81–90 of 96 posts
> Those could be installed everywhere from .. water heaters .. to scavenge some of the 65% of fossil fuel energy that winds up as waste heat. Modern condensing gas boilers for domestic use are better than 90% efficient, the exhaust gas is very cool so I don't think that thermoelectric devices have much to offer there.
Isn't the minimum exhaust temperature the same as the temperature of the heated water? How can it be less?
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Isn't graphene a high quality p type material as well? What makes a material p or n?
Kinda answered my own question with some searching - looks like p type has lots of electrons, n type has lots of holes, and graphene oxide (GO) makes an excellent and simple to use n type material. Graphene can be modified by changing its topology to be p or n, but GO is n by default. Do electron and hole features have to match in these constructions?
https://simple.wikipedia.org/wiki/P-type_semiconductor (property 2)
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Or you could have a battery and store that energy to supply your house with electricity, thus reducing your bills.
That would be useful energy, which thermodynamics says is impossible to extract from heat.
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When it was unusually hot over here, I was thinking about this. We can convert nearly every kind of energy into electricity and back. But for heat, for some bizarre reason, this only works one way. A lot of processes generate it, but you literally can't convert it into any other form of energy. You have to transfer it somewhere where it won't be as much of a problem. It would be very nice to have an AC where you don'…
> I thought about many ways to get rid of heat without having to dump it somewhere, but thermodynamics is such a terrible thing. This is likely a stupid question but temperature is a statistical property describing the energy of molecules right? Is there no way to tap the energy of the molecules for useful work without having a temperature difference?
I found it intreaguing and read more about it but I can't quite umderstand the proposed solutions, likely due to my lack of background in thermodynamics.
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You could also built completely silent refrigerators and freezers that last 100 years.
I suspect you would still need a fan to cool off the hot side, but very silent, very long lasting, and the only moving part could be generic easy to replace fans.
Selenium is moderately available but it is toxic waste when you need to replace it (all things have finite lifespans) and then need to dispose of the discard.
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I suspect you would still need a fan to cool off the hot side, but very silent, very long lasting, and the only moving part could be generic easy to replace fans.
Most current fridges have a fan on the cold side to circulate the coldness all around, and rely just on convection to pull away the heat (excepting RV propane fridges, which don't have a cold-side fan and have very uneven temperatures, but do have a hot-side fan because otherwise they don't work on hot days) Having had the evaporator fan go out in an old fridge once, I think you'll find fridge fans not as generic nor…
It says a ZT of 3.1, isn't that approaching 25% efficiency on par with more standard heat engines? Also more in line with say a solar panel for light to electricity. That kind of efficiency would be a big breakthrough if it where affordable, imagine the applications.
You could also built completely silent refrigerators and freezers that last 100 years.
Heat is energy. In summer, the sun (rudely) gives me excess unwanted heat in my house. I need to expend even more energy to get that heat from inside to outside my house. (We call this process "Air Conditioning".) What would be ideal is if the heat energy could be converted into some other form of energy that I could dispose of. Maybe if I could turn it into electricity I'd put a lightbulb in my window and shine the…