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  1. #11

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    Quote Originally Posted by dissonance View Post
    So would it literally change the average temperature by zero?
    Zero for practical purposes. Negligibly small. Unless you can get something cold that is increadibly dense, and has very high spefic heat (like a mini-blackhole jk).

    Accept the past. Live for the present. Look forward to the future.
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  2. #12
    Occasional Member Evan's Avatar
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    Ah. Well that was the point of me posting this. To get someone to tell me why it wouldn't work. If it would, I'm sure someone else would have talked about it by now...

    Thanks man.

  3. #13

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    I think it was a satisfactory explanation of why we'd have trouble cooling the environment by directly extracting heat.

    But I didn't really give an explanation on the work aspect.

    No engine using heat can be more efficient than a Carnot Engine. The maximum efficiency is (1-Tc/Th), where Tc is the temperature of our cold resevoir (energy sink), and Th is the temperature of the environment.

    Lets optimistically say that our magical heat engine can "pay" its temperature change cost only after it has done all its work, and that the heat capacity of our cold reservoir is C.

    The amount of work our cold reservoir can sink C(Th-Tc) in heat. But since our heat engine is only (1-Tc/Th) efficient, the maximum amount of work done is C(Th-Tc)(1-Tc/Th)=(C/Th)(Th-Tc)^2.

    The heat capacity C is in-turn directly proportional to the specific heat, density, and volume of our cold reservoir.

    So you can extract work from the environment, but considering how relative cold our environment is, running of our more convention engines has bee better.

    ...you know I wonder if we can create "cold-running" engines. How similar would these be to fuel cells?

    Accept the past. Live for the present. Look forward to the future.
    Robot Fusion
    "As our island of knowledge grows, so does the shore of our ignorance." John Wheeler
    "[A] scientist looking at nonscientific problems is just as dumb as the next guy." Richard Feynman
    "[P]etabytes of [] data is not the same thing as understanding emergent mechanisms and structures." Jim Crutchfield

  4. #14
    Glowy Goopy Goodness The_Liquid_Laser's Avatar
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    We could use outer space as a heat sink. It's plenty big and also cold enough.
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  5. #15
    にゃん runvardh's Avatar
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    The problem with space is that your only means of disposing of eat would be through radiation as there is nothing out there to help with the conduction or convection that we enjoy the use of while in an atmosphere with all our other neat toys. Its the reason why, even though it's approaching absolute zero out there, a person with no suit in space would die from suffocation first before hypothermia sets in.
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  6. #16

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    rundvah has the space idea covered.

    Beside the radiation is already in play.

    Accept the past. Live for the present. Look forward to the future.
    Robot Fusion
    "As our island of knowledge grows, so does the shore of our ignorance." John Wheeler
    "[A] scientist looking at nonscientific problems is just as dumb as the next guy." Richard Feynman
    "[P]etabytes of [] data is not the same thing as understanding emergent mechanisms and structures." Jim Crutchfield

  7. #17
    Glowy Goopy Goodness The_Liquid_Laser's Avatar
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    Quote Originally Posted by ygolo View Post
    rundvah has the space idea covered.

    Beside the radiation is already in play.
    Heh, my space comment was meant as a joke. I.e. the problem with global warming is that it traps too much heat in the atmosphere and not enough dissipates into space.
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  8. #18
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    Quote Originally Posted by The_Liquid_Laser View Post
    Heh, my space comment was meant as a joke. I.e. the problem with global warming is that it traps too much heat in the atmosphere and not enough dissipates into space.
    Perhaps we could just use a fan, and a series of tubes, to send part of our atmosphere to the Moon.

  9. #19
    Senior Member ptgatsby's Avatar
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    Quote Originally Posted by runvardh View Post
    The problem with space is that your only means of disposing of eat would be through radiation
    *shrug* Point a laser at the sun.

  10. #20

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    Quote Originally Posted by The_Liquid_Laser View Post
    Heh, my space comment was meant as a joke. I.e. the problem with global warming is that it traps too much heat in the atmosphere and not enough dissipates into space.
    Ah. That's what the wink was for. I've had bad luck interpreting ENTP winks lately. Still, it lead to an interesting idea.


    Quote Originally Posted by ptgatsby View Post
    *shrug* Point a laser at the sun.
    Laser cooling - Wikipedia, the free encyclopedia

    [...] laser cooling, in which photons are used to pump heat away from a material (normally a solid) and thus cool it. The phenomenon has been demonstrated via anti-Stokes fluorescence, and both electroluminescent upconversion and photoluminescent upconversion have been studied as means to achieve the same effects.
    Although, the other versions of laser cooling are intersting too.
    Laser cooling is a technique that uses light to cool atoms to a very low temperature. It was simultaneously proposed by Wineland and Dehmelt and by Theodor W. Hnsch and Arthur Leonard Schawlow in 1975, and first demonstrated by Letokhov, Minogin and Pavlik in 1976. One conceptually simple form of laser cooling is referred to as optical molasses, since the dissipative optical force resembles the viscous drag on a body moving through molasses. Steven Chu, Claude Cohen-Tannoudji and William D. Phillips were awarded the 1997 Nobel Prize in Physics for their work in laser cooling.

    Accept the past. Live for the present. Look forward to the future.
    Robot Fusion
    "As our island of knowledge grows, so does the shore of our ignorance." John Wheeler
    "[A] scientist looking at nonscientific problems is just as dumb as the next guy." Richard Feynman
    "[P]etabytes of [] data is not the same thing as understanding emergent mechanisms and structures." Jim Crutchfield

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