Fans traditionally used in greenhouses are called suction fans or vacuum fans. This fan unit is located on the side of the greenhouse. Negative pressure is generated during operation, and the air is drawn in from the opposite vent, and is discharged outside the greenhouse through the inside of the greenhouse. This fan introduces outside air during operation, which of course also causes internal air to flow. The inner circulation fan operates by sucking air from the rear and exhausting it to the front, so it can be hung inside the greenhouse for ventilation. When the fan is operated, air is only generated inside, and no outside air is introduced, so there is no influence on the internal temperature.
The main purpose of the inner circulation fan is to maintain the flow of air inside the greenhouse. Especially in the internal temperature reset range, the operation of the internal circulation fan is more important when the exhaust fan stops working. The domestic greenhouses should maintain good air tightness as much as possible, improve the evaporative cooling efficiency of the water wall in the summer, and maintain the heat preservation capacity of the heating machine in the winter. Due to the good air tightness, the inner circulation fan is used to promote the air circulation evenly. Therefore, the relative humidity control can be performed, so that the temperature internal microclimate adjustment increases the relative humidity parameter in addition to the original temperature and the amount of light, so the crop grows,control can be better.