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Thread: Directional heat?

  1. #1 Directional heat? 
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    Is there any way to 'beam' heat with a solid or liquid system given that you can alter the shape of the heat source and place it either external or internal to the system? Essentially, 'prevent entropy' in certain directions and promote it in another.

    Would wave theory apply to this at all? The wider you make a laser beam, the slower it widens. Perhaps a wide heat source would create a more directional conduction of heat?


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  3. #2  
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    You can certainly direct IR radiation in much the same manner as light or radio, it's the same "stuff" after all. You must have had an electric heater that had a reflector on one side of it in your past -- or present even. In that respect "wave theory" might be the mechanism to explain the directionality.

    I'm not sure about IR lasers though. Wiki has a very brief article:
    http://en.wikipedia.org/wiki/Far-infrared_laser
    and there are M(icrowave)ASERs, but I think they both function differently from higher freq IR to UV lasers.

    Uh, what was the question again?


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  4. #3  
    Forum Ph.D. Leszek Luchowski's Avatar
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    A google search for "infrared heater" will produce lots of devices that send IR in a certain direction. Is this what you are looking for?
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    I meant thermal heat, not electromagnetic. Sorry for not specifying.

    I am trying to explain a certain theory that I read about that no one can seem to fully answer, but part of my theory requires directional thermal heat convection, and I am not sure whether such a thing is reasonable or not. I thought that maybe if the source were wide enough, the 'walls' of the heat wave might reinforce the forward transmission of the energy like in a laser. This would be fairly severe directionality however....we are talking about a source 10 miles across beaming thermal heat 2000 miles + in the forward direction. It doesn't seem reasonable, does it? Just wanted to see what you guys had to say about this.
    Of all the wonders in the universe, none is likely more fascinating and complicated than human nature.

    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."

    "Great spirits have always found violent opposition from mediocrities. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence"

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  6. #5  
    Forum Ph.D. Leszek Luchowski's Avatar
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    If you are not talking about electromagnetic waves, what exactly do you mean by "beaming" heat? There is no "thermal heat radiation" different from electromagnetic.

    You also use the word "convection", which means a flow of some material medium, such as hot air or water. Of course that can be directed, by tubes for example. We do it all the time in household heating systems. For a huge project such as you describe, you would need some enormous walls or dams, or gigantic pipelines, to control winds or ocean currents.

    What are you trying to do in the first place?
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  7. #6  
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    The heat I am talking about is the same heat generated by your computer's heat sink.

    By beaming I mean making it unidirectional and opposed to omnidirectional.

    Yea, I tend to use certain words in my own way. I am using convection in terms of movement of heat.

    I am not trying to physically replicate this, but the idea of directional heat is a component of a strange theory I am working on. It would be a little difficult to make sense of it on this forum right now.
    Of all the wonders in the universe, none is likely more fascinating and complicated than human nature.

    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."

    "Great spirits have always found violent opposition from mediocrities. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence"

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  8. #7  
    Forum Radioactive Isotope MagiMaster's Avatar
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    From what I remember reading, you can't really make a unidirectional radiator, since you need to move the entropy with the heat for the radiator to work right. (http://www.projectrho.com/rocket/roc...html#radiators, mentions it in the second paragraph.)
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  9. #8  
    Forum Ph.D. Leszek Luchowski's Avatar
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    Heat can be transferred in three ways: conduction, convection, and radiation, as explained in this lesson of physics for example. Which of them are you trying to make directional?

    Your statement that you mean the way a CPU heat sink handles heat does not really answer my question, given that the sink uses all three. Conduction moves heat from the CPU to the sink and from the sink to the surrounding air; convection (often "enhanced" by a fan) then moves the warm air away from the sink and replaces it with fresh cooler air from the environment. Some heat is also radiated from the sink.

    Please try to use words in their recognized meanings, that's how language works. If you have a novel idea which does not yet have a name among the existing words, why on't you propose a new word or expression?
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  10. #9  
    Forum Junior Steiner101's Avatar
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    Leszek he is asking if conduction can be directional in a material, or if it just dissipates outwards radially from the source.
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  11. #10  
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    Heat conduction is somewhat similar to diffusion, smoothing out differences. If we want to talk about direction the closest we'd come is the (matematical) gradient. In other words, the direction of heat conduction in a point is the direction in which the temperature drops the most rapidly.
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  12. #11  
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    Could not one "focus" conducted heat using materials with different specific heat capacities (I think that's the quantity I want, e.g., the heat conduction difference between stainless steel and aluminum)? In that respect convection in gasses is a sub-set of conduction, but there's probably no way to control the density and capacity of a free gas.
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  13. #12  
    Forum Radioactive Isotope MagiMaster's Avatar
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    The word for this is anisotropy. Wiki mentions anisotropy of heat conduction.
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  14. #13  
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    Alright, thanks
    Of all the wonders in the universe, none is likely more fascinating and complicated than human nature.

    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."

    "Great spirits have always found violent opposition from mediocrities. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence"

    -Einstein

    http://boinc.berkeley.edu/download.php

    Use your computing strength for science!
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