Many of you may not have an idea of what evaporative cooling is all about. Sensible heat is absorbed from the air to be used as latent heat necessary to evaporate water. The amount of sensible heat absorbed depends upon the amount of water which can be evaporated.
Types of Evaporative Cooling
Evaporative cooling can be further divided into two types that is, direct or indirect or it can be termed as passive or hybrid. In Direct evaporative cooling, the water content of the cooled air increases because air is in contact with the evaporated water, whereas, in Indirect evaporative cooling, evaporation occurs inside a heat exchanger and the water content of the cooled air remains constant.
Direct evaporation can also be defined as the place where evaporation occurs naturally. A place can be cooled by passive evaporation where there are surfaces of still or flowing water, such as basins or fountains. The hybrid evaporative system applies for the place where evaporation has to be controlled by means of some mechanical device.
Evaporative cooling is based on the thermodynamics of evaporation of water, that is, the liquid phase of water changes to water vapor. This is the energy which is required to change a substance from liquid phase to a gaseous one without the change in temperature. Evaporation occurs when non-saturated air comes in direct contact. Also this phase requires energy too. In some cases, the best duct system is to blow the air into a large daytime occupancy room.
Some advantages of the indirect type evaporative cooling are as follows:
- Most used type of evaporative cooling and it can be used where electricity is expensive and where availability is limited that is scarce.
- It can be used as a pre-cooler for refrigerant air conditioning systems. since water stores the latent heat, and then the heat gets transferred from the surface to the water level, the surface becomes cooler, and this makes the entire living space cool.
- It allows the exhaust room air to be delivered to the cooling tower which will result in obtaining the lower water temperature and hence turning it to more cooling.
- There is a pump that circulates air from the reservoir to the cooling pad that enhances the quality of the air all throughout the rooms.
Differences between direct evaporative cooling and indirect evaporative cooling:
In a direct cooler, the blower forces the air through a water-soaked pad which are also permeable in nature. The air is filtered and cooled as well as humidified while it is passed through the pad. In an indirect type evaporative cooler carries with it a secondary heat exchanger that prevents humidity levels from being increased in the airstream.
It is a compact and lightweight system:
Evaporative coolers can be employed as a compact and often the one and only cooling system in a home. They can also be used in combination with a regular air conditioner system. This is because of the dehumidification of the air conditioners whereas evaporative coolers humidify. As a result, the two of the system, that is direct and indirect evaporative cooling will tend to work in opposition.
Therefore, this above article will help you know and learn what actually evaporative cooling is all about. It will give you each small information about the topic. Depending on the capacity of water that is to be stored in the reservoir, the price can go high or low. When the humidity is higher, the rate of evaporative cooling is lesser.