【 Weak current College 】 on principle and natural ventilation device

According to the principles of fluid dynamics, indoor temperature is excluded or harmful pollution of the air, or the outdoor fresh air into the Interior, its essence is the flow of the air, while in the air flow process will overcome the resistance of door, window, etc. To air creating a certain power is a necessary condition for ventilation.
Natural ventilation is the use of the indoor and outdoor temperature difference caused by hot pressing or wind effect caused by the pressure to achieve a ventilation air exchange.
First, hot-pressure caused by natural ventilation
When the air temperature inside and outside the workplace, indoor air temperature higher than outdoor air temperature, because the hot air is light, there is a power to run. Then the outdoor air from the bottom edge of the door, window or wall opening Office into a room.
Second, the wind on natural ventilation of
Leverage the power of natural wind or ventilate the room. For example, building on the doors and Windows, the wind can blow from the upwind side of the doors and Windows, and can put indoor air pressure from the Lee side of the doors and Windows, so that the workshop reached out for ventilation purposes.
Third, hot pressing, caused by wind pressure and natural ventilation
A building, windward side of the lower heat pressure, wind direction, the role of into the air to the role of specific heat pressure alone, if the air pressure in the upper part of the Windward face greater than hot pressing, it cannot be opened from the top, on the contrary will turn into an exhaust air inlet, into into fall.
Because outdoor wind speed, direction even in a day is also changing. Therefore, in order to guarantee the effectiveness of natural ventilation, and air pressure in the calculations generally not be considered. However, the air pressure is objective and existent, qualitative consideration of wind pressure on the natural ventilation, remains essential.
IV. application of natural ventilation
Natural ventilation rate is large, do not consume power, while inorganic machine ventilation produced by harmful noises. In addition, it is the most economic, effective ventilation.
The natural ventilation and air supply as partial and local exhaust ventilation in combination, are often the most reasonable.
5. natural ventilation unit
Commonly used for natural ventilation devices have skylight, windproof sunroof; local natural gas pipeline ends and the need to strengthen the overall ventilation wind on the roof of the CAP; textile mill set saw-shaped plant; steel plant roof set bottom loading skylights, etc.
Natural ventilation into industrialized production, and factory chemical production of air conditioning tank, brings the device volume reduced exhaust efficiency; at the same time bring the entire project cost reduction, but also significantly reduces HVAC project design staff workload.
6. natural ventilation device selection calculation
Design a natural ventilation engineering, computing content mainly has three: more calories Q workshop; ventilation G and ventilation equipment for exhaust area (throat area) F.