How to design and use chicken coop damper in winter
2020-12-16
The ventilation of the
chicken house in winter is very important. Poor ventilation not only affects the healthy growth of the chickens, but also affects the humidity of the chicken house. The requirement for air exchange in the chicken house is to meet the minimum demand for chicken activities. Since chickens with higher stocking density have high requirements for the small environment of the chicken house, it is necessary to increase the air exchange rate as much as possible to ensure that the air in the chicken house is fresh. The ventilation of the chicken house should pay more attention to the quality requirements. A good ventilation will not bring drastic changes to the temperature in the chicken house, but will also take away the dirty air in the chicken house. Therefore, it is necessary to make full use of the fan, air door, and pressure probe to work together to make the hot and cold air mix uniformly and achieve the desired effect.
effect
The damper is the passage through which air enters the chicken house and determines the direction of air flow. The air entering the chicken house, the cold air going up and mixing with the hot air at the top, and then falling to the ground is the goal to be pursued. The damper should point towards the roof or be parallel to the roof. If the angle of the damper is small, the wind will meet the roof and be reflected; if the angle is large, the wind will not reach the top of the chicken house and waste resources.
The air door and the fan are used properly. The fresh air enters from the air door, mixes with the hot air at the top of the house, and then falls to the lower end of the house to fill the whole house. The excess air is discharged through the fan. Whether the air is evenly mixed should meet two conditions: one is that the air door must have a certain angle to guide the direction of air flow; the other is that the incoming air must have a certain speed, and the air has a strong diffusivity, which must be before the air is diffused. The best way to reach a predetermined location is to increase the wind speed. After these two conditions are met, the incoming cold air will mix with the hot air at the top of the house.
The wind entering the chicken house must have a certain speed, generally 4.57 m/s. The higher the wind speed, the shorter the time to reach the top of the chicken coop, and it is easier to reach the top; if the wind speed is too low, the cold air will not reach the roof due to gravity, or even fall directly to the ground without going up.
Opening degree
The direction of the wind is the direction of the wind. The wind entering the chicken house will move upward along the roof and in the direction of the opening of the air door. When the direction of the air door is parallel to the direction of the roof, the opening degree is the largest at this time, and this angle is the complementary angle of the bottom corner of the roof. When the opening degree is small, the wind can reach the top of the chicken house in the direction of the damper, and it will not collide with the top wall; if the opening degree is smaller and the bottom angle of the damper is greater than a certain angle, the wind will collide with the top wall. The reflected and reflected wind cannot go up to the top of the chicken house due to the change of wind direction, which will affect the air mixing effect. The closer the reflected distance is to the damper, the worse the ventilation effect; the more the amount of reflected air, the worse the ventilation effect.
The effective area of the air inlet is the smallest area through which a certain amount of air enters the chicken house. The amount of air entering the chicken house through the air inlet is constant, and the smallest cross-sectional area through which this amount of air passes is the effective area of the air door. The effective area of the air door should be perpendicular to the wind speed direction. When the damper is opened parallel to the roof, the bottom angle of the damper at this time makes the wind entering the chicken house only one direction, and the wind direction parallel to the roof should be the maximum opening angle of the damper in an ideal state.
The reflected air is on the cross section of the chicken house, and a cool breeze can be felt at the same height as the air door. The specific position can be estimated by calculation. Under the condition that the wind speed of the air inlet remains unchanged, the smaller the opening of the air door, the more air volume changes in direction; the closer to the side wall, the worse the air mixing effect.
Quantity and regulation
In order to ensure the overall effect of ventilation, there must be a proper spacing between the dampers, or there must be a certain number of dampers, with a certain exhaust volume, and the wind speed of the air inlet depends entirely on the number of dampers. It is necessary to ensure that the air inlet has a suitable wind speed, but also to ensure the overall ventilation effect of the chicken house, which is related to the number of air doors. Too few dampers will affect the overall ventilation effect. There will be dead corners in the chicken house. If there are too many dampers, it is difficult to guarantee the wind speed at the air inlet, and the damper is difficult to open.
The opening of the air door is controlled by static pressure. The opening of the fan drives the air flow to generate wind speed. The pressure inside the chicken house becomes smaller, and the external pressure is stronger than the pressure inside the house. The air flows at the air inlet to generate wind speed and enter the chicken house. When there is no wind outside, the pressure and air density and the wind speed in the chicken house will not change with time. At this time, the air flow can be regarded as a fixed-length flow of fluid.
Under normal circumstances, the pressure probe is placed in a place where the wind speed is small, so the actual static pressure measured is smaller than that at the air inlet. When there is wind outside, if the outside wind direction is the same as the wind speed at the air inlet, the wind speed at the air inlet will increase, resulting in a high-pressure alarm. If the outside wind speed is opposite to the wind direction at the air inlet, the wind speed at the air inlet will decrease or even in the opposite direction, and the pressure sensor will fail. The air inlet can directly reflect the wind speed at the air inlet, but the value is much different from the other two places. Far from the air inlet and the same height as the air inlet, it can also indirectly indicate the wind speed of the air inlet. Any other place that is not at the same height as the air inlet will have an effect, and the pressure difference will change, but in the actual measurement, there is no change in the pressure difference at the same height away from the air inlet.
