Abstract refrigeration system

Question

Abstract refrigeration system

Answer 1

Evaporation of water thrown over the tents of Bedouins in the desert to cool their tents.

(Evaporation of the water, removes Sensible Heat of Cooling from the tent as Latent heat of Evaporation of the water).

Answer 2

The vortex tube where 100 psig air is dynamically separated into hot and cold streams. The cold air is used for spot cooling and in the cooling of personal environmental suits.  

Answer 3

You can use a cloth that draws up water and cools via evaporation but the coolest one is to run compressed air through a coil that has a small hole out of which the air escapes. Then you can cool water or what you like with it.