peltier module in space

[Tom_nerd]

hey guys

 

I was reading up about the Peltier effect because I found it interesting and lets be honest what else are you supposed to do in quarantine, anyway when you put electricity through the Peltier module it transfers all of the heat from one side to the other, and it works the other way, if you have a really hot thing on one side and something really cold on the other, it will generate electricity. I then was reading about Chris Hadfield and his space walk and he described it as "having the blazing heat of the sun from one side and the cold from the vacuum of space, this immediately made me think of putting a Peltier module up in space and how much charge it could generate. I was wondering if there was anything fundamentally wrong with this idea that I overlooked.

 

thanks in advance,

Tom

[Grabhanem]

4 minutes ago, Tom_nerd said:

hey guys

 

I was reading up about the Peltier effect because I found it interesting and lets be honest what else are you supposed to do in quarantine, anyway when you put electricity through the Peltier module it transfers all of the heat from one side to the other, and it works the other way, if you have a really hot thing on one side and something really cold on the other, it will generate electricity. I then was reading about Chris Hadfield and his space walk and he described it as "having the blazing heat of the sun from one side and the cold from the vacuum of space, this immediately made me think of putting a Peltier module up in space and how much charge it could generate. I was wondering if there was anything fundamentally wrong with this idea that I overlooked.

 

thanks in advance,

Tom

The issue with that theory is that there isn't really anything to be warm or cold in space-- if you put a thermometer out the window, it'll get warm because it's in the sun or cold because it's in the shade, but you aren't really measuring the temperature of much actual matter. You could put a Peltier element on a spacecraft, but it would just warm up the Peltier on both sides because there's nothing for it to really dissipate heat to.

[Sakkura]

When you're in the inner solar system, you can get more power from a photovoltaic panel than a thermoelectric generator, so there's no reason to make the latter.

 

When you're in the outer solar system, a thermoelectric generator can be very useful but only if you use another heat source, as the sun is too weak. Decaying plutonium is used in practice, in radioisotope thermoelectric generators.

[Enderman]

Space is a vacuum.

There is no physical material to cool down one side of the peltier.

You need something like a solid or liquid or gas that has atoms that can be heated up to vibrate and absorb energy.

[Sakkura]

16 hours ago, Enderman said:

Space is a vacuum.

There is no physical material to cool down one side of the peltier.

You need something like a solid or liquid or gas that has atoms that can be heated up to vibrate and absorb energy.

You rely on thermal radiation to cool down a spacecraft. That is just more limited than the conduction/convection/evaporation we're used to.

[Enderman]

7 hours ago, Sakkura said:

You rely on thermal radiation to cool down a spacecraft. That is just more limited than the conduction/convection/evaporation we're used to.

A peltier will not be able to dissipate anywhere near enough energy through radiation alone, it's basically insignificant.

[Unimportant]

On 4/14/2020 at 7:14 PM, Tom_nerd said:

<snip>

We already have devices which would be much more efficient at generating electricity in space: solar panels. With earth's atmosphere out of the way, solar panels in space would be much more efficient then down here on earth. The real problems are getting massive amounts of equipment up there, maintenance, and getting the generated power back down here again - all at a cost that can compete with the current systems.

 

(Imho, currently the only viable environmentally neutral way to produce massive amounts of energy is nuclear power. Modern technology is much safer then the old reactors still in use, and can even re-burn the waste of previous generations of reactors to reduce said waste even further. We should stop the current trend of ignoring nuclear power while constantly pushing the retirement date for old obsolete reactors forward because when push comes to shove the renewables are not yet ready to take over - until some accident happens with one of those old reactors that should've already been replaced with a modern one.)

[Hackentosher]

Peltiers are already used in space! Yes, they are horrendously inefficient, iirc from my research, the highest efficiency achieved in a lab was 15% efficiency. However, they're still used. NASA has used them for powering some satellites and even the Curiosity rover uses a peltier with a big radioactive rock taped to it. The heat from the the decomposition is significant enough to heat the hot side of a peltier and power the rover. Russia also used them to power some super remote installations like light houses I think. The wikipedia page on RTGs (Radio-isotope Thermalelectric Generators) is super interesting. 

[Sakkura]

On 4/16/2020 at 9:56 PM, Enderman said:

A peltier will not be able to dissipate anywhere near enough energy through radiation alone, it's basically insignificant.

It provides all the power used by most of the probes sent to the outer solar system. So, not that insignificant. Juno is the first outer solar system probe to use solar panels instead.

[Enderman]

11 minutes ago, Sakkura said:

It provides all the power used by most of the probes sent to the outer solar system. So, not that insignificant. Juno is the first outer solar system probe to use solar panels instead.

That's because there's almost no sunlight there so solar panels are ineffective.

With sunlight solar panels are far more powerful which is why basically every satellite or rover has them.

 

"RTGs use thermoelectric generators to convert heat from the radioactive material into electricity. Thermoelectric modules, though very reliable and long-lasting, are very inefficient; efficiencies above 10% have never been achieved and most RTGs have efficiencies between 3–7%."

 

Plus you do need a way to cool them through radiation only which means massive fins on the outside as well as coolant loops.

[Bloudy_Parrot]

On 4/14/2020 at 8:14 PM, Tom_nerd said:

hey guys

 

I was reading up about the Peltier effect because I found it interesting and lets be honest what else are you supposed to do in quarantine, anyway when you put electricity through the Peltier module it transfers all of the heat from one side to the other, and it works the other way, if you have a really hot thing on one side and something really cold on the other, it will generate electricity. I then was reading about Chris Hadfield and his space walk and he described it as "having the blazing heat of the sun from one side and the cold from the vacuum of space, this immediately made me think of putting a Peltier module up in space and how much charge it could generate. I was wondering if there was anything fundamentally wrong with this idea that I overlooked.

 

thanks in advance,

Tom

satelites use radiators to disapate (i hting i have writen it wrong but anyway) heat that is been produced by the machines to space.

if you had the one side of the peltier tuching the hot electronics and the other tuching the cold radiators less heat will be wasted. 

bUT sence  the electronics must stay cool radiators will sill being in use.

Also, for the side of the peltier to get warm enough ,to produce energy you will need to  have it in a large scale and even then deu to the non existing atmosphere  around the peltier, sun's "radiation" wont be captured to raise the tempreture to a surtant pooint.

YOu will also need somehow to transport the energy produced back to earth. 

 

 

[Bloudy_Parrot]

On 4/14/2020 at 8:22 PM, Grabhanem said:

The issue with that theory is that there isn't really anything to be warm or cold in space-- if you put a thermometer out the window, it'll get warm because it's in the sun or cold because it's in the shade, but you aren't really measuring the temperature of much actual matter. You could put a Peltier element on a spacecraft, but it would just warm up the Peltier on both sides because there's nothing for it to really dissipate heat to.

no air no heat RIGHT????

[Grabhanem]

15 minutes ago, IamA-kid-LEARNING said:

no air no heat RIGHT????

There's nothing outside to be hot or cold, but the peltier itself can still have a temperature, just like it would on Earth. As it absorbed light from the Sun, it would warm up as the light energy was converted to heat, and it would radiate a small amount of energy back as infrared light, but it would mostly just get hotter.

 

The ISS and other spacecraft have huge radiator panels that are designed to absorb as little light as possible while radiating back as much as possible in order to keep temperatures reasonable for the crew. You could connect one of those to a Peltier, but you'd be better off just using a solar panel.

 

As Enderman mentioned, the more reasonable way to use a Peltier element is to put a radiator on the cold side and something that can produce more heat than sunlight, like a radioactive slug, on the hot side. This is typically done for long-range missions that need to operate too far from the sun for solar power to be effective.

[Bloudy_Parrot]

5 minutes ago, Grabhanem said:

There's nothing outside to be hot or cold, but the peltier itself can still have a temperature, just like it would on Earth. As it absorbed light from the Sun, it would warm up as the light energy was converted to heat, and it would radiate a small amount of energy back as infrared light, but it would mostly just get hotter.

 

The ISS and other spacecraft have huge radiator panels that are designed to absorb as little light as possible while radiating back as much as possible in order to keep temperatures reasonable for the crew. You could connect one of those to a Peltier, but you'd be better off just using a solar panel.

 

As Enderman mentioned, the more reasonable way to use a Peltier element is to put a radiator on the cold side and something that can produce more heat than sunlight, like a radioactive slug, on the hot side. This is typically done for long-range missions that need to operate too far from the sun for solar power to be effective.

my mum bought me a 50w one for my birthday as long as a multimeter and i tried the ice-peltier-candle sandwich and it barely lit up!!!

[Hackentosher]

4 hours ago, IamA-kid-LEARNING said:

my mum bought me a 50w one for my birthday as long as a multimeter and i tried the ice-peltier-candle sandwich and it barely lit up!!!

That's the poor efficiency you're running into. The best peltiers are like 10% efficient, meaning you would have to put in 500W of heat (and subsequently get rid of 500W of heat on the cold side iirc) to see the 50W of electrical output its rated for.

[Beerzerker]

I'm not sure they are THAT bad in terms of efficiency but certainly not efficient by any means.

Info I've seen before suggests somewhere around 30% or so, based on how it's setup and how it's used. That's still terrible efficency and the issues with it are why so few even bother with them period, that much is certain.