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A jacket that harvests drinking water from the air

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Re: A jacket that harvests drinking water from the air

#92
post #12
post #9

This sort of thing can't work as it would break basic laws of thermodynamics. Best case it's a dehumidifier with extra steps.

Why would it break the laws? Per the article it uses the heat from sunlight to do some of its work, it's not some kind of magic fabric.

The thermodynamic issue is not that there's not enough energy, it's that the heat output has nowhere to go.

Re: A jacket that harvests drinking water from the air

#95
Not specifically about drinking water or jackets, but I've often wondered why air-conditioning condensate is plumbed into the sewer instead of someplace useful. An A/C is a water-from-air device, and they run in much of the year in most homes in the southern US.

The typical design that I've seen plumbs the main condensate drain into the sewer, and usually has an overflow that dumps somewhere harmless if the main line clogs. (like out of the ceiling over the bathtub or out of an exterior wall in a visible location, so you can see it and fix it)

The few times I've seen the overflow, it's been quite a fair amount of water. Certainly enough to help with garden irrigation, if nothing else.

Re: A jacket that harvests drinking water from the air

#97
post #95

Not specifically about drinking water or jackets, but I've often wondered why air-conditioning condensate is plumbed into the sewer instead of someplace useful. An A/C is a water-from-air device, and they run in much of the year in most homes in the southern US. The typical design that I've seen plumbs the main condensate drain into the sewer, and usually has an overflow that dumps somewhere harmless if the main line…

It's very common to plumb into grey-water systems where they're installed, because you're right, it's perfectly useful water. Plumbing it into some kind of cistern like a rain catchment system would also make sense.

Re: A jacket that harvests drinking water from the air

#98
post #46

Earlier quoted context omitted.

Both devices handwave on how the cooling required to condense the water occurs.

I believe this uses absorption; not cooling [condensation].

Abortion release the same amount of heat than condensation. So you can cool the material before and get condensation or absorb the water and cool the material later.

Sweating keeps you cool, absorbing the sweat will cancel the cooling effect and you will overheat and may die.

Re: A jacket that harvests drinking water from the air

#99

Nearly all passive water-from-air devices described in articles are based on false claims. Peltier-based, desiccant/absorption/adsorption based, etc. All end up not working, or not existing. This has been common for ~10 years. Which category does this fall into?: - Fraud - Incompetence / misunderstanding that wasn't cleared up prior to publishing an article - Neither; this works as expected

The claim on this one is that the textile is supposed to be substantially better than extant desiccants:

> Compared with conventional water-harvesting materials, the textile showed a three- to 10-fold improvement at scale.

Technology Connections has a video on this general technique with a demo from a typical commercially available unit [0]

The "in a jacket" angle is novel... there's no blower. Even though this desiccant may be "3 to 10" times more effective, the passive nature is going to presumably make the rate of extraction quite poor compared to units with a blower to keep moist air moving over the substance.

Based on the wording, this improvement is due to some kind of gradient where moisture is collected on the surface of the jacket/textile, then channeled towards some internal chamber where the desiccant is constantly being heated to extract moisture - without the need to heat the exposed textile to extract water from that portion.

Of course increasing the rate of collection doesn't matter much on its own! You can't drink a damp textile. What takes energy is the removal of the moisture from the desiccant - and how much energy that requires is a detail suspiciously absent from the article (presumably because the efficiency isn't improved versus other desiccants).

So personally, I have trouble imagining this is as efficient as the blower-based commercial units, which are... far less efficient than "normal" compression cycle dehumidifiers (in the above video, real world testing shows the "normal" dehumidifier is 5 times more efficient than the desiccant one).

[0] https://www.youtube.com/watch?v=JzClLWL-Eys

Re: A jacket that harvests drinking water from the air

#100

Nearly all passive water-from-air devices described in articles are based on false claims. Peltier-based, desiccant/absorption/adsorption based, etc. All end up not working, or not existing. This has been common for ~10 years. Which category does this fall into?: - Fraud - Incompetence / misunderstanding that wasn't cleared up prior to publishing an article - Neither; this works as expected

The claim on this one is that the textile is supposed to be substantially better than extant desiccants: > Compared with conventional water-harvesting materials, the textile showed a three- to 10-fold improvement at scale. Technology Connections has a video on this general technique with a demo from a typical commercially available unit [0] The "in a jacket" angle is novel... there's no blower. Even though this desic…

Damn... I was hoping we'd finally get Stillsuits.

https://dune.fandom.com/wiki/Stillsuit

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