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Author Topic: Thermoelectric generator - candle and cold water  (Read 56704 times)

Offline Pirate88179

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Re: Thermoelectric generator - candle and cold water
« Reply #30 on: August 28, 2012, 06:15:28 AM »
Mags:

Thanks.  Yes, I read not to full power the 400 watt one without sinks because it will melt the solder on the hot side pretty fast.  Do I really need to use some of that thermal paste like I read about?  The ceramic substrates are pretty flat and I can  lap the bottom of my sinks on a piece of glass with some sand paper to make very flat.  It seems like overkill to me to use the paste but...if I need it, I will find some.

I did notice that on the big one, the side between the ceramic plates are sealed with a ceramic cement.  On my lower powered one, they are open.  I don't guess these are waterproof to any extent are they?  I was thinking of sealing the open one up with some high temp silicone but...I don't know.

I am just fascinated by these things.  It is a great example of how nature works: Put voltage in, get hot one one side, cold on the other.  Put hot on one side, cold on the other, get electricity out.  Beautiful.

Bill

Free Energy | searching for free energy and discussing free energy


Offline Magluvin

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Re: Thermoelectric generator - candle and cold water
« Reply #31 on: August 28, 2012, 07:28:03 AM »
Hey Bill

YES absolutely use the silicone compound.  Imagine looking under a microscope at the surfaces. It is used on transistors to transfer heat to the sink. Without, the transistor wont survive full power ratings. its all about getting the heat away from the component.
In our case, one side is all about getting it 'evenly' hot, and keeping the other side evenly cold, for best results. These things conduct heat well, considering the contrary belief once you feel the 2 surfaces while being powered.  ;] So heating one side, the other side gets just as hot. If we dont provide the best path for the heat to be absorbed from the 'cold' side, eff will go down. So its best to do your best.  ;] Use the compound. ;]

RS has some thin liquidy stuff that I dont care for much. Maybe they have something better now. Best to get some online. You will need a bit. Or if you have a local parts distributor. We had Vance Baldwin here, but not any more. I dont know if Alpha Electronics is still around. We have a cb/ham radio shop that carries some unusual parts. So maybe where you are there are distributors. Electronics repair shops in larger cities have places to go to get parts directly. I know some order all parts.  Just tryin to give ideas as to get things locally. ;]

My approach would be to use a large aluminum block on the cold side with fins as many as possible. This will ensure a consistent colder temp for the cold side. A small heat sink on the cold side wil get very warm from the candle powered hot side, even with a fan. So more bulk and fins will keep it cool to generate the best output.

The hot side, fed by candle, maybe not so big block, but a  cupped heat catch, even insulated with auto parts store fiberglass wrap for headers to help keep it hot as not to lose heat anywhere other than the Peltier module.  Theres lots that we can do to increase efficiency.  ;]

MaGs



Offline conradelektro

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Re: Thermoelectric generator - candle and cold water
« Reply #32 on: August 28, 2012, 09:42:06 AM »
Hey Conrad

The 80ma 1.3v , was that on a load?

Can you show what you have there? Its hard to tell what is what other than some heat sink, water bucket and wires.  I just want to see how the heating and cooling are done here. It might be better to have the element on the side of the container, with the candle burning under fins of a heat sink, with a thin metal shield to help hold the heat in that area.  And the rising heat wont heat the water unnecessarily more than the cold side of the chip provides it. A vid i saw on YT the guy had the candle burning right under the bare chip, with a fan and sink on top.  Ill see if I can find it.

Thanks for showing

Are you using 2 chips here?  If so, the 2 chips will transfer more heat to the water, there by keeping the 'hot' side colder, thus less output.

If you just use 1, and get better results, then what you need for 2 is 2 candles. ;]

MaGs

The 80ma 1.3v were measured on a load. The load was a Joule Thief.

The short circuit current is a bit more, about 100 mA. Open circuit Voltage (10 Mega Ohm Voltmeter) goes up to 2.8 Volt (1.4 Volt per element).

I attach some photos showing the construction around the two Peltier elements.

It is difficult to come up with a good solution to hold the heat sink (on the cold side) and the heat distribution means (hot side, flame of the candle should not touch the ceramic) against the ceramic plates of the Peltier element. A good heat resistant glue seems to be necessary. Some use 0,8 mm copper plates as spacers (but that also needs a glue).

My "heat sink" and my "heat distribution means" are both aluminium plates 60 mm x 30 mm x 4 mm, because the Peltier elements are 30 mm x 30 mm and are located next to each other.

I need two candles in order to generate enough heat.

There is an important difference between Peltier elements for cooling and for electricity generation.

- cooling element: max temperature allowed on the hot side is around 100° Centigrade, max effective temperature difference between hot and cold side about 70° Centigrade, plastic isolation is useful because it keeps moisture away from the metals

- generator element: max temperature on the hot side at least 200° Centigrade (there are elements for much higher temperatures like 1000° Centigrade), temperature difference between hot and cold side as high as possible, plastic isolation is a bad idea because it will melt

Greetings, Conrad

Offline wizkycho

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Re: Thermoelectric generator - candle and cold water
« Reply #33 on: August 28, 2012, 11:18:49 AM »
     Peltier is not overunity element. it means it has efficiency lower then 100% actually only 10-20%,
the best ones only 50% (but made only experimentaly, not available on market yet).
So what are you trying to do with these ? heat the house.
This ain't gona work because if you use current from peltier and connect it to some heater
peltier will apparently cool down his hot side and the current from it will dimminish.
Unless you eventually cool down cold side of peltier to temperatures colder then air or earth.
And that would take lot a energy !!!
This is not working not even in space on -273
   Guy is trying to sell peltiers this way or just yet hasen't realized that this is dead end for FE and OU.
 
think of it this way: Peltier element is very poor thermal isolator.
or - if it would be better isolator it wouldn't give of electric current
 
Igor Knitel
Perihelion Labs
 


Offline conradelektro

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Re: Thermoelectric generator - candle and cold water
« Reply #34 on: August 28, 2012, 04:40:26 PM »
     Peltier is not overunity element. it means it has efficiency lower then 100% actually only 10-20%,
the best ones only 50% (but made only experimentaly, not available on market yet).
So what are you trying to do with these ? heat the house.
This ain't gona work because if you use current from peltier and connect it to some heater
peltier will apparently cool down his hot side and the current from it will dimminish.
Unless you eventually cool down cold side of peltier to temperatures colder then air or earth.
And that would take lot a energy !!!
This is not working not even in space on -273
   Guy is trying to sell peltiers this way or just yet hasen't realized that this is dead end for FE and OU.
 
think of it this way: Peltier element is very poor thermal isolator.
or - if it would be better isolator it wouldn't give of electric current
 
Igor Knitel
Perihelion Labs

Yes, I know, Peltier elements are definitely not OU.

The idea is to use waste heat (although the efficiency is very low). The heat would be wasted any way.

I want to come up with a good design, which can be done at home (without fancy tools).

In winter I heat my house with a conventional wood stove and I want to use some of the heat from the stove to create electricity. This is not new, there is no invention, may be there will be a nice design. The idea to use part of the heat from the stove to charge a battery pleases me. It is probably not very useful and by no means a replacement of my connection to the electricity grid.

I do not sell anything, my experiments are for my personal education and enjoyment.

I posted my contraption under Conventional alternative energy systems and there in All other conventional alternative energy creation systems.

So, it should be clear, it is a conventional system for energy creation.

My contraption is "alternative" in the sense, that waste heat is rarely used. A good example for a good use is the rover Curiosity which rolls on Mars just now. In fact, the news about Curiosity inspired me to play with Peltier elements. (I will not use Plutonium for heating. I generate heat by burning wood or candles, which in itself is a bit "alternative" nowadays.)

I think it is interesting, that one can generate additional light (with a LED-lamp) when lighting candles. The waste heat from the candles is turned into electricity by the Peltier elements. (And one has the light from the candles as well.) Yes, not very exciting, no business opportunities, but nice nevertheless.

Greetings, Conrad

Free Energy | searching for free energy and discussing free energy

Re: Thermoelectric generator - candle and cold water
« Reply #34 on: August 28, 2012, 04:40:26 PM »
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Offline Pirate88179

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Re: Thermoelectric generator - candle and cold water
« Reply #35 on: August 29, 2012, 02:55:50 AM »
Conrad:

I agree with you 100%.  No OU of course but I like the challenge of finding a way to use these where we are already paying for the hot, or the cold.  One example a buddy of mine used it for was against his cold window in the winter, and the heat from his house inside, that he paid for anyway....he could light a large led bulb via a jt circuit and it was free.  The reverse might be true in the hot summer with the ac on.

To me, this is the fun of it....trying to find out new and unique ways to apply this technology.  It is not easy as the hot and cold sides are very close together but...with some good thinking, I know folks will find some great ways to use these.

Bill

Offline DreamThinkBuild

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Re: Thermoelectric generator - candle and cold water
« Reply #36 on: August 29, 2012, 05:34:48 AM »
Hi Conrad,

You are doing very good work. I like the idea of reclaiming heat that would've been lost anyway. In the winter you have plenty of snow to keep one side cold. :)

Maybe add a freezable cup that can be popped on and off the top. Stick a couple in the freezer, since your paying for the power already for the fridge reclaim some of that energy too. When one starts to warm down just pop it to the freezer and pop on a new frozen cup.

You could also add some solar panels and capture the light from the candles. Get high current cells, like .5vdc, 7amp cells with artificial lights you lose about 98% power. So a 7amp cell will be more like 140ma. Three panels will give you enough to charge a battery or ultra-cap to 1.5vdc.

I toyed with the idea when the power went out during the snow storm Alfred:

http://www.overunity.com/11635/pyro-photo-voltaic/

Keep experimenting. ;)

Free Energy | searching for free energy and discussing free energy

Re: Thermoelectric generator - candle and cold water
« Reply #36 on: August 29, 2012, 05:34:48 AM »
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Offline Magluvin

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Re: Thermoelectric generator - candle and cold water
« Reply #37 on: August 29, 2012, 05:54:54 AM »
Hi Conrad,

You are doing very good work. I like the idea of reclaiming heat that would've been lost anyway. In the winter you have plenty of snow to keep one side cold. :)

Maybe add a freezable cup that can be popped on and off the top. Stick a couple in the freezer, since your paying for the power already for the fridge reclaim some of that energy too. When one starts to warm down just pop it to the freezer and pop on a new frozen cup.

You could also add some solar panels and capture the light from the candles. Get high current cells, like .5vdc, 7amp cells with artificial lights you lose about 98% power. So a 7amp cell will be more like 140ma. Three panels will give you enough to charge a battery or ultra-cap to 1.5vdc.

I toyed with the idea when the power went out during the snow storm Alfred:

http://www.overunity.com/11635/pyro-photo-voltaic/

Keep experimenting. ;)

Well, solar panels work better when cool vs hot, so we could mount these on the back of the solar panel(hot side), and the cold side could transfer the heat to water pipe system for producing hot water.

So now our solar cells work better, we also get power from the Peltier's and hot water to boot. All in the same square area. ;] Just a little thicker. ;]

MaGs

Offline Pirate88179

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Re: Thermoelectric generator - candle and cold water
« Reply #38 on: August 29, 2012, 06:18:51 AM »
Mags:

Exactly the type of thing I was talking about.  I saw a tube video last night where a guy had a 300 watt peltier and ran it from a computer power supply.....the cold side made a large blob of water into ice in less than 36 seconds.  That has to be useful somehow.

Bill

Offline Magluvin

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Re: Thermoelectric generator - candle and cold water
« Reply #39 on: August 29, 2012, 06:34:55 AM »
Like a microwave ice maker. ;]  Quickice.  Nestley IceQuick  ;]

MaGs

Free Energy | searching for free energy and discussing free energy

Re: Thermoelectric generator - candle and cold water
« Reply #39 on: August 29, 2012, 06:34:55 AM »
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Offline twinbeard

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Re: Thermoelectric generator - candle and cold water
« Reply #40 on: August 29, 2012, 06:56:07 AM »
You guys are totally on the right track with using these to cool down photovoltaic, then move the heat away in water pipes.  I came here to recommend that, but you guys are already thinking correctly:)

Offline Pirate88179

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Re: Thermoelectric generator - candle and cold water
« Reply #41 on: August 29, 2012, 07:09:45 AM »
Twinbeard:

ARRRR...good to see you again.  I believe there are many new uses we can find for these things.  I just watched a vid on the tube where a guy charged his cell phone while camping using the campfire and some cold river water.  As mentioned by someone above, not efficient but, it got the job done when nothing else would.  Even works at night or on a cloudy day.

Bill


Offline Magluvin

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Re: Thermoelectric generator - candle and cold water
« Reply #42 on: August 29, 2012, 07:12:37 AM »
Well, solar panels work better when cool vs hot, so we could mount these on the back of the solar panel(hot side), and the cold side could transfer the heat to water pipe system for producing hot water.

So now our solar cells work better, we also get power from the Peltier's and hot water to boot. All in the same square area. ;] Just a little thicker. ;]

MaGs

Lol, then we can take the power stored from the peltiers, power that we collected heating water, for free, ;] , then use that stored power to pump the water in cycles. So now we have a solar panel, that heats water, not using the power from the solar panel to do so, and we get water cycling energy from the peltiers.

Just trying to think of a logical use for that energy. Sounds like a marketable combo system, while increasing the solar panel efficiency as a plus, plus.  ;]

maGs

 

Offline Magluvin

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Re: Thermoelectric generator - candle and cold water
« Reply #43 on: August 29, 2012, 07:25:10 AM »
Twinbeard:

ARRRR...good to see you again.  I believe there are many new uses we can find for these things.  I just watched a vid on the tube where a guy charged his cell phone while camping using the campfire and some cold river water.  As mentioned by someone above, not efficient but, it got the job done when nothing else would.  Even works at night or on a cloudy day.

Bill

Son, go out and chop some logs for the fire, I think we will run the A/C tonight. ;]

Use the fire to generate, to run a peltier A/C unit.

That 400w jobby, I bet would blow some really cold air with the right combination of heat sinks and blowers. My little 40w produces some cold air. That 1 400w module could probably surprise you.  My buddy want to try to make an ac for his elcamino. We have to test larger or multiples to see what happens. The peltiers are not expensive to play with.

MaGs


Offline conradelektro

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Re: Thermoelectric generator - candle and cold water
« Reply #44 on: August 29, 2012, 09:32:22 AM »
I am very happy with the many ideas presented in this thread.

Pirate: cold window. I have a "cold window" next to both of my stoves (see photo). Some Peltier elements with the cold side against the window and hot water or steam from a kettle through some pipes to a heat exchanger on the hot side of the Peltier elements. Have to think about the heat exchanger (where to salvage it from) ? Since I do not want to glue something against the three glass windows, the whole thing should only lean against the cold window.

DreamThinkBuild: I should have found your Pyro Photo-Voltaic thread in order to use it, sorry. The idea with the frozen cup works here in winter by just putting it outside in the freezing weather for an hour. Good idea to use solar cells in combination with the candles. Are there solar cells that like infra red as a light source? I guess the solar cells rather lean towards ultra violet light?

Magluvin: Yes, that is right, Peltier elements on the back side of solar panels. Wood: around here you could get broken down trees for free as long as you remove them from the woods by your self. A lot of work, a few liters of gas for the transport, but almost for free. A friend of mine gets the cut off (mostly bark) from a saw mill for free. He just has to collect this low grade wood. He cuts it and uses it for his stoves. Again, some work, but his heating is cheap. When I was a kid, people used to cut down bushes and make brushwood bundles for the kitchen stove. All this will come back with the shrinking world economy.

I ordered four 40 mm x 40 mm Peltier elements sustaining 200° Centigrade from eBay. There are better ones, but they cost more. For a home project it would not matter to use a few more as long as they are cheaper than the high power stuff. Once we have a good and practical design, it might be worth to get some really good ones for about 60.-- Euro each (60 mm x 60 mm, 250° Centigrade).

I will also get some heat resistant and heat conducting paste and some heat resistant and heat conducting glue (a bit expensive).

Is it better to press the heat exchanger against the Peltier element? If yes, it is not so easy to come up with a design that does not heat the cold side as well. Something has to press against the hot side and the cold side and this something will conduct heat away from the hot side and heat to the cold side via a support structure.

How strong is the Peltier element mechanically? The ceramic plates seem to be brittle and gluing something onto them seems to be the only good way. The brackets I built do not seem to work very well. The brackets can not grip well because the space in between the ceramic plates where the metals are is very limited (short circuit has to be avoided, only one ceramic plate should be touched by the bracket).

As some said, it is not straight forward to build something good and practical around a Peltier element, and it becomes more difficult in case one wants to combine a lot of elements. Glue, paste and heat exchangers pressed against the element seem to be the standard design choices. There are elements that support open flames at 1000° Centigrade (of course they are expensive).

Greetings, Conrad

Free Energy | searching for free energy and discussing free energy

Re: Thermoelectric generator - candle and cold water
« Reply #44 on: August 29, 2012, 09:32:22 AM »

 

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