Solar cooling with 2 clay pots ! Very cheap genius idea !

[triffid]

I too have read about Donkey's solar icebox and am curious about that natural building material"cob",I would love to learn more about it.I also wonder how much heat those al oxide pellets can hold?
Anyone here have the answers?Triffid

[ResinRat2]

Well the solar pot experiment has been running eight days in my basement. I have been recording temperatures every 24 hours and adding water as needed to the sand. The center is half-filled with aluminum oxide powder.

Air temperature for my basement has varied from 66 down to 59 during the week and the temperature differential between the ambient air and the center pot has remained very steady at 3.9°F. So in my dark, reasonably temperature-controlled basement the unit maintains a sustained and almost four degree (°F) temperature difference. Not much, but it is consistent and not being driven by anything except evaporation alone.

I am anxious to get it outside in the sun where it can really rock, but we have had freezing temperatures and snow lately, so once there begins a warmer stretch of weather I will begin recording the numbers.

I am hoping to achieve a forty to fifty degree temperature differential in the hotter weather, strong enough to get a low temperature Stirling Engine going at a good and hearty clip, hopefully enough to power a small motor generator.

Thanks for your interest, RR2

[infringer]

ResinRat2 interesting results !

Glad to hear you are attempting this haven't seen you post as much as you used to.

Maybe I'm just not reading the threads your posting in could be but anyhow keep us posted on your progress ...

Do you have a digital camera if so mind taking some snapshots of your setup?

[ResinRat2]

The larger clay flower pot is 11 inches across and tall, the smaller clay pot is 9 inches across and tall. The space between them was filled with fine playbox sand. I covered the bottom holes with plastic, but the inside pot water bubbles into the pot so I placed a layer of aluminum foil on the inside to protect the Aluminum Oxide Powder contents. Aluminum has a fantastic heat transfer rate so this should work well.

Right now I am keeping the top covered with plastic so all the cooling comes from the water that permeates the sides of the outer clay pot and evaporates. This is the cooling mechanism. The aluminum oxide center should resist temperature changes.

The goal is to set the unit in the sun so that the heat differential cools the center al. oxide below ambient and keeps a Stirling motor set on top of the al. oxide powder running. A motor that runs off the water evaporation. When the sun goes down the whole unit cools with the ambient temperatures, but the aluminum oxide should always cool at a different rate, thus again creating and maintaining the heat differential. My fingers are crossed that I can develop a unit that runs the motor continuously both night and day.

This unit is small, but larger units should have greater potential for developing and maintaining a heat differential that should be able to power larger Stirling Engines. That is what I am hoping for.

[infringer]

Too sweet finally a good sterling approach ! We hope

Thanks bud!