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Peltier / Seebeck effect
smart51 - 17/11/08 at 11:41 AM

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.

Mr Whippy - 17/11/08 at 11:52 AM

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]

02GF74 - 17/11/08 at 11:58 AM

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.

Mr Whippy - 17/11/08 at 12:06 PM

some solar power systems use stirling engines to turn generators, if thats any help. wikilinky

02GF74 - 17/11/08 at 12:11 PM

^^^^ but he lives in Birmingham, not Scotland.

Mr Whippy - 17/11/08 at 12:13 PM

quote:
Originally posted by 02GF74
^^^^ but he lives in Birmingham, not Scotland.


?

smart51 - 17/11/08 at 12:17 PM

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.

02GF74 - 17/11/08 at 12:17 PM

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.

Mr Whippy - 17/11/08 at 12:21 PM

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]

smart51 - 17/11/08 at 12:55 PM

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.

MikeLR - 17/11/08 at 01:05 PM

We had a couple of pieces of kit that used the Peltier effect for cooling, it seemed to be very good.
Mike

Mr Whippy - 17/11/08 at 01:07 PM

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?

smart51 - 17/11/08 at 01:30 PM

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]

Mr Whippy - 17/11/08 at 02:05 PM

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....

MikeRJ - 17/11/08 at 04:28 PM

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