What are the cell pads?
Cell pads consist of corrugated sheets of cellulose gathered in an opposite sequence, which generates air passage inside the cell. These sheets have very high ability in absorbing water and are chemically treated to prevent disintegration.
How do cell pads work?
The idea of cell pads in poultry houses depends upon inducing a negative pressure inside the house by using suction fans where passage of air is restricted only within the saturated cells with water. The air works on evaporating the water that is contained in the cells and passes inside the house with calculated velocity.
The decrease in temperature felt by birds depends upon:
1) Water Vaporization: it means conversion of water as a liquid into vapor (steam). Converting one liter of water into vapor needs energy equal to 560 kilo calories or 2.2 B.T.U 9 (British Thermal Unit). For the water to evaporate it needs energy. This energy is obtained from the surrounding area (the pads).
2) Wind Chill Factor: when the wind speed is high, the feeling of coldness increases. Although the temperature has not changed whatsoever, there is a directly proportional relationship between wind speed and cold feeling. Example:
1. At a temperature of 17 OC, a feeling of chilliness occurs (motionless air). Increasing the air speed to 16 km/h will result in the feeling of coolness as if it were 6.1 OC and rising the air speed to 57 km/h will result in the feeling of coldness at –16 OC.
2. Increasing the air speed from 0.5 m/sec. to 2.5 m/sec. will lead the birds to feel a decrease in temperature approximately 5 OC.
How to calculate the surface area of cell Pads needed to cool down the production unit?
It depends on many methods. First of all, calculate the volume of air in the unit that is required to be changed once a minute. Then, calculate the number of fans, which are capable to change the air mass once an hour.
First Technique
It depends on the need per meter from the unit of certain volume of air each hour and it is approximate, where it is required for every meter 200 m3 from air in an hour.
Example:
A house of 100 m long and 12 m wide has a surface area of 1200m2 needs 270,000 m3 of air in an hour. (225 x 1200) = 270,000 m3.
Second technique
It depends on the amount of air needed for every kilogram of living body weight that exist in the house per hour. But it neglects very important facts.
They are for example: * A production unit has a surface area of 12m x 100m =1200m2. This has the ability to contain. - 12,000 birds with a rate of 10 birds per m2 OR - 20,400 birds with a rate of 17 birds per m2 OR - 23,000 birds ( batteries ) with a cage area of 500 cm2 per bird.
*Every 1 Kilogram body weight needs 6 m3 to 9 m3 of air in an hour with good insolated structure. Therefore, it is important to calculate accurately the needs of the units; this depends fully on the amount of meat present and purpose of the usage of this unit.
Third technique
This technique is considered the closet to accuracy, where the volume of air ( per unit of production ) is calculated. The aim is to change it every minute.
Example: A unit with measurements of 100 m long, 12m wide and 3m high. Size of air mass = 3,600 m3 is changed every minute; it means 216,000 m3 per hour.
Important notifications
1) The capability of the fans in the market is calculated at zero Pascal meaning that the pressure before the fan and after Wards are equivalent. When the fans in the units are exposed to batteries or concrete columns inside the house the fans airflow capacity in reduced. Therefore, careful consideration must be taken into account that 10% to 25% of the fans capacity is increased to be more precise.
2) Square meter of the cell pad with a thickness of 10 cm has the ability to pass : o 1 m3/sec meaning 3600m3/h (1 x 60min x 60 sec.) OR o 1.5 m/sec. Meaning 5400m/h (1.5 x 60 min. x 60 sec) OR o 2 m/sec meaning 7200m/ hr ( 2 x 60 min x 60 sec )
The Cell pads with thickness 15 cm are equivalent to 1 ½ cell pad with a thickness of 10 cm.
Important considerations
1- The accuracy of calculations and maximum production of the house should be taken into consideration. 2- The condition of the house whether it is closed well or if there is any leakage, which has a negative impact on the efficiency of the cooling system, should also be taken into consideration. 3- The degree of isolation of the walls and ceiling and the amount of heat leakage is to be considered too. 4- The relative humidity that is inside the house should be regarded. Whenever the relative humidity is lower, the efficiency of the cooling system is higher. Also whenever the temperature is at the maximum record, the relative humidity will be at its lowest records (Functioning hours).
Usage of cell Pads
Cell pads can be used in:
- Poultry farms, rabbit farms, dairy farms. - Green houses. - Warehouses and factories. - Indoor Gyms. - Living houses (desert cooling).
Heat stress in poultry farms
Temperature plays an important role in poultry houses. The optimum temperature for the adult birds vary between 17 oC to 28 oC and in that range we can get the optimum production aimed at (meat and eggs )Increasing the temperature above 28 oC reveals symptoms such as :
1) Reduction in feed intake with slight increase in water consumed by birds. It will affect feed conversion and increase water intake. This will lead to ruining of litter, with addition to the disturbance of electrolyte balance in the body, which might lead to death.
2) Panting: accelerated breathing affects the respiratory tract (dryness and congestion). This will result in the respiratory system to be more susceptible to viral and bacterial infection. Also, Carbon dioxide produces more than normal will result in reduction pf carbonates, which is the most important portion in forming eggshell. Also, Carbon dioxide plays an important role in keeping blood acidity. Shortage of Carbon dioxide will lead to alkalinity, which is fatal.
3) Mortality: the symptom of mortality begins at 35 oC especially in the well-matured birds (heavy weight). The effect of high temperature will be aggravated so we can not imagine that we have a living bird at 47 oC.
Economical losses from high temperature
1) Bad conversion ratio in the broilers. Bad quantity and quality in egg production. Bad fertility and hatchability. 2) Complication resulting from high temperature; a) Respiratory diseases b) Coccidia c) Electrolytes and vitamins deficiencies. These are needed in heat stress especially vitamin C. d) Immunological disturbance, which leads to reconsideration of vaccination program. e) Mortality is complicated to be evaluated with accuracy. High temperature may lead to disasters.