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Zeer pot refrigerator
The pots can be produced locally by artisans, and made from local clays. The pots allow people to store tomatoes and other produce for 21 days or more instead of three or four.
The Zeer pot, also known as simply a Zeer (in Arabic) or a pot-in-pot refrigerator, was developed in Africa. It was created for people to store food for longer periods of time. There are two pots, a small ceramic pot inside of a larger ceramic pot. Between the two pots there is sand, and when water is poured on the sand it makes the inner pot colder via evaporation (evaporative cooling). This is used like a refrigerator to keep things cold.
An article in the online Science in Africa explains: "The zeer is a large pot inside which fits another smaller pot with a clay lid. The space between the two pots is filled with sand, creating an insulating layer around the inner pot. The sand is then kept damp by adding water at regular intervals — generally twice a day — reducing the temperature within the inner pot."
An analysis of this technology can be found here.
Suggestions for further research
Because of poor road conditions and lack of fast transportation from the fields to the market place, many farmers experience rapid drop of quality on their vegetables. The price they can get out of their produce on the market depends on this quality. And it is potentially much profit for each farmer to make here if we can develop a transportation vessel of the same principle as the zeer pot. The design and material choice needs to fulfill some requirements, such as low weight so it not waste too much fuel of the transportation vehicle. And it needs to be sturdy and reusable or recyclable. And perhaps even able to combine with solar still technology?[Suggested project]
Researching chimney addons, to reach into air higher up, with more wind speed[Suggested project]
Researching how to increase surface area of the sand layer[Suggested project] (possibly you can make the outer clay pot's interior and exterior surface carved, rugged, roughened or chiseled, to increase surface area, to increase evaporation. There are zeolits, with extremely large surface area, very porous)
- Zeer pot refrigeration (design) - detailed design issues and modeling.