High Temp Thermoelectric Generator 2

[Griz42]

I am looking for a high temp thermoelectric generator. It would need to be a Peltier type generator. I would like something that could tolerate a constant temperature of 500 deg C on the hot side, but might consider something that can handle a lower temperature.


Thanks
-Griz

 

[VEBill]

There was a flurry of tech news recently about automobile makers experimenting with appending alternators with thermoelectric generators working off the exhaust system heat. Reportedly the concept is quite effective and improves overall efficiency by a small percentage.

When I read this news, I had assumed that they were using the 'old fashioned' two metal junction system (Seebeck effect). The system would have to be installed up near the headers to see any heat, but that part of the exhaust can be glowing red hot under full load.

Are Peltier diodes capable of surviving 500C? If not, then look at bi-metal junctions.

 

[roydm]

What is the best combination of metals for a generator?
There must be a trade off over mV produced vs Material resistance.
Roy

 

[Griz42]

VE1BLL: I think your right. I might be able to use a two metal junction system instead of a standard Peltier TEG. All of the Peltier TEG units I've found wouldn't work because the solder would melt. Maybe I could also use a thermopile set up or something similar.

Does anyone know some good references for designing something along those lines?

Thanks
Griz

 

[itsmoked]

Your stated temperature really would make more sense for a sterling engine. Probably 10x the power output too.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ScottyUK]

Type 'E' has the highest specific output of the common thermocouples. Relatively expensive because of the materials used.


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If we learn from our mistakes I'm getting a great education!

 

[roydm]

Scotty, Yes but type T might put out more current with one wire of copper.
But then again it would be hard to keep the heat from the cold junction.
I know they use propane powered generators for some remote telecom sites in BC, I wonder what they use.
Roy

 

[sreid]

Doesn't NASA use thermoelectric generators for interplanetary probes (hot end is a radioactive source)? I'd start looking a NASA reports.

 

[btrueblood]

Cassini spacecraft is the most recent launch using an RTG (radio-isotope thermal generator). There was a great deal of work done in the '70s regarding efficiency and specific power output of thermopiles for high temperatures. Also, if you can get hot enough, consider thermionic emission piles (uses vacuum-tube technology to achieve results similar to semiconductors at low temp's.).

 

[VEBill]

So far as I know, all deep space probes use RTGs. This is due to the Sun being a mere spec when viewed from the further reaches of the solar system and beyond (solar panels useless).

 

[roydm]

Found this interesting site.

http://www.hi-z.com/papers/

Roy

 

[Griz42]

Thanks for all the good info. I've been looking at dtic.mil and they list a lot of reports related to these types of devices. Most of the reports aren't online so I might have to buy them but they look like a good starting point.

Thanks
-Griz

 

[sreid]

A hot item for a while was Thermovoltaics, basically solid state voltage sources powered by heat rather than photons.

 

[bogeyman]

Try

http://www.dself.dsl.pipex.com/index.htm

Doug's museum of retro tech has a thermo gen section

 

[Compositepro]

You haven't described your current or voltage needs but perhaps you can use thermopiles that are available at the hardware store. They are used in millivolt thermostat systems for gas heating furnaces. The heat from the pilot light generates enough current to latch the main gas valve open.