Download Poultry house ventilation system Poultry house

12/8/2009
Poultry house ventilation system
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Basically consists of
exhaust fans and air inlets.
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Exhaust fan draw in fresh
air
Poultry House Ventilation System
Design
Michael Czarick III
The University of Georgia
Poultry house ventilation system design
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How much exhaust fan capacity should a
house have?
Basically consists of
exhaust fans and air inlets.
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Exhaust fan draw in fresh
air
Inlets direct the fresh air to
where we want it to go.
go
Exhaust fan capacity rule of thumb
Example:
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60’ X 300’ broiler house
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60’ X 300’ X 7 = 126,000 cfm (25 – 24” fans)
Minimum exhaust fan capacity for a power-ventilated
broiler/turkey house:
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7 cfm per square foot of floor space (130 m3/hr per m2)
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This should ensure that there is no more than a 5oF (2.7oC) increase
from the inlet to the exhaust fans
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This is minimum…
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The typical U.S. broiler/turkey house:
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Heat produce by broilers has increased
approximately 20% in the last 20 years.
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8 – 10 cfm per square foot of floor space.
60’ X 300’ = 144,000 – 160,000 cfm
How much has your ventilation system changed over 30
years?
50 years ago
Minimum exhaust fan capacity for a powerventilated broiler-breeder house:
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30 years ago
Today
Commercial layer
5 cfm per square foot of floor space (90 m3/hr per m2)
For a 40’ X 300’ broiler-breeder house
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40’ X 300’ X 5 = 60,000 cfm (12 – 24” fans)
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Typically around 7 cfm/bird:
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What type of fan should a house be
equipped with?
High as 9 cfm/bird…Low as 6 cfm/bird
Exhaust fan selection criteria
1.
To obtain desired air exchange rate exhaust fan capacity
must be determined at a minimum static pressure of
0.10” (25 Pa).
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Not only do we want a fan that is energy
efficient, we want a powerful fan as well.
Exhaust fan selection criteria
Energy efficient
2.
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Cfm/watt
The higher the rating…the lower your operating costs will be.
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Dirty fan shutters
Clogged inlet screens
Winds
Should have an energy efficiency of at least 20 cfm/watt
@0.10” (34 cmh/watt)…..ideally +20.8 cfm/watt (35 cmh/watt)
or better
A fan with a high air flow ratio is less
affected by the wind
Fan output vs. static Pressure
(48” fans, between 20,000 and 22,000 cfm)
Air flow ratio = air flow (0.20”)/ airflow (0.05”)
Wind p
pressure (in)
Cfm
An indicator of how well the fan will hold up to high static
pressures caused by:
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Desired energy efficiency rating
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Exhaust fan air flow ratio
3.
It is not how much power a fan uses…it is how many cubic
feet per minute it can move with each watt of power:
26,000
24,000
22,000
20,000
18,000
16,000
14,000
12,000
10,000
8,000
6,000
4,000
2,000
0
0
0.05
0.84
0.1
0.84
0.15
0.2
Static Pressure
0.86
0.74
0.25
0.76
0.3
0.2
0.18
0.16
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
0
0.35
5
0.67
This is a serious problem with variable
speed fans!
10
15
20
Wind speed (mph)
Air flow ratio
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Minimum acceptable
Ideal
= 0.73
= 0.78 or higher
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Fan performance information is available at
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WWW.BESS.UIUC.EDU
Exhaust fan selection criteria
Size
4.
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Keep small fans to a
minimum
Small fans are a very poor
investment:
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Estimated initial fan cost
Fan size and energy efficiency
(the larger the fan the more energy efficient it tends to be)
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$12,000
$11,000
$10,000
$9,000
$8,000
$7,000
$6,000
$5,000
$4,000
$3,000
$2,000
$1,000
$0
Energy Efficie
ency (cfm/watt)
Fan C
Cost ($)
60’ X 300’ house with 126,000 cfm of fan capacity
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19
17
15
13
11
9
7
5
12
24
36
48
12
60
Fan Size (“)
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$29.00
$27.00
$25.00
$23.00
$21.00
$19.00
$17.00
$15.00
$13.00
$11.00
$9.00
$7.00
$5.00
48
60
The optimal exhaust fan system stages from small to large
fans quickly:
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36
36
This does not mean you can’t install a few
small fans but…
(100,000 cfm for 24 hours @ $0.10 per Kw*hr)
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24
Fan Size (“)
Fan operating cost
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Higher initial cost
Higher operating cost
Higher maintenance cost
48
Two - four 24” fans – minimum ventilation fans
Two - four36” fans – moderate weather
Then 48” fans or larger for the remainder of the required fan
capacity
it – hot
h t weather
th
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Fan Size (“)
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Another advantage of keeping the number of
small fans to a minimum
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Cold spots near exhaust fans
Reduces the potential for shutter air leakage
100.0°F
100
½ the shutters… ½ the cold spots
90
80
70
60.0°F
Problems with leaky shutters can be further
reduced by placing exhaust fans in groups
Minimizing cold spots
Leakage exits adjacent minimum ventilation fans
The fact is that fans do not have to be
evenly spaced down the length of the house
Poultry house with a single fan and four air
inlets
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Poultry house with two fans and air four
inlets
Poultry house with a single fan and eight air
inlets
Poultry house with a single fan and 16 air
inlets
Poultry house with a single fan and 16 air
inlets
Poultry house with a single fan and 16 air
inlets
But you MUST establish a negative pressure if
you want to gain control over the environment
.08”
.08”
.08”
.08”
.08”
.08”
.08”
.08”
950 ft/min
950 ft/min
950 ft/min
950 ft/min
950 ft/min
950 ft/min
950 ft/min
950 ft/min
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Outside
Ventilation system design
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Air inlet system design
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It is very important to realize that though fan placement
can be of some importance…
Inlet design/placement is by far, more important when it
comes to maintain proper environmental control
+80% of ventilation system design is proper inlet design
and placement maybe 20% or less is exhaust fan
placement
Air inlet capacity
How much inlet area should a house have?
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General rule of thumb:
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Air inlet example:
40’ X 300’ with 84,000 cfm (7 cfm/ft2)
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Inlet area = 84,000 cfm / 750 cfm
= 168 square feet (16 m2)
If the house had a single continuous inlet…
1 square foot for every 750 cfm of exhaust fan capacity.
or
1 square meter for every 4,800 m3/hr
Air inlet system(s)
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For optimal control a modern poultry house should have
a minimum of two inlet system….ideally three
Each inlet system is specifically designed to be used to
obtain specific objectives
Inlet width = total inlet area/ house length
= 168 ft2/300 ft
= 0.56’ feet or 6” or 15.2 cm
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1) Cold weather inlet system
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It is specifically designed to bring in just enough air to
maintain air quality during very cold weather:
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Minimum ventilation inlet system
Designed to maximize bird heat removal
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Produce high air velocities over the birds to maximize heat
removal
Minimum ventilation inlet system
Specifically designed for use for very cold weather for use
with just a few exhaust fans…minimum ventilation fans.
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Designed to control house temperature during moderate
weather.
Without causing drafts
With t causing
Without
i excessive
i ffuell usage
3) Hot weather inlet system
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Maximize heating of incoming cold air
Distribute fresh air throughout the house evenly
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2) Moderate weather inlet system
1 – 2 cfm per square foot.
60’ X 300’ X 1.5 = 27,000 cfm
Might consist of only 10 to 20 inlets
Minimum ventilation inlet guidelines
Located towards the center of the house
1)
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That is where your hottest air tends to accumulate
Furthest distance from the birds
99.0°F
99.4
97.4
95
94.2
90
92.1
89.6
86.1
85
83.6°F
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Example of minimum ventilation inlets
Example of minimum ventilation inlets
Desired air flow pattern from minimum
ventilation inlet
Desired air flow pattern from minimum
ventilation inlet
96.2°F
95
90
85
80
75.0°F
80
90
85
75
80
75
70
70
65
65
60
55
50
60.0°F
45
40
30
25
21-Feb
19-Feb
17-Feb
9-Feb
15-Feb
7-Feb
13-Feb
5-Feb
3-Feb
11-Feb
Date
65
1-Feb
30-Jan
28-Jan
26-Jan
24-Jan
22-Jan
20-Jan
18-Jan
16-Jan
20
8-Jan
70
35
14-Jan
75
6-Jan
78.2°F
12-Jan
Less affected by wind
Warmer air for a portion of the day
10-Jan
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Tempe
erature (F)
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85.0°F
85
4-Jan
Draw air out of the attic
2)
Attic vs. outside temperatures
2-Jan
Minimum ventilation inlet guidelines
attic
60
55
53.1°F
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Minimum ventilation inlets above tube
heaters
Minimum ventilation inlet guidelines
3)
Located above a house’s heating system to help temper
incoming cold air
95.0°F
90
71.5
57.9
43.4
80
70
60
44.5
55.0°F
95.0°F
58.2
73.7
90
80
70
60.0°F
Minimum ventilation inlets above hot water
fin pipes
Minimum ventilation inlets above hot water
system
105.0°F
100
90
80
70
60
53.4°F
A continuous inlet is a very poor
minimum ventilation inlet
Very difficult to obtain a uniform small
opening…
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Continuous inlets do not tend to produce
adequate tempering of incoming air
Side wall or a ceiling continuous inlet
100.0°F
100
90
80
70
60.0°F
60.0
F
100.0°F
100
100.0°F
100
90
90
80
80
70
70
60.0°F
60.0°F
To maximize the tempering of the
incoming air…
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We must keep the air away from the birds as long as
possible
Little tempering/mixing of incoming air
103.5°F
100
95
5C
10 C
15 C
20 C
90
85
80
78.3°F
Air dumping to floor during minimum
ventilation..
Heating not being utilized on the far side of
the house.
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Birds becoming chilled directly under inlet.
Fan side of house birds are significantly
warmer.
Air inlet systems
Moderate weather inlets
1)
2)
Cold weather - minimum ventilation
Moderate weather – temperature control
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More needed than minimum ventilation inlets
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5 cfm per square foot of floor space
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Inlets on both sides of the house maximum
temperature and air quality uniformity
Around three times as much as minimum ventilation inlets
If not tunnel ventilated (7+ cfm/ft2)
Located along both side walls pulling air from directly
outside
t id th
the house
h
Air inlets on one side wall do not work as well for
temperature and air quality uniformity (especially in
wider houses)
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What makes a good temperature control
inlet?
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Air flow directed toward ceiling at an angle
Directs the air where you want it to go.
Air flowing out of recessed inlet in 50’ wide
house
What makes a good temperature control
inlet
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Surface mounted inlet sits on the wall…
a recessed inlet sits in the wall.
Directs the air when you want it to go.
Recessed inlet
Cold air exiting sides of air inlet
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Air flowing out side of inlet
Warm air flowing the side of recessed inlet
90.0°F
90
85
80
75
70.0°F
Air focused at top of the inlet which
improves throw
Examples of recessed side wall inlets
85.0°F
85
80
75
70
65
60.0°F
Moderate weather inlets
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More needed than minimum ventilation inlets
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5 cfm per square foot of floor space
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Air flow along the floor during warmer
weather
Around three times as much as minimum ventilation inlets
If not tunnel ventilated (7+ cfm/ft2)
Located along both side walls pulling air from directly
outside
t id th
the house
h
Ideally can direct the air up toward the ceiling during
cooler weather and down toward the floor during
warmer weather
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Side wall inlet capable of directing incoming
air downward
Deflector board for hot weather bird cooling
Deflector board for hot weather bird cooling
Air inlets
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Cold weather – minimum ventilation
Moderate weather – temperature control
Hot weather – bird heat removal system
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Importance of air movement when it comes
to cooling birds
Hot weather is whenever it is warmer outside than you want it
inside.
In order to cool a bird we have to get air
to move over its body...
100.0°F
100
95
90
85
80
More air speed…
more cooling
75.0°F
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Still Air - 25oC
300 ft/min - 25oC
Turkeys
0.75 m/sec - 26oC
(26oC – 150 ft/min)
39.0°C
38
36
34
32
30
28
26
26.0°C
2 m/sec - 26oC
2 m/sec - 26oC
39.0°C
38
36
34
32
30
28
26
26.0°C
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Air movement in traditional cross-
Designed to conserve heat and not to
produce air movement over the birds
ventilation during hot weather
5C
10 C
3.5 m/sec
20 C
Very little air movement at floor level during
cold weather
Designed to produce little air movement at bird level
5 m/sec
15 C
2.5 m/sec
1.5 m/sec
less than 0.25 m/sec
During the summer they will tend to
conserve heat also…
Very little air movement during hot weather
as well
2.5 m/sec
26oC
26.5oC
1 m/sec
5 m/sec
27oC
28oC
0.75 m/sec to 0.5 m/sec over limited areas
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Things are improved if you have inlets on
both sides of the house
Downward facing hot weather inlet improves
the situation even more
1 m/sec
2.5 m/sec
5 m/sec
5 m/sec
2.5 m/sec
0. 5 m/sec
<0.25 m/sec
0.75 m/sec to .025 m/sec
Downward facing inlets on both sides of th
house even better
Downward inlet on one side of a house
35.0°C
35
35.0°C
35
30
30
25
25
20
20.0°C
20
20.0°C
103.0°F
103.0°F
5 m/sec
100
100
95
95
90
90
85
85
80
80
75.0°F
1.5 m/sec
1 m/sec
75.0°F
Even with inlets that direct air
downward cooling fans may be required.
Using circulation fans for bird cooling
5 m/sec
1.5 m/sec
1 m/sec
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36” circulation fan coverage area
15’
50’
50’
50’
Poor air movement distribution
50’
40’ wide house
36” circulation fans blowing across the
house
Limited coverage area
39.0°C
38
36
34
32
30
29.0°C
Most houses don’t have enough circulation
fans to provide the necessary air movement.
Birds directly in front of fan
39.0°C
38
36
34
32
30
29.0°C
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Best heat removal system is tunnel
ventilation
Air inlets
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Cold weather – minimum ventilation
Moderate weather – temperature control
Hot weather – heat removal system
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tunnel ventilation is just another inlet system
Air exchange and air velocity
Cross ventilation vs. Tunnel ventilation
100.0°F
100
95
Air velocity of between
2 and 3 m/sec
90
85
80
100.0°F
100
75.0°F
Air exchange typically less than every
60 seconds
95
90
85
80
75.0°F
Tunnel ventilation is just an additional
stage of ventilation
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Minimum ventilation
For most of the year the house is no different from what
you may already be doing.
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Fewer side wall/chimney fans
Fewer side wall inlets
+0.5 C
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Moderate ventilation
+1.5 C
Low level tunnel ventilation
+3 C
High level tunnel ventilation
Moderate ventilation
+2 C
Medium level tunnel ventilation
+4 F
[email protected]
(706) 540-9111
+4.5 C
www.poultryventilation.com
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