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Edition 01 : 11 December, 2010

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SOME RECOMMENDED DEVELOPMENT TECHNOLOGIES.

Locally built zeer pots for food conservation,

Zeer pots are simple traditional conservation systems thought to have originated in North Africa which enable food products to be cooled for a short term in most environments. Delicate foods such as milk and meat can usually be conserved for up to 2 days and other foods for up to 20 days depending on the nature of the food in question. Within the framework of integrated development projects they can be locally made using 100% locally available materials in any project area using the local money system set up there. This means that no formal money resources are needed.

For a general introduction to simple equipment for food conservation see E. Rusten, Understanding Evaporative Cooling, Volunteers in Technical Assistance (VITA), Technical Paper 35, Arlington, 1985. The paper is published by Peter Weir.

For step by step description on how to make zeer pots see The Clay Refrigerator on pp. 15-19 of Clay-based technologies, Practical Action, Khartoum, Sudan, August 2007.

For a detailed parametric analysis of zeer pots see Appropedia : zeer pot refrigeration (design), which concludes :

“the device performs well only in climates possessing a low relative humidity. The velocity of the wind and the area available for evaporation to occur on/through are two primary factors that can addressed to improve the performance of the pot-in-pot refrigerator.

“It has been shown that increasing the radius of the outer pot from 0.25m to 0.45m, almost doubles the total cooling effect. The adaptation of this however, is restricted by the increase in cost associated with using more materials. It is suggested that the strategy to make larger pot-in-pot refrigerators be employed only if community members are willing and able to pool their resources to share a device with superior performance.

“It is unrealistic to assume that electricity is available to ensure that their is a constant and adequate source of air flow. The device is dependent solely on naturally occurring winds. To maximize air flow, it is recommended that Zeer refrigerator be placed as high above the ground as possible. This can be accomplished by building a simple frame to support the device, and placing them on high ground or on top of buildings.

“There remains the potential for future analysis of this device. The development of a detailed conduction model to analyse heat transfer and mass diffusion mechanisms within the various layers would aid in identifying factors limiting performance and how they can be addressed. Additionally, by experimentation, a study could be performed to replace the permeability correction factor used in this analysis with real diffusion rates of moisture through clay. “

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Some recommended technologies.

Model homepage.

Bakens Verzet homepage

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"Money is not the key that opens the gates of the market but the bolt that bars them."

Gesell, Silvio, The Natural Economic Order, revised English edition, Peter Owen, London 1958, page 228

“Poverty is created scarcity”

Wahu Kaara, point 8 of the Global Call to Action Against Poverty, 58^th annual NGO Conference, United Nations, New York 7^th September 2005.

"In the end, it's about love for mankind. Freedom begins with love.

Our challenge is to learn to love the world"

Nigerian writer Ben Okri, interview in Ode Magazine, Dec 2002-Jan 2003, p.49

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