GREENHOUSE COOLING SYSTEM-WATER PAD

The layout of the wet curtain-fan system in the greenhouse is the most common layout of the wet curtain-fan cooling system in the greenhouse. The wet curtain device is installed on one side of the gable of the greenhouse, and the fan is installed on the opposite gable. The fan draws air to the outdoors, causing the indoor air to form a negative pressure, and the outdoor air on one side of the wet curtain enters the room through the wet curtain.
Cooling properties of wet curtains The wet curtains used in greenhouses are basically paper wet curtains. Paper wet curtains are cardboard made of paper pulp with strong force added. They are corrugated and arranged and stacked in a certain form. They are bonded with water-resistant glue and then cut into polyethylene. The paper has good wet strength and large water-air contact area. Large, stable performance, easy for industrial production and other advantages
The parameters describing the characteristics of the wet curtain mainly include the heat transfer efficiency of the wet curtain, the resistance of the wet curtain and the specific surface area of ​​the wet curtain.
(1) The wind speed passing through the curtain is the wind speed passing through the wet curtain. Since the wind speed inside the wet curtain cannot be measured, the wind speed outside the wet curtain is used instead. In practice, the wind speed measured at a certain distance away from the wet curtain is usually called the passing wind speed.
(2) Heat exchange efficiency: The heat exchange efficiency of the wet curtain is a comprehensive technical indicator that describes the evaporative cooling heat transfer performance of the wet curtain. It indicates the sufficient degree of air exchange with water through the wet curtain. It is affected by the air flow rate (also known as passing through the curtain). The influence of factors such as wind speed) and wet curtain thickness
(3) Wet pad resistance: The wet curtain produces resistance to the air passing through it. The resistance passing through the wet curtain is related to the material and thickness of the wet curtain and the air flow rate through the wet curtain.
(4) Specific surface area of ​​the wet curtain: The cardboard used to make the wet curtain is pressed into a corrugated shape to form a larger outer surface: after being bonded into a wet curtain, a larger contact area between the wet curtain and water can be obtained. The ratio of the sum of the surface areas of the wet curtain cardboard layered to its volume is the specific surface area of ​​the wet curtain, that is, the contact area between air and water. The specific surface area of ​​the wet curtain directly affects the heat transfer efficiency of the wet curtain and the resistance produced by the wet curtain to the air. Usually the specific surface area of ​​the wet curtain is greater than 350m2/m3.