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Professors Claim Passive Cooling Breakthrough Via Plastic Film (sciencemag.org)
What if you could cool buildings without using electricity? charlesj68 brings word of "the development of a plastic film by two professors at the University of Colorado in Boulder that provides a passive cooling effect."
The film contains embedded glass beads that absorb and emit infrared in a wavelength that is not blocked by the atmosphere. Combining this with half-silvering to keep the sun from being the source of infrared absorption on the part of the beads, and you have a way of pumping heat at a claimed rate of 93 watts per square meter.
The film is cheap to produce -- about 50 cents per square meter -- and could create indoor temperatures of 68 degrees when it's 98.6 outside. "All the work is done by the huge temperature difference, about 290C, between the surface of the Earth and that of outer space," reports The Economist.
The film is cheap to produce -- about 50 cents per square meter -- and could create indoor temperatures of 68 degrees when it's 98.6 outside. "All the work is done by the huge temperature difference, about 290C, between the surface of the Earth and that of outer space," reports The Economist.
You non-RTFA infidel! The article states the temperatures as 20C and 37C respectively.
Ask me how the Heisenberg Principle may or may not have saved my life.
"Passive cooling on the order of what this article talks about would seem to be too good to be true. If it is true these guys should be filthy rich soon."
Don't forget to sell your Air Conditioning stock.
Its interesting that they have made the film, yet have not demonstrated it in a practical application. That makes me skeptical as they are relying on performance claims when they shouldn't have to. Why could they not take the film and cover a small structure (like a shed), and simply tell us the resulting cooling effect? And maybe compare against a simple reflective coating
Yeah, but how many is that in Kelvin?
Some people encrypt by using rot-13 twice. I prefer the more secure method of using rot-1 a total of twenty six times.
It's called physics, even if you don't find it interesting.
1) Letting visible light through in principle lets the PV work while keeping it cool. The increase in output with lower temperatures is quite significant, thus the presence on the market of combined PV/Thermal panels for example. (And absorbing more of the visible light and removing the energy as electricity rather than letting it turn into heat would be good too, natch, and that one is being worked on.)
2) Outer space is at ~3K/-270C: having that as your cold sink *day and night* is really quite significant. What I cannot work out is if clouds are transparent at the same wavelengths, eg if this could be used to make the cold end of a Seebeck device even under cloudy skies: that would allow a small amount of power generation day and night also, if so.
This looks plausible to me and and an astonishingly good thing if it works even a 1/10th as well as the researchers hope.
Sometimes the science is good before the marketing people get to it.
Rgds
Damon
http://m.earth.org.uk/
Yeah, but WHEN? When will we see this available for consumer use?
I see news stories every damn day about some amazing breakthrough in this field or that field, but fuck all if it ever seems to make it to market.
I must have seen 100 stories in the last few years about more efficient and less expensive solar cells, but where the fuck are they?
The same with medications and advances in medical technology....lots of news and hype and excitement but rarely does anything ever appear.
FFS, all I want is to be buried in a casket made of an advanced polymer plastic film that eliminates diabetes and has a 98% solar conversion efficiency rate, and that can autonomously pilot itself down I-5 during rush hour. Is that too fucking much to ask?? Oh, and the battery has to last for a full week without a charge.
Just cruising through this digital world at 33 1/3 rpm...
Mao's political method was to enter a village and kill every leader who didn't agree with him. Get a new set of leaders, kill every leader who didn't agree with him. Repeat until purified.
The words "nuance and subtlety" do not apply. His central committee was thugs and murderers like himself.
Just WTF are people being taught these days?
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Outer space is at ~3K/-270C: having that as your cold sink *day and night* is really quite significant.
Radiative cooling doesn't work that way: all that matters is your temperature. You don't radiate more into a cold area than a hot (a hot area sends more thermal radiation to warm you up, but that's orthogonal). It would be different if the atmosphere reflected IR, but that's not the case.
Socialism: a lie told by totalitarians and believed by fools.
But, can it cool a Beowulf Cluster?
-Unresolved symbol? Byte me!
Just WTF are people being taught these days?
Apparently they're not taught the difference between a real comment and trolling
lucm, indeed.
in order to sink heat you must have something to heat, and vacuum just ain't that.
If you can get heat into radiative form (which this gadget can) and it doesn't get reflected back at you, effectively, it is sunk.
Second - I don't suppose there is some kind of magic involved in this discover, that magically allows IR radiation to bypass the several kilometers of atmosphere you have before outer space.
It's called an absorption spectrum. In this case, specifically it's called the Infrared Atmospheric Window.
Someone had to do it.
This sounds almost like Maxwell's Demon -- which makes me very skeptical.
It doesn't work like that. Radiative heating/cooling works via exchange of IR. You're not just giving it up; everything you're radiating at is proportionally radiating back at you. So you cool the most when you're radiatively exchanging with something that's very cold. Aka, you want to be radiatively exchanging with the cosmic microwave background, not with low-altitude clouds. That's the whole point of radiating at low absorption frequencies in the atmosphere: so that you're exchanging with space, not with atmospheric air.
I'll never forget the last thing grandma said to me before she died: "What are you doing in here with that knife?!?"
No you couldn't embed them in glass, because the glass beads work by being resonate at a frequency that atmosphere is transparent to. The beads aren’t normal glass, they are transparent infra-red, most glass is rather opaque in infra-red. what you could do is apply it like a window tint, but I suspect it would have a lot of distortion and possibly an opalescent effect.
The film unsilvered is highly transparent to visible light, so the ideal application, would be to apply it to PV solar cells to help cool them and prolong their live span.
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