Journal of Energy & Environment
Journal homepage: www.uniten.edu.my/jee
Theoretical and Experimental Investigation of Energy Efficiency Improvement of the
Ceiling Fan by Using Aerodynamic Blade Profile
T.M.I. Mahlia1*, H. Moradalizadeh1, M.N.M. Zubir1, T. Olofsson2
1
2
Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia
Department of Applied Physics and Electronics, Umea University, Sweden
KEYWORDS
ABSTRACT
Energy efficiency
Ceiling fans
Airflow
Airfoil
Aerodynamic design
Ceiling fans are commonly used in tropical climate for providing comfort in domestic
buildings. Although fan energy consumption is relatively low in comparison to air
conditioning, it suffers from some degree of electricity loss which is mainly due to its
mechanical inefficiency. This paper demonstrates an approach to improve the efficiency of
a ceiling fan by replacing its conventional blades with newly designed blades. This blade
adopts a thin airfoil shape which is an essential element to improve its performance. Series
of experiments have been conducted to test the blades on actual ceiling fan. The
performance of the fan was evaluated through experimental and computational techniques.
The results show that the ceiling fan with the newly designed blades is more efficient than
conventional design.
© 2011 Universiti Tenaga Nasional. All rights reserved.
1. INTRODUCTION
Ceiling fans are essentially used to provide thermal
comfort in most household and commercial sites due to their
favorable attributes including high portability, having
considerably low cost per unit value as well as low
maintenance cost in comparison to air conditioning unit. They
are commonly found in abundant in most tropical countries
which experience high level humidity and hot weather
condition such as Malaysia. They comprise between 3 to 5
paddles or blades and in some model, a lighting facility is
incorporated as ornamental [1]. This type of fan is most
practical to be used in tropical climate area where heat
dissipation through convection is essential due to the high
level of humidity and temperature. Furthermore they are cheap
and easy to install and these criteria allow them to be widely
used in large scales. Even with the extensive use of air
conditioning units, ceiling fans remain their vital role in
providing thermal comfort. Although ceiling fans use a
relatively low amount of energy in comparison to the airconditioning units, they suffer from significant level of
electricity loss due to their inefficiencies. The unreasonably
high consumption of energy of the conventional ceiling fan is
due to high losses at the blades, as they are not designed for
optimum aerodynamic performance [2].
In addition, the noise emission from a conventional
ceiling fan at high speed is also a persistent problem [3]. In
ceiling fans, the electric energy is transformed into mechanical
energy by the rotation of the motor shaft that is controlled by a
speed controller. This energy is then converted into kinetic
energy of the airflow by interaction with the blades. Each of
these energy conversion steps collectively contribute to the
total electricity losses. However, a large portion of the losses
in conventional ceiling fans occurs at the blades. The poor
performance of the fan is attributed to the blade configuration.
This component needs further improvement to attain high
efficiency ceiling fans.
The most common blade profile being used in
conventional ceiling fans adopts a flat parameter with a fixed
nominal tilt. The weight of each blade ranges between 600 to
700 grams depending on the material used in its fabrication
[4]. Their high weight to power ratio and inexistence of an
aerodynamic feature are the predominant deficiencies which
translate into high electricity consumption and ultimately
reducing the effective air delivery of the fan. By reducing the
weight of blades, the power needed for operating the ceiling
fan will be decreased. Further, by adding an aerodynamic
feature to the existing flat profile, the fan air delivery can be
increased to provide better performance. The coefficient of
performance (COP) of a ceiling fan which describes the fan
efficiency will be expected to increase by reducing the weight
and enhancing the profile of the blades. Thus, this research
aims to conduct a comparative study on the use of a newly
designed ceiling fan which incorporates special aerodynamic
profile and lighter set of blades in comparison to the
conventional blades.
*Corresponding author Tel.: +60-3-7967-5228; Fax: +60-3-7967-5317
E-mail address: T.M.I. Mahlia < indra@um.edu.my >.
40
T.M.I. Mahlia et al./ Journal of Energy & Environment, Vol. 3 (2011), No. 1, 40-49
2. CONVENTIONAL CEILING FAN
Conventional ceiling fan typically encompasses 3 to 5 fan
blades mounted concentrically around a circular disc with full
scale diameter ranging between 68 and 150 cm [5]. The
diameter of the fan blade is generally related to the room size
and cooling capacity. A number of factors including the size,
shape, number of blades, and blade pitch contribute to airflow
effectiveness. From energy consumption perspective,
conventional ceiling fan constitutes a complex mechanism,
with four basic components that contribute to the total energy
consumption: motor, blades, control, and lighting. As there are
in average of 1 to 2 ceiling fans in each room of every
household in the tropical and subtropical countries, and each
fan operates continuously over long periods of time, often
more than 8 hours per day, the operational expenditures
accumulate substantially over time [6]. The average energy
consumption of a conventional ceiling fan is about 346
kWh/year [7]. For estimating and evaluating the energy
consumption of ceiling fans, both experimental and theoretical
methods have been pursued. Although experimental method
provides more accurate and precise representation of the
actual fan-airflow interaction, in some cases they are mostly
time consuming and less economical. In conducting fan
related research via experimental route, there are five existing
test procedures that have been developed to measure the
coefficient of performance of a ceiling fan [8]. Other related
references can be found in Refs. [9, 10]
Nowadays beside experimental methods, numerical
computation provides a practical platform to simulate the
actual condition at much lower cost with acceptable agreement
with experimental technique. Its emergence has played a
crucial role in revolutionizing testing method. Computational
method profoundly helps designers to model their idea and
achieving high accuracy design. It also facilitates designers to
reduce the manufacturing cost by conducting rigorous analysis
on the model with special software. In particular, using
computational fluid dynamics (CFD) software for modeling
and analysis paves a much more economical avenue for
designing a fan blade. The COP of a ceiling fan is formulated
by the following equation [11].
(1)
where
is average air delivery and
needed power for running the fan
is the average
41
where the velocity of the air around the blades is relatively
low. Thus airfoils that have good performance in low
Reynolds number regime are highly suitable to be used for fan
blade design. In this study, a Gilbert Morris-15 airfoil (GM15)
airfoil has been selected as the profile for the fan blade. The
selection of this variant of airfoil is based on its thin profile
having exceptional climb, glide and endurance capabilities
which are the essential elements to achieve high performance
operation in low Reynolds number. Further this type of airfoil
also produces high lift to drag ratio with maximum lift
coefficient of 1.32 at an angle of attack of 16 degrees [12].
Fig. 1 shows the schematic of the GM15 airfoil.
Fig. 1. Gilbert Morris-15 (GM15) airfoil
3.2. The airflow around the fan blade
For analyzing the air flow around the fan blade, some
characteristics of the air should be defined. For all calculation
therein, standard air viscosity will be taken as equal to 1.79E05
. As this problem is an external stream case, the
Reynolds number for airflow should be larger than 500,000
for the flow to become turbulent [13]. The Reynolds number is
derived from following theorem [14]:
(2)
Where ρ is density of air, v is velocity of the air around the
blade, l is dimension of the blade and μ is dynamic viscosity
of the air.
Another component that describes the characteristic of the
air is the Mach number. The Mach number is defined as the
ratio of local flow speed to the local speed of sound [15]. Fluid
flow in which Mach number is less than 0.3 is treated as
compressible while any value beyond this will be regarded as
incompressible [16]. The equation that represents Mach
number is given as:
(3)
3. PEMFC MODEL IMPLEMENTATION
3.1. Blade’s profile
Extensive researches have been conducted on different
kinds of airfoils such as semi-symmetrical airfoils,
symmetrical airfoils, flat bottom airfoils and positive camber
airfoils. Some of these airfoils have good performance in high
flow velocity and high Reynolds number regime and are
mostly suitable for supersonic applications. Nevertheless,
there are also some other airfoils that demonstrate high
performance in low flow velocity regime. Conventional
ceiling fans normally operate in low Reynolds number regime
where, in this case,
is the maximum blade speed that
in which is the radius of the fan and denotes its angular
speed. The fan angular speed is defined as
by which
n is the revolution of the blade per minute (RPM). In Eq. (3)
the speed of sound is given as
in which is the
√
ratio of specific heats, (
, is unique constant for air
and
is the air temperature.
T.M.I. Mahlia et al./ Journal of Energy & Environment, Vol. 3 (2011), No. 1, 40-49
3.3. Modeling and analyzing the new blade
The purpose of this part is to model and validate the
analytical model of a fan blade in a wind tunnel using
simulation software. The model of the newly designed ceiling
fan blade is presented in Fig. 2. The blade encompasses
straight outline along its axial direction and has a specific
profile with a width of 170 mm at the blade root, up to 90 mm
at the tip. The average between these two dimensions (root
and tip) is 130 mm which is equal to the width of the
conventional blade. The conventional blade that has been
selected for this study is Panasonic ceiling fan blade model FMY153 with the length of 600 mm and width of 130 mm. It is
made of steel sheet of one millimeter thickness with the
nominal tilt of 12.5 degrees. The length of the new blade is
equal to 680 mm which is 80 mm longer than the conventional
blade. The angle of blade is set by adjusting the bracket to
12.5 degrees which is identical to the angle of the
conventional blade.
42
compared to evaluate the effectiveness of the newly designed
fan blade.
Fig. 3. Embedded blade in the meshed wind tunnel
3.4. Mass of the Blade
Fig. 2. Newly designed blade sketched by SOLIDWORKS
Upon completion the newly designed fan blade, the model
is then exported to ANSYS@ to proceed with the analytical
process. Although numerical simulation is a useful tool in
predicting the airflow around a ceiling fan, modeling of a
ceiling fan as a rotational body is very complicated and
requires high computing power. Therefore, in this study, only
one blade of the ceiling fan is analyzed in a simulated wind
tunnel facility. The blade is positioned inside the tunnel
concentrically. In this study, the flow around the blade is
simulated using a fixed mesh arrangement instead of
simulating the blade using rotating mesh approach. Therefore,
the blade must first be subtracted from the wind tunnel to
represent a homogenous material prior to the meshing
procedure. Standard air properties are chosen in this numerical
study. The thermal conductivity and fluid specific heat in this
case are set as constant. Other parameters described in the
previous part such as Mach number and Reynolds number are
required as the input data for simulation. On the aspect of
meshing of the computational domain, the wind tunnel model
will be discretized into multiple elements of varying sizes.
More refined elements are placed near the blade profile and
their sizes gradually coarsen towards the imaginary wall of the
wind tunnel. By simulating the model in seven states of input
air velocity (i.e. 1 to 7 m/s) along with proper boundary
conditions, the flow solver will solve the governing equations
for each element and produce series of results in the form of
graphs, plots and special contours. Fig. 3 shows the embedded
blade model in the meshed wind tunnel. Likewise, simulation
of the conventional blade will be conducted under similar
conditions and the output results of the two blades will be
The new blade is formed by bending an aluminum sheet
of half millimeter thickness in the shape of an airplane wing.
The pure mass of the blade can be calculated by multiplying
the volume with the density of the aluminum blade. As shown
in Fig. 4, the aluminum sheet is in the form of trapezium
shape, so the area, volume and mass of the aluminum sheet
can be calculated by the following equation:
(4)
(5)
(6)
3.5. Power required for Driving the Blade
Power is defined as the time rate at which work is done.
In the case of a rigid body rotating at an angular velocity of
acted upon by a moment , the power may be expressed as
the following equation [17]:
(7)
For calculating the power consumption of the three blades
at specific revolution, both the moment and the angular speed
should be calculated by relative equations. The moment is the
product of the mass moment inertia of three blades with the
fan’s angular acceleration. The related equations are presented
below [18]:
̅
̅
(8)
(9)
(10)
T.M.I. Mahlia et al./ Journal of Energy & Environment, Vol. 3 (2011), No. 1, 40-49
Since the shapes of the newly designed and conventional
blades are different, the mass moment inertia of each blade
should be calculated by Eq. (9) in which, is the radius of
gyration and , is the mass of the blade. The radius of
gyration is equal to
√
43
exerted forces. Fig. 5 shows the fabricated blade with related
dimensions.
by which , is moment of inertia
and
is the area of the blade and. K is defined as the distance
at which the entire mass of the body should be concentrated if
its moment of inertia remains unchanged. In Eq. (10), is the
estimated time for the blade to reach the maximum angular
speed. The angular velocity
can be calculated by the
following equation:
(11)
in which , is the revolution of the blades per minute.
3.6. Coefficient of Performance
Coefficient of performance is used for evaluating the
performance of the ceiling fans. In the following formula, the
coefficient of performance is given [11]:
Fig. 4. Dimensions of the aluminum sheet and airfoils
(12)
The average air delivery of ceiling fan is calculated by two
methods; experimental and theoretical methods. The fan’s
motor power can be calculated by using the equation stated in
the previous section.
3.7. Fabricating the Blade
The newly designed blade is fabricated by forming a
trapezium aluminum sheet. In order to form this aluminum
sheet to the desired shape, two solid aluminum airfoils with
specific chord are used as the reference frame. The dimension
of the aluminum sheet and the two reference airfoils is
provided in Fig. 4. The shape and the strength of these two
airfoils are the basic parameters in designing the blade, so that
wood or plastic can also be retrofitted as the materials of these
two airfoils. In this study, aluminum is selected as the airfoils
material. The chord length of the larger airfoil positioned at
the root of the blade is 170 mm while the chord of the small
airfoil at the blade is 90 mm.
The blade is constructed by folding the aluminum sheet
over its symmetric line and restraining it in both sides of the
airfoil. The sheet is then rolled slightly over these two airfoils
to complete the shape. This configuration allows the blade to
rotate smoothly in the air leading to an increase in the air
delivery. Furthermore, using these two airfoils as a frame in
fabricating the blade increases the strength of the blade against
the exerted forces and moments. Although aluminum sheet of
0.5 mm thickness is not a good choice for the blade
construction due to its low strength and payload, folding the
sheet over these two airfoils however can significantly
increase the strength and resistance of the blade against the
Fig. 5. Fabricated blade with related dimensions
3.8. Experimental test
An experimental facility has been established with the
primary objective to measure fan power consumption as well
as airflow delivery of the ceiling fan. A digital hot wire
anemometer is mounted on a tripod to measure air velocity
and a digital power meter is used to measure electricity
consumption. This power meter is connected to a computer for
data reduction. Fig. 6 shows the facilities used in the
laboratory for measuring the needed power for driving the
ceiling fan.
The newly designed ceiling fan is mounted in a room at
approximately three meter above the room’s floor. As
mentioned before, the propeller of the blade resembles a true
airfoil to maximize airflow and efficiency. Fig. 7 shows the
newly designed ceiling fan in the laboratory
T.M.I. Mahlia et al./ Journal of Energy & Environment, Vol. 3 (2011), No. 1, 40-49
44
density of the air, is the air velocity around the blade, is the
width of the blade and is the dynamic viscosity:
As the result indicates
, the flow around this
blade, which is fixed inside the simulated wind tunnel and do
not rotate, is in laminar regime. To determine the regime of
the stream whether it is compressible or incompressible, the
maximum blade’s speed and speed of sound are required.
After calculating the blade’s speed that is equal to the local
flow speed and the local speed of sound, the Mach number is
obtained by using Eq. (3). The maximum revolution of blade
per minute is approximately 250 RPM, so that the angular
speed, linear speed and the speed of the sound in ambient
temperature can be estimated by Eq. (11).
Fig. 6. Facilities in the laboratory for measuring the fan
power
√
√
Where:
So for Mach number the Eq. (3) is used:
Fig. 7. Newly designed ceiling fan in the laboratory
The air flow measurements are made underneath the
blades at vertical distances of 150 cm from the floor and 120
cm from the ceiling fan blades. Twelve air flow measurement
stations were established starting directly below the centerline
of the fan and traversing out in radial direction at 15 cm
increments from the centerline. Air velocity was measured at
each of the air flow stations with the fan on low, medium and
high speed. The measured velocities between each
measurement station are multiplied by the corresponding area
and then multiplied by 60 to yield the volumetric flow
An efficiency index was calculated by dividing
the airflow with the measured motor power and this signifies
the coefficient of the performance of the ceiling fan or COP.
The result confirms that the Mach number is less than 0.3
so the air flow is treated as incompressible. After defining all
of the input parameters for simulation, the computation was
performed for seven different input velocities: 1 m/s to 7 m/s.
This range of velocity has been selected due to the fact that the
revolution of the ceiling fans per minute is between 50 RPM
and 250 RPM [18], and the mentioned velocity range is not
out of this fan revolution range. The summary of the
maximum absolute output values for these seven input air
velocities around the newly designed blade and conventional
blade are presented in Table 1 and Table 2, respectively. The
air flow around the blade travels downward in negative y
direction. Fig. 8 shows the velocity contour for the new blade
with the input wind tunnel air velocity of 7 m/s.
Table 1. Maximum CFD absolute values for the new blade
Input wind tunnel air velocity (m/s)
Output Velocity
(m/s)
Node
X component
4. SIMULATION RESULTS
4.1. Theoretical results
The outputs of theoretical results of this study consist of
pressure, velocity and vector contours. On top of that, two
input parameters (i.e. Reynolds number and Mach number)
need to be calculated to complete the theoretical study. The
Reynolds number is calculated from Eq. (2) in which is the
1
2
3
4
5
6
7
6383
1.635
3.271
4.906
6.541
8.176
9.812
11.447
Y Component
6240
-0.43
-0.86
-1.30
-1.73
-2.17
-2.60
-3.040
Z Component
6264
0.400
0.801
1.201
1.602
2.002
2.403
2.803
SUM
6383
1.653
3.307
4.960
6.613
8.267
9.920
11.573
T.M.I. Mahlia et al./ Journal of Energy & Environment, Vol. 3 (2011), No. 1, 40-49
Table 2. Maximum CFD absolute values for the conventional
blade
45
Table 4. Y component velocity, Air delivery and CFM for
conventional blade
Input wind tunnel air velocity (m/s)
Output Velocity
(m/s)
Conventional blade
Node
1
2
3
4
5
6
7
X component
6880
1.528
3.056
4.585
6.113
7.642
9.170
10.699
Y Component
9584
-0.42
-0.84
-1.27
-1.69
-2.11
-2.54
-2.964
Z Component
3657
0.427
0.854
1.281
1.708
2.135
2.562
2.990
SUM
6880
1.573
3.147
4.721
6.294
7.868
9.442
11.016
Fig. 8. Velocity contour for the newly designed fan blade
The y-component vector of air velocity which impacts the
blade is an important output parameter which determines the
air delivery capacity of the fan. The air delivery as volumetric
flow, in cubic meter per second, can be calculated by
multiplying this downward velocity with the area of the blade.
In Table 3 and Table 4, the y-component velocity, air
delivery and CFM for the newly designed and conventional
blades are tabulated for seven input air velocity. Air delivery
can be calculated by the following equation:
Air delivery (
of the blade (
) = Y Component velocity (m/s) × Area
) × 60 (s)
Table 3. Y component velocity, Air delivery and CFM for
newly designed blade
Wind
Velocity
(m/s)
1 m/s
Y component
velocity (m/s)
Air Delivery
(
)
CFM
0.42
2.15
77.16
2 m/s
0.85
4.29
154.33
3 m/s
1.27
6.44
231.49
4 m/s
1.69
8.59
308.65
5 m/s
2.12
10.74
385.81
6 m/s
2.54
12.88
462.97
7 m/s
2.96
15.03
540.21
For calculating the coefficient of performance, the
average air delivery and the input power for operating the
ceiling fan are required. For calculating the power, the mass of
the blades should be defined. Eq. (4) to Eq. (7) are used to
calculated the mass and the input power for both variant of the
blades. As mentioned before, the newly designed blade has
been formed by bending an aluminum sheet over two airfoils,
so the estimated blade’s volume is equal to the product of the
area of aluminum sheet with the thickness of sheet and the
mass of the blade is equal to volume of the blade times the
density of the aluminum. The corresponding calculations are
presented as follows:
[
(
)]
The density of aluminum is equal to
so
the mass of the newly designed fan blade is obtained from Eq.
(6).
(
)
Newly designed blade
Wind
Velocity
(m/s)
1 m/s
Y component
velocity (m/s)
Air delivery
(
)
CFM
0.43
2.30
82.72
2 m/s
0.87
4.60
165.44
3 m/s
1.30
6.91
248.15
4 m/s
1.74
9.21
330.88
5 m/s
2.17
11.51
413.60
6 m/s
2.60
13.81
496.33
7 m/s
3.04
16.11
579.05
The mass of the fabricated blade with its bracket and two
airfoils is equal to 0.43 kilogram. Similarly, the mass of
conventional fan blade can be calculated by using the above
formula:
T.M.I. Mahlia et al./ Journal of Energy & Environment, Vol. 3 (2011), No. 1, 40-49
(
)
By comparing the mass of these two blades, it is evident
that the power needed for the fan motor to rotate the newly
designed fan blade is less than the conventional fan blade. In
order to verify this finding, the power for rotating the newly
designed and conventional blades from stagnation state to 250
RPM was calculated by using Eq. (8) to Eq. (11).
Parameters required for determining the power of the newly
designed fan blade are given as follows
46
Table 5. Blade physical quantity between conventional and
newly designed blade
Blade physical quantity
Conventional blade
Newly designed
blade
Moment of inertia (m4)
0.00936
0.0115219
Area (m )
0.078
0.0884
Radius of gyration (m)
0.3464
0.3611
0.22
0.1682
26
26
3.25
3.25
Moment (N.m)
0.7163
0.5466
Power (W)
18.62
14.21
2
Mass moment of inertia (kg.m)
-1
Angular speed (rads )
-2
Angular acceleration (rads )
Moment of inertia:
Area of blade:
The maximum air delivery of each newly designed and
conventional ceiling fan blade is tabulated in Table 3 and
Table 4. The COP of each fan is equal to the product of
maximum air flow of all the blades divided by the fan power.
Using Eq. (12), the COP of each ceiling fan in the stagnation
state based on computational approach is given as follow:
(
Radius of gyration:
√
√
Total mass moment inertia for three blades:
̅
Angular speed of blade:
(
)
)
The COPN of new ceiling fan is
whereas
the COPC of the conventional ceiling fan is
. Therefore, it is evident that the performance of the new
ceiling fan is better than that of the performance of the
conventional fan.
4.2. Experimental result
4.2.1. Result for new fan
Assuming that the blade reaches the above angular speed from
stagnating state within 8 second, the angular acceleration can
be calculated by Eq. (10):
Now the resulting torque is calculated from Eq. (8).
̅
Finally, the power needed for driving the three blades is
obtained as:
The power for driving the conventional blade is determined
via similar procedure as for the newly designed blade. For
convenience, the results obtained for both fans are presented
in tabular form as shown in Table 5.
Three fabricated blades were assembled on the fan motor
and the complete unit was tested for three different speeds
(low, medium and high). The data were obtained from the
twelve designated stations as specified in the previous section.
The purpose of this test was to measure the air delivery and
the power needed for running the ceiling fan. For increasing
the accuracy of the results, the test was repeated three times
for each of these three mentioned speeds and the final result
was recorded by calculating the average of these three
measurements. In this section, experimental results for the
new ceiling fan are presented. Table 6 shows the results of fan
performance at low, medium and high speeds for each of the
twelve stations.
The air velocities were measured by an anemometer for
each of the twelve stations. Then, by multiplying the air
velocity with the area of the fan, the volumetric flow is
obtained. Figs. 9-10, show the air velocity and volumetric
airflow at low, medium and high speeds, respectively. The
results show that the airflow velocity and volumetric airflow
of the fan register a distinctive increment from station 1 to 3.
On the other hand results between station 3 and 5 demonstrate
T.M.I. Mahlia et al./ Journal of Energy & Environment, Vol. 3 (2011), No. 1, 40-49
47
a decreasing trend. In general, a maximum value of volumetric
airflow is recorded at almost 30 cm away from the centerline
of the fan. Nevertheless the magnitude drops sharply after
crossing this boundary until 75 cm away from the centerline of
the fan. Beyond these two active regions, the airflow velocity
and volumetric airflow gradually become zero.
Table 6. Experimental results for the new fan at three speeds
Air velocity (m/s)
Volumetric flow (
)
Station
Low
speed
Medium
speed
High
speed
Low
speed
Medium
speed
High
speed
1
0.18
1.00
1.90
22.81
126.74
240.81
2
0.25
1.15
2.00
31.69
145.76
253.49
3
0.23
1.25
2.08
29.15
158.43
263.63
4
0.26
0.60
1.50
32.95
76.05
190.12
5
0.10
0.40
0.68
12.67
50.70
86.19
6
0.08
0.20
0.26
10.14
25.35
32.95
7
0.04
0.08
0.18
5.07
10.14
8
-
0.04
0.10
-
9
-
-
0.04
10
-
-
11
-
-
12
-
-
Fig. 10. Volumetric airflow of the new fan at three speeds
Table 7. Average COP of the new fan
Description
Low
speed
Medium
speed
High
speed
22.81
Volumetric flow
32.95
158.43
263.63
5.07
12.67
power
20
45
79
-
-
5.07
COP
1.648
3.521
3.337
-
-
-
-
-
-
-
-
-
-
-
-
Average COP
2.850
4.2.2. Result for the conventional fan
The experimental results of the conventional ceiling fan
for three different speeds (low, medium and high speeds) are
tabulated in Table 8. Figs. 11-12 show the plot of air velocity
and volumetric airflow for each of the twelve stations at low,
medium and high speeds.
Table 8. Experimental results for the conventional fan at three
speeds
Air velocity (m/s)
Fig. 9. Airflow performance of the new fan at three speeds
The power required for driving the new ceiling fan at low
speed is equal to 20 watts. Its value increases to 45 and 79
watts respectively at medium and high speed. By dividing the
volumetric airflow in these three speeds with the
corresponding input powers, the coefficient of performance of
the newly designed ceiling fan can be obtained. Finally, an
average between these three values denotes the final
coefficient of performance of the fan or COP. The COP of the
newly designed ceiling fan in this study is found equal to 2.85.
These results along with other relevant quantities are given in
Table 7.
Volumetric flow (
)
station
low
speed
medium
speed
high
speed
low
speed
medium
speed
high
speed
1
0.23
1.15
2.00
23.74
118.68
206.40
2
0.28
1.34
2.29
28.90
138.29
236.33
3
0.31
1.44
2.36
31.99
148.61
243.55
4
0.35
1.00
1.90
36.12
103.20
196.08
5
0.13
0.80
1.40
13.42
82.56
144.48
6
0.04
0.09
0.80
4.13
9.29
82.56
7
-
0.04
0.08
-
4.13
8.26
8
-
-
0.04
-
-
4.13
9
-
-
-
-
-
-
10
-
-
-
-
-
-
11
-
-
-
-
-
-
12
-
-
-
-
-
-
T.M.I. Mahlia et al./ Journal of Energy & Environment, Vol. 3 (2011), No. 1, 40-49
48
5. CONCLUSIONS
Fig. 11. Airflow performance of the conventional fan at three
speeds
Fig. 12. Volumetric airflow of the conventional fan at three
speeds
The power consumption for the conventional ceiling fan
at low, medium and high speed is measured for comparison
with the new design. In this case, the input power for
operating the ceiling fan at low speed is equal to 21 Watts and
for the medium and high speed, its value is equal to 45 and 76
watts, respectively. By dividing the volumetric airflow at each
speed by the power input, the COP of the conventional ceiling
fan will be obtained.
Table 9 shows the volumetric flow, power and COP of
conventional ceiling fan in three speeds (low, medium and
high). The average COP of conventional fan shows that the
performance of the conventional ceiling fan is less than the
COP of the newly designed ceiling fan.
This paper focused on developing a new blade
configuration of a ceiling fan that is capable of reducing the
power consumption of the conventional blade leading to
higher efficiency fan. The newly designed blades mounted on
the ceiling fan have been tested using the same setup as for the
conventional fan. At low speed, the new fan produces 32.9
airflow and consumes 20 watts of power. The airflow
produced and power consumption for running the
conventional fan are 36.1
and 21 watts respectively
under similar condition. The power consumption for both fans
at medium speed is 45 watts but the airflow delivery of the
newly designed fan is 158.4
which is higher than the
conventional fan which deliver 148.6
of air. This
indicates that the COP of the newly designed fan at medium
speed is higher than the conventional fan. At high speed, the
air delivery of the fan incorporating the new blade is 263.6
with power consumption of 79 watts whereas the
airflow delivery and input power for the conventional fan are
243.5
and 76 watts respectively. It is evident that the
newly designed blade for the ceiling fan also results in higher
COP than the conventional fan at this particular speed. The
higher amount of airflow of this new blade configuration is
substantially attributed to its size, weight and aerodynamic
feature. By averaging the measurements of COP for both fans,
it was observed that the COP of the newly designed ceiling fan
is 2.85
while the COP of the conventional fan
is 2.74
. Thus this study has shown that the new
ceiling fan demonstrates better performance in comparison
with the conventional ceiling fans. One of the advantages of
this new ceiling fan is associated to the low level of
complexity in fabricating the blade. Further, the new blade
possesses higher size to weight ratio in comparison to the
conventional fan blade. This feature profoundly enhances the
volumetric airflow delivery of the fan.
NOMENCLATURES
C
cfm
COP
Scalar x components of acceleration
The surface of the airfoil
Any arbitrary extensive property
Sound speed
Cubic Feet Per Minute
Coefficient of Performance
Lift coefficient
Theoretical lift coefficient
Drag coefficient
Momentum coefficient
The relative velocity of two layers in fluid
Table 9. Average COP of the conventional fan
The length of fluid element
Description
Low
speed
Medium
speed
High
speed
Volumetric flow
36.12
148.61
243.55
power
21
45
76
COP
1.720
3.302
3.205
Average COP
2.740
The width of fluid element
The height of fluid element
The substantial derivative
The internal energy of moving fluid element
The total energy of moving fluid element
T.M.I. Mahlia et al./ Journal of Energy & Environment, Vol. 3 (2011), No. 1, 40-49
F
49
Exerted force on the body
Scalar x component of the force
The place change rate in z direction in a fixed
point
Scalar y component of force
The time change rate in a fixed point
Scalar z component of force
I
The gradient symbol
Moment inertia
̅
The time rate of change of (
Mass moment inertia
Total mass moment inertia
̅
K
Radius of gyration
L
m
M
Dimension of the body in Reynolds number
Mass
Moment
Mach number
Pressure exerted in the fluid element
The overall heat flux
P
̇
̇
Heat transfer in x direction
̇
Heat transfer in y direction
̇
R
T
V
W
Z
τ
REFERENCES
[1]
[2]
[3]
[4]
[5]
Heat transfer in z direction
[6]
Gas unique constant
[7]
Reynolds number
Temperature
Time (second)
The flow velocity in x direction
The work done due to the pressure in x direction
The flow velocity in y direction
The work done due to the pressure in y direction
The flow velocity
The flow velocity in z direction
Fan motor power (Watt)
The work done due to pressure in z direction
The ratio of lift coefficient to the drag coefficient
Shearing stress or viscous force per unit area
Shearing stress in x plate in x direction
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
Shearing stress in y plate in x direction
Shearing stress in z plate in x direction
[16]
Angular velocity
[17]
П
The pi Buckingham theorem symbol
α
The fan blade angle of attack
β
The molecular viscosity coefficient
μ
Intensive property corresponding to
λ
Second viscosity coefficient
The place change rate in x direction in a fixed
point
The place change rate in y direction in a fixed
point
) in a moving fluid
[18]
Galarraga I, González-Eguino M, Markandya A. Evaluating The Role
Of Energy Efficiency Labels: The Case Of Dish Washers. Working
Papers. 2010.
Wikipedia.Org. Incentives Program. 2012. <Availabel Online At:
Http://En.Wikipedia.Org/Wiki/Incentive_Program>.
Taylor NW, Kipp MJ, Ruppert KC. Energy Efficient Homes: Incentive
Programs For Energy Efficiency. 2009.
Parker, D. Callahan, M. Sonne, J. (1998). Development Of A High
Efficiency Ceiling Fan: The Gossamer Wind. (Florida Solar Energy
Center).FSEC-CR-1059-99.
1998.[Availbale
At:
Http://Alpha.Fsec.Ucf.Edu/~Bdac/Pubs/CR1059/CR1059.Html].
Transue M, Felder FA. Comparison Of Energy Efficiency Incentive
Programs: Rebates And White Certificates. Utilities Policy.
2010;18:103-11.
Abhyankar N, Phadke A. Impact Of Large-Scale Energy Efficiency
Programs On Utility Finances And Consumer Tariffs In India. Energy
Policy. 2012;43:308-26.
Peterman A, Kourula A, Levitt R. A Roadmap For Navigating
Voluntary And Mandated Programs For Building Energy Efficiency.
Energy Policy. 2012;43:415-26.
Sawyer SW, Friedlander SC. State Renewable Energy Tax Incentives:
Monetary Values, Correlations, Policy Questions. Energy Policy.
1983;11:272-7.
Geller H, Harrington P, Rosenfeld AH, Tanishima S, Unander F. Polices
For Increasing Energy Efficiency: Thirty Years Of Experience In OECD
Countries. Energy Policy. 2006;34:556-73.
Dutra RM, Szklo AS. Incentive Policies For Promoting Wind Power
Production In Brazil: Scenarios For The Alternative Energy Sources
Incentive Program (PROINFA) Under The New Brazilian Electric
Power Sector Regulation. Renewable Energy. 2008;33:65-76.
Schultz D, Eto J. Carrots And Sticks: Shared-Savings Incentive
Programs For Energy Efficiency. The Electricity Journal. 1990;3:32.
Blank L, Gegax D. Objectively Designing Shared Savings Incentive
Mechanisms: An Opportunity Cost Model For Electric Utility Efficiency
Programs. The Electricity Journal. 2011;24:31-40.
Stern PC, Berry LG, Hirst E. Residential Conservation Incentives.
Energy Policy. 1985;13:133-42.
Wirtshafter RM, Denver A. Incentives For Energy Conservation In
Schools. Energy Policy. 1991;19:480-7.
Umstattd RJ. Future Energy Efficiency Improvements Within The US
Department Of Defense: Incentives And Barriers. Energy Policy.
2009;37:2870-80.
Maruejols L, Young D. Split Incentives And Energy Efficiency In
Canadian Multi-Family Dwellings. Energy Policy. 2011;39:3655-68.
Lancaster RR, Berndt MJ. Alternative Energy Development In The USA
The Effectiveness Of State Government Incentives. Energy Policy.
1984;12:170-9.
Mahlia TMI, Saidur R. A Review On Test Procedure, Energy Efficiency
Standards And Energy Labels For Room Air Conditioners And
Refrigerator–Freezers. Renewable And Sustainable Energy Reviews.
2010;14:1888-900.