ASHRAE Journal - October 2023 - 62

TECHNICAL FEATURE
FIGURE 7 Case 1 vertical temperature stratification (Point 1 - Point 4 refer to Online Figure 5).
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
* Point 1
* Point 2
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
285 288 290 293 295 298 300 303 305 308 310
Temperature [K]
* Point 3
* Point 4
285 288 290 293 295 298 300 303 305 308 310
Temperature [K]
temperature stratification (Figure 7).
Case 2: Meeting Room: Contours of temperature
distribution and velocity vectors are analyzed in the
meeting room in cooling mode, where the meeting room
is equipped with eight occupants, eight panels, two
lights and a window with a temperature of 40°C (104°F).
The distance between the human and the window (wall
with a temperature of 40°C [104°F]) is 900 mm (35 in.),
which has a major effect on the satisfaction of two
humans near the window and temperature distribution
(Online Figure 9).
Online Figure 10 shows symmetry in temperature and
velocity distribution through the room. Online Figure 11
shows the temperature distribution through the room
does not exceed 22°C (72°F) around the human body.
So CFD simulation results show good flow, temperature
and velocity distribution (Online Figure 10) and good
vertical temperature stratification (Online Figure 11).
Case 3: Control Room: Contours of temperature
distribution and velocity vectors are analyzed in the
control room in cooling mode, where the control room is
equipped with six occupants, six computers, two lights
and window with a temperature of 40°C (104°F). The
distance between humans and the window (wall with a
temperature of 40°C [104°F]) is 1200 mm (47 in.), which
has a medium effect on the satisfaction of two humans
near the window and on temperature distribution
(Online Figure 12).
Online Figure 13 shows symmetry in the temperature
and velocity distribution through the room. Online
Figure 14 shows the temperature distribution through
the room does not exceed 21°C (69°F) around the
human body. So CFD simulation results show good
flow, temperature and velocity distribution (Online
Figure 12) and good vertical temperature stratification
(Online Figure 14).
62
ASHRAE JOURNAL ashrae.org O CTO B ER 2023
Conclusion
The energy savings potential of ACB
systems for a simulated building (total
area of 450 m2 (4,844 ft2) in a dry
climate areas is analyzed in this study
for cooling load estimation and CFD
analysis. The simulated building consists
of two floors, each with 13 office rooms,
two meeting rooms and one control
room in Aswan, Egypt. Air conditioning
is provided for the simulated building
using AHUs (Case A) and ACB (Case B)
to estimate the amount of energy savings between the
two systems. The results indicate the amount of energy
savings due to using ACB rather than AHUs is about 32%.
The simulation building enclosure (office room) was
validated with measurements35 from a field study in an
office equipped with ACB in cooling and heating mode
(Case 1, Validation Case).
In addition, remaining building enclosures such as
a meeting room and control room in cooling mode
(Case 2, Case 3) were studied. The results showed
that using ACB in dry climates has a greater effect on
energy savings and temperature distribution than using
traditional air-conditioning devices such as an airhandling
unit, where the chilled water temperature for
ACB varies from 14°C to 18°C (57°F to 65°F); however,
the chilled water temperature for traditional airconditioning
systems such as AHUs varies from 6°C
to 12°C (43°F to 54°F) during cooling mode, which
reflects reduced energy consumption and chiller plant
capacity, higher thermal efficiency for chillers, no
need for a condensation system due to a sufficiently
high inlet water temperature equal to or above the
dew-point temperature of the room air of 14°C (57°F),
low maintenance cost, reduced amount of ductwork
installation required and reduced construction time.
There are several recommendations for future work,
such as preparing analysis of airflow distribution
and energy savings by using an active chilled beam
system versus a traditional air-conditioning system in
other types of buildings such as hospitals and medical
centers, where most health-care buildings require
total fresh air with no bacterial infection and working
24 hours per day.
Preparing an economic analysis of active and passive
chilled beam system applications will help promote
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