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Thread: experimental pot design

  1. #1
    Av8tor1's Avatar
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    Cool experimental pot design

    An idea of mine for a self cooling pot I had been tossing around for quite a few years but never got around to trying...
    Based on an ancient technology used to preserve food but with Cp application modifications

    A dear friend sent a nice cobra so what better time to try :-)

    Pictures are self explanatory I believe
    Porosity of the terra cotta is critical of course.






















    no moving parts and nothing to fail = elegant imho


    Relevant variables:
    RH 46%
    Dewpoint 63%
    Maximum ambient surface temperature detected by FLIR thermography 93.7f
    Pot 78.9f
    DeltaT 14.8f

    thanks for looking,

    I did not adjust for thermal emissivity or reflectivity so take the temps with a grain of salt.
    Last edited by Av8tor1; 06-12-2016 at 11:28 AM.

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    Lotsa blue bluemax's Avatar
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    An interesting idea - evaporative cooling for pot-dwellers. So, the 93.3 F is the surface temperature of something nearby and not the air temperature?
    - Mark

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    Av8tor1's Avatar
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    yes,

    But to pick the fly dung out of the pepper..... infrared thermography doesn't measure temperature per say but emitted radiation.... has to do with emissivity of the object etc etc.
    If emissivity is "1" then these two line up fairly well, flat black for example has a emissivity of close to one, whereas chrome is very low
    The camera would see the chrome object as being colder than the black, when both could have the same surface temperature.
    An object's absorbtivity will also equal it's emissivity, and there are also variables such as reflectivity and transmissivity....

    quiz in the morning :-)


    but yes, the actual air temperature is in the low 90's
    Last edited by Av8tor1; 06-12-2016 at 12:13 PM.

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    fredg's Avatar
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    More fly dung.

    I see that the medium temperature is higher than the outside of that pot.
    What temperature is the medium at AND how does that compare to a standard Darlingtonia pot or a Darlingtonia in a flooded Sphagnum tray.

    Sometimes one can just wonder why one got up in a morning
    Fred

    Quot Homines Tot Sententiae

    http://fredg.boards.net/

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    Av8tor1's Avatar
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    good question, just had checked that using a metal probe, the media at root depth is currently about 12 degrees cooler than actual air temp....

    have no idea about a comparison, but all things being equal, if no means of cooling/heating is taking place the temperature of an object should equal ambient under isothermal conditions

    errr at least I think, not my area of expertise though :-)
    maybe someone with more knowledge can chime in on that
    Last edited by Av8tor1; 06-12-2016 at 12:35 PM. Reason: additional comment :-)

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    nimbulan's Avatar
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    As I understand it infrared thermometers generally default to 0.95 emissivity, which is pretty close to the value for most materials. I remember looking up values the first time I tried starting seeds to monitor soil temperature.

    How much did that thermal camera set you back?

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    Av8tor1's Avatar
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    flat black grill paint and 3m electrical tape are close to 0.95, whereas chrome can be significantly less.
    I demonstrate this to my students with an old clothes iron that I have painted one half flat black and left the other half normal stainless steel.

    I have three, that particular camera is a cheapie (relatively speaking) at 2.5k, I have a nice FLIR that was 18k
    Last edited by Av8tor1; 06-12-2016 at 07:03 PM.

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    Av8tor1's Avatar
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    when I say "I" I mean my lab, not my personal camera

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    Hello, I must be going... Not a Number's Avatar
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    Hmm, seems like I mentioned Zeer pots back in 2009:

    Cool Pot (it's not what you think!)

    A Practical Zeer Pot (evaporative cooler / non-electrical refrigerator)

    Of course with all evaporative cooling relative humidity plays a big role.
    Grand Hotel... always the same. People come, people go. Nothing ever happens.

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    Av8tor1's Avatar
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    I honestly didn't remember those but I bet they are probably what planted the seed in my head!!!

    I must give credit where credit is due :-)

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