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Exhaust fan selection
Selecting the right fan... By far the most important aspect of
designing a tunnel ventilated house:1) Determines the grower’s ability to cool his
birds: Wind-chill Temperature uniformity Trapped heat removal Reduces the effects of high humidity
2) Determines the grower’s electricity costs Electricity is quickly becoming a grower’s largest
expense.
1) Air moving capacity2) Energy efficiency energy efficiency ratio
3) Air moving capacity vs. static pressure air flow ratio
4) Drive type5) Quality of construction6) Price
Six factors to consider:
Air moving capacity of a 48 - 50” fan 15,000 to 30,000 cfm+
1) Air moving capacity
Bird cooling
Large differences in air moving capacitycan result in large differences in coolingif a poultry company only specifies thenumber of fans a house should have.
15,000 cfm Cfm = 135,000 cfm Temp diff. = 7.9 F Air vel. = 1.63 m/s Wind-chill = 2.7 C
23,000 cfm Cfm = 207,000 cfm Temp diff. = 2.8 C Air vel. = 2.5 m/s Wind-chill = 6.1 C
12m X 150m House with ninefans
Most poultry companies donot do this anymore...
But, you must be careful not to specifytunnel fans just by type ormanufacturer either.
Because there can be large differencesbetween fans of the same type, evenwithin the same manufacturer.
Example:
Choretime cone fans (0.05”) 38450-4822 17,900 cfm 38441-4822 20,400 cfm 43575-4822 22,800 cfm 38264-4821 24,000 cfm
Tunnel fan selection:
The first step in selection a fan for atunnel house is to understand thedifferent styles of fans available.
1) Traditional exterior shutter2) Slant wall3) Slant wall – Cone Most fan models are offered in all
three configurations
Three basic fansconfigurations
Exterior shutter Fan is often installed
in it woodenshipping box.
48” shutter mountedon the outside ofthe house.
Exterior shutter The relatively small
shutter, 48” shutteron 48” diameter fan,reduces air flow.
The exteriormounted shuttermakes it difficult topush air out of thehouse.
Air flow into a fan
Spinning fan blades
Spinning fan blades
Air exiting a fan
Shutters restrict this flowpattern
Slant wall fan Larger shutter Air is pulled though
shutter instead ofbeing pushed.
Interior shutter
Larger shutter Air is pulled though
shutter Fan is tilted slightly
Match shutter angle Protects fan from
weather
Slant wall
Tilted fan
The combinationof the slant andthe interiorshutter increasesair flow 5 to 10%
Slant wall
Belt drive (Coolair NBF/CBL 48) exterior shutter (17,100 cfm) slant wall (19,200 cfm)
Fan configuration example
Larger shutter Air is pulled
though shutter Fan is tilted
slightly Easier to clean! Collects less dust
Slant wall
1) Traditional exterior shutter2) Slant wall
5 to 10 percent more air
3) Slant wall – Cone
Three basic fansconfigurations
Discharge cone fans Interior shutter
advantages Reduces “back”
pressure on fans
Tilted fan
Discharge cone
Discharge cone fans The discharge cone
can increase air flowan additional 5 to10%
Belt drive (Coolair NBF/CBL 48) exterior shutter (17,100 cfm) slant wall (19,200 cfm) slant wall with cone ( 21,000 cfm)
Fan configuration example
Though…
Slant wall tend to move more air thanfans with exterior shutters…
Cone fans tend to move more air thanslant wall fans…
There can still be significant differencebetween fans of the same configuration
Example
Choretime slant wall (0.05”) 38785-4822 16,500 cfm 42331-4822 18,000 cfm 45576-4822 20,500 cfm
Though… Slant wall tend to move more air than
fans with exterior shutters… Cone fans tend to move more air than
slant wall fans… There can still be significant difference
between fans of the same configuration This is why you must specify either fan
cfm or total cfm
Fan specifications:
Total cfm Or number of fans of that move a specific
amount of air I.e. nine fans that move between 22,000 and
24,000 cfm
Interior shutter Cone optional
1) Air moving capacity2) Energy efficiency energy efficiency ratio
3) Air moving capacity vs. static pressure air flow ratio
4) Drive type5) Quality of construction6) Price
Six factors to consider
Exhaust Fan Selection(energy efficiency)
Not specifying specific energy efficiencyratings for fans can result in... excessive energy bills for the producer poor bird management loss of income for the grower/company
The label “Energy Efficient” on a motormeans very little...
How much power will aparticular fan use?
Motor size does not tell the whole story. 1 h.p motor can use more power than a 1.5
h.p. motor
How much power will aparticular fan use?
Fan power(Two different 48” fans with discharge cones)
Bess #92093 1.5 h.p motor 24,600 cfm 1300 watts
Bess #98229 1.0 hp motor 21,500 cfm 1310 watts
Motor size does not tell the whole story. 1 h.p motor can use more power than a 1.5
h.p. motor
Plate amperage can be misleading. indicates full load amperage…not necessarily
working amperage.
How much power does a fanuse?
How much power will the fan use? motor size does not tell the whole story.
1 h.p motor can use more power than a 1.5h.p. motor
plate amperage can be misleading. indicates full load amperage…not necessarily
working amperage.
Just because a fan uses less powerdoes not mean it will save you money.
Energy efficiency
Fan power usage:(two different 48” fans)
Bess # 96321 918 watts
16,800 cfm
Fan power usage:(two different 48” fans)
Bess # 96321 918 watts
16,800 cfm
Bess #96132 1116 watts (18 % +)
24,000 cfm (30 % +)
A fan’s energy efficiency must beexpressed in terms of how much air itwill move per watt of power used:
Energy efficiency
Cfm/watt
A fan’s energy efficiency must beexpressed in terms of how much air itwill move per watt of power used:
Energy efficiency
1 Cfm/watt
For every 1 cfm moved…the fan will use 1 watt of power
A fan’s energy efficiency must beexpressed in terms of how much air itwill move per watt of power used:
Energy efficiency
The higher the number the better
Energy efficiency ratings typically rangebetween 15 and 25 cfm/watt
Can be obtained from independent fantest lab booklets.
Energy efficiency ratings
Fan A = 17 cfm/watt Fan B = 22 cfm/watt
Fan comparison(20,000 cfm, power cost $0.09 per kw*hr)
Power usage
Watts = cfm / cfm per watt
Fan A = 17 cfm/watt
Watts = 20,000 / 17 = 1,176
Fan B = 22 cfm/watt
Watts = 20,000 / 22 = 909
Fan comparison(20,000 cfm, power cost $0.09 per kw*hr)
Power usage
1 Kw = 1,000 watts
Fan A = 17 cfm/watt
Watts = 20,000 / 17 = 1,176
Kw = 1.18
Fan B = 22 cfm/watt
Watts = 20,000 / 22 = 909
Kw = 0.91
Fan comparison(20,000 cfm, power cost $0.09 per kw*hr)
Power usage
Cost = Power rate X Kw
Power rate is the charge of using 1 kw ofpower for an hour
Fan A = 17 cfm/watt 1.18 Kw 10.6 cents per hour
Fan B = 22 cfm/watt 0.91 Kw 8.2 cents per hour
Fan comparison(20,000 cfm, power cost $0.09 per kw*hr)
Fan A = 17 cfm/watt 1.18 Kw 10.6 cents per hour Eight fans
$ 142 per week $ 2,544 per year
Fan B = 22 cfm/watt 0.91 Kw 8.2 cents per hour Eight fans
$110 per week $1,968 per year
Fan comparison(20,000 cfm, power cost $0.09 per kw*hr)
A 2 cfm/watt difference will result inapproximately a 10 percent differencein electricity usage… Minimum acceptable rating is 19.1 Ideal rating is 20.1 or better
Energy efficiency ratings
Fan specifications:
Total cfm Or number of fans of that move a specific
amount of air
Interior shutter Cone optional
Minimum Cfm/watt = 19.1 Ideal 20.1 or better
1) Air moving capacity2) Energy efficiency energy efficiency ratio
3) Air moving capacity vs. static pressure air flow ratio
4) Drive type5) Quality of construction6) Price
Six factors to consider
Fan Output vs Static Pressure
02000400060008000
10000120001400016000
180002000022000
0 0.05 0.1 0.15 0.2 0.25
Static Pressure
Cfm
Fans react differently toincreases in static pressure...
Fan Output vs Static Pressure
02000400060008000
10000120001400016000
180002000022000
0 0.05 0.1 0.15 0.2 0.25
Static Pressure
Cfm
Most houses day one will operate at apressure around 0.10”
Over time it will increase Dirty shutters Evaporative cooling pads
Clogged evaporative cooling pads
You want a fan that holds upwell under pressure…
One way to quantify this iscomparing fans air flow ratio’s
Air Flow Ratio = air flow (0.20)/air flow (0.05)
Fan Output vs Static Pressure
02000400060008000
10000120001400016000180002000022000
0 0.05 0.1 0.15 0.2 0.25
Static Pressure
Cfm
AR = 1 AR=0.82 AR=.68 AR=0.55
Fan specifications: Total cfm
Or number of fans of that move a specific amountof air
Interior shutter Cone optional
Minimum Cfm/watt = 19.1 Ideal rating = 20.1+
Minimum air flow ratio = 0.67 Ideal rating = 0.72 +
Output at different static pressure Energy efficiency Air flow ratio
Independent fan performanceinformation
BESS Labs (Univ. of Ill) or AMCA
Independent fan performanceinformation
Tests conducted with shutters andguards in place.
Manufacturers can challenge oneanother
Poultry companies can send fans in fortesting
Independent fan performanceinformation
Obtaining information
Test booklets Web site
www.bess.uiuc.edu
Fan manufacturers
1) Air moving capacity2) Energy efficiency energy efficiency ratio
3) Air moving capacity vs. static pressure air flow ratio
4) Drive type5) Quality of construction6) Price
Six factors to consider
Direct drive advantages: No belts to tighten No belts to replace
Direct drive vs. Belt drive
Direct drive disadvantages Tend to move less air Tend to be less energy efficient
Direct drive vs. Belt drive
ACME AGD direct drive with cone 19,700 cfm (19 cfm/watt)
ACME BDR 48” slant wall with cone 21,400 cfm (21.4 cfm/watt)
Direct drive vs. Belt drive
ACME AGD direct drive with cone 19,700 cfm (19 cfm/watt)
ACME BDR 48” slant wall with cone 21,400 cfm (21.4 cfm/watt)
10 percent less air 10 percent less energy efficient
Direct drive vs. Belt drive
Direct Drive Tend to move less air Tend to be less energy efficient Often do not hold up as well under higher
static pressures
Direct drive vs. Belt drive
Direct Drive Tend to move less air Tend to be less energy efficient Often do not hold up as well under higher
static pressures expensive motors
But, if they meet the previously listedspecs, they can be used.
Direct drive vs. Belt drive
1) Air moving capacity2) Energy efficiency energy efficiency ratio
3) Air moving capacity vs. static pressure air flow ratio
4) Drive type5) Quality of construction6) Price
Six factors to consider
Quality of construction
Difficult to determine Thickness of metal/fiberglass on
housing and fan blades Length of warrantee Reputation
1) Air moving capacity2) Energy efficiency energy efficiency ratio
3) Air moving capacity vs. static pressure air flow ratio
4) Drive type5) Quality of construction6) Price
Six factors to consider
Price
Better fans tend to cost more...
Aerotech, Inc.
American Coolair
Canarm
Chore-Time
Cumberland
Ellison & Ellison Co., Inc.
General Shelters of Texas,S.B., Ltd.
Glacier Cor
Hired Hand, Inc.
Munters
TekSupply