The pot-in-pot refrigerator
, also known as a Zeer الزير
in Arabic, is a refrigeration
device which keeps food cool without electricity by using evaporative cooling
It is constructed by placing a clay pot within a larger clay pot with wet sand in between and a wet cloth on top. As the water evaporates it cools, allowing food stored in the inner pot to be kept fresh for much longer in a hot, dry climate. It must be placed in a dry, ventilated space for the water to evaporate effectively towards the outside.
Mohammed Bah Abba invented the device in 1995 and was awarded a Rolex Laureate (Rolex Awards for Enterprise) in 2000 for developing this "pot-in-pot preservation/cooling system".