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Author Topic: Solar cooling with 2 clay pots ! Very cheap genius idea !  (Read 88794 times)

ResinRat2

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #15 on: May 09, 2008, 03:29:03 AM »
I just found it interesting. I could use just water to produce the heat differential. Since the Seebeck effect that laci mentioned can produce a current from a heat differential, I just figured that something like this, with the localized heat differential, could produce an electrical current for FREE. You know, like power produced from a natural, renewable resource. LOL!  Namely, the Sun's heat.

HEY! That's called overunity. :D

That's why I was interested. I just have not heard of anyone putting these two technologies together to produce a constant electrical output.

Just some crazy idea that crossed my already overloaded mind. :D
« Last Edit: May 09, 2008, 04:33:49 AM by ResinRat2 »

Koen1

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #16 on: May 09, 2008, 01:50:38 PM »
I was just surprised that evaporative cooling was such a new area for so many.

Hans, I guess many people have grown so accustomed to refrigerators that they
don't really know the old technology anymore...
Your example of hanging sheets in front of the windows with the bottom sticking in a
bucket of water is one I hadn't really heard before. I suspect it doesn't work as well
in very humid areas (like the Townsville region for example) ? Nice application though.
I was told stories of similar "bush fridges" when I lived in South Africa, by old people
who still remembered the days they didn't have any electricity nor electrical cooling.
A few described a cooler box that had cloth wrapped around it which was either regularly
watered by hand, or was hung in a vessel containing water to soak it up. The box itself
would be either fine wire mesh to allow air to move through the box, or it would be
a metal box. One old lady told me how they used a slightly different mechanism
where water from a container on top of the box was allowed to flow down the fine
wire mesh box and collected at the bottom, and part of the water would evaporate
during the downflow of course, cooling the box and contents.
Works like a charm, if you have enough water to waste on evaporation. :)

ResinRat2

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #17 on: May 10, 2008, 07:23:20 PM »
Well I have some results from my two pot experiment.

I took four readings over the last 36 hours.

The first was about two hours after the unit was built, then I took another 12 and 24 hours after starting. This test as run in my basement which has a pretty constant temperature and because I have a dehumidifier going constantly, the humidity level should be pretty well controlled and constant.


Elapsed Time (hrs:min)         Air Temp(F)                     Inner Pot Temp(F)                     Differential(F)
    2:00                                             63                                     57                                        6
   12:00                                            63                                     57                                        6
   24:00                                            65                                     57                                        8
   36:00                                            65                                     57                                        8

So It appeared to have stabilized at 57 F.

I then transferred the unit outside into the sunlight. It sat in the sun for an hour and I took the following readings.

Elapsed Time (hrs:min)      Air Temp(F)                     Inner Pot Temp(F)                    Differential(F)   
  1:00                                         75                                     60                                        15
  2:00                                         75                                     61                                        14
Which is where it stands now. I want to let it sit in the sun for several hours to allow the unit to equilibrate. I was actually hoping the temperature would drop, but so far this did not happen.

Just out of curiosity, does anyone know what type of heat differential is required to run a Stirling engine?
I'll see if I can find the information.

Thanks for your interest.
« Last Edit: May 10, 2008, 08:34:28 PM by ResinRat2 »

ResinRat2

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #18 on: May 10, 2008, 07:33:20 PM »
Here's a link:
http://www.howstuffworks.com/framed.htm?parent=stirling-engine.htm&url=http://www.stirlingengine.com/

This unit runs on a temperature difference of only 7.2 degrees F.

Could this have possibilites?

Hmmmm... I'll have to think about it for a bit to see if I could dream up a configuration that could utilize this temperature difference with a small stirling engine.

Thanks for your interest.



ResinRat2

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #19 on: May 10, 2008, 07:52:32 PM »
Actually, reading on how the Stirling engine works, all I would have to do is place the base of the engine on the moist rag that covers over the top of the unit. This temperature differential should then start the engine operating.

Could it be that simple?

I wonder what type of differential a really LARGE pair of pots would create.

Does anyone out there own a small Stirling engine and would be interested in trying this?

Thanks for your interest.

hansvonlieven

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #20 on: May 10, 2008, 10:31:37 PM »
G'day Dave,

The answer is yes, Stirling motors have been built that use evaporative cooling to increase output. The so called dipping bird or its more modern version the Minto wheel also rely on evaporative cooling for their effect.

Hans von Lieven

ResinRat2

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #21 on: May 10, 2008, 11:10:07 PM »
Hi Hans,

I think I remember you saying something about submarines that used stirling engines. What was the substance that it used to store the heat? Something about a tank filled with this component that held heat for the engine. I'm thinking of filling the center pot with whatever that was, that way it would be easier to hold the temperature difference.

Thanks

ResinRat2

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #22 on: May 10, 2008, 11:14:04 PM »
Aha!!  Found it:

aluminium oxide pellets

Thanks Hans!!

hansvonlieven

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #23 on: May 10, 2008, 11:15:01 PM »
G'day Dave,

From memory the medium to store heat were aluminium oxide pellets.

Hans

hansvonlieven

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #24 on: May 10, 2008, 11:16:49 PM »
LOL  ;D ;D ;D ;D ;D ;D ;D

I love those simultaneous posts

infringer

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #25 on: May 11, 2008, 10:43:46 PM »
Sure the application has been around for ages...

Swamp Coolers are used in dry regions to add water to the air for cooling...

While AC is used in damp regions to remove dampness from the air...

But the idea is not bad at all clay pots enable a similar reaction without the need for electricity this is the importance of this discussion.

No electricity and cooler temperatures!

That is the punch line folks and that is what interests people!
-----------------------------------------------------------------------------------------------------------

I have an excellent solar expirament I wish to share with everyone.

I will gladly do so in another thread soon.

Koen1

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #26 on: May 13, 2008, 07:29:39 PM »
I guess though that people in regions with a lot of available water all know
similar traditional and relatively intuitive ways of using evaporative cooling...

And it seems to me that the main areas where cooling is needed,
the very dry and hot zones of the world, also have very little water
to go around, and thus they also have less water available for
evaporative cooling systems...
So it's still not a solution for the Sahara for example.

In such regions a form of cooling that converts heat directly into
electrical energy would be much more usefull. But those systems
are still far from available. The only system I know of that actually
converts ambient air temperature into additional electrical output
is this: http://jnaudin.free.fr/html/nzaevncp.htm
And that needs special ferroelectric capacitors that are apparently
not available at all...

ResinRat2

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #27 on: May 13, 2008, 08:15:25 PM »
Hi Koen1,

In desert areas this won't be an option. I am thinking more along the lines of it working in more temperate regions where water is available. It doesn't have to necessarily be drinking quality water either. All I am looking for is a sustained temperature difference.

The Seebeck effect looks like it produces very small amounts of output. So maybe a Sterling Engine may be more of a possibility. Even these seem to be very weak, from what I have read so far. Aluminum oxide pellets were mentioned as holding heat. I am thinking that it would be better if the material in the center pot would give up its heat quickly rather than slowly. That way the center would give up heat faster and produce and maintain a temperature differential at a faster rate. Filling it with aluminum, which gives off its heat quickly, would probably work well. This is something I will try in the future. Maybe even just putting a aluminum sided pot, or aluminum pellets in the center pot would work better. That way a larger heat differential would form more quickly and keep up with changing air temperatures.

Just some thoughts I had. Right now I want to work on my other project, so I will return to this at a later date.

Thanks everyone for your interest.

hansvonlieven

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #28 on: May 13, 2008, 09:39:10 PM »
G'day Dave and all,

The best evaporative coolers used to be the old fashioned canvas bags. Here is a picture of a really pretty one, most were without decorations. (http://i16.ebayimg.com/06/i/000/ef/58/ccb3_1.JPG) You simply fill it with water, a little keeps seeping through the canvas and the evaporation cools the water inside. In Australia they are still in use in the bush. People hang them from bullbars, motorcycle handlebars and horse saddles.

The best temperature differential can be achieved by using the liquid itself for lower temperature source. As far as I can see the two pot system is only there so that dry matter can be cooled without getting wet. It is not as efficient as direct evaporation.

Hans von Lieven

ResinRat2

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #29 on: May 13, 2008, 09:53:04 PM »
Hi Hans,

Yes, that bag is very pretty indeed. LOL!     :D

So how could this bag be designed to run a Sterling Engine from the heat differential? That's the question.