The pot-in-pot refrigerator , also known as a Zeer Ø Ù Ø Ù Ø in Arabic , is a food cooling device which keeps food cool without electricity by using evaporation . The pot-in-pot refrigerator , also known as a Zeer Ø Ù Ø Ù Ø in Arabic , is a refrigeration device which keeps food cool without electricity by using evaporative cooling .