scientifiques (articles dans des
revues à comité de lecture, livres, communications, etc …)
15
4102 ‫برنامج دعم البحوث العلمية‬
Grant Program for Scientific Research in Lebanon – 2012
Programme de subvention à la recherche scientifique au Liban – 2012
Attach a copy of each publication as it appeared in the journal) / (Joindre une copie de
chaque publication telle qu'elle a paru dans la revue)
A. The following peer-reviewed journal paper has been accepted for publication and
it acknowledges NCSR support

M. Kanaan, N. Ghaddar, K. Ghali, G. Araj. New Airborne Pathogen Transport
Model for upper-room UVGI spaces Conditioned by Chilled Ceiling and Mixed
Displacement Ventilation: Enhancing Air Quality and Energy Performance. Energy
Conversion and Management, accepted for Publication, may 2014.
Energy Conversion and Management Journal Impact Factor is 3.07.
B. The work has resulted so far in the following peer-reviewed conference papers:



Kanaan M., Ghaddar N., Ghali K. Localized Air-Conditioning with UpperRoom Ultraviolet Germicidal Irradiation for Energy Conservation and
Reduction
of
Disease
Transmission.
Accepted
for
Presentation/Proceedings of CLIMA 2013 11th REHVA World Congress
& 8th International Conference on IAQVEC "Energy Efficient, Smart &
Healthy Buildings" on June 16 - 19, 2013, Prague.
M. Kanaan, N. Ghaddar, K. Ghali. N. G. Araj, W. Chakroun, M. Darwish.
Upper Room UV-Disinfected Mixed Air Use for Chilled Ceiling
Displacement
Ventilation
System
to
Enhance
Air
Quality and
Performance. First ASHRAE International Conference on Energy, Indoor
Environment in Hot Climates. Feb. 24–26, 2014 Doha, Qatar. Paper
presented and appeared conference proceedings.
M. Kanaan, N. Ghaddar, K. Ghali. Air Quality in Localized AirConditioned
Spaces
Utilizing
Upper-room
UVGI
System.
Oral
Presentation in the International Conference and Exhibition on Mechanical
& Aerospace Engineering, September 30- October 2, 2013 San Antonio,
Texas, USA.
6. Oral presentations or posters in national, regional and international
conferences / Présentations orales ou affichées à des congrès nationaux,
régionaux ou internationaux.
16
4102 ‫برنامج دعم البحوث العلمية‬
Grant Program for Scientific Research in Lebanon – 2012
Programme de subvention à la recherche scientifique au Liban – 2012
(Attach a copy of each presentation as it was presented or published in refereed
conference proceedings)/ (Joindre une copie de chaque présentation telle qu'elle a été
affichée ou publiée dans les comptes rendus des congrès)
E. The following poster has been presented in the 4th Annual AUB Biomedical
Research Day, Feb. 15, 2014, Beirut, Lebanon:
M. Kanaan, N. Ghaddar, K. Ghali, G. Araj. The use of Upper-Room Ultraviolet
Germicidal Irradiation for Chilled Ceiling Mixed Displacement Ventilation System
to Reduce Disease Transmission.
F. The following paper has been submitted to the ASHRAE International Conference
on Efficient Building Design: Materials and HVAC Equipment Technologies,
which will take place Oct. 2-3, 2014, in Beirut, Lebanon.:
M. Kanaan, N. Ghaddar, K. Ghali. G. Araj. CFD Investigation of the Performance of
Localized Air-Conditioning with Upper- Room Ultraviolet Germicidal Irradiation in
Reducing Cross-Infection.
17
4102 ‫برنامج دعم البحوث العلمية‬
Grant Program for Scientific Research in Lebanon – 2012
Programme de subvention à la recherche scientifique au Liban – 2012
How to submit the final report ?
Comment soumettre le rapport final ?
-------The final report must be submitted to Council in two versions :
 A hard copy which can be mailed or delivered directly to the Council
administrative seat;
 An electronic version, Word document, on CD-ROM or USB drive or email sent to the Council at the following address : grp@cnrs.edu.lb
Le rapport final doit parvenir au Conseil en deux versions :
 Une version sur papier qui peut être envoyée par la poste ou déposée
directement au siège administratif du Conseil ;
 Une version électronique en format Word sur CD-ROM ou sur clé USB, ou
envoyée au Conseil par e-mail à l'adresse suivante : grp@cnrs.edu.lb
18
4102 ‫برنامج دعم البحوث العلمية‬
Grant Program for Scientific Research in Lebanon – 2012
Programme de subvention à la recherche scientifique au Liban – 2012
‫برنامج دعم البحوث العلمي في لبنان لعام ‪2112‬‬
‫صفح ‪8‬‬
‫‪--------‬‬‫‪ .11‬تقديم التقرير النهائي‪:‬‬
‫‪ .0100‬في نهاية المشروع (سنة أو سنتين)‪ ،‬على الباحث تقديم تقرير نهائي (نسخة ورقية ونسخة‬
‫إلكترونية بصيغة ‪ Word‬على قرص مدمج أو ‪ USB‬أو ترسل إلى المجلس بواسطة البريد‬
‫االلكتروني على العنوان التالي‪ ،grp@cnrs.edu.lb :‬وذلك وفقاً للنموذج المعتمد في المجلس‬
‫والموجود على موقع المجلس ‪ http://www.cnrs.edu.lb‬مرفقاً بالتصفية المالية لمشروع‬
‫يبين فيه ما‬
‫البحث‪ .‬ال يقبل التقرير النهائي إالّ إذا عرض الباحث بشكل واضح جدوالً مفصالً ّ‬
‫تم إنجازه مقارن مع تصوره لمخرجات المشروع عند قبوله‪ ،‬على أن ال يتضمن سوى ما له‬
‫عالقة مباشرة بمشروع البحث المدعوم من المجلس دون إغراقه بأية تفاصيل أو نشاطات أخرى‬
‫والتركيز حص اًر على النتائج التي توصل اليها الباحث‪.‬‬
‫‪ .0104‬يعتمد المجلس في تقييم التقرير النهائي على األهمية العلمية للمقاالت الصادرة عن الباحث‬
‫وذات العالقة بمشروع البحث المدعوم من المجلس من خالل عدد من المعايير والمؤشرات‬
‫الدولية نذكر من بينها على سبيل المثال ‪Impact Factor, Citation Index:‬‬
‫‪19‬‬
‫برنامج دعم البحوث العلمية ‪4102‬‬
‫‪Grant Program for Scientific Research in Lebanon – 2012‬‬
‫‪Programme de subvention à la recherche scientifique au Liban – 2012‬‬