Radiant Cooling with Liquid Nitrogen

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Don't know much about vacuums, do ya, boy?
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in message wrote:

I was refering to the outside surface of the envelope...... be it a glass tube, or steel or whatever. For it to be effective, its going to have to be below dew point.
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On Wed, 22 Dec 2010 12:44:10 -0800 (PST), GreenXenon

    And as the heat leaves that outer layer, via radiation across your vacumn, bringing your 'protective layer' to some point between room temperature and absolute zero ( and FAR FAR BELOW freezing ) .. then what ?
Really, try to think at least a LITTLE bit before posting.
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wrote:

...of each of the digits of your fingers if you touch it!
Good answer. Everything at that low temperature would be below a phase change point compared to what we call our comfortable ambient (what? 72F?), so would definitely condense as liquid or crystalline solid on the surface of the "wessel" the LN2 is in.
So, what do the other inert gasses look like in liquid form? Like xenon, for instance.
What would the resistance be of a fluorescent type lamp tube filled with a liquid instead of a gas? Would it still flow like a plasma?
It would not longer produce photons, and simply conduct?
I know it would e hard to do as the tubes are very thin.
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On 24/12/2010 01:35, TheGlimmerMan wrote:

You would get LOX preferentially liquifying. So you'd suffocate in the remaining N2 shortly before your solid frozen feet exploded in a pool of LOX and incinerated you.
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On Fri, 24 Dec 2010 02:19:12 +0000, Dirk Bruere at NeoPax

    Wow, that would kinda suck.
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Thinking of radiant cooling would do better by having couple glasses of good Bourbon!!!
Hi:
I thinking of a radiant cooling device for houses and buildings in which the cooling -- in the direct sense -- involves only radiation. Sort of like a glass-ceramic radiant-stove-top in reverse. Indirectly, however, some amount of convection and conduction will be needed [liquid nitrogen, cold metals]. The cooling panel is the ceiling and cools objects below it.
Quote from http://en.wikipedia.org/wiki/Glass-ceramic :
"A glass-ceramic stove uses radiant heating coils as the heating elements. The surface of the glass-ceramic cooktop above the burner heats up, but the adjacent surface remains cool because of the low heat conduction coefficient of the material."
Here is an example of a radiant stovetop switched on:
http://www.istockphoto.com/file_thumbview_approve/4799702/2/istockphoto_4799702-glowing-ceramic-stove-top.jpg
My theoretical glass-ceramic radiant cooler is similar to the infrared radiant stovetop described in the wikipedia link, except:
1. It faces downward 2. The coils are hollow [as opposed to being solid all the way through], this hollow within the coils allows liquid nitrogen to flow through them can cool them down to near absolute zero 3. Liquid nitrogen -- not electricity -- flows through the coils. 4. Obviously, the coils get cold instead of hot.
The radiant cooling panel is on the ceiling of the room it is supposed to cool. Those standing under it will feel cold.
Yes, heat absorbed into the radiant cooling panels is carried off using convection and conduction -- but this is not what the subject inside the room feels. The direct cooling effect on anything/anyone inside the room is radiant.
By direct radiant cooling, I mean that if you place your body at a noticeable distance from panel, you'll feel cold because the extreme cold of the coil will draw IR radiation away from your body.
Im thinking of more intense versions of this hypothetical glass ceramic radiant infrared cooler to be used in refrigerators and freezers.
This radiant cooling is something that I am deeply interested in. I don't know why.
Radiant cooling will feel to the object like "cold rays" just like radiant heating feels like "heat rays".
I know there is no such thing as "cold rays", it's simply heat radiating from my body to a colder object. My body is giving of heat rays causing it's temperature to lower, thereby giving me a perception of coldness.
Thanks a bunch,
Green Xenon
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If you must top-post, do so elsewhere. Why do you think they came up with /dev/null?
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Mr. Briggs you don't like my wise remark hmmm I will cry all night long.
Stupidity is not my coup of tea and maybe you should stop cross posting!
wrote:

If you must top-post, do so elsewhere. Why do you think they came up with /dev/null?
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On Thu, 23 Dec 2010 23:40:42 -0600, "Oscar_Lives"

There is only one?
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Don't forget the ball cap with the fan in it.
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On Wed, 22 Dec 2010 09:43:28 -0800 (PST), GreenXenon

    And then the panel becomes immediately frosted over, and then quickly iced over. Said ice being a good insulator ( ask any Eskimo ). Oops.

    'Flows' under what impetus ? Pressure ? Pressure created how, where, at what power cost ? And the nitrogen goes where ? Atmospheric release ? So, you get new Nitrogen where ? At what power cost ?

    No, it will be well insulated with ice after a very few minutes, and those standing under it will feel mainly the drip-drip-drip of the surface of that ice melting on them.
    Also, any little kids who jump up and put their tongues on it will hang there in the middle of the room, stuck to your 'near absolute zero' plate :-)
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There seems to be a lot of ignorance in this thread.
No, liquid nitrogen is not a good way to do radiant cooling. The energy required to manufacture the N2 is too much to be cost effective.
Yes, radiant cooling works fine. "Cold plates' are commonly installed. They are cooled from a chiller, just like a fan coil is.
No, they don't drip. You have to dehumidify your make up air. No big deal.
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wrote:

They do NOT "cool" from any source.
They REMOVE HEAT. The heat is what moves.
Cooling should not be considered as a verb.
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Dehumidify how?? mechanical refrigeration?? that defeats the purpose. Dessecants?? That has its own drawbacks. The RH will have to be lowered to a point where the "cold plates" are several degrees above dew point..... the building envelope will have to be absolutely vapor tight, and even then your still going to have a frost problem.
Consider..... Walk-in freeze boxes are generaly vapor and water tight.... why do they have a need for defrost? .... or am I making too much sense??
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You're bringing up lots of objections that seem to be logical to you.
However, they reveal you are unaware that radiant cooling is a viable commercial option and has been for several years.
Sorry, but you need to keep up.
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You're bringing up lots of objections that seem to be logical to you.
However, they reveal you are unaware that radiant cooling is a viable commercial option and has been for several years.
Sorry, but you need to keep up.
I haven't dealt with radiant cooling here in south Mississippi for 2 reasons.... first and formost is that 95% of what I do is high-end residential heat pumps and dual fuel/hybrid systems, second is that the latent loads here are extremely high. Humidity control is a very big issue here.
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oooohhhh.... Steve knows big words...
The 'load' between your ears is easier to describe by referencing your eye color and that foul ooze and stench emanating from your ears.
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On Fri, 24 Dec 2010 16:52:14 -0800 TheKraken

And the load in your mouth? That's your Father's.
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On 12/24/2010 6:44 PM, Steve wrote:

We have high humidity here in Alabamastan too and one of the criteria we use to define the performance of an air conditioning system is whether or not the stream of water coming out of the evaporator drain line looks like someone turned on a kitchen sink. On those days when the air is so humid it slows down your vehicle from the increased density of the air, I always wonder how my distant ancestors the Cavebillies ever survived summer weather. It was the radiant cooling of the caves of course. :-)
TDD
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