Breathing in winter sheds is critical, and bad ventilation not only affects the healthy growth of chickens, but also affects the humidity in the shed. The requirement for ventilation in a shed is to meet the minimum demand for flock activity. Due to the high requirements on the environment of chicken houses due to higher stocking density, ventilation should be maximized to ensure fresh air inside the house. The ventilation of the coop should pay more attention to the quality requirements. A good ventilation will not bring drastic changes to the temperature in the house, but will also take away the gas in the house. Therefore, we should make full use of fans, dampers and pressure probes. The three must work together in order to mix hot and cold air and achieve the desired results.
effect
The air door is the passage for the air to enter the house and determines the direction of the air flow. The goal of pursuing the goal is to enter the cold air from the air into the coop and fully mix the hot air at the top and then fall to the ground. The damper should point to the roof or parallel to the roof. With a small flap angle, the wind will meet the roof and be reflected; at a large angle, the wind will not reach the top of the house and waste resources.
When the damper is properly used with the fan, fresh air enters through the damper and is mixed with the hot air at the top of the house and then falls to the bottom of the house to fill the entire chicken house. The excess air is discharged through the fan. The air is mixed to meet two conditions: First, the damper must have a certain degree of angle for the direction of the air flow; Second, the incoming air must have a certain speed, the air has a strong diffusion, to be spread before the air The best way to reach a scheduled location is to increase the wind speed. After these two conditions are met, the incoming cool air will mix with hot air at the top of the house.
The wind entering the coop must have a certain speed, which is generally 4.57 m/s. The higher the wind speed, the shorter the time to reach the top of the house and the easier it is to reach the top; if the wind speed is too low, the cold air will fall off due to gravity and cannot reach the roof, or even fall directly to the ground.
Degree of opening
The wind direction is the direction of the wind. The wind that enters the coop will rise along the roof, and will also rise in the direction of the door opening. When the direction of the damper is parallel to the direction of the roof, the maximum opening degree is the corner angle of the roof. When the opening degree is small, the wind will just reach the top of the house in the direction of the door, and will not collide with the top wall; if the opening degree is smaller, the wind will collide with the top wall when the angle of the damper is larger than a certain angle. However, the reflected wind is not able to reach the top of the house due to wind direction change, which will affect the air mixing effect. The closer the reflected distance is to the damper, the worse the ventilation effect will be; the more air is reflected, the worse the ventilation effect will be.
The effective area of ​​the air inlet is the minimum area that a certain amount of air passes into the house. The amount of air entering the house through the air inlet is constant. The minimum cross-sectional area through which the air passes is the effective area of ​​the damper. The effective area of ​​the damper should be perpendicular to the direction of wind speed. When the damper is opened to parallel with the roof, the angle of the damper at this time makes the wind entering the house have only one direction, and the wind direction and the parallel building should be the maximum angle of the damper opening in an ideal state.
The reflected air is in the cross section of the house, and the cool wind passes through the same height as the damper. The exact location can be estimated by calculation. Under the condition that the wind speed at the air inlet is constant, the smaller the air door opening, the more air will be changed in direction; the closer to the side wall, the worse the effect of air mixing.
Quantity and regulation
In order to ensure the overall effect of ventilation, there must be a proper spacing between the dampers, or a certain number of dampers, a certain amount of exhaust air, and the wind speed of the air inlet completely depends 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 of the chicken house, which is related to the number of throttle. The number of throttles is too small, and it affects the overall ventilation effect. There will be a blind spot in the houses. If there are too many air intakes, the wind speed at the air inlets is difficult to guarantee, and the dampers are difficult to open.
The opening of the damper is controlled by the static pressure. The fan turns on to drive the air flow to generate the wind speed. The pressure in the house is reduced, and the external pressure is stronger than the pressure in the house. Air flows at the air inlet to generate wind speed and enter the house. In the absence of wind outside, the pressure and air density and the wind speed inside the house will not change with time, and the air flow at this time can be seen 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 measured static pressure is smaller than at the inlet. When the outside wind conditions, if the outside wind direction and the air inlet speed in the same direction, the wind speed at the inlet will increase, resulting in 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 reverse, and the pressure sensor will fail. The air velocity at the air inlet can be directly reflected at the air inlet, but the difference between the numerical value and the other two is larger. Being away from the air intake and being at the same height as the air inlet can also indirectly indicate the wind speed at the air inlet. Any other places that do not have the same height as the air intake will affect the pressure difference, but the pressure difference between the actual measurement and the air inlet at the same height is not changed.
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