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Author Topic: Solar cooling with 2 clay pots ! Very cheap genius idea !  (Read 88781 times)

hansvonlieven

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #30 on: May 13, 2008, 10:31:34 PM »
Simply by using the bag as a reservoir and feed the cool water into the jacketed working cylinder, than recirculate it back into the bag. The bag would need to be large with a big surface area.

Hans

EDIT Or simply wrap a rag around the working cylinder and dribble water on it

Pirate88179

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #31 on: May 14, 2008, 01:57:40 AM »
What about using a peltier junction along with these systems to produce free electricity?  Put the cold side to the cold, generate power, put the hot side toward the hot, more power.  Just a thought.

Bill

ResinRat2

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #32 on: May 14, 2008, 03:21:33 AM »
Hi Bill,

That was mentioned earlier in the thread by laci as the Seebeck effect. You mentioning the Peltier effect, or it's related title of  the Peltier?Seebeck effect. Personally I am not sure how to do this. What specific piece of equipment would be used to initiate the electron flow?
I assume you mean a thermocouple. I am just not sure what type of thermocouple to use, and from what I have read so far, the amount of electricity produced would be very small. I might be wrong.

Any suggestions that anyone has I am open to right now. To me this is interesting that you can have the sustained temperature differential.

Pirate88179

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #33 on: May 14, 2008, 03:33:04 AM »
ResinRat2:

I don't know any more about them except I have seen them in a few surplus catalogs for reasonable prices.  I know they are used in the 12 volt cooler technology (we made some of the original ceramic parts for that) and also, the small things that keep coffee hot.  I know you can power them to have a cold side and a hot side and with no power, if you heat and/or cool the appropriate sides, it produced electricity.  I know nothing of the efficiency ratings for these devices, or, if they are indeed related to thermocouples.  Thanks for telling me the complete name, I did not recognize it by the Seebeck name. I learn something new here every day.

Bill

Koen1

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #34 on: May 14, 2008, 12:15:52 PM »
@Hans: nice pic of a waterbag :D
When I lived in South Africa I used to go out camping and fishing etc
in the bush every weekend with some friends, and one of them
always brought a couple of oldfashioned leather waterbags along.
He hung them off his bullbar and a tiny bit of water would seep out
and evaporate, that and the cooling effect of the air rushing past it
kept the water nice and cold.

Another 'trick' I saw that guy pull was to dig a shallow hole in the ground,
put your beer cans in the hole, cover it up with sand again, and then just
pour some water over the spot every now and then. The water evaporated
and cooled the sand layer just under the surface enough to keep your
beer cool. ;D

Although of course if you have enough water it is easier to just put the
water in the shade and put your beer cans in the water...

Funny enough the native bushfolk seemed to know the principle of
evaporative cooling too, but they apparently didn't grasp the concept
of condensation to obtain clean drinking water...

Pirate88179

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #35 on: May 14, 2008, 06:01:58 PM »
@ Koen1:

Who needs clean drinking water when you have cold beer? (ha ha)


Bill

Koen1

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #36 on: May 14, 2008, 06:32:15 PM »
Who needs clean drinking water when you have cold beer? (ha ha)

:D Hehehehe Good point Bill! ;)

ResinRat2

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #37 on: March 25, 2009, 05:11:15 PM »
I  always knew I would return to this project someday. I was looking at a posting by member jeanna at :

http://www.overunity.com/index.php?action=dlattach;topic=4627.0;attach=23007

that showed Donkey's solar refrigerator. This led me to consider using a stirling engine on top of the flowerpot system to see if it could give a continuous running motor that kept the temperature differential intact even with a stirling motor running on the top of the system.

The first picture shows the two clay flowerpot design that has aluminum oxide filling the center pot and sand and water filling the outer ring between the first and second flowerpots. The hope here is that the aluminum oxide center will cool or heat up at a different rate than the outer ring of sand and water as that area cools. This should draw heat away from the center and always keep the temperature difference as the water freely evaporates.

The second picture shows the same system except that now a stirling engine is resting on top of the aluminum oxide center and the area around the engine base is insulated with a wool ring to isolate it from the environment. That way all the cooling will be from the water and sand ring around it, and all heating will be from the stirling engine. I researched the specific heat values of aluminum oxide, clay, and quartz sand. These gave values of 0.21, 0.33, and 0.19 (cal/g/oC) respectively. I am hoping this will allow the outside pot to always cool faster than the inner core.

My hope is that no matter what the outside temperature is, there will always be a temperature differential that will keep the stirling engine operational. As long as the whole system is above freezing temperatures of water that is. Although it might even work below freezing, I don't know for sure until it is tested.

I should receive my aluminum oxide in three days. At that point I will put the system together without a stirling engine and run it for several days with a temperature probe in the center. I will record the temperature differential between the system center and ambient temperature and see what kind of difference will result. This will let me know if it is worth it to purchase the engine. I saw one for about $100 US dollars that doesn't seem too unreasonable.

Thanks for your interest.

RR2
« Last Edit: March 25, 2009, 05:37:57 PM by ResinRat2 »

Koen1

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #38 on: March 26, 2009, 11:59:19 AM »
Interesting idea, that. :)

It reminds me of an idea, not sure who came up with it first, but
it is beginning to see a bit of revival recently in the sustainable energy
industry, anyways, an idea where the heating or cooling is done by
using the earth as reservoir.
Basically, in summer when air and surface temperatures are relatively
high, temperature a few meters under ground is relatively low (as
that remains fairly constant around 18 degrees or so). A water reservoir
placed a couple of meters under ground could be used as a heat sink
and a stirling engine or thermocouple could be used to produce energy
from the thermal energy flow.
Similarly, in winter the air and surface temperature in most places is
a fair bit lower than the temperature under ground, and now the under-
ground water reservoir will be warmer than the outside air, so now
the outer environment can be used as a heat sink and thermal energy
from underground can flow out, producing energy again via the same
stirling engine or thermocouple.
This is what they're doing in many new housing projects, using the ground
as heat or cold supply.

Regards,
Koen

ResinRat2

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #39 on: March 26, 2009, 01:03:54 PM »
Hi Koen,

Yes, similar principle. Spelunkers and well-water users know how cold water underground can be.

If this unit works like I think it will, there should be a good temperature differential (perhaps 40°F or so.) That should give a good boost to the Stirling and maybe give enough torque to perhaps run a very small motor as a generator. Those Stirlings are notoriously weak, but if the motor it powers is very small it could prove the viability of the concept. I would like to scale it up a bit in the future if good results could be obtained.

What I like is that this type of system would work even when the sun goes down. Unlike the solar-powered Stirling units they have developed that stop when the clouds block out the sun.
« Last Edit: March 26, 2009, 05:07:34 PM by ResinRat2 »

triffid

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #40 on: March 29, 2009, 06:24:13 AM »
If you fill a jar or aquarium with carbon dioxide gas.That greenhouse gas(the carbon dioxide) will be 4 F degrees warmer than the outside of the jar or aquarium.I have heard that methane gas(being a super greenhouse gas absorbs 20 times the heat that CO2 will .So does that mean a jar or aquarium full of methane will be 80 F degrees warmer than outside the container?Just throwing out some thoughts I had on the subject.If its true maybe clothes made out of material full of methane bubbles would keep us warm in the coldest places? Like in outer space? Triffid

triffid

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #41 on: March 29, 2009, 06:26:13 AM »
If you use natural gas to cook with,It's mostly methane.I use all electric myself.Triffid

triffid

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #42 on: March 29, 2009, 06:30:30 AM »
Mixing baking powder from the store with water releases carbon dioxide gas.Baking powder is not the same as baking soda.So now we have have a very cheap source of these two greenhouse gases for someone here to try to experiment with.Triffid

Pirate88179

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #43 on: March 29, 2009, 07:24:53 AM »
triffid:

An even cheaper source of this so called "greenhouse gas" CO2, is to just exhale.  This is why I think all this carbon tax bs is full of crap.  Every time someone opens a soda (like Coke) now, they will have to pay a carbon tax for emitting a "greenhouse" gas.  If it were not for these gases in the atmosphere, our planet would be about 100 degrees or more colder.  Talk about high heating bills.

Bill

triffid

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Re: Solar cooling with 2 clay pots ! Very cheap genius idea !
« Reply #44 on: March 30, 2009, 04:26:32 AM »
I agree we exhale carbon dioxide but its not much percentage wise.Which is why we can do mouth to mouth on someone who needs it.Triffid