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BY AYESHA AIMAN
ECH Fan Operation in Broiler Management to Control
Humidity, Temperature in Winter / Summer / Monsoon.
By
Dr. Naeem TahirASM Jadeed Sales Office Faisalabad.
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The bird!
Homoeothermic
Body temperature---------------105-107˚F(41-42˚C)
Upper lethal body temp.-----------------115˚F(46˚C)
Environment comfort zone--------70-75˚F(21-23˚C)
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Where is the most heat coming from?
18% ceiling
2%side wall
80%bird
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Methods of heat loss:
Conduction Convection
Radiation
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Higher wind speeds increase sensible heat loss and reduce latent heat loss in broilers.
Objective of Fan SystemA System that delivers fresh air into the poultry house and removes obnoxious gases from the poultry house
Fan Operation At a GlanceFan System is For
Moving FRESH AIR INTO a house and moving STALE AIR OUT of the house;
Sending UNWANTED heat, EXCESS moisture, ammonia, OUT of the house; and
AIR MIXING to get heat, moisture, ammonia INTO THE AIR that leaves the house.
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Objectives of Fan Operation
o Maintain uniform temperatureo Provide fresh airo Remove undesirable gaseso Remove moistureo Keep the litter dryo Keep uniform condition in the house
What is ventilation ?Ventilation means moving the right
amount of air at the right time and in such a way to manage temperature, humidity and other environmental factors for optimum bird performance
Types of ventilation:
Minimum ventilation
Transitional ventilation
Tunnel ventilation10
VENTILATION PARAMETERS: Tunnel fans capacity. Cooling pads area. Minimum ventilation fans. Air inlets. Climate controller. Insulation.
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VentilationFor ventilation purposes weather can be divided into three types
Weather types
1. Winter2. Summer / Monsoon3. Moderate
Types Of Ventilation
1. Winter => Minimum ventilation2. Summer / Monsoon =>Tunnel ventilation3. Moderate weather =>Transitional ventilation
Relative HumidityMoisture holding capacity of
air at certain temperature.OR
A ratio of the quantity of water vapor in the air compared with the total that can be held at a given temperature
Important Terminology
Relative Humidity
Warm air significantly hold more water than cold air
Water holding capacity of air doubles with each 11oC increase in temperature
Important Terminology
Dew Point TemperatureTemperature at which water vapors are transformed back to liquid
Static PressureWhen we run the exhaust fans a
negative pressure is created inside the house. To measure the difference of outside and inside pressure we use the term ‘Static Pressure’. It is mentioned in Pascal or inches.
CFM
Volume of air being moved by a fan or entering an air in let
Air inlet & Air jet A controllable opening generally located
at the eave controlling the velocity of air
Air that is allowed to travel adjacent to a smooth surface, generally a ceiling or side wall.
Throw The distance an air jet will travel before
its maximum speed is decreased to 75 feet per min.
Less than 75 fpm the air moves aimlessly
Measures of Poultry House
Length 450 ft Width 45 ft Height 8 ft
Fan Calculation
Volume of House Cross Section of House Desire Air Velocity Fan Capacity
Fan Calculation
Volume of House = Length x Width x Height
= 450 x 45 x 8
= 162000 cub. ft
Fan CalculationCross Section of House
Width X Height
45 X 8 = 360 sq. ft
Fan CalculationDesire Air VelocityLength of the houseMostly we recommend (length + 50-75)500 ft/min
Fan Capacity18000 cfm22500 cfm
Fan Calculation (1)
Cross Section x Air Velocity ÷ Fan Capacity = No of Fans
360 x 500 ÷ 22500 = 8
Fan Calculation (2)Volume of House ÷ Fan Capacity = No. Fans
162000 ÷ 22500 = 7.2
= 8
Air Exchange ≤ 1
Air Exchange = House Vol. ÷ Tot. Fan Capacity
= 162000 ÷ 180000
= 0.9-min
Air Velocity Calculation
Air Velocity = Tot. Fan Capacity ÷ Cross Section
= 180000 ÷ 360
= 500 ft/ min
Pad Area Calculation
Pad Size (2``, 4``, 6`` )
Total Fan Installed
Air Velocity for Pad
Pad Area Calculation
Pad Size Air Velocity
2`` 150 ft/min
4`` 250 ft/min
6`` 350-400 ft/min
Pad Area CalculationPad Area = Tot. Fan Capacity ÷ Air Speed
= 180000 ÷ 250/400
= 720 sq.ft ( 4``)
= 450 sq.ft ( 6`` )
MINIMUM VENTILATION / WINTER VENTILATION
Fan Calculation for Minimum Ventilation
No. of Fans = _______________________Avg. body weight × No of birds× CFM requirement per kg
CFM of Fan
Example
Avg body weight = 2.5 kg Cfm required = 0.5 /kg Cfm of fan = 9000 No. of Fans = (2.5 x 30000 x 0.5)/9000 No. of Fans = 4.16 5 fans will be needed for winter
ventilation
Operating time for Fan
Operating Time = _______________Total CFM RequirementTotal Fan Capacity
Example
Total cfm requirement = 37500 Total fan capacity = 9000 x 5 = 45000 Operational time = 37500/45000=0 .83
= 0.83 x 60 sec= 49.9 sec
It means that in 1 min fan should be on for 50 sec and off for 10 sec.
To get reasonable operational time, we multiply by 450 x 4 = 200
It means in 4 min fan should be on for 3 min & 20 sec and off for 40 sec
Inlet Calculation
Inlet area (sq. in.) = Total cfm required ÷4 = 37500/4 = 9375 sq inch = 65.10 sq ft
No. of Vents = Area Required/Area of Vent = 65.10/ 1m x 0.4 m = 65.10/ 3.2808 x 1.3123 = 65.10/4.30 = 15. 13
16 inlets will be required
Inlet Calculation on basis of CFMNo. of inlets = capacity x average weight x
0.5cfm(per kg)/2000cfm
= 30000 x 2.5 x0.5 /2000 =18.75
This formula suggests 19 inlets should be used
Transitional Ventilation Fans
Vol. of House x 40 % ÷ Fan Capacity = No.of Fans
162000 x 40 % ÷ 22500 = 2.88
= 3
Transitional Inlets Calculation
For each 10000 cfm we require 15 sq.ft inlet area Size of each vent
Length Width Area
46`` 6`` 1.91 sq.ft
46`` 8`` 2.55 sq.ft
Transitional Inlets Calculation
No.of fans x capacity ÷ 10000 x 15 = Inlet Area
3 x 22500 ÷ 10000 x 15 = 100.5 sq.ft
Inlet Area ÷ Size of Inlet = No.of Vents
100.5 1.91 52.61 (54) 100.5 2.55 39 (40)
Minimum Ventilation Fan
Number of birds in the houseBody weightCfm per Kg.Fan Capacity
Minimum Ventilation Fan
No.of birds X B.W. X cfm/kg ÷ Fan capacity
30000 X 1.8 X 0.5 ÷ 9000 = No. of fans
= 3
= 3
Side wall Fan spacing
Length of house ÷ (No. of fans X 2) = feet from wall
400 ÷ ( 3 X 2 ) = 67 ft 67 X 2 = 134 ft
Side wall Fan spacing
67 134 134 67
A B CCC
FansPads
Cool Air
Estimated effective temperature reduction when air temp is 85-90˚F:
Air velocity Bird age
Ft/min 1 week 4 weeks 7 weeks100 -4 -2
200 -12 -5 -2
300 -22 -10 -4
400 -15 -7
500 -18 -10
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Air Velocity Bird Age
Minimum Ventilation Rates per bird
Week Days Cfm/Bird1 1-7 0.102 8-14 0.253 15-21 0.354 22-28 0.505 29-35 0.656 36-42 0.707 43-49 0.808 50-56 0.90
Age (days) Max Airspeed Max Airspeed (m/s) (fpm)
0 – 14 days 0 - 0.5m/s 0 - 100fpm
14 – 21 days 0.5 – 1.8m/s 100 – 350fpm
Air speed for Young Birds
How a bird releasesheat?
A bird releases excess body heat in 2 ways: 1. To the air around it – Sensible Heat – 11BTU/kg or 5BTU/lb. The cooler the air the greater the amount of heat loss. The warmer the air, the
smaller the amount of heat loss 2. Through evaporation of moisture from respiratory system – Latent Heat – 15BTU/kg or 7BTU/lb. the amount of heat a bird loses through the
evaporation of moisture off of its respiratory system depends on the relative humidity of
the air it breathes
3 Areas Where Broilers Release Heat
1. Head,2. Legs,3. Under wing
Heat Loss & Air Speedo Without airspeed evaporative cooling is potentially dangerous and as air velocity increases, the importance of relative humidity to a bird decreases
o If the temperature of the air moving over a bird is equal to its body temperature essentially no heat will be lost to the air. It is not an either/or situation.
o A producer needs to utilize both air movement and evaporative cooling during hot weather to keep birds comfortable and productive.
Wind Chill Effect – Effective Temperature
Any wind-chill curve is an estimation!!– Effective temperature (what a bird perceives thetemperature to be) is a function of:1. Air temperature2. RH3. Bird Age4. Stocking Density5. Wind Speed6. Amount of radiant Heat – roof or side walls
As a result it is very difficult to come up with a chart/formulathat accurately predicts effective temperature!
How much does the air heat up?
1. Amount of heat added to the air in a house the more heat added to the house, the hotter the house will be2. How quickly we exchange the air in the house. the faster the air exchange rate, the cooler a house will be
Remove heat from the house by: rapidly exchanging the air in the house. If we don’t exchange the air rapidly large temperature differences can occur between the inlet and exhaust ends of the house.
Fan Timer Setting Cfm per bird X No. of birds ÷ Fan capacity
0.5 30000 ÷ 27000
= 0.55 (55%)
= 0.55x60= 33 sec.or0.55x300=
165 sec. On and 135 sec. Off
Tunnel Ventilation
Tunnel Ventilation
Transitional Ventilation
Minimum Ventilation
Ventilation with end fans side inlets
Side inlets and side fans
Potential problems:
Not uniform temperature in the house: Proper insulation of the house. First go on tunnel ventilation, then
cooling.
Increased heating cost: Center house brooding. Proper insulation.
Potential problems: Uneven ventilation: Excessive leakage near the pads area, doors, windows, and air inlets. Litter caking :
During Winter: Improper minimum ventilation. Requires proper air inlets opening along with proper no. of 36”
fans.During Summer:
Low air movement. Proper ventilation. (First go on tunnel ventilation, then cooling).
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Thank You!87
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