wats the role of evaporation in desert cooler(or normal coolers)?

Answer 1

Evaporation is a cooling process. When a liquid evaporates, it happens below its boiling point. The liquid as a whole has not reached the boiling point. However, individual molecules have attained sufficient energy to break the bonds between themselves and the other molecules in the mass of liquid, becoming gaseous. As a result, it is the most energetic molecules that evaporate, leaving behind the less energetic molecules. Energy translates into temperature, so the liquid left behind will cool down as the more energetic particles leave the mass. This phenomenon is called evaporative cooling.

This is the basic principal behind the desert cooler, which is in fact typically called an evaporative cooler. Since the evaporative cooler dumps water vapor into the air, it is most useful in dry environments; if there is already significant humidity in the air, less water will evaporate, and the surroundings will become very clammy.

Answer 2

The evaporation of water (from skin or a desert cooler) removes heat energy lowering the temperature of the cooler and air passing through it. The air must be dry because evaporation is poor at high humidity. The effect is also related to the wet-bulb effect.

Answer 3

evaporation of refrigents makes a temperature drop by which it absorbs heat from surrounding there by reducing the heat of surrounding