International Journal of Agriculture and Forestry 2014, 4(3): 145-153
Air Velocity Produced by Different Types of Mixing and
Ceiling Fans to Reduce Heat Stress in Poultry Houses
Amani Al-Dawood1,*, Wolfgang Büscher2
1Ph.D. in Animal Physiology, Hygiene and Environment, Researcher at the National Center for Agricultural Research and Extension
2Prof. of Livestock Technology, Department of Livestock Technology, Institute of Agricultural Technology, University of Bonn,
Abstract Poultry sector is still facing many problems due to heat stress during the periods of high temperatures. These
include high mortality due to heat stroke, low chicken's growth rate, body gain, feed consumption and feed efficiency.
However, air velocity is a main factor involved in thermoregulation. To overcome high temperature, it is necessary to
increase the rate of air movement over the chicken. Fans can play an important role in the ventilation of poultry houses.
Therefore, the present study aimed at investigating fan performance and air distribution and velocity by two different types of
mixing fans (M4E/40 and M2E/40) and ceiling fans (PV60 and PV36). The effect of fan's height and tilt angle on air velocity
in the bird’s area was presented. The study was conducted in an experimental building at the Institute of Agricultural
Engineering, University of Bonn, Germany. The results indicated that air velocity produced by M2E/40 was significantly
greater than M4E/40 with a mean of 3.94 m/s vs. 2.18 m/s, respectively (F=1.32; P<0.05). Overall, in all measuring locations
the air velocity produced by fans was significantly low, and then increased until the 4th and 8th m of distance, and hereafter
decreased until the 10th m for both M2E/40 (F=9.57; P<0.05) and M4E/40 at both tilt angles of 60° and 55° (F=11.77;
P<0.05). The air velocity produced by M4E/40 was significantly greater at 60° than 55° with means of 1.11 m/s vs. 0.58 m/s,
respectively (F=5.386; P<0.05). The air velocity produced by PV60 was 1.5-fold greater than PV36, but it was not
significantly different with means of 1.56 m/s vs. 1.036 m/s for both fans, respectively (F=0.246; P=0.184). It is to be
mentioned that an air velocity of 1.5-3.0 m/s is the optimal to achieve an optimal birds' performance under very hot conditions.
In the current study, this optimal air velocity was obtained at different distances and measuring locations for all fans tested. In
conclusion, agricultural fans used in this study could provide adequate air velocity, which can decrease the effective
temperature inside poultry houses. Selection of fan location and modifying of fan's tilt angle are very important points to be
taken into account to obtain the best air distribution and velocity to prevent heat stress effect on birds.
Keywords High Ambient Temperature, Chicken, Cooling System, Tilt Angle, Air Distribution, Agriculture Technology
The raising of livestock for meat has been increasing in
nearly all the industrialized countries since 1950's and today
accounts for at least half of the total amount of agricultural
output in every industrialized country . Current global
livestock production is growing more dynamically than any
other agricultural sector around the world . The poultry
sector continues to be a major protein supplier to the world.
Over the last years, world chicken meat and hen eggs'
production have shown an accumulative increase [3, 4].
Poultry sector faces many problems, in which one of them is
associated with the development of an intensive poultry
industry in countries with a hot climate, where heat stress is a
* Corresponding author:
email@example.com (Amani Al-Dawood)
Published online at http://journal.sapub.org/ijaf
Copyright © 2014 Scientific & Academic Publishing. All Rights Reserved
main problem during periods of high environmental
temperatures. Even in some temperate climates, there is a
danger that broiler chicken will die of heat stroke if they
suddenly exposed to unusually high environmental
temperature [5, 6]. High temperature influences intake,
digestion, absorption and metabolism of energy of chickens
, and resulted in a high mortality and low performance of
the chickens [5, 8, 9]. The main environmental factors
affecting performance of broiler chickens are ambient
temperature, relative humidity, air velocity , and air
quality such as oxygen concentration, carbon dioxide,
ammonia, dust and microbial contamination . Air
velocity is one of the main environmental factors involved in
thermoregulation, especially at high ambient temperatures.
Convective heat loss increased significantly with increasing
air velocity . To overcome high temperature, it is
necessary to increase the rate of air over the flock. This could
be achieved by mechanical ventilation in closed housing .
Optimum poultry production requires a housing environment
146 Amani Al-Dawood et al.: Air Velocity Produced by Different Types of Mixing
and Ceiling Fans to Reduce Heat Stress in Poultry Houses
that offers well-distributed ventilation within the house .
One of the most effective ways of cooling birds during hot
weather is to have indoor fans that either can blow the air
around or can be directed onto the birds . Agricultural
fans are simple and inexpensive way to create air circulation,
and could play an important role in ventilation of poultry
houses and moving the air inside them, thus reducing the side
effects of heat stress. The selection of fan location is a key
point to be taken into account to obtain the best air
distribution, and to avoid the expecting problems that can be
faced by labour inside the poultry houses . Therefore, the
current study aimed at investigating the performance and air
distribution by four types of mixing and ceiling fans. The
effect of fan's placement height, tilt angle and measuring
location on air velocity at the bird’s area was thoroughly
2. Materials and Methods
Table 1. Technical data of mixing fans (M4E/40 and M2E/40), ceiling fans
(PV36 and PV60) and rotating vane (FV A915 S220/S240, Ahlborn
Company) used in the study
Mixing fan M4E/40 M2E/40
Nominal diameter (mm) 400 400
Voltage (V) 230 230
Amperage (A) 1.1 2.7/3.3
Power consumption (kW) 0.23 0.63
Number of blades 6 6
Frequency (Hz) 50 50
Blade material Polypropylene Polypropylene
Blade angle (°) 40 25
Air displacement (m3/h) 5050 6000
Ceiling fan PV36 PV60
Diameter of fan (mm) 900 1400
Air displacement (m3/h) 13.60 21.25
Power consumption (watt) 60 70
Speed (rpm) 250 230
Stroke length (cm) 52 52
Rotating vane FV A915 S220/S240
Accuracy (%) ±1 of final value ±3 of measured value
Maximum resolution (m/s) 0.01
Operative range (°C) -20 to +140
Measuring head diameter
Sensor length (mm) 165
Inlet opening (mm) 15
Cable length (m) 1.5
Nominal temperature (°C) ±22
Measuring range (m/s) 0.5 to 40
The used fans in this study were of the type, Multifan
Mobile and produced by Vosterman Ventilation B.V.
Company. They are easy to transport with a wide range of
applications, double wire-guard, motors with thermal
protection and vertical blowing direction is possible. Mobile
fans can be mounted horizontally and vertically. The
capacity of the fans is controllable in a continuously variable
way by changing the number of revolutions of the motor via
the main voltage. The mixing fans, M4E/40 and M2E/40
were used in this study, and their characteristics are listed in
table 1. In addition, two ceiling fans of the type PV36 and
PV60 were used. PV fans have aluminium blades, which are
matched and balanced to provide a smooth air delivery and
wobble free performance. The technical data of the used PV
fans are summarized in table 1.
2.2. Measuring Air Velocity
An anemometer of the type ALMEMO 2290-4S was used
in this study. ALMEMO measuring instrument can acquire
virtually any measurable variables and master any measuring
task. When measuring flows using ALMEMO sensors, the
ALMEMO instrument provides important data functions for
averaging and for volume flow measurement. For measuring
the flow velocity, rotating vane of the type FV A915
S220/S240 with technical data mentioned in table 1 was used.
It consists of a disc of angled vanes attached to a rotating
spindle. The speed at which the vane assembly rotates is a
measure of the air velocity. The flow velocity is determined
through a frequency measurement. The advantages of this
type of vane are high accuracy at medium flow velocities,
medium ambient temperatures and insensitive to turbulent
2.3. Experimental Procedure
The experiments were conducted in an experimental
building at the Institute of Agricultural Engineering,
University of Bonn, Germany. In order to determine the fan
performance, different parameters were taken into account
namely; fan placement height, fan tilt angle, measuring
location and distance from the fan. Velocities were measured
using the fore-mentioned anemometer and rotating vane.
When the fans were located at the floor region, the air
velocities produced by M4E/40 and M2E/40 mixing fans
were measured at a height of 0.15 m (bird’s area) at different
locations; in the middle directly in front of the fan, at 0.15,
0.3, 0.5, 0.6, 0.7, 0.8 and 1 m. All measurements were made
up to 10 meters. The measurements were made for one side
since both sides supposed to be identical. When the fans
located at 1.5 m from the floor region, air velocities were
also measured at a height of 0.15 m in the middle directly in
front of the fan, at 0.5 and 1 m at two different fan's tilt
angles of 55° and 60°. Ceiling fans of the types PV36 and
PV60 at heights of 3.8 m and 3.2 m from the floor region,
respectively, were tested at 1 m height from the floor region
with different measuring points: at the middle, 0.15, 0.3, 0.5,
0.8 and 1 m.
International Journal of Agriculture and Forestry 2014, 4(3): 145-153 147
2.4. Statistical Analysis
The statistical analysis was performed using the proc
GLM of the statistical package SigmaStat version 16.0 .
The data were analyzed by one way ANOVA to detect any
differences among the different fans, tilt angles and distances
. When significant differences were detected, differences
among the different distances were compared using LSD at
P≤0.05 . T-Test was used for comparisons between fans
as well as tilt angles .
3.1. Mixing Fans
3.1.1. Fans Located at Floor Region
Figure 1. Air velocity profile (m/s) at 0.15 m height for M4E/40 and M2E/40 mixing fans located at floor region
Distance from fan (m)
Distance from fan (m)
148 Amani Al-Dawood et al.: Air Velocity Produced by Different Types of Mixing
and Ceiling Fans to Reduce Heat Stress in Poultry Houses
Figure 2. Air velocity profile (m/s) at 0.15 m height for M4E/40 and M2E/40 mixing fans located at 1.5 m height above the floor region with 60° tilt angle
Air velocity profiles obtained along the experimental
building showed that the point of maximum velocity moves
downward with increasing distance from the fan location.
Area averaged-velocities near the floor region were based on
the measurements at a height of 0.15 m above the floor. The
measured air velocity ranged from 0 to 10 m/s for M4E/40
fan, and from 0 to 14 m/s for M2E/40 fan (Fig. 1). In the
middle (direct in front of the fan), the air velocity was very
high and valued 8-10 m/s in the 1st m, and then it decreased
with increasing the distance until it reached 0 m/s at the 10th
m in case of M4E/40 fan. While for M2E/40 fan, the
measured velocity in the middle of the fan was 8-10 m/s, and
it decreased with increasing the distance until the 10th m,
where the air velocity was 0 m/s. For M4E/40 fan at 0.15 m
measuring location, the velocity was 6-8 m/s for the 1st m,
and hereafter it decreased until the 7th m, where the air
velocity valued 0 to 2 m/s. At the 8th m, the air velocity
increased to 2-4 m/s, and then it decreased again. While at
0.15 m for the M2E/40 fan, the air velocity valued 12-14 m/s,
and then it decreased until the 9th m. From the 9th to 10th
meters, the velocity was only 0 to 2 m/s. For the measuring
locations 0.3 and 0.5 m, the air velocity valued 4-6 and 2-4
m/s, respectively in the first three meters for M4E/40, and
then it decreased until the 7th m. While for M2E/40 at 0.3 and
0.5 m measuring locations, the air velocity was 4-8 m/s, and
then it decreased with increasing distance from the fan. From
0.6 to 1 m, the air velocity was 0-2 m/s at the 1st m, and then
it increased to 2-4 m/s for M4E/40, while for M2E/40 at the
same measuring locations, air velocity was 0-2 m/s until the
2nd m, and then it increased and hereafter decreased until the
10th m. Air velocity produced by M2E/40 was significantly
greater than M4E/40 with a mean of 3.94 m/s vs. 2.18 m/s,
1 m 2 m 3 m 4 m 5 m 6 m 7 m 8 m 9 m 10 m
1 m 2 m 3 m 4 m 5 m 6 m 7 m 8 m 9 m 10 m
Distance from fan (m)
International Journal of Agriculture and Forestry 2014, 4(3): 145-153 149
respectively (F=1.32; P<0.05). Overall, in all measuring
locations the air velocity produced by fans was significantly
low, and then increased until the 4th and 5th m of distance,
and hereafter decreased until the 10th m for both M2E/40
(F=9.57; P<0.05) and M4E/40 (F=11.77; P<0.05).
3.1.2. Fans Located at 1.5 m Height
220.127.116.11. 60° Tilt Angle
The air velocities in blowing direction of M4E/40 and
M2E/40 fans located at 1.5 m height were measured at 0.15
m height at different measuring locations namely; at the
middle, 0.5 m and 1 m. Figure 2 showed that in front of the
fan, the air velocity ranged from 0 to 1 m/s until the 3rd m for
M4E/40. From the 4th m until the 9th m, the air velocity has
increased from 1 to 3 m/s and then decreased again at the 10th
m. Maximum air velocities of 2-3 m/s at the 4th and 5th m
were distributed from the middle to 0.5 m. For M2E/40, a
maximum air velocity of 3-4 m/s was recorded (Fig. 2). At
0.5 m measuring location, the air velocity was 2-3 m/s at the
5th-7th m, and thereafter the air velocity decreased with
increasing the distance until it reached 1-2 m/s at the 8th m
and 0-1 m/s at the 10th m. The same trend was observed for 1
m measuring location. The air velocity produced by M2E/40
was significantly the same as for M4E/40 with a mean of
0.98 m/s vs. 1.11 m/s, respectively (F=0.659; P<0.05).
Overall, in all measuring locations the air velocity produced
by fans was significantly the highest in the distance ranged
from 5th until 7th m for both M2E/40 (F=17.91; P<0.05) and
M4E/40 fans (F=48.32; P<0.05).
Figure 3. Air velocity profile (m/s) at 0.15 m height for M4E/40 and M2E/40 mixing fans located at 1.5 m height above the floor region with 55° tilt angle
150 Amani Al-Dawood et al.: Air Velocity Produced by Different Types of Mixing
and Ceiling Fans to Reduce Heat Stress in Poultry Houses
Figure 4. Air velocity profile (m/s) for PV36 and PV60 ceiling fans at 1 m height above the floor region
18.104.22.168. 55° Tilt Angle
The results demonstrated that air velocity for M4E/40 fan
at the middle location was 0-1 m/s for the first two meters
(Fig. 3). Thereafter, it increased with increasing the distance,
where the maximum air velocity was 3-4 m/s at the 3rd-6th m.
At measuring locations of 0.5 m and 1 m, the air velocity was
1-2 m/s at the 3rd-4th m, and then it valued only 0-1 m/s until
the 10th m. For M2E/40, the velocity at the middle was 0-1
m/s for the first three meters (Fig. 3). Maximum air velocity
of 3-4 m/s was recorded at the 5th m, and then it started to
decrease until it reached 0-1 m/s at the 10th m. The same
trend of results was recorded for 0.5 m and 1 m measuring
locations. The air velocity produced by M2E/40 was
significantly greater than M4E/40 with a mean of 1.09 m/s vs.
0.58 m/s, respectively (F=3.358; P<0.05). Overall, in all
measuring locations the highest air velocity was significantly
produced by M2E/40 (F=34.29; P<0.05) in the distance
ranged from 5th to 8th m, while for M2E/40, the highest air
velocity was significantly obtained at 3rd to 5th m (F=1.79;
By comparing 60° and 55° tilt angles, the results revealed
that at 60° for M4E/40 the air velocity profiles distributed
widely than that of the same fan at 55°, where the air velocity
distributed until 1 m measuring location for 60°, and only to
0.5 m measuring location for 55° as seen in figures 2 and 3.
For M2E/40, the results showed that there is no big variation
in the distributed air velocity between 60° and 55° tilt angles
as shown in figures 2 and 3, where the maximum air
velocities were 3-4 m/s at the 5th m. The statistical analysis
indicated that there were no significant differences between
60° and 55° tilt angles for M2E/40 fan (F=0.139; P=0.719),
while the air velocity produced at 60° was significantly
greater than 55° for M4E/40 fan with a mean of 1.11 m/s vs.
0.58 m/s, respectively (F=5.386; P<0.05).
3.2. Ceiling Fans
PV60 ceiling fan placed at 3.8 m and PV36 ceiling fan
located at 3.2 m (Fig. 4) above the floor level were tested at 1
m height from the floor region. The air velocities were being
integrated to include all the air entrained at the tested plane.
The results revealed that at the middle location, the air
velocity was 2.19 m/s and 1.33 m/s for PV36 and PV60,
respectively. The air velocity started to decrease while
moving away from the middle location until it reached 0 m/s
at 0.8 m measuring location for PV36. For PV60, the air
velocity began to rise until reached 2.4 m/s at 0.3 m
measuring location, and then it decreased to 0 m/s at 1 m.
The air velocity produced by PV60 was 1.5-fold greater than
PV36, but there were no significant differences between the
two fans (F=0.246; P=0.184).
Air velocity is one of the main environmental factors
involved in thermoregulation, especially when outdoor
temperature and relative humidity are high and the efficiency
of the evaporative cooling systems is limited. However,
increasing the rate of air movement over the birds is
necessary to protect them against high temperature .
Agricultural fans can play an important role in ventilating
poultry houses and reducing the side effect of heat stress.
Additionally, type, placement location and tilt angle of the
fan influence air velocity in the bird’s area. The current
results showed clearly that when the fans (M4E/40 and
M2E/40) located at the floor region the air velocity
distributed along 10 meters. Also, the point of maximum air
velocity moves downward with increasing the distance from
fan location. The air velocity was declined when moving
from the middle location toward the other measuring
1 m 0.80 m 0.50 m 0.30 m 0.15 m middle 0.15 m 0.30 m 0.50 m 0.80 m 1 m
Air velocity (m/s)
International Journal of Agriculture and Forestry 2014, 4(3): 145-153 151
locations (0.15, 0.3, 0.5, 0.6, 0.7, 0.8 and 1 m) for both fans
tested. In a similar fashion, Bottcher et al.  reported that
air velocities increase along the centreline from 3 to 9 m
from the fan and then declined with distance. While
according to Bottcher et al. , the air velocities increased
from 0.5 to 1 m/s directly below the center of the fan, and
reached its maximum (1.5-2.0 m/s) at the 3rd m from the
center, and then slowly decreased to 0.5-0.9 m/s at the 8th m
from the fan center. These results of Bottcher et al. [22, 23]
are in agreement with the present results, where the air
velocity increased significantly and then decreased with
increasing the distance from the fan. In addition, the current
results showed that M4E/40 generates significantly air
velocities less than M2E/40, where the maximum air
velocity resulted from M2E/40 fan was 15 m/s as compared
to only 10 m/s for M4E/40 fan. This indicates that M4E/40
might cause fewer disturbances for the birds than M2E/40.
These results are in agreement with a conclusion made by
Bottcher et al. , where high air velocities disturb the birds.
Additionally, Bottcher et al.  mentioned that it may be
possible to effectively cool birds with maximum velocities
above 2 m/s. This is in line with the current results when the
fans located at the floor region, where the air velocities close
to fan were more than 2 m/s for both mixing fans. According
to Yahav et al. , an air velocity of 1.5-2 m/s is the optimal
to achieve an optimal birds' performance under very hot
conditions (< 35°C). In this study, for example, at 0.15 m
height when fans located at the floor region for M4E/40, an
air velocity of 2 m/s was obtained from the 6th to 10th m. For
M2E/40, an air velocity of 2 m/s was recorded for the whole
10 meters starting from 0.5 to 1 m measuring locations.
During acute exposure to high temperature of 30°C, an air
movement in the range of 0.30 to 1.05 m/s may be employed
as an effective form of cooling, decreases the demand for
evaporative heat loss and reduces body temperature .
Further studies pointed out that air velocity up to 1 m/s seems
to have a beneficial effect on young chicks . Furthermore,
even air velocities as high as 2.5-3.0 m/s help chickens to
tolerate increasing temperature up to at least 40°C .
Therefore, apparently it can be managed by locating birds at
a certain distance from the fans to achieve the optimal
Modifying mixing fan tilt angle to increase air velocity at
bird level has the potential to prevent heat stress effect on
birds' performance without necessarily resulting in an
excessive bird migration toward the fans . The present
results demonstrated that when the fans (M4E/40 and
M2E/40) located at a height of 1.5 m at 60° tilt angle, air
velocity in front of the fan was increased and then decreased
again for both fans. Maximum air velocities of 2-3 m/s for
M4E/40 and 3-4 m/s for M2E/40 were recorded. The same
trend was observed for measuring locations of 0.5 and 1 m.
Therefore, in general the maximum air velocity generates by
M2E/40 was greater than M4E/40 as noticed when the same
fans located at floor region. At 55° tilt angle, the results
showed that air velocity at the middle was 0-1 m/s in the 1st
m for M4E/40 and in the first four meters for M2E/40.
Thereafter, it increased with distance, where the maximum
velocity was 3-4 m/s for both fans. In this regard, Bottcher et
al.  reported that air velocities are found to decrease with
increasing the horizontal distance from the fan, fan produced
air velocities at bird level of 3.4, 2.5 and 2 m/s at distances of
1.8, 3 and 4 m from the fan, respectively. In general, this
observation is agreed with all measuring locations for 55°
and 60° tilt angles of the current study. Furthermore, our
results revealed that by comparing tilt angles of 60° and 55°
for M4E/40, air velocity profiles were widely distributed at
60° than 55°, where the air velocity distributed to 1 m
measuring location for 60° and only to 0.5 m measuring
location for 55°. Furthermore, for M2E/40, the results
showed that there were no significant differences in the air
velocity distribution between the two angles, while the air
velocity produced at 60° was significantly greater than 55°
for M4E/40 fan with means of 1.11 m/s vs. 0.58 m/s,
respectively. The results of the present study for fan located
at 1.5 m have similar trend with the results of Bottcher et al.
, who reported that for tilt angles below 20°, the area
averaged velocity increases with tilt angle and decreases
with increasing fan height; at higher tilt angle the
area-averaged velocity raised very little with fan height, at
tilt angle below 10° the maximum velocities for two lower
measurement heights of 0.41 and 0.1 m differ only slightly.
As mentioned before, Bottcher et al.  and Yahav et al.
 found that an air velocity of 2-3 m/s and 1.5-2 m/s,
respectively, is the optimal for birds. This range of air
velocity was found at different fan heights and measuring
locations at the bird’s level. For example, when fans located
at 1.5 m at 60° tilt angle, air velocities of 2-3 m/s at bird’s
area were reported from the 2nd to 6th m from the middle to 1
m measuring location. While for M2E/40, 2-3 m/s air
velocity was observed from the 5th to 7th m from the middle
to 1 m measuring location.
The results of the current study on PV60 and PV36 ceiling
fans (placed at 3.8 m and 3.2 m above the floor level,
respectively) showed that the air velocities tested at 1 m
height from the floor region are being integrated to include
whole air entrained at the tested plane. At the middle location,
the air velocity was 1.33 m/s and 2.19 m/s for PV60 and
PV36, respectively. Thereafter, the air velocity started to
decrease while moving away from the middle location for
PV36. For PV60 the air velocity began to rise, and then it
decreased again. The present results agreed with Gavaret
, who stated that the air velocity decreases when distance
from the centre increases. Furthermore, he mentioned that at
the maximum fan speed, the air velocity near the floor
reaches a peak of 2.2 m/s, and air movement can be
measured out to a distance of 5.5 m from a point on the floor
directly under the centre of the fan. The air is supposed to
move with air velocity at a level of approximately 2 m/s
through all the length of a building, thus cooling the birds by
convection . Gavaret  reported that ceiling fans are
well suited for air circulation in poultry houses because they
are simple and inexpensive way to create air circulation
where birds are located at a height of 45 cm. According to
152 Amani Al-Dawood et al.: Air Velocity Produced by Different Types of Mixing
and Ceiling Fans to Reduce Heat Stress in Poultry Houses
Daly , ceiling fans might be seated with the head directly
in the air stream. Ernst  indicated that vertical ceiling
fans are used to cool chickens locating them about 3.7 m
above the birds.
One of the most serious problems associated with using
ventilation fans is the migration of broilers toward the high
air velocity. Therefore, the effect of air velocity in poultry
houses on the migration of birds should be taken into account,
when determining the performance of a certain fan.
Consequently, birds 'crowding reduces performance due to
increased heat stress as they considered as heat source.
Runge  suggested that air speed over heat stressed birds
should be limited to avoid excessive birds' migration into
areas of high air speed. Kuczynski  reported that such a
profile of air velocities from 0.5 to 2 m/s encourages broilers
to move looking for the thermal conditions, which would
best suit their needs. In addition, the tilt angle in which the
fan is directed can play an important and significant role in
air distribution and birds' migration. Also, migration fences
are a key point to maintain birds' uniformity down the length
of the house without causing dead air spots.
In conclusion, it is clear that mixing and ceiling fans used
in the current study are feasible to be used for poultry barns
to reduce heat stress. The air velocity produced by M2E/40
was significantly greater than M4E/40, and at 60° tilt angle
than at 55°. Overall, in all measuring locations the air
velocity produced by fans was significantly low, and then
increased, and hereafter decreased until the 10th m for both
fans. When choosing a fan, there are some important criteria
should be taken into account, i.e. quantity of air delivered at
different static pressures, energy efficiency, quality of dealer
service and support, reliability and life, sustainability and
costs . Selection of fan location and number of fans/barn
are very important points to be taken into account to obtain
the best air distribution and to avoid the expecting problems
that can be faced by labour inside poultry houses. Thus,
further studies are required to test the effect of the
combination of different types of fans inside poultry houses,
number of fans/barn, and to examine if these fans are
appropriate for poultry houses located at very hot and dry
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