The best things may come by accident, which is where it sometimes just starts to get good.
But what are the difference in odds for someone who is constantly experimenting versus someone who experiments not at all?
Regardless of what you really set out to accomplish to begin with.
And which has the momentum to continue experimenting, even in the case of a major pivot?
Looks like they really have hit the sweet spot and it's a bit like creating molecular sieves which are tuned to release the collected moisture without excess energy.
Could also be harvesting a little ambient energy and working to "zone refine" the atmospheric fluid.
As a similar comment note, it's like a high tech Dehumidifier bag. https://www.amazon.com/Wisesorb-Moisture-Eliminator-Fragranc... The bags have Calcium Chloride and absorb water from unsaturated air and make small drops of water. It's obvious that they get depleted, and to use them again you must buy a new one or boil all the water to get the crystals again.
In this new material, the droplets are attached to the material. To remove them you must use energy. They don't just drop to a bucket bellow the device magically. You can't use it to "harvest" water without energy. You can sweep the droplets with a paper towel, but now to remove the water from the paper towel you need energy.
> With a material that could potentially defy the laws of physics in their hands
This does not break the laws of physics. It would be nice that the PR department of the universities get a short course explaining that if they believe the laws of physics are broken, then they must double check with the authors and then triple check with another independent experts. Tech journalist should take the same course.
Note that the bad sentence and the misleading title is from the university https://blog.seas.upenn.edu/penn-engineers-discover-a-new-cl...
Like diplomats, they're sent abroad to lie for their university, and the university president cries all the way to the bank for the sins of his hirelings.
If you want science, read journals. If you want to see who is likely to get more money, read university PR releases.
Even in this case -- "defying the laws of physics" is sensationalist narrative manufacturing.
The real claim is actually more moderate, and the research is not really close to commercial yet.
You're correct in that: (1) it doesn't break the law of physics; (2) to remove the droplets, you still need energy. But it sounds like if the droplets are moving to the surface, the energy needed to release the droplets could be far lower than most active dehumidification methods (e.g. Peltier junctions).
[1] Thirsty Hippos -- which are very effective in small spaces.
https://www.amazon.sg/Thirsty-Hippo-Dehumidifier-Moisture-Ab...
Basically a supercharged silica gel.
It's interesting, but without the details (and with a lot of PR speak) I'm skeptical as hell about this in practice.
This is a good time to note that I see one of these articles ~once every two years, for the past 10 years. I haven't observed one make it beyond the initial discovery phase.
it's not estrogen where you would expect breast growth (and can't count on any particular changes to sexual function anyway), it's inhibiting conversion of testosterone to dihydrotestosterone which could have that effect, much like you could spontaneously develop gynecomastia without intentionally fiddling with your hormone balance. calling it unsolved sounds a lot like calling the very many conditions with medications that have more likely and worse side effects equally unsolved.
Actually, it is. Reducing DHT levels causes the body to elevate both testosterone and œstrogen levels, via homeostasis. But yeah, it's not a direct effect, and if it's a problem you can twiddle further to make it go away. (You could even do that pre-emptively, though you normally get days and days of warning before breast development actually starts, so I'd advocate the "wait and see" approach.)
> what else would you expect the side effect profile of something mediating the effects of a potent androgen on the body to look like?
Oh, almost forgot: any messing around with sex hormone levels puts you at risk of depression. That's big side effect #3 (though again, many people don't even notice it).
No breasts. And no other issues.
My Gmail username is the same as my HN username if you prefer to answer in private. Thanks
Finasteride is less potent, but is normally recommended for cis men; not sure why. Theoretically, I'd expect dutasteride to be the better medication (and https://doi.org/10.2147/CIA.S192435 bears that out) if you can get hold of it.
I'd have thought finasteride and dutasteride weren't safe to take if there's a chance of you getting someone pregnant, but https://www.nhs.uk/medicines/finasteride/fertility-and-pregn... says it's fine, actually. https://doi.org/10.4103/0974-1208.86093 goes into more detail on that. (I'm not aware of any other impacts on fœtal development, only the intersex condition mentioned in that article – note that the backdoor pathway described in https://doi.org/10.1002/dvdy.23892 also requires the 5α-reductase enzyme –, but I'd still advise caution.)
[1] https://www.amazon.com/Ultrasonic-Humidifiers/s?k=Ultrasonic...
> Sure, why not?
https://dynomight.net/air/ estimates that using an ultrasonic humidifier for one night shortens your life by 50 minutes. Getting rid of any ultrasonic humidifiers is his top tip to extend your life cheaply.
Dedicated post on them: https://dynomight.net/humidifiers/
https://www.cambridge-news.co.uk/news/cambridge-news/cyclist...
https://www.cyclingweekly.com/news/latest-news/driver-carele...
https://veronews.com/2022/08/06/no-jail-time-for-driver-of-c...
many other examples exist
I'm aware of the hundred thousand words spent justifying the idea. I will consider reading them once I've been convinced to ignore the result of this trivial - and I do use the following phrase with careful consideration aforethought - sanity check. You'll more likely give the goalpost another kick, though, I suspect.
From the articles:
> A good heuristic is that an increase of 33.3 PM2.5 μg/m³ costs around 1 disability-adjusted life year. Correia et al. (2013) estimated something close to this from different counties in the US, and more recent data from many different countries confirm this. The most polluted cities in the world have levels around 100 PM2.5 μg/m³.
> When inhaled during an 8-hr exposure time, and depending on mineral water quality, humidifier aerosols can deposit up to 100s of μg minerals in the human child respiratory tract and 3–4.5 times more μg of minerals in human adult respiratory tract. > (Yao et al., 2020)
The amount of particles people breathe in in a night of worst case ultrasonic humidifier use is 8x more than the particle level in the air of the most polluted cities in the world.
We could talk about this utter misrepresentation of https://pubmed.ncbi.nlm.nih.gov/23211349/ but why? You haven't read it. You won't. At most you will follow the examples you cite in prooftexting from it like a Southern Baptist inveighing against homosexuality. Kindly find someone else whose time so to waste.
I get it, you're desperate to appear smart and superior, but arguing that lamely isn't doing it. Of course I'm not going to read your link, try and guess what misrepresentations you're coming up with, make some argument about them and their context in the wider post, only for you to ignore it and post some more nonsense in response. Or engage with you further.
You could not by now have done more to prove my point that you aren't bothering to actually know anything about what you present yourself able knowledgeably to discuss. Thanks for that. Feel free to embarrass yourself with further flagrant scientism if you like. Enjoy your day.
> You've attributed a causal claim
> your sources
> your argument
> what you present yourself able knowledgeably to discuss.
No, no, no, nope and no. None of these accusations are correct. Feel free to embarrass yourself with lacking basic reading and quoting comprehension; I am not the author of the Dynomight article.
Who chose to bring it up? Who chose to insist on its baseless conclusions? Who then demonstrated the inability to defend those conclusions for their total lack of substance?
No, you don't get to represent the source you chose as accurate only until that fails to go your way, and then turn around and try to disclaim it. The embarrassment you now feel is amply earned.
This is what it feels like to have failed to evaluate your sources, argued strenuously in support of total nonsense, and thus made a complete and negligent fool of yourself. You should draw a lesson from that for next time you consider starting a conversation like this one.
You won't; you are too deeply in love with the idea of yourself as a clever person, and you won't dismiss the offense I gave to consider the substance of my remarks. This is a level of predictability I would not be comfortable with in myself. But that, too, is no problem of mine.
You've tried moving the goalposts again, had you noticed? If I let you get away with it, we wouldn't be talking about the factual inaccuracies, facial implausibilities, and ignorant misrepresentations of research, in the source you so uncritically chose, at all...
Don't complicate
"dew" was a funny typo there :)
I'd assume if the amount of energy required to collect the water is low then we're looking at something interesting.
For context, that amount of heat is five times the amount needed to heat 1kg of liquid water from 0° to 100°C (without thawing or boiling it). So it's not in any way a trivial amount.
From figure 4 (& backed up by simulation fig 3E) it looks like stuff begins to happen only at 97% relative humidity & after a few minutes (at micrometer scale)
https://www.science.org/doi/10.1126/sciadv.adu8349
Granted, it's almost easy enough to try at home: melt some poly gloves into "freeze dried" silica powder
Also, they do a really good job of making it sound like it violates thermodynamics. Since it doesn't, and dehumidifiers already do a good job of getting water out of air for the energy price you have to pay, there has to be some other selling point. Right? But I'm not sure I see it.
Windtraps [0].
I'm not aware of any passive, solid state dehumidifiers which are not chemical, which condense water to a chemically loaded solution, which what a Windtrap is not.
So, even though it may not be 100% clear how from their description, their device is nothing but a novel way of making a dehumidifier that needs some kind of active component - perhaps the AC that is keeping the temperature steady in their experiment (since water condensation generates large amounts of heat, it's likely that, without the AC, temperature would rise and their water droplets would evaporate right back).
No, there's a way without running afoul of thermodynamics. You need to bleed the heat to a cooler surface efficiently, and you can do it without any external power.
You can use heat pipes to effectively wick away heat to a heat sink, like the Earth itself. Similar systems exists for cooling and heating, which uses buried pipes to extract or dump heat to the Earth's crust. You can sink the heat similarly without any external power (sans wind to push air through the material).
In the Windtrap example, the other side of the opening is a deep well basically. Cooler than outside world. The rocks sink the heat probably, too. Sı it's possible to create self-sustaining process without external electricity. Yes, an heat-pipe is not solid-state per se, but it's insulated and works on the principle of heat difference only.
> their device is nothing but a novel way of making a dehumidifier that needs some kind of active component...
No, their paper say that they forced air through it and it worked on a temperature differential. Maybe a compressor or Peltier device can acclerate the process, sure, but sinking the heat to the earth and blowing air through it will work equally well.
Have a friend who designs heat-pipes for space applications. That things are way faster than we see on computer applications, but equally more expensive.
> Before they understood what was happening, the researchers first thought that water was simply condensing onto the surface of the material due to an artifact of their experimental setup, such as a temperature gradient in the lab. To rule that out, they increased the thickness of the material to see if the amount of water collected on the surface would change.
There's a temperature gradient in their lab setup. i.e. one side of the material is cooler than the other side. This is where I extrapolated that you can increase the performance of the material by bleeding the heat into the Earth.
I was trying to figure out if your comment was informed.
They do a terrible job. Condensate dehumidifiers are as expensive to run as an AC, produce unwanted heat, and are noisy. Dessicant dehumidifiers are even less energy-efficient.
If there's a way to extract moisture from the air with less energy and less noise, that would be huge.
That sure seems to imply that there's no need for a noisy and power hungry compressor.
It takes energy to condense water, so where does it get it? If it isn't external, it runs out.
They’re claiming they have a material that will do it at higher temperatures. Assuming such a material gets hotter as it works, there’s no thermodynamics problem here.
That's ok, but the amount of water you get is fixed - the process can't continue. You install the device into your room, it condenses 1L of water as droplets on its surface (or, more likely 1ml of water), and it's now done, that's all the water it's going to remove/produce, if this is the right explanation. It would be perfectly equivalent to bringing in a cold slab of metal from your fridge into your room - it will condense some water as it gets hotter, and it will eventually get as warm as the room and stop condensing anymore water, forever.
Conversely, if the process were continuous (say, as long as you remove the condensed droplets, new droplets form), as they seem to claim, that would very likely violate thermodynamics again.
https://en.wikipedia.org/wiki/Air_well_(condenser)
Check out the passive section of the above
Thousands of years old, I think.
[0] https://www.bbc.com/future/article/20210810-the-ancient-pers...
Less noise: I agree, but you still need some air flow so the corners of the room that are far away also get dehumidified. Perhaps a slow fan in enough, and when you run them slowly they are quieter.
Less energy: It's not clear that this uses less total energy. It's easier to imagine what is happening if you compare it to a high tech Dehumidifier Bag. https://www.amazon.com/Wisesorb-Moisture-Eliminator-Fragranc... But instead of sending the drops down, they get attached to the device. You can use it only once unplugged. Then you have to buy a new one or use energy to extract the water (like boiling the water of the dehumidifier bad until you get the crystals again). It's not clear if building a new copy of this is cheaper than building some new calcium chloride salts, and/or if regenerating the new device is cheaper than regenerating the calcium chloride salts (that is usually not done).
Obligatory Technology Connections video on the topic: https://www.youtube.com/watch?v=j_QfX0SYCE8
That said, his demo is not under typical operating conditions in that a dehumidifier is normally expected to actually be able to catch up and reduce humidity in the room, while his demo ensures that the humidity levels stay high throughout the hour. So it's likely that under normal operating conditions the mechanism's proportion of the waste heat is higher than it is in his demo.
Nope. It's almost all (>80%) latent heat. I believe, the theoretical limit is around 90% for typical room temperatures.
A dehumidifier movies heat from one side to another using electricity to do the work. One side gets cold so the water can condense on it, while the other side gets hot from extracting the heat from the cold side. Heat is still generated from this process even if there are 0 water molecules in the air and no water is collected. The water does not create the heat, the electricity does.
I don't think there has to be any heat involved with collecting water molecules in the air into a larger volume of water, depending on the process used.
> I don't think there has to be any heat involved with collecting water molecules in the air into a larger volume of water, depending on the process used.
The only other option is to increase the pressure in the room or in a space within the room, which this material pretty clearly isn't doing.
For the water to condense, there must be heat given off, unless I’m fundamentally misremembering my high school physics class.
at least for water solid to liquid
Possibly this doesn't happen if the condensation happens in a capillary (there is some funkyness related to energy levels), but then it must stay trapped there.
I vote we write to our legislators to update the laws of thermodynamics to enable this. Typically I would agree we should leave well enough alone, but in this case it seems like the benefits outweigh the costs.
In reality, you would need to convene an international consortium to approve to the change, and the Chinese wouldn't sign on unless we agree to a temporary suspension of Newton's third law.
I say we skip that process, test it in a lab somewhere in rural midwest where nobody lives, and see if gravity starts changing or whatever. As long as cows don't start to float in a 3 mile radius within 4-5 hours, that's probably good enough validation to move forward with changing thermodynamic legislation.
[edit] we should also probably make sure the boiling point of water stays the same
From the paper [1]:
Remarkably, when these amphiphilic nanoporous PINFs are exposed to high yet subsaturating conditions [i.e., relative humidity (RH) < 100%], macroscopic water droplets appear spontaneously on the film surfaces without the need for cooling, as illustrated in Fig. 1C and shown in Fig. 1D.
Sorry, I don't know the correct physics lingo. Heat of enthalpy or formation or whatever.
If so, it could be that the water vapor coming from the eggs no longer mixing with the hot gases coming from the flame around the pan, allowing it to drop below the dew temp (?) and allowing it to condense right above the pan. IOW the water vapor is always there, you just can't see it until it is able to condense in lower ambient temps.
The other commenter that wonders if it's a gas stove might be onto something.
First you get water, and as a result material heats up a little bit, then it can cool down passively back to ambient.
Thanks! there were a few comments there and we'll merge them hither.
Like, not even ironically.
I know this isn't reddit and all, but, well..
We already have substances that remove water from air. In those the water becomes absorbed. This seems to work on a similar principle. The real difference is the water doesn’t stay absorbed.
I'm fairly certain they've created some form of a Brownian Ratchet: https://en.wikipedia.org/wiki/Brownian_ratchet
People love to claim there's no external energy source, but then when you look closely, you'll find a hot-cold differential, and then you need external energy to maintain that differential. I'd put a large sum of money that either the material is colder than the ambient environment or the incoming moisture is warmer than the ambient environment. It might even be a differential within their material, and the lab lights are warming one side! There's a lot of passive devices that rely on the hot-cold cycle of day and night, that still counts as energy input from the sun.
The article even mentions they tried to rule out a thermal gradient by increasing the thickness of the material, I'm not sure I understand why that would rule it out... the gradient would still exist.
I hate this, because if they aren't intentionally supplying energy, it's probably really efficient (assuming they aren't taking samples out of the freezer or something) so it's still a big deal and important but apparently we have to claim something is a perpetual motion machine to get attention among the public.
I feel that it disserves science in the end, the belief that some magic material is going to break the second law of thermodynamics is closer to alchemy than chemistry.
"All measurements were performed at 20° ± 0.2°C maintained by an air circulation system unless otherwise noted. The temperature of the films was controlled using a heating/cooling unit (THMS350V, Linkam Scientific Instruments, Salfords, UK) when necessary."
So the latent heat is conducted away by the cooling apparatus, it's just not explicitly stated, to sound more sensational.
My understanding of it now is that since it can work at a higher temperature in an environment where the ambient temperature is low enough the latent heat can be passively radiated away. Even if using an active heat pump the higher temperatures would allow for a more efficient process. A closed system would eventually reach an equilibrium but there is no need to maintain a closed system.
Is there a corollary to Betteridge's Law that says that popular science journalism will always overatate the result?
In theory, if that makes it hotter than ambient air in the process, that would be a good thing - usually we have to cool things down below ambient air to get moisture out.
Not a good thing if you want to measure maximum moisture extraction, but cooling something to ambient temperatures is a much easier task.
It could still be a useful material, but the science would be bad.
> And no, this is not something permitted by the second law of thermodynamics.
If that's true we just need to balance energy, which the cooler does.
My other comment here (and and a reply to a similar question) has more detail [1], but in short: this is true for capillaries and pores, it is not true for "collectable" droplets on a flat surface.
Devices like that would be essential during 'wet bulb' days where the temperature and water content of the air created dangerous conditions for people. A passive device that takes no energy and just sucks water out of the air? Could be a lifesaver.
The researchers also noted that the water that was expressed to the surface of the material did not evaporate (as one would expect). There some interesting speculation as to why that is. It wasn't clear whether or not the water would move across the nano-structure if it was affected by gravity (aka dripping) but I can imagine several ways to transport it off the surface so I'm sure the researchers can too.
[1] The description in the paper is that capillary action forces the vapor into the interior of the structure where it collapses into liquid.
This is basic thermodynamics, you can do however much hydrophobic/hydrophilic nanomaterials, but you won't get condensation unless you somehow conduct away the latent heat. This can be done by storing energy in the material itself (that's how desiccants work), or by providing a temperature gradient (a cooler).
> This can be done by storing energy in the material itself (that's how desiccants work)
This is exactly where the energy goes. From the paper (in it's Materials and Methods section) -- All measurements were performed at 20° ± 0.2°C maintained by an air circulation system unless otherwise noted. The temperature of the films was controlled using a heating/cooling unit (THMS350V, Linkam Scientific Instruments, Salfords, UK) when necessary.
So the hypothesis is that the heat in the water vapor goes into the nano-pore material, which in their experiment they were actively maintaining at 20 degrees C. So yes, they are actively removing the heat created by the phase change.
One difference with desiccants is that once they are saturated you have to restore them through heating them up, but this stuff doesn't have that property. And while it may sound like nonsense it was reproduced in another lab[1].
Apparently capillary condensation is a thing, its the popping out of the liquid water that was unexpected.
[1] With a material that could potentially defy the laws of physics on their hands, Lee and Patel sent their design off to a collaborator to see if their results were replicable.
There is no cube. The droplet's are attached strongly to the surface.
If the droplets drop to a cube, you can replace the cube with a cotton mat and let the water evaporate and get a low temperature mat. And then use the difference of temperature to generate electricity https://en.wikipedia.org/wiki/Thermoelectric_generator and turn on a lamp. And now you are breaking the second law of thermodynamics.
Consider a typical unplugged dehumidifier with Calcium Chloride. It generates water that drops to a cube, but it's salt water that evaporates less than fresh water, so you can't do the trick.
If you use silica gel, the water is trapped inside the material, so there is no cube.
With this new material the droplets are on the surface, but they refuse to fall down.
With an AC you get a cube full fresh water, but it obviously work only while plugged, so there is no magic.
> And while it may sound like nonsense it was reproduced in another lab [1].
They reproduced the visible droplets in the surface of the material. In neither lab they had a cube filing process. The sentence you quoted in [1] is very misleading.
You coat a piece of aluminum with nano-pore material and hang it vertically. Air flows over it and droplets appear on its surface (based on the paper). You also hang a frame of vertical wires (unenergized just small diameter wires, kind of like a screen but without the horizontal members) in front of the sheet by 1/2 the droplet's diameter. The wires don't touch the surface, they are suspended 1/2 droplet away.
Now when a droplet forms, it grows and intersects the wire (which is not hydrophobic) Surface tension puts the droplet around the wire and it slides down to the bottom of the wire frame, impacting any other droplets that had formed below it.
The resulting liquid water drops off the bottom of the wire frame into a catch pan below.
If one of these assemblies generates net water production from RH 70% air then an array of then would generate more water.
What am I missing?
1. Have the drops fall on some surface and let them evaporate. This can happen because the relative humidity is below 100%.
2. This surface will get cooled by the evaporation.
3. Now use that temperature gradient to get free energy!
The new material is very hydrophilic, so the water prefer to be attached to it than been vapor.
If the wire is even more hydrophilic then the droplets will jump and collect around the wires, but they will be so attached that they will not fall down from the lower extreme of the wires.
If the wires are not so hydrophilic, the water will prefer to keep attached to the surface, or even the droplets will be smaller to avoid the wires and the collection will stop earlier.
Tweaking smartly the hydrophilic values and separations between the wires and the separation with the surface you may get interesting capillarity effect, but the water will be trapped again.
Anyway, it's difficult to look at all the details, but at the end of the day "The second law of thermodynamics. It's now trivially easy to create a free energy:"
It sounds good on paper because everybody knows that water can travel up a wick. But of course, if the end of the wick in the upper reservoir is submerged in the water, then water will just as happily travel _down_ the wick. And if the end of the wick is in free air, then water will not drip from it because the same capillary forces prevent it.
1. Drops fall from the sky
2. They collect and flow down a river
3. We use that river to generate hydroelectric power to get free energy!
Water vapor, in air, has both thermal and potential energy that under the right conditions can be converted into a more useful form. We agree on that yes?
In case of hydroelectric power, there's a temperature gradient, driven by the Sun. Water evaporates in higher temperatures, radiates the heat into space, and falls out as rain.
"Water evaporates in higher temperatures, radiates the heat into space, and falls out as rain."
The paper says, "Water vapor in the nano-pores radiates its heat into the material and comes out to the surface as liquid water."
So you don't believe that the researchers experiment did what they say it did?
That's fine, typically in science you go and see if you can reproduce it.
So you don't believe that the researchers correctly described what was going on when it did what it did?
That's fine, typically in science you go and propose a way to falsify their hypothesis and test that.
My point was simply, if the researchers were presumptively accurate in their understanding (that's the principle of giving them the benefit of the doubt), then it would imply their material would pull liquid water out of the air below the temperature and conditions in which it would normally precipitate out.
They go to some length in their exposition to describe how they think it does that and where the energy comes from and where it goes. But if you don't believe them, then sure.
Then the _material_ is a store of energy. Once it's exhausted, the condensation will stop.
> So you don't believe that the researchers correctly described what was going on when it did what it did?
The article is very low-quality. They must understand that their work implies the conservation law violations, so there must be some unaccounted source of energy. But they have not attempted to find it.
And it can be as simple as energy from the moving air. Or maybe an electrostatic charge, or something similar.
Once the energy source is identified, they should have calculated the efficiency of their setup, compared to regular dehumidifiers.
> Then the _material_ is a store of energy. Once it's exhausted, the condensation will stop.
The paper points out that the sample was surface that maintains a particular temperature (20 degrees C in this case). The water condenses, the material heats up, the thing its sitting on removes that excess heat to maintain the temperature. No violation of CoE or TD.
Without that temperature controller, the material would presumably continue to store the heat, which would make it hotter than the ambient temperature. By how much is, as you point out, something to be characterized.
Thermodynamics says that the heat will equalize, so that excess heat will conduct to the air around it (it's not in a vacuum so it doesn't have to radiate it). That will lower the temperature of the material which will then condense more water and heat up again. My original thought was you could enhance that conduction by putting a heatsink on one side of the material.
The paper states that inside the pores they have managed to create a space that changes the parameters around the vapor carrying capacity of the air which results in the water condensing even though it would not have condensed outside those pores. Then they go on to describe how the effects of hydrophillic and hydrophobic materials, used in conjunction, create spaces near the molecular limit of water molecules and how the forces acting on that water might result in it condensing. When the vapor does condense, the heat goes somewhere, and they assume its going into the material (reasonable assumption in my opinion) and that their temperature controlled platform is then removing it. I found the description of how that water expresses to the surface a bit more "hand wavy" but that they observed liquid water on the surface, and that it is somehow coming from the material they created, seems reasonably well supported.
I think for the purposes of this discussion we're done. I really do appreciate that you are skeptical and feel that some of the more well tested laws of physics are being violated :-). Since we can only go on what they wrote up, I did make the presumption that they too know the laws of physics and have a good faith belief that they are not being violated either. It is one of the things I look for in papers that talk about things like this. Also the journal where they published their paper, Science Advances, is a refereed journal so I would presume that the reviewers were also satisfied they weren't violating any well known laws of physics. Doesn't mean that you should believe what they say, just that it's not obviously wrong.
> When water droplets reach a certain size, the system reaches a steady state. As the volume of voids decreases with increasing ϕPE, the growth and coalescence of water droplets are slowed down.
That does not break the current laws of physics.
Form the press release:
> these films could be integrated into passive water harvesting devices for arid regions
I asume "harvesting" mean we can collect the water and drink it or use to irrigation or something interesting. Not just absorbing it like silica, even if the unusable water is visible.
Passive as using the day-night temperature different to collect water: It has been done.
Passive as a continue stream of running water: It breaks the second law of thermodynamics.
But the paper suggest that it will condense at ambient anyways, because it gets warmer so radiation to ambient is enough for it to work.
This is really moist air that's only barely short of forming dew. A lot of people are focusing on sensational "violation of physics", when it's an incremental improvement on process that happens naturally.
Their experiments suggest that tiny water droplets appear inside the material at 70% RH (relative humidity). If this is true, then I expect there is a way to extract the droplets using very little energy. Ideas:
- make open collection points on the film
- use ultrasound to bounce the droplets around and consolidate them
- make the film on a material that can be saturated with water so the new droplets can easily join the flow
What if you could eventually program the pore size? This would mean you could change the inflow/outflow balance of the reservoirs on-demand. Imagine smart clothing. Hot out -> increase pore size so the material dumps water, cold out -> pore size shrinks so the water is less likely to evaporate.
I am peeved by the "violates physics" verbiage in the article though.
People there usually have a surplus of moisture in the air most of the time.
It produces about 3 gallons of water a night.
34.997387, -116.380048
See the big tube sticking up? There's a miner's hotel built there.
Always testing the AI's I thought this might be a fun one to watch how they think through it since it is about technology that they would not have been trained on. Grok thought through the process more thoroughly than I (B.S.ChemE) would've .
https://grok.com/share/bGVnYWN5_e80e8100-3682-4157-879e-c5ca...
Their mumbo-jumbo about water being "squeezed out" onto the surface by the hydrophobic component is totally bogus as well. The condensation will just stop earlier, without overflowing. Water condensing in concave pores and being squeezed into convex droplets requires hydrostatic pressure to be positive and negative at the same time.
The possibilities I see are: 1) contaminated surfaces 2) miscalibrated relative humidity or 3) they've neglected to mention a cooling plate that keeps the material below ambient.
What you're referring to is condensation and is caused by air oversaturation due to a temperature drop which doesn't seem to be the case here.
Theoretically speaking, you can have a material that somehow absorbs high moisture from the air but has microscale properties that promote creation of droplets then somehow these droplets are separated from the rest of the air (with something like a smart vapor retarder, a passive material) and the water gets harvested.
Forming a convex surface, on the other hand, requires an at least slightly hydrophobic material and produces a positive internal pressure. This is a key difference, because condensation into a hydrophilic pore is favorable in terms of free energy, while condensing onto a hydrophobic surface is unfavorable (unless you have a supersaturated vapor).
> Theoretically speaking, you can have a material that somehow absorbs high moisture from the air but has microscale properties that promote creation of droplets then somehow these droplets are separated from the rest of the air
That "somehow" is what makes the paper's claims impossible. The water condenses spontaneously into the pore because it thereby lowers its free energy. Extruding it onto the surface is then even more unfavorable than direct condensation. Unfortunately, no passive system can achieve this feat, no matter how cleverly nanostructured, as it would go against the arrow of increasing entropy. You need an external energy source to drive that process.
It filled the critical gaps in my intuition that I didn't have the brain cycles to formulate hypotheses against.
Water harvesting in pristine lab conditions may break down rapidly in realistic scenarios. Something that’s wet attracts dust and microbes. Dust plus water means more microbes. You’ll have lichen growing on this stuff in no time.
If you have power, you can harvest water from the air wherever you are. Desalination generally requires trucking the water from the ocean to you.
I don't have the slightest idea whether transportation costs can ever be large enough to make water harvesting more efficient?
Seems to me that if you have a device that requires no extra material consumable input that's pretty interesting? Plenty of places with access to electricity that could benefit from the lack of other material input in theory.
Put one of these next to every tree. Or lines of them along rows of crops.
Run one in homes to make your ac more efficient and manage humidity.
Collect water on mountains or tall buildings and make hydro power?
Keep your pool topped off.
Basically Let salt water saturate the air in a closed system and use these to collect the water.
There's no free lunch, but removing water from a fabric matrix is a well understood process. Thats what washerwomen have done for millenia.
DocTomoe•8mo ago
WalterGR•8mo ago
DocTomoe•8mo ago
the__alchemist•8mo ago