What is Evaporative Cooling?

     Evaporative Cooling is a universal natural phenomena. For example, in summer, we would feel cool when the wet arm expose to the air. It is because of the evaporation of water, which absorbs heat to cool our body, but not temperature shift. We feel cool if we sweat or sponge the body with alcohol. It is also because of evaporative cooling. In fact，evaporative cooling is a powerful and economical cooling technology.
    What is evaporation? The evaporation of water lies on the relative humidity of air, but not air temperature. Evaporation occurs even if the water freezes. No matter what the temperature, there are some very active molecules in liquids can fly out of the liquid surface and becomes vapor molecules when the air is unsaturated, this is the evaporation.
    Why evaporation causes cooling? The molecules must have heat taken while flying out of the liquid into vapor. This heat is taken from the water that remains in the liquid state when evaporation occurs. It results in cooler liquid water.
    There are three main factors affecting evaporation:
    Firstly, the relative humidity. There are always some molecules fly out of water into vapor molecules as long as the relative humidity of air is lower than 100% saturation. However, the evaporation would not occur if water is located in saturated air.
    Secondly, the surface area. The molecular number near to air increases when liquid surface area enlarges, more molecules may fly out of the liquid. Consequently, liquid surface area increases, evaporating faster.
    Thirdly, the air velocity. The vapor molecules may return liquid water because of the collision with other vapor molecules. If the air flows fast, the vapor molecules have less chance to return, resulting in more evaporation.

    Evaporative cooling equipment reject heat base on these principles. As shown in above enthalpy-moisture chart, air conditions changes from point A to point B while evaporating. The enthalpy of air increases. The moist air takes lots of heat from liquid, resulting in cooler liquid water. It is the essential design concept of evaporative cooling equipment to make sure that the hot and moist air discharged from devices is saturated or infinitely close to saturation.
    Evaporative cooling equipment includes Closed Circuit Coolers, Evaporative Condensers, Cooling Towers, etc.
    Learn more about evaporative cooling technology, keep an eye on our website and blog, or Contact Us today.