Utilises the capacity of certain substances to adsorb water on their surface, from where it can be separated again with the application of heat - dry air is obtained. If this dry air comes into contact with water it again absorbs water vapour.


The evaporation of new water produces a cooling effect. The adsorptive medium afterwards may be dried with solar heat, coming from cheap "hot air" collectors. The machines are heavy and big. Refrigeration below 0C is not possible.


Adsorption cooling with a "closed cycle" is possible too.