Livestock Equipment

Why should wet curtains be cooled with warm water?

 

  The principle of the cooling of the wet curtain is to evaporate and cool down, and the principle of absorbing the environmental heat by evaporation of water molecules is realized. When the water vapor content in the air does not reach saturation, the water molecules evaporate rapidly and become water vapor, while absorbing heat. In this process, the humidity of the air increases and the temperature decreases.

 

        The energy required to cool down is the energy required to overcome the increase in the surface tension of water. When 1 cubic meter of water becomes a 10 micron cube, the surface tension requires about 43200 joules of energy and the latent heat of evaporation is 2.2 billion joules. The theoretical energy efficiency ratio is as high as 50,000, and the air conditioner is limited by the laws of thermodynamics. The theoretical maximum energy efficiency ratio of 5 °C at 30 °C is about 60.

 

       Factors affecting the efficiency of evaporation and cooling are air temperature, air humidity, water temperature, air flow rate, atmospheric pressure, and evaporation area. When the atmospheric pressure, curtain wind speed, air temperature, air humidity and wet curtain area are constant, the higher the water temperature, the higher the evaporation efficiency and the better the cooling effect.

 

       Assume that the wet curtain area of ​​the house is 54m2 (its effective evaporation area is about 6500m2), 8 sets of 50 type wind turbines, atmospheric pressure is 1.01bar, wind speed of curtain is 1.7m/s, outdoor air temperature is 35°C, outdoor relative humidity It is 50%. When all 8 fans are started, the air intake of the house is 82m³

 

When the water temperature is ≤ 23 ° C, the temperature of the part of the air passing through the wet curtain close to the wet curtain paper is lowered from 35 ° C to 23 ° C, the relative humidity is increased from 50% to 100% and thus saturated, and the water in the wet curtain cannot evaporate. The wet curtain does not work; when the water temperature is ≥27°C, the inlet air temperature is at least 25°C, the inlet air relative humidity is 100% and reaches saturation state, it is impossible to evaporate more water, and the evaporation cooling efficiency reaches the limit even if the water temperature It is also impossible to further lower the temperature even higher.

 

       Here to remind the farming users, use the wet curtain to cool down, use normal temperature water to cool down, do not use low temperature well water to cool down, otherwise it is counterproductive.