The main equipment of fan wetted pad ventilation cooling system are the negative pressure fan and water screen, and the ventilation cooling system utilizes the principle of negative pressure suction and the water evaporation cooling. Before knowing the cooling principle of the fan wetted pad ventilation cooling system, we know two nouns at first: The first one is the negative pressure, and the other one is the evaporation cooling. Negative pressure: Before knowing the concept of negative pressure, imagine it as a large plastic bag.

When we extract the air in plastic bag with the needle tube, the pressure in the plastic bag would become less, at that time, the plastic bag would collapse when the air is extracted, and the air out of the bag attempts to enter and fill up the vacuum in this part. The vacuum state generated in the greenhouse fan causes the outside fresh air filtered through water screen enters the greenhouse. Evaporation and cooling: We have the following experience in life. After the water is smeared on the surface of skin, we could feel cooling when the wind blows. The water absorbs the heat in the air in the evaporation process of water and then the air temperature reduces, which is the evaporation and cooling of water. Wetted pad adopts that principle to achieve the cooling.