Apot-in-pot refrigerator,clay pot cooler is an evaporative coolingrefrigeration device which does not use electricity. It uses a porousouterearthenware pot, lined with wet sand, contains an inner pot (which can be glazed to prevent penetration by the liquid) within which the food is placed - the evaporation of the outer liquid draws heat from the inner pot. The device can be used to cool any substance. This simple technology requires only a flow of relatively dry air and a source of water.
The most elaborate versions of these used special cuts to channel air flow and allowed the ancient Persians to create frozen delicacies in the summers. Sharbat, anyone?
