smart51
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| posted on 17/11/08 at 11:41 AM |
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Peltier / Seebeck effect
Peltier effect devices can be bought from eBay for under a tenner. They convert electricity into a temperature difference between to plates but they
can also create electricity from a temperature difference between the plates.
I think this is a great idea. I could make a solar powered battery charger or a car radiator powered one or an exhaust gas powered one or anything.
The problem is I can't find any info on the rate of electricity generation from heat for these devices. Does anyone know a good source of info?
A watts of heat in to watts of electricity out factor is what I'm looking for.
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Mr Whippy
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| posted on 17/11/08 at 11:52 AM |
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Saw something similar on tomorrows world where some gas burners heated tubes of some metal looking blocks and they generated the electricity to power
the car.
Haven’t seen anything about it since
I also think this is what generates the power on deep space probs like voyager as they use the heat given off by nuclear fuel and covert it directly
into electricity
quote:
Voyager 2 uses three of these radioisotope thermionic generators. In them, the heat from decaying plutonium, applied to metal strips, generates
a flow of electrons. The device has with no moving parts, no flow of fluids and no turbines. The three units are now producing about 375 watts of
electricity to power all the spacecraft's systems. This amount of current is far less than a kitchen toaster or a hair dryer require. Perfectly
Working Units
Weighing 83 pounds each, the individual units were developed by the Department of Energy, and the radioactive cores were built by the General Electric
Company. The units have worked perfectly since Voyager was launched in 1977 and are expected to do so for many years to come as the craft moves beyond
the solar system.
Such nuclear devices have powered 22 American space missions, and are scheduled to do so in the future. In October, a space shuttle is to carry aloft
the Galileo spacecraft on a mission to explore Jupiter. The Galileo will be powered by the devices.
[Edited on 17/11/08 by Mr Whippy]
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02GF74
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| posted on 17/11/08 at 11:58 AM |
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Without googling I reckon it is a non starter.
Imagine a sliver of the material placed in front of a heat source e.g. exhaust.
Within no time at all it will heat up so that the tempereature difference across it is small i.e. no electricity being generated.
The problem you are going to face is how to keep the oposing face cool. You'd problabmy need a fridge for that and end up using more
electricity than you get out!.
I don't think they are particularly efficient either.
To keep a battery topped up, I think you are better off buying a solar panel charger.
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Mr Whippy
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| posted on 17/11/08 at 12:06 PM |
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some solar power systems use stirling engines to turn generators, if thats any help. wikilinky
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02GF74
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| posted on 17/11/08 at 12:11 PM |
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^^^^ but he lives in Birmingham, not Scotland.
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Mr Whippy
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| posted on 17/11/08 at 12:13 PM |
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quote:
Originally posted by 02GF74
^^^^ but he lives in Birmingham, not Scotland.
?
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smart51
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| posted on 17/11/08 at 12:17 PM |
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quote:
Originally posted by Mr Whippy
quote:
Originally posted by 02GF74
^^^^ but he lives in Birmingham, not Scotland.
?
A play on words with the town Stirling.
Peltier devices are solid state and quite cheap. Stirling engines are complicated and expensive. They do a similar thing, though.
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02GF74
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| posted on 17/11/08 at 12:17 PM |
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quote:
Originally posted by Mr Whippy
some solar power systems use stirling engines to turn generators, if thats any help. wikilinky
oh dear, you are slipping up MR W, and it is just down the road fromo you too. 
quote:
Stirling (Gaelic: Sruighlea, Scots: Stirlin) is a city and former ancient burgh in Scotland, and is at the heart of the wider Stirling council
area.
The city is clustered around a large fortress and mediæval old-town. It is a centre for local government, higher education, retail, and light
industry. Its population (as of the 2001 census) was 41,243, making it the smallest city in Scotland.
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Mr Whippy
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| posted on 17/11/08 at 12:21 PM |
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hmm ok smarty pants I ain't had my coffee rations yet
whats the heat range anyway? ones I see are quite low temp
how to linky
[Edited on 17/11/08 by Mr Whippy]
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smart51
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| posted on 17/11/08 at 12:55 PM |
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quote:
Originally posted by Mr Whippywhats the heat range anyway? ones I see are quite low temp
That's when you put electricity in. you get 60° or 80° difference in temperature between the 2 plates (max). If you apply heat to 1 surface
(either solar or waste hot water etc) and have a heat sink on the other side, the cold side will be as much as 60° or 80° colder than the hot side.
The more heat you can pull out, the more current it generates.
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MikeLR
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| posted on 17/11/08 at 01:05 PM |
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We had a couple of pieces of kit that used the Peltier effect for cooling, it seemed to be very good.
Mike
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Mr Whippy
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| posted on 17/11/08 at 01:07 PM |
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yeah sounds fine using radiator or sun but I doubt it would survive anything to do with the exhaust unless you were very careful with the location.
Why are you looking at this method anyway is it just out of curiosity or are you going to use this in the cabin scooter? instead of a conventional
charging system?
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smart51
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| posted on 17/11/08 at 01:30 PM |
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quote:
Originally posted by Mr Whippy
yeah sounds fine using radiator or sun but I doubt it would survive anything to do with the exhaust unless you were very careful with the location.
Why are you looking at this method anyway is it just out of curiosity or are you going to use this in the cabin scooter? instead of a conventional
charging system?
No, not for the scooter, I'm just full of bright ideas. I made a solar powered water heater once, just for the fun of it. It worked reasonably
well. I just wondered if the efficiency of a solar peltier could be better than PV panels.
The best new project I'm thinking of is a parabolic mirrored dish or "solar furnace". I'll concentrate the suns rays into a
tightly confined beam that I can use as a death ray on the cats that soil my back garden.
[Edited on 17-11-2008 by smart51]
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Mr Whippy
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| posted on 17/11/08 at 02:05 PM |
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quote:
Originally posted by smart51
The best new project I'm thinking of is a parabolic mirrored dish or "solar furnace". I'll concentrate the suns rays into a
tightly confined beam that I can use as a death ray on the cats that soil my back garden.
[Edited on 17-11-2008 by smart51]
uh hu this is you ain't it....
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MikeRJ
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| posted on 17/11/08 at 04:28 PM |
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quote:
Originally posted by smart51
The best new project I'm thinking of is a parabolic mirrored dish or "solar furnace". I'll concentrate the suns rays into a
tightly confined beam that I can use as a death ray on the cats that soil my back garden.
[Edited on 17-11-2008 by smart51]
Then you probably won't want to look at using general purpose thermoelectric coolers, they are not very robust at all and are generally low
temperature devices. What you probably want is a thermopile which uses thermocouples. They can withstand very high temperatures, but even so you you
need many thousands of junctions to get useful power outputs.
A Stirling engine is likely to be a better proposition for useful amount of power generation, or even a steam turbine (which can be made from plain
disks with no blades).
http://uk.youtube.com/watch?v=rRYfsAExkUw
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