Selection of Ventilation Methods for Outdoor Fan and Animal Husbandry Fan
Fan EC Motor Fan Permanent Magnet Synchronous Motor Selection Part 9-Selection of Ventilation Methods for Outdoor Fan and Animal Husbandry Fan
For outdoor fans such as air conditioner, large equipment cooling fan, cooling tower fan and animal husbandry fan, so why choose negative pressure exhaust?
There are two main ventilation modes for fans: positive pressure air supply and negative pressure air exhaust.
Negative pressure ventilation is forced ventilation and natural ventilation. Its working principle is that the fan draws indoor dirty air out of the air outlet. At this time, the indoor air pressure is kept in a negative pressure state, and fresh outdoor air enters the room from the designed air inlet to achieve the ventilation effect.
Positive pressure air supply is forced air supply and forced air exhaust. Its working principle is that through the operation of the fan, fresh outdoor air can be sent into the room and dirty indoor air can be discharged out of the room through gaps in the space.
Outdoor fans such as air conditioning external machines, cooling fans for large equipment, cooling tower fans, etc. are easily affected by the natural environment. Natural wind will interfere with the running fans, causing turbulence rather than laminar flow at the fan outlet, increasing the friction resistance and energy loss of the equipment. Under special circumstances, turbulence may cause fan stall and surge, increase fan blade load and noise, thus endangering the safe operation of equipment.
In addition, due to the relatively complex outdoor environment, the adoption of positive pressure air supply for outdoor fans will also reduce the passive protection capability of the fans, and other substances may be inhaled during operation, which will also affect the safety of equipment operation.
The animal husbandry fan uses negative pressure air exhaust instead of positive pressure air supply, because the breeding house is usually rectangular with a large area, and the fan and the air inlet have a span of about 70 meters. For positive pressure air supply to such a large-span space, air supply pipes must be designed, otherwise the air exchange efficiency and effect are not sufficient, but this is precisely related to the feed and meat return that the animal husbandry pays most attention to. Negative pressure exhaust produces laminar flow inside the breeding house, and the flow rate can be adjusted according to the growth stage of animals.
Fan inlet noise is lower than outlet noise. Low noise can improve animal living environment and obtain better feed and meat returns. Negative pressure exhaust is beneficial to the control and treatment of animal husbandry waste gas pollution, and can also reduce the influence of natural environment on animal husbandry fans.