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The Zeer Pothttp://www.scienceinafrica.co.za/2004/september/refrigeration.htmThe 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”.Pot-in-Pot Refrigeratorhttp://www.seed.slb.com/en/scictr/lab/pot_refrigerator/index.htmMohammed Bah Abba is from northern Nigerian. He won the 2001 Rolex Awards for Enterprise for his invention of a simple cooling system that can help preserve food in rural areas where there is no electricity. Eggplants stay fresh for 27 days, instead of the usual three. Tomatoes and peppers last for up to three weeks. The Pot-in-Pot system works by putting a smaller clay pot inside a larger one. The two are separated by constantly moist sand. Evaporation causes a cooling affect in the inner pot.At a recent SEED workshop in Malaysia we decided to try this for ourselves. We also replicated the experiment later with different pots.Tools and MaterialsTwo clay pots, one larger than the otherSandWaterCloth to cover the potsClay, cork or other material to plug holes in the pots if they have themThermometerGoGo Board with temperature sensors (optional)What To Do1. The smaller pot should fit inside the larger one with a space of one to three centimeters. If the pots have holes in the bottoms, as flower pots usually do, plug them with clay, cork or some other suitable substance. This prevents the sand from running out of the larger pot and keeps water from flowing into the inner pot.2.Put a small amount of sand into the larger pot. The layer should be thick enough so that when you put the small pot inside the larger one, the tops of the two pots are at the same level.3. Fill the space between the pots with sand.4. Pour water on the sand until it can absorb no more5. Dampen the cloth and cover the inner pot.6. Use a thermometer to check the temperature inside and outside the pot every few minutes and keep track of your results in a chart like the one below. We used a digital thermometer, but an alcohol one will do as well.Pot-In-Pot Coolerhttp://other90.cooperhewitt.org/Design/pot-in-pot-coolerHow a zeer pot fridge makes food last longerhttp://practicalaction.org/?id=zeerpotsPot-in-pot coolerhttp://solarcooking.wikia.com/wiki/Pot-in-pot_coolerPermaculture Reflections: Passive Coolinghttp://permaculturetokyo.blogspot.com/2006/11/passive-cooling.html
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