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Evaporative cooling

9K views 31 replies 23 participants last post by  Mullinater116 
#1 ·
I ran across this while looking at other links. On one hand it sounds like it will work. On the other hand I have my doubts.

I don't have two pots. Is anyone interested in giving this a try and recording the inner temperature?

http://www.shtfplan.com/emergency-preparedness/off-grid-shtf-survival-ancient-technology-for-refrigeration_09252011


"SHTF Survival: Clay Pot Refrigeration
by Tess Pennington

Have you ever wondered what our ancestors did without refrigeration? How were they able to prevent their food from spoiling? Some of our ancient civilizations did in fact have refrigeration and used simple items they had on hand to create it.

The zeer, or clay pot refrigeration keeps food cool (icy cold) without electricity by using evaporative cooling. Essentially, a porous outer earthenware pot, lined with wet sand, contains an inner pot (which can be glazed to prevent penetration by the liquid) within which the food is placed. The evaporation of the outer liquid draws heat from the inner pot."
 
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#2 ·
I am guessing they are using "icy cold" as a subjective term rather than truth.
I have however used evaporative cooling combined with convection to cool a room down by 15° but it failed as the humidity went up. Maybe in a dry enough and cold enough environment you could achieve icy cold but mid summer I'm betting cool to the touch is the best that can be achieved small scale.
 
#3 ·
I lived in kenya, east africa when I was a kid... parents were missionaries. We had one of these pots that we used to keep drinking water cool. Basically an unglazed pot filled with water on a metal stand to maximize surface area.

In kenya with almost no humidity it worked great, it was not "ice cold" but it was not something you would want to dump down your pants. I remember taking a shower, putting on my clothes without drying off and walking 200 yards to my room arriving completely dry.

It does not work so well with humidity. I tried it here in Arkansas and it got maybe 10 degrees cooler than ambient temperature.

Another thing to consider though is that if you take the average of the hottest it generally gets and the coldest it gets in your area it is about that temperature all year round if you dig down 6 feet or so. Here that comes out to about 65 degrees. If you bury a bunch of thermal mass (like 55-gallon drums of water) then pump it through a radiator with a fan you can make a cheap geothermal cooler. I am actually planning on doing this in a couple of weeks... going to take a while to dig a big hole.
 
#6 ·
Saw this on one of the "learn me" channels.
It was one of the things that encouraged me to learn more about Heat.

The sand creates a "heat vacuum" so the interior pot loses heat.

What's really outstanding is that our ancient parents figured this out.
I'm beginning to think that they were a heck of a lot smarter than we are.
Oh yeah, no doubt about it.
Most tech is either rediscovered, batteries are an example, or improperly attributed to, like the blast furnace.
 
#11 ·
I just completed an experiment with a homemade "Zeer Pot".

with just a little airflow around the pot and moderate humidity in the air I got 6 to 7 degrees cooling from the pot. With lower humidity and a breeze around the pot I got 9-11 degrees of cooling.

My video about the build and trials:
 
#12 ·
Thanks CC!

I'd about given up on the idea due to the high humidity. Even though it doesn't work as well as it might in a drier climate those precious degrees are worthy of working on.
 
#17 ·
You're welcome.
I think those few degrees are worth the effort as well. In a real serious situation, you might get your foods/medications to last a few days longer which can save you having to make multiple trips to forage for replacements. That conserves resources like drinking water, calories, bartering materials, maybe fuel if you still have it.

Being able to avoid spending time foraging might allow you to spend less time having potentially dangerous encounters with nature or other people. More time to protect your own people and assets. Fewer trips to the foraging site means less chance that' you 'll educate others about those resources. Might help you to avoid becoming a predictable target for people (in the foraging environment) who might want to steal from you what they know you'll be coming out to forage. By not being a predictable target, you weaken the predators.

In a way, evaporative cooling can become a force multiplier.
 
#15 ·
Kind of off topic,but in Afghanistan we obviously had no way to refrigerate our stuff. So we would take old socks and hang them from the posts and put bottles of water in them. Then you pour water on the sock and make sure it stays damp. It actually would get pretty cold right near the end of the day. Id guess around 50-60 degrees. This was in 130-140 degree weather so it could possibly get alot colder here.
 
#26 ·
for cold water in the desert i use what we call desert water bags.

https://lh4.googleusercontent.com/_bPH4DhY__Yg/TW2-Haox3II/AAAAAAAACfk/E8bZfYZt9Z4/P1020658.JPG
buy the long ones if you can find them they hold more water and buy two that way one is always cold.

The biggest one i ever saw was the size of a navy sea bag and held about 30 gallons and it was military surplus.

Years ago i worked a mine near Death Valley Calif and had a window evaporative cooler in the trailer i was staying in. i ran about 25 foot of 1/2 inch clear plastic tubing in the water in the bottom of the cooler and to the inside of the trailer with a valve that i could fill my drinking glass from.
That water was ice cold at the end of the day.
For water in the mine i had two of the desert water bags i hung in the shade in the entrance of the mine
 
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