In our last post, we discussed about what evaporative cooling pads are, how they function and their application purposes in various industries. In this article, we will discuss the overall design of this mechanism and the way the cooling pads work.
Most of the designs take benefit of the fact that water has one of the largest known enthalpy of vaporization (also called latent heat of vaporization) values of any general substance. Due to this reason, evaporative coolers use simply a fraction of the energy of vapor-compression or an absorption air conditioning systems. Unluckily, except in very arid climates, the single-stage (direct) cooler can upsurge relative humidity (RH) to a level that makes the occupants uncomfortable. Two-stage and indirect evaporative cooling pads keep the RH lower.
Direct evaporative cooling (that is called open circuit) is used to decrease the temperature and boost the humidity of air by utilizing latent heat of evaporation, transforming liquid water to water vapor. In this course, the energy in the air does not change. Warm dry air is transformed to cool moist air. The heat of the outdoor air is used to evaporate water. The RH increases to 70 to 90% which decreases the cooling effect of human perspiration. The moist air has to be repeatedly released to external atmosphere or else the air becomes drenched and evaporation stops.
Passive direct evaporative cooling may happen anywhere that the evaporative cooled water can make a space chilled without the support of a fan. This can be accomplished through application of fountains or more architectural designs like the evaporative downdraft cooling tower, also termed as a “passive cooling tower”. The passive cooling tower design enables outside air to flow in through the top of a tower that is constructed within or adjacent to the building.