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radiant wave

RICK JAMES
RICK JAMES Member Posts: 11
We were talking about the wave and how it travels ,how far will the radiant wave travel?

<ol><li>will its energy decrease as it gets farther away from the the source??</li><li>how fast will the wave travel??

</li><li>what occurs naturaly that will affect the wave as it travels

</li></ol>

Comments

  • Mark Eatherton
    Mark Eatherton Member Posts: 5,839
    edited March 2010
    Wave form.

    Radiant waves travel until they are absorbed by a solid object.



    It doesn't weaken but it does diffuse. If you continue to pump radiant energy into a space, you will eventually raise the MRT, which is what drives the bus of human comfort. If you continue to pour radiant energy into a space, it will eventually increase the MRT to human DIS-comfort, which is not comfortable.



    It travels at the speed of light. Can your forced error system say that? :-) 670,616,629 miles per hour. Say that REAL slow. Six hundred and seventy million, six hundred and sixteen thousand, six hundred and twenty nine. That's 186,000 miles per second. Buckle your seat belt! :-)



    Reflection is the one thing that can affect the traveling rays. Partially absorbed, partially reflected. Definitely reduced in intensity at that point.



    A common saying is that radiant energy travels omni-directionally, thru the path of least resistance. And from the source, that statement is true.



    However, once it strikes another solid surface, it becomes heat in the form that we understand and can feel it. Energy in general has a tendency to accumulate in the upper regions of a given structure/setting. And I'm not EVEN talking convective energy.



    You see this kind of stuff when you're looking at things through the eyes of an InfraRed camera. ;-)



    Another overlooked potential is on the opposite end of the system as we know it. It is called night sky re-radiation. Let's say you have a large solar thermal array. At night, outer space is SUPER cold, like -454 degrees F or something outrageous like that. Anyway, you circulate fluid thru the collectors at night, and it will reject heat into outer space. Connect it to your radiant floor, and you have active/passive radiant cooling, and very little chance of approaching the dew point.



    Radiant Rules!!



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Leo_G
    Leo_G Member Posts: 89
    But Prof...

    If you push those dastardly IR's out through your solar panel, you KNOW that the accumalating CO2 will absorb and reradiate up to 50% of the energy back to earth, thus helping to raise our planet's temp!



    :)
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,839
    It's part of the plan....

    I just bought an Al Gore Carbon Credits franchise :-)



    Carbon credits anyone?



    Trees for sale.



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • ECW
    ECW Member Posts: 14
    Wave quality, diffusion, intensity and comfort

    I asked on another thread but got no reply to this:



    Does the surface shape of a rad affect its heating quality and efficiency?



    I am told a flat panel rad will "beam" its heat, making exposure to it intense (focused and narrow) and uncomfortable whereas the more undulating surface (i.e.ridges, tubular or old style rads, surfaces more directions) will diffuse IR more evenly, in all directions perdendiculr to the surface, and so be more efficient, more comfortable througout the space as well as more comfortable when one is close to the rad.



     
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,839
    Good questions...

    Not sure I am the most qualified to answer them, but I will give you my gut feelings about them.



    In my minds eye, shape has less to do with it than does color. Metallic colors have e tendency to emit less radiant energy, hence the reason for painting radiators in metallic colors (or not...). The energy leaves the surface in an omni-directional pattern, hence the use of the term radiant, with a Greek root in radians. Increase surface areas make the emitter more efficient in transferring heat from one fluid (water or steam) to the surrounding surfaces.



    I have seen simple round pipes, conveying steam that had the ability to significantly raise the MRT in a given space. Minimal area, but continuous emissions.



    When it comes to absorption, the more of the radians of energy your body intercepts, the more your body can sense the radians and associated heat energy attached to it. So, when receiving radiant solar energy, a panel at a right angle to the incident incoming angle to the radiant energy will absorb more energy than will a panel at a parallel angle (DUHHhh!). Think of the shadow the absorber represents. The greater the shadow, the greater the energy intercepted.



    Your proximity to a given radiant energy emitter will determine the intensity of the flux your body intercepts, and the feeling of heat it generates. MRT (mean radiant temperature) affects human comfort more than any other measurable energy. But MRT is a great topic for a WHOLE other thread :-)



    If you could stand next to the sun, you would evaporate due to the energy intensity, whereas here on Earth, the intensity is tolerable. At Pluto, you would freeze in an instant.



    HTH,



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • ECW
    ECW Member Posts: 14
    "Fundamental Concepts of Radiation"

    Here is PPP that says IR travels in a spherical direction from point source. But its more refined than that: I think the math shows that the greater intensity and volume of IR are concentrated perpendicular to the emitter's surface.

    http://wwwme.nchu.edu.tw/Enter/html/lab/lab516/Incropera%20-%20PDF/12.pdf

    Probably color and texture are important due to the quantum level features of IR.

    I think I will choose undulating as opposed to smooth panel rad surface to try and eek out some advantage for diffusion of the heat.

    ECW

    ME - did I not talk with you 10 years ago: you were in Golden I believe; I was at the top of Coal Creek Canyon.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,839
    edited March 2010
    Probably me...

    or someone with my same name but worse credit ratings :-)



    Am in Denver, so yeah, probably me. 10 years ago, I was still in Denver (Advanced Hydronics, Inc).



    15 years ago I was with AAA Service Plbg who was in Golden.



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
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