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Scientist Creates Self-Filling Water Bottle

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Re: Scientist Creates Self-Filling Water Bottle

#2
This sounds nifty, but what I'd love to know is, what's the rate of filling, for an apparatus that's small enough to be roughly bottle-sized? Obviously many of the technical details (battery size, etc) are still being worked out, but I'm betting that rate of condensation is already known---and it's an important constraint.

Re: Scientist Creates Self-Filling Water Bottle

#3
post #2

This sounds nifty, but what I'd love to know is, what's the rate of filling, for an apparatus that's small enough to be roughly bottle-sized? Obviously many of the technical details (battery size, etc) are still being worked out, but I'm betting that rate of condensation is already known---and it's an important constraint.

Yeah, they talk about using it for runners but how quickly does it fill? Would it require a full marathon length to fill a single water bottle? It may still be practical even if that's the case. I'd like to know more.

Re: Scientist Creates Self-Filling Water Bottle

#4
Hmm air can carry a few grams of water per kG of air [1] and 1kG of water is one liter, so if you can pull 1g of water out of each kG of air you need 1,000 kG of air. Stole this from wikianswers: "Each mole has a volume of 22.4 liters and a mass of 28.97g/mol at STP, therefore a cubic meter of air is 1.293 kg at 0o Celsius on the coast. An average mass of 1.2kg per m3 at room temperature and standard pressure is often used as a rule of thumb." so that would suggest about a thousand cubic meters of air flowing past this bottle's extractor area to get one liter of water out of the air.

No idea how long that would take though.

[1] http://en.wikipedia.org/wiki/File:Relative_Humidity.png

Re: Scientist Creates Self-Filling Water Bottle

#5
Info I've found so far on rate of water capture:

(MIT, 2011) "In some field tests, fog harvesters have captured one liter of water (roughly a quart) per one square meter of mesh, per day. Chhatre and his colleagues are conducting laboratory tests to improve the water collection ability of existing meshes."

http://web.mit.edu/newsoffice/2011/fog-harvesting-0421.html

Re: Scientist Creates Self-Filling Water Bottle

#6
This may be a stupid question, but if the device requires power in order to move air over the water-collecting surface, would it work without power if it were outside in a breeze? Or is there something about the air flow in terms of its characteristics or location in/on the device that requires a manufactured flow?

Re: Scientist Creates Self-Filling Water Bottle

#7
post #4

Hmm air can carry a few grams of water per kG of air [1] and 1kG of water is one liter, so if you can pull 1g of water out of each kG of air you need 1,000 kG of air. Stole this from wikianswers: "Each mole has a volume of 22.4 liters and a mass of 28.97g/mol at STP, therefore a cubic meter of air is 1.293 kg at 0o Celsius on the coast. An average mass of 1.2kg per m3 at room temperature and standard pressure is ofte…

Good work. I imagine 1g/1m^3 is roughly what you'd expect - especially in a desert.

If the extractor area is the size of the bottle's cap (2cm x 2cm = 4e-4m^2) then to get a litre of water (1e3 m^3 air) requires 2.5e6m of air to flow past it - If you want it full in a day that's 30m/s... hmmm... doesn't seem likely.

However if the size of the extractor area is as large as the bottle (say 10cm x 10cm = 1e-2m^2) then a 1 m/s wind may do it.

Based on this I'm not confident in the "marathon runner" claim, but I'm sure techniques for extracting water from wind have been used before, but improvements could be made.

Scaling up the technology obviously increases the viability, yielding something like this: http://www.geek.com/articles/geek-cetera/prototype-wind-turb...

Re: Scientist Creates Self-Filling Water Bottle

#8
> Sorenson notes there is more than three quadrillion gallons of water in the air, which is essentially a massive untapped resource.

For what it's worth, air with low humidity can be pretty damaging. Lots of materials would become excessively brittle at very low humidities, causing them to break easily. This interesting white paper [1] suggests that, for most materials, the optimal humidity is between 40-60%.

Still, this is a very cool concept.

[1] http://www.descoenergy.com/pdf/Humidity%20How%20it%20affects...

Re: Scientist Creates Self-Filling Water Bottle

#10
post #7
post #4

Hmm air can carry a few grams of water per kG of air [1] and 1kG of water is one liter, so if you can pull 1g of water out of each kG of air you need 1,000 kG of air. Stole this from wikianswers: "Each mole has a volume of 22.4 liters and a mass of 28.97g/mol at STP, therefore a cubic meter of air is 1.293 kg at 0o Celsius on the coast. An average mass of 1.2kg per m3 at room temperature and standard pressure is ofte…

Good work. I imagine 1g/1m^3 is roughly what you'd expect - especially in a desert. If the extractor area is the size of the bottle's cap (2cm x 2cm = 4e-4m^2) then to get a litre of water (1e3 m^3 air) requires 2.5e6m of air to flow past it - If you want it full in a day that's 30m/s... hmmm... doesn't seem likely. However if the size of the extractor area is as large as the bottle (say 10cm x 10cm = 1e-2m^2) then a…

i think you're confusing collecting area with airflow cross-section. they're completely different things, unless somehow the air is blowing through the side of the (solid) bottle.
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