The principle of wet curtain cooling is evaporation, which is realized by the principle of absorbing environmental heat by evaporation of water molecules.When the content of water vapor in the air does not reach saturation, the water molecules quickly evaporate and become water vapor, while absorbing heat in the process, the humidity of the air will increase and the temperature will decrease. 

The energy needed for cooling is the energy needed to overcome the increase of the surface tension of water. When 1 cubic meter of water becomes a 10 micron cube, the energy required for its surface tension is about 43200 joules, and the latent heat of evaporation is as high as 2.2 billion joules. The theoretical energy efficiency ratio is as high as 50, 000. Limited by the laws of thermodynamics, the theoretical energy efficiency ratio of cooling 5 ℃ at 30 ℃ is about 60. 

The factors that affect the cooling efficiency of evaporation are air temperature, air humidity, water temperature, air velocity, atmospheric pressure and evaporation area. When the atmospheric pressure, wind speed, air temperature, air humidity and wet curtain area are constant, the higher the water temperature is, the higher the evaporation efficiency is, and the better the cooling effect is. 

Suppose the wet curtain area of the chicken house is 54m2 (its effective evaporation area is about 6500m2), there are 8 50 fans, the atmospheric pressure is 1.01bar, the wind speed over the curtain is 1.7m/s, the outdoor air temperature is 35 ℃, and the outdoor relative humidity is 49.99%. When all 8 fans are started, the inlet air volume of the chicken house is 82m / cm / s / s / s. Through calculation, we can get the following data:

Note: the calculation in the table ignores the water-cooled cooling caused by thermal radiation. 

It can be seen from the above data that under the above conditions, when the water temperature is ≤ 23 ℃, the temperature of the part of the air passing through the wet curtain close to the wet curtain paper decreases from 35 ℃ to 23 ℃, and the relative humidity increases from 49.99% to 99.99%, thus reaching saturation. The water in the wet curtain cannot evaporate, and the wet curtain does not work. When the water temperature is ≥ 27 ℃, the inlet air temperature is as low as 25 ℃, and the inlet air relative humidity is 99.99%. It is impossible to evaporate more water, and the evaporation cooling efficiency reaches the limit, even if the water temperature is high, it is impossible to further reduce the temperature. 

Here to remind aquaculture users, the use of wet curtain cooling, the use of normal temperature water cooling can be, do not use low-temperature well water cooling, otherwise it will be counterproductive.