http://www.scienceinafrica.co.za/2004/september/refrigeration.htm

This is a zeer pot. You have two clay pots, one nests inside the other. Fill the space between with sand, keep the sand damp, and the evaporation keeps the interior pot cool, but maybe not by much.

The article says adding water is required maybe 2 times a day. Anybody know anything about this? I'd be willing to think it would be cooler inside than ambient air, but I'm not willing to think I'd keep my milk in there for a few days.

I got a headache half way thru the article, but I noticed no mention of a lid. Seems to me that a lid of some kind might keep things even cooler inside...

A lid is mentioned in the 1st line of description of the zeer pot (in the 4th paragraph)...

Well, evaporative cooling isn't a new idea. Its where the old wives' saying about thundery weather making milk go bad comes from. I think the only way to see how well it works is for someone on here to make one and test it. Any volunteers?

It's basically a portable root cellar. It's not really an alternative to a refrigerator so no milk, meat etc.

It does look like a nice simple solution to a probelem. Depending on the vegetable you're putting in you could also add dry sad to the inside to help them keep longer.

For an alternative to a refrigerator for no power areas look into making something like the old Crosley icyball.

My mother grew up in Liberia, the workers' village has something who's description sounds similar.

Any such device cools by the evaporation of water, and therefore wont work well in humdid contions, which discourage evaporation.

In optimum conditions, the temperature can be reduced by as much as 15 degrees F but its usually less.

Such limited cooling is better than nothing, and would slightly extend the life of meat or milk, but only slightly.
A better though much more expensive solution would be a high efficiency DC refrigerator and PV system.

One experiment that I would like to try with a zeer pot is comparing placement in sun and shade.

Set up the zeer pots as usual, covered with a damp cloth (perhaps wicking water continuously) and place one in the shade and one in the full sun, and compare temperatures.

But everything is cool here now, too late!

Sue