Scientist Creates Self-Filling Water Bottle • Hacker News Board

Re: Scientist Creates Self-Filling Water Bottle

#51

Post by ars » Thu, Nov 22, 2012, 9:57 AM UTC

ajuc wrote: post #50

ars wrote: post #34

Earlier quoted context omitted.

Any water you capture will just be sent back into the air later. Think of what you drink - all of it end up in the air or land again later.

The important thing is the speed of capturing and returning the water to the air, not only the fact that it will be eventually returned. When we change one or both of the speeds - the balance shifts, and the effective humidity of air changes to new stable value.

But there is a feedback loop - the faster you take the water, the slower you can get it.

And the more water is returned the faster it ends up in the air. My estimate from wind speeds is that everything will stabilize within 2 days.

i.e. taking water from the air will have no impact. See: http://news.ycombinator.com/item?id=4816580 where I expanded on the topic a bit.

Re: Scientist Creates Self-Filling Water Bottle

#52

Post by ars » Thu, Nov 22, 2012, 10:02 AM UTC

nickbarone wrote: post #49

ars wrote: post #32

Earlier quoted context omitted.

You won't get hyponatremia from overly "pure" or distilled water. The amount is water is utterly dwarfed by the amount in food. If there are pollutants in air they will be in the water, but it's not a actually a problem because, although they might be bad to breath, most air pollutants are harmless when eaten. Carbon (soot), Ozone, NOs, sulfur dioxide (smog), etc are harmless to eat.

Interesting. Are there any that are the other way around - dangerous when eaten, but not when inhaled? I'd imagine it'd have to do with the digestive ecosystem, if there were any that worked that way.

I don't know of any.

But if there were it would be something that requires acid or digestion to "activate". Or perhaps something that can't be absorbed without something the only exists in the gut.

Bacteria actually could do that. Inhaled they would rapidly die, but in the gut they could live (more food for them) and cause illness.

Also, the gut will absorb things faster than the lungs. So I could easily imagine a toxin that has little effect when inhaled (since it's absorbed too slow to cause damage) but causes trouble when eaten (everything is absorbed at once).

But I don't know of any specifically.

Re: Scientist Creates Self-Filling Water Bottle

#53

Post by lloeki » Thu, Nov 22, 2012, 10:54 AM UTC

Someone wrote: post #29

Background info: http://en.wikipedia.org/wiki/Air_well_(condenser) The device in India shown there produces 15 liters of water per square meter per year. The surface area of a bottle is, say, 500 square cm, or 1/20 of a square meter. That would produce about a liter in a year. http://www.iimahd.ernet.in/publications/data/2005-01-05gshar... talks of 0.042 liter per square meter per day, in extreme.y high humidity. Cle…

This instantly reminds me of the fictitious windtraps in Dune (mistakenly used as powerplants starting with the second game)

[0]: http://dune.wikia.com/wiki/Windtrap

Re: Scientist Creates Self-Filling Water Bottle

#54

Post by primitur » Thu, Nov 22, 2012, 3:06 PM UTC

Jabbles wrote: post #25

andrewcooke wrote: post #10

Earlier quoted context omitted.

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.

Not really. This volume of air has to make contact with the bottle, whatever the collecting area's shape. Imagine loosely fitting a tube around the neck of the collecting area. All the air has to pass through that tube.

Well, think of the most efficient collector of water (and sunshine) you can. Water bottles have to look like that, or at least .. have a spigot you can attach a bottle to ..

Re: Scientist Creates Self-Filling Water Bottle

#55

Post by primitur » Thu, Nov 22, 2012, 3:07 PM UTC

ggchappell wrote: post #36

If I might channel my inner grumpy-old-man for a moment: I find it curious that people who design nifty new devices are regularly referred to as "scientists". This is not science; it is engineering . Why not call it that?

Because the guys in this story are actually scientists, doing the discovery and research, as well as engineers .. and it is 'implied' that scientists can do engineering also, so I guess its Venn diagram time .. ?

Re: Scientist Creates Self-Filling Water Bottle

#56

Post by Someone » Thu, Nov 22, 2012, 6:39 PM UTC

novaleaf wrote: post #46

Someone wrote: post #29

Background info: http://en.wikipedia.org/wiki/Air_well_(condenser) The device in India shown there produces 15 liters of water per square meter per year. The surface area of a bottle is, say, 500 square cm, or 1/20 of a square meter. That would produce about a liter in a year. http://www.iimahd.ernet.in/publications/data/2005-01-05gshar... talks of 0.042 liter per square meter per day, in extreme.y high humidity. Cle…

if you read further down in the wikipedia article, it shows zibold's collector which produced about 0.9 liters/square-meter/day just pointing out that efficiency may be better than what you are estimating.

It may be, yes, but Wikipedia isn't convinced. Even further down, it states:

"Zibold's condenser had apparently performed reasonably well, but in fact his exact results are not at all clear, and it is possible that the collector was intercepting fog, which added significantly to the yield.[10] If Zibold's condenser worked at all, this was probably due to fact that a few stones near the surface of the mound were able to lose heat at night while being thermally isolated from the ground; however, it could never have produced the yield that Zibold envisaged"

That made me look for more recent data. That PDF from 2005 was the best I could find.