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Making ice with a solar oven at night ("radiant fridge" concept")  RSS feed

 
Robert Ray
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Has anyone else played with making ice with solar ovens at night?
 
Shawn Bell
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I have a pdf file that shows how to make a solar ice maker, I can't afford to make it now...but one day.
What plans are you looking into?
 
Robert Ray
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I've just used my regular solar oven, a cone concentrator and have success. 
Seems to be better in a flat pan than a deep pot but 1/2 inch thick pie pan size cubes.
 
Steve Evans
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Location: South Gloucestershire, UK
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Hello Robert,

Interesting idea. How much ice were you able to make?

Presumably you just loaded up the solar oven with a low pot of cool water, closed the lid, attached the collector, aimed away from the rising sun and then collected your ice next morning?
 
Robert Ray
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I've been told that the lid on say a "Global Oven" needs to be left open. I have never tried a solar oven with a lid. so I'm just wondering what other experiences have been.
My experiments have all been done clear nights with ambient high of 45 degrees to a low of 38 and have been able to produce a consistent disc of ice in a low flat pan. Canning jars haven't frozen solid, deep pans haven't either.
  I have used my own deisgned solar cone collector only.  I do have a large parabolic but haven't played with it to see its results. Just looking and learning.
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Shawn Bell
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So the reflector radiates heat into the atmosphere cooling the water enough to freeze it?
 
Robert Ray
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Yes, I think it's collecting the cool since it takes below the 38 threshold I've placed on my tests.  It does have to be clear night sky. 
 
Rob Sigg
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Can someone splain this interesting process to me?
 
Robert Ray
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Rather than my explanation I'll link to one, he uses night sky to create a solar cooler in his description as well.

http://solarcooking.org/radiant-fridge.htm

Similar to what I have done and his shallow pan disc like mine seems to be all that one should expect.
 
Rob Sigg
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So can this be done with any vessel that is reflective? And I assume the water is poured right into the vessel itself and not sitting in a bowl of some sort? Thanks for the link.
 
Robert Ray
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I used a plain pie tin within my solar oven, my solar oven is shown in an earlier post and would not hold water. I designed it for backpacking and kayaking.
 
Rob Sigg
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A new project for me
 
Julia Winter
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Here is the "radiant fridge" from the website linked above about harvesting coolth at night.  You need a clear sky, trees will mess this up, clouds also. 

Fascinating.
 
Creighton Samuiels
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Yeah, I've done this using a good cooler with a removable top, wrapped on all sides with reflective mylar.  I've heard it called a space refrigerator.  The basic idea is that, since everything in your environment radiates infrared according to it's current temp, you are always receiving some heat exchange from your environment, even at 40 degrees.  However, if you can limit the amount of ambient heat that your cooler receives, while also maximizing the amount of radiant heat it can emit, you can push down the apparent temps inside the cooler.  It must be a clear, cool night, with a northern exposure to the sky.  There cannot be any amount of moon in the view of sky from the perspective of your cooler.  It won't make much ice, and I've never got it to make any above about 40 degrees.  More of a science experiment than a reliable ice production method.
 
Dennis Clover
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omg, i have been trying to find out more abt solar oven because i thought it would be great to cook without carbon emissions.
but this is so cool too, dual purposes for any new solar oven i get
never realise i can use a solar oven to actually make ice!

even more carbon emissions cutting!
 
Erwin Decoene
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Location: Courtrai Area, Flanders Region, Belgium Europe
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For folks wanting to cook without CO2-emissions. Perhaps this is something ? http://www.solsuffit.be/en/index.html
Friends of mine wanting to do something about cleancutting african forests for cooking fuel came up with the idea.

As to cooling without electricity - i thought those designs were mostly based on black body fysics ~ ie your 'fridge' should be painted black on the inside - when you open it on clear sky nights, you can cool it down to freezing.

I once read that this technique was used by the babylonions to make ice. Don't know if that's correct. I certainly don't know of archeologicals digs confirming this. It was described to me as a dugin earthware vessel coated with black bitumen. In the daytime it should be closed.

There is an alternative based on evaporating water. https://en.wikipedia.org/wiki/Mohammed_Bah_Abba This should work best on windy days in the shade.


 
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