Most people don’t understand how ice cream is made, so I’ll start there. Most people think that in an ice cream churn, you put the cream in the container, dump the ice around it, turn the container with the paddle inside, and then
the ice imparts it’s coldness to the cream thus making ice cream.
In reality, it’s the exact opposite! Actually, there is no such thing as “coldness”. There is only heat and lack of heat. It’s the heat that is being transferred when you make ice cream.
You see, when water changes phases from solid to liquid or from liquid to gas, that process requires heat. Where does it get that heat from? Answer: from the cream container. So, you dump your solid ice around the cream container, you make the ice melt faster by sprinkling rock salt on it, when the ice melts, it must have heat. So it sucks all the heat out of the cream container and uses that heat for it’s phase change from solid to liquid.
Guess what? You can use the same phase change process to make a simple refrigerator. Some people call it a clay pot cooler, or pot-in-pot cooler, or a zeer. All you need is evaporation. The human body is a great example of the power
of evaporation to cool. Did you know that you could die within an hour on a hot day if you did not sweat?
So, to make the refrigerator, just put one large clay pot inside another with a sandwich of sand between them. Pour water in the sand to keep it moist. Put your vegetables in the clay pot and cover with a wet towel. Keep it in a dry warm place to promote evaporation.
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Or this company actually sells a cool modern day version (needs no ice or electricity - just water)...