Why will placing a damp towel over a fan increase its ability to cool a room?

Question

Avery Adams · Accepted Answer

Water has a relatively high volatility, which is the ease at which a liquid evaporates. Therefore, the water needs energy to evaporate. Where does it get the energy? It gets it from the surroundings.

The energy required for the water to evaporate (which is related to volatility, or how easily a liquid evaporates) on the towel is high, so the water must absorb energy from its surroundings in order to evaporate. This will lower the room's temperature, but you also need to think about how the evaporated water will affect the room's humidity. For example, if a person is sitting in this room and perspires, the humidity in the air from the damp towel will cause the rate of net sweat evaporation to be the same, but the rate of condensation of sweat back on the skin will be higher, meaning the person will perspire more even though the room will be cooler.

Axel Alvarado · Answer

undefined Placing a damp towel over a fan increases its ability to cool a room because the evaporating water from the damp towel absorbs heat from the air, thus lowering the temperature of the air blown by the fan. This process, known as evaporative cooling, enhances the fan's cooling effect by reducing the temperature of the circulated air.