4 ms·

I wonder if you could get it small enough to use with CPUs. Could extend the battery of a laptop for example. I’m also thinking of AC units, where it could lowe

by calgoo 5y ago

I wonder if you could get it small enough to use with CPUs. Could extend the battery of a laptop for example. I’m also thinking of AC units, where it could lower the power consumption at the same time as lowering the heat we diffuse into nature, especially in big cities where the most rooftops feel like saunas.

yetihehe 5y ago
> I’m also thinking of AC units, where it could lower the power consumption Nope, if you use this on hot side, AC will have to work more to get rid of heat, but this device will still provide less power than ac must now use. Design criterium for AC's is that hot side should be as cool as possible (so it has a big fan to cool it down), but thermoelectrics require hot side to be as hot as possible. AFAIK compressor units are still way more efficient than this device, so no reason to bog them down with something with less efficiency.
- wiredfool 5y ago
  I don’t think that’s right. The solid state methods can sustain a temperature differential with a given power/heat flow. If the hot side is cooler, the cold side can be cooler, or less power is required.
  - yetihehe 5y ago
    If you insert something between hot side and air to extract energy, there will be more heat resistance and lower heat transfer, but this resistance will be bigger than what you get from your energy extracting device. If you use that new device as a cooling enchancer, you will have to provide some power. If your first cooler user more efficient method, you should just make bigger unit using more efficient method, because otherwise whole apparatus will be less efficient.
  - deleted 5y ago
    [deleted]
  - s1artibartfast 5y ago
    Thermoelectric elements add resistance. You are literally adding a giant resister between the hot and cold side, which decreases the thermal Flux for a given temperature difference.
grishka 5y ago
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't need to deal with that. I thought about many ways to get rid of heat without having to dump it somewhere, but thermodynamics is such a terrible thing.
- wiredfool 5y ago
  Thermodynamics -- you can't win, you can't break even, and you can't even leave the game.
- blueblisters 5y ago
  > 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?
  - davidinosauro 5y ago
    You might want to read about Maxwell's daemon [1]. I came across this a few weeks back, two links away from the HN homepage. 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. [1] https://en.m.wikipedia.org/wiki/Maxwell's_demon https://en.m.wikipedia.org/wiki/Maxwell's_demon
    - blueblisters 5y ago
      Clearly, Maxwell was much better (and funnier) in articulating what I was asking. Looks Maxwell's demon can work some of the time at a molecular level, but on average, you need to do work to extract useful heat from matter at a macroscopic level. The hypothesis being that you need to do work just to identify hot/energetic molecules from the cold/low-energy molecules.
France_is_bacon 5y ago
I'd be interested, too. I once read in some article that CPUs have the same power consumption as equivalent output of a nuclear reactor, based on size, of course. So the 1 inch of a CPU takes as much energy as 1 inch of a nuclear fusion output from a nuclear reactor. Again, I don't know if this is true, but if it is, that's a lot of heat energy, given the number of computers in the world. But maybe I remember wrong, this was probably 15 or 20 years ago that I read this.
- fy20 5y ago
  Must have been a Pentium 4.

by calgoo 5y ago

yetihehe 5y ago

> I’m also thinking of AC units, where it could lower the power consumption Nope, if you use this on hot side, AC will have to work more to get rid of heat, but this device will still provide less power than ac must now use. Design criterium for AC's is that hot side should be as cool as possible (so it has a big fan to cool it down), but thermoelectrics require hot side to be as hot as possible. AFAIK compressor units are still way more efficient than this device, so no reason to bog them down with something with less efficiency.

wiredfool 5y ago
I don’t think that’s right. The solid state methods can sustain a temperature differential with a given power/heat flow. If the hot side is cooler, the cold side can be cooler, or less power is required.
- yetihehe 5y ago
  If you insert something between hot side and air to extract energy, there will be more heat resistance and lower heat transfer, but this resistance will be bigger than what you get from your energy extracting device. If you use that new device as a cooling enchancer, you will have to provide some power. If your first cooler user more efficient method, you should just make bigger unit using more efficient method, because otherwise whole apparatus will be less efficient.
- deleted 5y ago
  [deleted]
- s1artibartfast 5y ago
  Thermoelectric elements add resistance. You are literally adding a giant resister between the hot and cold side, which decreases the thermal Flux for a given temperature difference.

grishka 5y ago

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't need to deal with that. I thought about many ways to get rid of heat without having to dump it somewhere, but thermodynamics is such a terrible thing.

wiredfool 5y ago
Thermodynamics -- you can't win, you can't break even, and you can't even leave the game.
blueblisters 5y ago
> 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?
- davidinosauro 5y ago
  You might want to read about Maxwell's daemon [1]. I came across this a few weeks back, two links away from the HN homepage. 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. [1] https://en.m.wikipedia.org/wiki/Maxwell's_demon https://en.m.wikipedia.org/wiki/Maxwell's_demon
  - blueblisters 5y ago
    Clearly, Maxwell was much better (and funnier) in articulating what I was asking. Looks Maxwell's demon can work some of the time at a molecular level, but on average, you need to do work to extract useful heat from matter at a macroscopic level. The hypothesis being that you need to do work just to identify hot/energetic molecules from the cold/low-energy molecules.

France_is_bacon 5y ago

I'd be interested, too. I once read in some article that CPUs have the same power consumption as equivalent output of a nuclear reactor, based on size, of course. So the 1 inch of a CPU takes as much energy as 1 inch of a nuclear fusion output from a nuclear reactor. Again, I don't know if this is true, but if it is, that's a lot of heat energy, given the number of computers in the world. But maybe I remember wrong, this was probably 15 or 20 years ago that I read this.

fy20 5y ago
Must have been a Pentium 4.