
How to cool your apartment for free: DIY aircon uses old plastic bottles - palerdot
http://www.dailymail.co.uk/sciencetech/article-3635710/How-cool-apartment-free-Electricity-free-DIY-aircon-uses-old-plastic-bottles-used-used-25-000-Indian-homes.html
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grizzles
This probably work by admitting air (as a window would) and denying solar
radiation (as a window would not).

Other factors to consider include the optics associated with light passing
through the bottle and how focused air might affect people's perception of
temperature (wind chill).

The bottles might reflect enough light away from the structure to have a
discernible effect.

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sidcypher
I suppose if the air is compressed by the bottles, the inlet is on the outer
side of the cardboard membrane and discharge is on the inner side.

Excessive heat is then released into the bottle and stored in the plastic
until it radiates away - mosly by the large, voluminous bottle part.

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kazinator
According to the DIY build instructions, the bottles are cut in half, so they
provide horn-like flares, open on both ends.

(Not that this adds any plausibility.)

The technical claim is summarized in this image:

[http://i.dailymail.co.uk/i/pix/2016/06/10/18/3521DBE60000057...](http://i.dailymail.co.uk/i/pix/2016/06/10/18/3521DBE600000578-3635710-image-a-25_1465578468761.jpg)

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Nomentatus
Compressing, then expanding air, so this is the same principle as a fridge
uses with freon (ok, not freon any more), on a much gentler scale, with much-
lesser-but-still-useful results.

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GhostVII
And it removes the heat through... magic? All this does is redirect the air
into your house, and compress it a little (causing it to heat up very
slightly). Sure, it will feel cooler because you have air circulation, but
opening a window has the same effect.

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dTal
I can see a _theoretical_ way it could work - the air enters the wide end,
compresses as the bottle narrows, heats up above ambient temperature due to
the compression, _dumps its excess heat to the plastic of the bottle_ , and
then expands back to ambient pressure as it exits the nozzle _thus cooling
below ambient temperature_ \- the bottle then radiates away the heat, either
mostly outside through virtue of the shape of bottle, or just equally outwards
and inwards which still results in _some_ cooling effect.

I find it very hard to believe that you'd have any appreciable compression
without gale force winds though. And you don't get to "accumulate" minute
amounts of cooling either - the temperature of the "chilled" air coming in is
the coldest it will get.

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throwaway848483
I think you don't need to invoke the heat exchange with the bottle to be
relevant. I also believe that you get to accumulate it but there is a negative
feedback due to the temperature gradient which prevent you to reach a high
temperature difference.

For what it's worth (I'm not a physicist), here is my mental model of how I
think it works. We are working at equilibrium we don't care about the
macroscopic flow of air as it balances out. When the wind blows in the bottle
it creates a more ordered arrangement of the air molecules (imagine laminar or
vortex) at the neck (zone of low entropy). The internal energy will diffuse
toward the region of more order (Second principle). So internal energy of the
inside air flows towards the interface where it then diffuse into the nearby
flow and get carried away by the wind.

As soon as there is a temperature difference between the inside air and
outside air, traditional heat exchanges also occurs at the interface which has
an opposite effect.

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roryisok
Euch. Daily mail - No thanks.

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ebcode
Don't shoot the messenger.

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roryisok
In this case the messenger is a loud-mouthed racist bigot, and I wouldn't
trust him to tell me the time.

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eveningcoffee
Can somebody explain where does the heat go in such process?

Also please note that while the difference between two thermometer readings is
10C, drop they claim is actually 5C.

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Markoff
plastic bottles are free? that seem like good country to set up recycling
plant

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aszantu
Thank you so much!

