EEVblog Electronics Community Forum
Electronics => Power/Renewable Energy/EV's => Topic started by: KNSSoftware on April 13, 2017, 09:48:09 pm
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Uh oh, can you smell, what I can smell... Eau de BS, Dave style
http://www.sciencemag.org/news/2017/04/new-solar-powered-device-can-pull-water-straight-desert-air (http://www.sciencemag.org/news/2017/04/new-solar-powered-device-can-pull-water-straight-desert-air)
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That is a summary of a legitimate scientific research article published in Science (http://science.sciencemag.org/content/early/2017/04/12/science.aam8743) - one of the 2 most prestigious scientific journals in the world (the other one being Nature).
It's about as far from BS as it gets.
I agree with Wilfred - the "debunking" meme is way past it's prime. It may work well as click-bait, but an unfortunate side effect is it leaves many unable to distinguish between real science/engineering and solar-roadways type BS.
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It's about as far from BS as it gets.
Looks like BS to me or at least abysmal reporting. Titled "This new solar-powered device can pull water straight from the desert air" they show a drawing of what looks like a cube shaped box with this MOF material on the roof and very specifically state
The setup works so well that it pulls 2.8 liters of water out of the air per day for every kilogram of MOF it contained
Maybe someone can check my figures but cool desert air at 10% RH weighs about 1.25kg/m^3 and contains 0.1% water by weight. To extract 2.8l of water they need to pass 2250 m^3 of air across their MOF material and extract 100% of the water content. What size box does it need to get good 'contact' between 2250m^3 of air and its 'roof' during a night and why would the air want to flow through the box anyway? Are they going to have solar cells and batteries and fans?
Then there is the problem with reversing the process where in a hot sunny desert you have to get rid of substantial amounts of heat to keep the bottom of the box cool enough to condense.
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The quality of reporting is a judgement call and in any case is not really relevant to the veracity of the findings in the source journal article.
I'd suggest you read the original source article in Science (http://science.sciencemag.org/content/early/2017/04/12/science.aam8743). Then, if you feel you're qualified to question Kim et al.'s methods or dispute their data I'd love to hear why and so would the editors of Science as well as the peer reviewers of the journal article.
If you have a valid criticism of their methods or data, you could write a letter to the editor of Science and it will be published. In doing so you would instantly achieve some notoriety in the scientific community.
If that sounds sarcastic - it really is not meant to be. Findings published in Science are widely read in the scientific community and hold great weight. Careers are literally made by having a research article published in this journal. If there is a fundamental flaw in the methods or data of an article published there, then publishing that could in itself could make a career :)
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Nothing new:
http://edition.cnn.com/2014/04/24/tech/innovation/machine-makes-drinking-water-from-air/ (http://edition.cnn.com/2014/04/24/tech/innovation/machine-makes-drinking-water-from-air/)
http://water-gen.com/ (http://water-gen.com/)
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Nothing new:
:palm:
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In contrast to the waterseer this concept actually works!
After reading the article the only big criticism I see is that the 3l of water per kilogram MOF seems a bit high,
the test results I saw in real world testing were always clearly under 1l per kg.
But it wasn't exactly the same device, it was much simpler as it was only a proof of concept.
Short explanation of the science behind it:
The MOF is like a sponge on a molecular scale and has the ability to absorb water, like e.g. silica gel does (the little drying packs shipped with most electronics for this reason)
and therefore the dew point is higher for this material.
But it doesn't hold the water as good as for example the silica gel does, especially when you rise the temperature the water can easily be removed again.
Therefore rising the temperature of the water-saturated MOF creates a high humidity atmosphere in the box,
rising the dew point to the level that the water can condense at the head sink at the bottom.
After condensing the water you need to let the MOF cool to ambient temperature and simply repeat the cycle over and over again...
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The concept with the water absorber is different from just pure cooling. This way it also does one more step: depending on the selectivity of the absorber it can also provide purification - this simple cooling method is more like producing water with quite some dust inside. So it still needs purification.
However this system will not work in all areas. There are deserts with a soil that has water adsorbing properties too - this causes a surprisingly low humidity at night too, because the soil also cools and essentially work the same as the MOF. This can be so bad as having less than 5% RH even at night. At this level very little, if at all humidity can be caught. However there are also deserts where chances are really good.
The 3 L number, like the number from the other cooler type systems seem to be valid for best conditions - so maybe in a coastal region or rain forest, where humidity at night is near 100%.
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And the same story badly reported here
http://news.berkeley.edu/2017/04/13/device-pulls-water-from-dry-air-powered-only-by-the-sun/ (http://news.berkeley.edu/2017/04/13/device-pulls-water-from-dry-air-powered-only-by-the-sun/)
Dry air does not contain any water for starters.
Again they claim 2.8l in 12 hours from 1kg of MOF material and say there is room for improvement because the current MOF can only absorb 20% of its weight in water. How is that supposed to add up? The reporting of this story has Batteriser levels of BS.
edit: I hadn't noticed the above story includes a video which clearly shows a large peltier module on top of the relatively huge heatpipe CPU cooler used as a condenser. They seem to have glossed over that and the large solar panel that would be required to power it from the sun.
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One could operate the cooling/ absorbing and heating/de-sorbing cycle several times a day. However 14 cycles with full absorption sounds like a lot. So it should at least not that it might be 2.8 L in 12 hours with sun and 0 L for the next 12 hours in the dark. So more like 2.8 L in 24 hours.
From the pictures the prototype looks like very much smaller - so 1 kg of absorber might actually be quite a big unit. Without a fan (and supporting PV) the system would also need some wind.
At least the required level of 20-30 % RH sounds like reasonable. In a real desert this might mean it will not work every day, or only parts of the day and of cause only when the sun shines. At least 20-30% RH should be easy to obtain if sea water is available; one might even provide some additional cooling this way.
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Maybe I should take this as read, since we're on an engineering forum but:
Device used for an experiment =/= proof of concept =/= prototype =/= final deployable product.
What's shown on the videos and photos is not a prototype; in some it's the experimental rig they used to measure the properties of 1.8 g of MOF, in some others it's a proof-of-concept device with 1.3 g (that's grams, not kg) of MOF, with a lot of additional instrumentation attached.
(https://pbs.twimg.com/media/C9yRRMEVYAA5KkU.jpg)
(https://pbs.twimg.com/media/C9yRTaWUMAA4ZTg.jpg)
Because they wanted to test different temperatures in the experiment, they attached a Peltier effect cooler to the system, just like a plane model inside a wind tunnel has a mount that can change the model's angle of attack and that doesn't mean that real planes need mounts. Given that it shows in some photos, some might assume that Peltier cooling is part of the device (it's not, the paper is very clear on that; the solar energy is used for heating the MOF and releasing the moisture).
Must agree with others who think "debunking" has jumped the shark. This being a Science paper and all, a real debunking is a rejoinder sent to the journal for peer review and publication; at least if the debunker is, say, a professional chemist who makes YouTube videos for extra cash.
Must applaud Dave's answer in another thread,
I have zero knowledge in this area.
If this post reads a bit testy, that's the result of me having to defend IHTFP & Berks U.
(The images above are screencaps from the Science paper. Sorry about the size, no idea why they came out so big.)
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Peltier cooling is part of the device (it's not, the paper is very clear on that; the solar energy is used for heating the MOF and releasing the moisture).
So what in the proof of concept rooftop experiment kept the condenser at a stable and substantially below ambient temperature if it wasn't the 'not part of the device' peltier?
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I'll reserve the right to object to the deliberate omission of the latent heat of vaporization from the energy balance of a device designed to condense water vapor, thank you very much. That makes me an engineer, not a philistine.
Huh? Can you explain how that is relevant? In any case, water's latent heat of vaporization is known (as is its heat of condensation which might be more relevant here) and it's a given that anyone with a serious interest in their research already knows this. Temperatures are documented in the paper. Have you read it?
Factual and science-based debunking of pseudoscience, when done well, is not passé.
I agree. The problem arises when those who are doing the debunking (or proposing it be done) are unable to distinguish between genuine science and pseudoscience.
The other problem is when those with technical expertise in one field assume they have sufficient expertise to adequately evaluate something in any technical field.
It's one thing to do a "busted" type youtube debunking video on some crowdfunded type marketing scheme but quite another to do one on a peer-reviewed research article or even a privately funded research or engineering project being developed by reputable scientists or engineers. Sure, if one has real background and expertise in that area - then a serious, data-driven critque is fair game - but I've seen none of that here or in some recent youtube videos.
The big concern I have is that contrary to the goal of debunking pseudoscience, this trend seems to be encouraging those without any expertise in a particular field to feel qualified to say "BS" to real science or engineering - just because it seems unlikely to them or it doesn't "smell right" ,etc. - or because their favorite youtube video blogger does a debunking video on it.
IMHO that is no better than the type of science denying that the anti-evolution, anti-vaccine or AGW doubters flourish in. Seeing even hints of that kind of thinking here on this forum just depresses me. :(
Science in America (https://www.youtube.com/watch?v=8MqTOEospfo)
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An idea for a product floated in a blue sky scientific paper may be as completely impractical as a bogus crowd-funded project, but one should not equate both as being bad science. Typically, stuff in science papers:
- the science is sound - ie. works in the lab (probably, subject to peer review etc)
- may not work as well in the field
- the engineering may need a LOT of work
- the economics may not be there at all
In particular, the paper notes that Zirconium at $150/kg would not make it practical, and a cheaper material would be needed. A lot of puffery around science papers is created by the PR dept and then the popular press.
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I think much of the dismissal here is due to the field being plagued with scams (Waterseer? Self-filling bottle? That stupid metal leaf thing?). Once people have seen a series of devices claim to make bulk water from desert air, all of which were conclusively dismissed as unworkable, of course they will assume the same is probably true of anyone else who makes the same claim.
I don't know if this can work or not. The materials science is beyond me. As best I can tell, it's using a novel water-absorbing material to concentrate the very low humidity in the air, a process powered by day/night temperature difference - one thing that a desert usually has plenty of. Even if it can in principle though, the engineering issues are going to take years to solve, so it might just be a case of the PR department taking the actual research and running with it.
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It's about as far from BS as it gets.
Looks like BS to me or at least abysmal reporting. Titled "This new solar-powered device can pull water straight from the desert air" they show a drawing of what looks like a cube shaped box with this MOF material on the roof and very specifically state
The setup works so well that it pulls 2.8 liters of water out of the air per day for every kilogram of MOF it contained
Maybe someone can check my figures but cool desert air at 10% RH weighs about 1.25kg/m^3 and contains 0.1% water by weight. To extract 2.8l of water they need to pass 2250 m^3 of air across their MOF material and extract 100% of the water content. What size box does it need to get good 'contact' between 2250m^3 of air and its 'roof' during a night and why would the air want to flow through the box anyway? Are they going to have solar cells and batteries and fans?
Then there is the problem with reversing the process where in a hot sunny desert you have to get rid of substantial amounts of heat to keep the bottom of the box cool enough to condense.
2250m3, over 8 hous of night time, or 4.6m3/min. Easily achievable with a 40 watt fan (looking at one on digikey right now) Who says this has to be a completely passive thing? Cover a roof with a box with the adsorber on the top of the inside, solar panels on the outside, with good contact between them and the box. Solar panels get hot, driving off moisture from the adsorber, and generate electricity to run a small refrigeration compressor that condenses the water (way more efficient than peltiers used in a test rig) and charges the batteries to run fans overnight.
It's just a demonstration of the new material and a demonstration of a potential application with a lab setup that isn't a 100% fleshed out ready to produce design. Save the fits of rage for shitty authors who write articles saying how it's going to change everything, rather than a lab demo of new materials tech. I.E. "NEW BATTERY UNLOCKS CHARGING PHONES IN 5 SECONDS" headline after a university assembles nanolithium battery with atomic microscope, can charge in 5 seconds, but is in no way shape and form mass manufacturable yet.
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The system does not need a temperature below ambient - though a low temperature can help a little.
Judging from the size of the proof of concept with a little less than 2 g of MOF and maybe 1/100 of a m² in size. A 1 kg unit would be around 5 m². 2.8 L/ day / kg of MOF sounds a lot more attractive than maybe 1 L / m² / day. Of cause the demo unit is not build to be effective with the solar heat.
From the science side, the interesting part would be whether the MOF is actually better than more conventional absorbing materials like zeolites.
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I'll reserve the right to object to the deliberate omission of the latent heat of vaporization from the energy balance of a device designed to condense water vapor, thank you very much. That makes me an engineer, not a philistine.
Huh? Can you explain how that is relevant? In any case, water's latent heat of vaporization is known (as is its heat of condensation which might be more relevant here) and it's a given that anyone with a serious interest in their research already knows this. Temperatures are documented in the paper. Have you read it?
(I deleted my original post 5 mins after writing it because I realized I don't even want to debate this stuff anymore, but here I go anyway.)
I haven't gotten past the paywall yet, but what I'm referring to was the media summary of the scientist's research which claimed the basis for a liquid water production device - which is a far cry from what the scientists only wish to discuss: "it absorbs lots of water vapor." Also, the article in question was substantially amended to make the claims far less spectacular than in its original publication.
Once the claim was made that this invention was for the creation of liquid water, I don't recognize one's right to eliminate what we all learned in Physics 101 - the latent heat of vaporization plus the efficiency of the condenser - which has a massive impact on the practicality of an energy claim. If one doubts this, I would like to direct said one to a nearby thermal power plant to witness the size of the condenser.
All that needs to be done is to keep the claims within the system boundaries. That's really not a lot to ask of a professional scientist, is it?
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In particular, the paper notes that Zirconium at $150/kg would not make it practical, and a cheaper material would be needed. A lot of puffery around science papers is created by the PR dept and then the popular press.
This was the problem with cadmium-telluride solar cells a while ago. Great performance in the lab, until someone noticed that tellurium is as rare as platinum (on Earth, that is; apparently not so in the asteroid belt), so no way to produce them at scale.
As Don Sadoway said about grid-level storage batteries, if you want them dirt-cheap, you have to make them out of dirt (i.e. abundant elements).
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Once the claim was made that this invention was for the creation of liquid water, I don't recognize one's right to eliminate what we all learned in Physics 101
Original research journal articles do not review basic principles for good reason. As for media reports meant for mass consumption - well that's another issue. But it is probably not easy to strike the right balance between informing the general public of a new finding and educating them on underlying scientific principles at the same time (which would surely drive away many readers)
All that needs to be done is to keep the claims within the system boundaries.
This is a good illustration why critiquing a media report on a scientific finding is not the same as critiquing the research or journal publication itself. We all know how good the media is at getting technical reporting right.. ::)
As far as I can tell based on my admittedly non-expert reading of the journal article, there are no such unreasonable claims made. But far more important than my opinion is the opinion of the peer reviewers who are experts in the field (and likely rivals of the PIs) and the opinion of the editor of Science. These people do this for a living and have reputations at stake.
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Once the claim was made that this invention was for the creation of liquid water, I don't recognize one's right to eliminate what we all learned in Physics 101
Original research journal articles do not review basic principles for good reason. As for media reports meant for mass consumption - well that's another issue. But it is probably not easy to strike the right balance between informing the general public of a new finding and educating them on underlying scientific principles at the same time (which would surely drive away many readers)
All that needs to be done is to keep the claims within the system boundaries.
This is a good illustration why critiquing a media report on a scientific finding is not the same as critiquing the research or journal publication itself. We all know how good the media is at getting technical reporting right.. ::)
As far as I can tell based on my admittedly non-expert reading of the journal article, there are no such unreasonable claims made. But far more important than my opinion is the opinion of the peer reviewers who are experts in the field (and likely rivals of the PIs) and the opinion of the editor of Science. These people do this for a living and have reputations at stake.
Once again, I have to point out that the article was EDITED, so what you're reading now is a toned down version of the original, which claimed that 3.5L of water could be obtained from a few grams of material.
Critique of these mass media science articles does matter to a certain extent. They are usually the basis for a seemingly infinite number investment schemes into technological applications for this research. Think what you will, but there is an enormous amount of society's capital being wasted on schemes founded on these claims. The original article had more than a faint aroma of this. That was the basis of my comment. I have little doubt about this new material being capable of absorbing the amount of water vapor that is claimed. That is not my point.
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Don't abracadabra with technical words, please.
This isn't specifically directed at any of the comments above, but it pains me to see engineers use words as if they were incantations rather than technical concepts that have precise meanings.
To wit: talking about "thermodynamics" or "enthalpy of evaporation" without taking a minute to do some calculations. And no, you don't need to read the Science paper or solve the heat equation to avoid wrong statements.
The point of contention is the 3 liters of water per kg of MOF per day. So, how much energy are we talking about and how big a surface to dissipate it?
The enthalpy of evaporation for water is 2.3 MJ/l and because it's so high you can pretty much ignore the energy of temperature change within the gas or liquid phases; only the phase change matters to a first approximation.
3 liters times 2.3 MJ/l = 6.9 MJ - per day, therefore (divide by 24*3600) 80 W of power.
(At this point most engineers should realize that there's no problem; 80 W from a metal surface in open air will almost surely be peanuts. A human being radiates about 100-200 W depending on the level of activity, or at least that's the number used for HVAC dimensioning when I was in college, back in the Pliocene.)
How big an area are we talking about? Again, even without reading the paper we can do some basic calculations, assuming planar geometry for the MOF deposition.
If the MOF were as dense as lead, 11.34 kg/l, a thin(ish)-film deposition over the base material, say 1/25 mm, would lead to 2.2 m^2 of area, or a square about 1.5 m on the side. To dissipate 80 W. Piece of cake.
But since the MOF is much less dense than lead and is deposited to maximize porosity (that's how the MOF works, it's all physics, no chemistry), it's more like styrofoam, and the area would be around 24 m^2, which makes the "enthalpy of evaporation problem" a non-starter. (It was already a non-starter with 80 W in 2.2 m^2, but the 24 m^2 is closer to reality.)
(The actual geometry of the deposition is more complex, highly non-planar, making use of a copper foam that is infused with the MOF powder, all on a copper substrate, but to know that you'd need the actual paper.)
We are engineers; let's not act like muggles and resort to lobbing words around as if technical terms were incantations. If it's an engineering word, there are probably numbers hiding behind it somewhere. Get those numbers.
You shall know the numbers, and the numbers shall set you free.
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Once again, I have to point out that the article was EDITED
Well I guess that's part of the confusion here. I really have not read the media reports closely -I assumed they're inaccurate (nothing new there). I've been talking about the actual journal article which documents the science as the authors meant. That has not been edited since publication. I have paid little attention the the media reports or the Science News article which it appears you're focused on.
As far are the Science News article. Looking at it shows it was edited on March 14th at 12:28pm (likely EST)- before all but maybe the first 2 posts in this thread. If they corrected an error then good on them -that may be relevant to a discussion of news reporting but it's not relevant to the science under discussion here.
Honestly, I'd be shocked if there were no errors in the media reporting - but that's not the science.
Which gets back to my original concern - people seem to be mixing the 2 up and in some cases (I'm not pointing at anyone here) unable to distinguish real science from media reporting or worse from pseudoscience. That's scary IMO.
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(At this point most engineers should realize that there's no problem; 80 W from a metal surface in open air will almost surely be peanuts.
How can you write drivel like that with even mentioning temperature? You can dissipate 80W from something the size of a pin, but, water does not condense on incandescent tungsten.
It is more like 160W anyway because at a guess it spends half the day absorbing water.
The question is can you practically dissipate 160W from a condenser maintaining a temperature differential between it and the solar heated MOF that allows extraction of all the water in the MOF. If you can why didn't their proof of concept roof top experiment try to prove that instead of using a peltier device to hold the condenser at a substantially below ambient 24C?
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(At this point most engineers should realize that there's no problem; 80 W from a metal surface in open air will almost surely be peanuts.
How can you write drivel like that with even mentioning temperature? You can dissipate 80W from something the size of a pin, but, water does not condense on incandescent tungsten.
It is more like 160W anyway because at a guess it spends half the day absorbing water.
The question is can you practically dissipate 160W from a condenser maintaining a temperature differential between it and the solar heated MOF that allows extraction of all the water in the MOF. If you can why didn't their proof of concept roof top experiment try to prove that instead of using a peltier device to hold the condenser at a substantially below ambient 24C?
Yup. Right here.
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Don't feed the troll.
It isn't necessary that it spend half the day absorbing water. Active cooling is not required.
This is not meant to be a product demonstration. It's a scientific investigation with a small part devoted to a proof-of-concept device. It is not an engineering paper. If this MOF technology was ever incorporated into an actual product and depending on temperature differentials and other design considerations, it might make the most sense to have it absorbing primarily at night (but non necessarily for 12 hours) - but those type of design considerations are not what this paper is about. It's about a novel use of MOF-801 and its advantages over conventional adsorbents.
Just read the F'in paper! :palm:
Here's the last page:
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Full article seems to be here
http://yaghi.berkeley.edu/publications.html#2017 (http://yaghi.berkeley.edu/publications.html#2017)
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Don't feed the troll.
It isn't necessary that it spend half the day absorbing water. Active cooling is not required.
This is not meant to be a product demonstration. It's a scientific investigation with a small part devoted to a proof-of-concept device. It is not an engineering paper. If this MOF technology was ever incorporated into an actual product and depending on temperature differentials and other design considerations, it might make the most sense to have it absorbing primarily at night (but non necessarily for 12 hours) - but those type of design considerations are not what this paper is about. It's about a novel use of MOF-801 and its advantages over conventional adsorbents.
Just read the F'in paper! :palm:
Here's the last page:
The name calling is unnecessary and beneath you. I read the paper. The authors simply assert that water will condense onto a heat sink without considering the energy the heat sink is required to dissipate.
The authors' entire argument ignoring the latent heat of vaporization is presented as:
For visualization purposes, we used a condenser with a temperature controller to maintain the temperature slightly below ambient, but above the dew point, to prevent vapor condensation on the inner walls of the enclosure. However, active cooling is not needed in a practical device since the hot desorbed vapor can condense at the cooler ambient temperature using a passive heat sink.
The condenser plate in their "practical device" CANNOT remain at a constant temperature. A heat sink at ambient temperature dissipates no power. Thermodynamics tells us this, full stop.
I came up with just over 150W of heat dissipation required during condensation in order to maintain the temperature of the heat sink with the assumption of 1kg of MOF. Water will indeed condense onto the heat sink initially, but the energy released will cause that heat's temperature sink to rise substantially (Without a clear definition of the size of the "practical" device I'm guess-estimating at least 10C+ for a VERY large naturally convection-cooled heat sink) relative to the 40C temperature differential between the MOF and condenser plate. It is challenging, to say the very least, for a heat sink to dissipate heat without becoming warmer, particularly one that is cooled by natural convection. It is telling that the authors know this because a "heat flux sensor" is included as part of the test apparatus, but nowhere in the article or the supplementary materials is the heat flux required to maintain the condenser at ambient temperature presented, nor is the "practical" case investigated of a condenser plate that increases in temperature, as would be expected without a thermoelectric cooler to, ahem, "visualize" the results.
And the article, I would argue, is unequivocally directed at the development of a device designed to dehumidify air and produce liquid water - as opposed to focusing on the water adsorption wonders of MOF-801. I can discern this from the first four words of the title, "Water Harvesting From Air ..." Also, the supplement contains, "Section S3. Efficiency comparison of MOF-based water harvesting system" which compares this supposededly non-refrigerated system against refrigeration-based water condensation systems.
Once again, I submit that critiquing the paper, peer-reviewed as it may be (for what, grammar, science, we don't usually know), is valid.
(edited for grammar and clarity)
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Full article seems to be here
http://yaghi.berkeley.edu/publications.html#2017 (http://yaghi.berkeley.edu/publications.html#2017)
Only partial. Does not include the supplemental material.
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Oh, and a Thank You to mtdoc for the final impetus to join AAAS. This discussion got me off the fence.
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The name calling is unnecessary and beneath you.
It was not directed at you. The prior poster has earned the title.
The authors simply assert that water will condense onto a heat sink without considering the energy the heat sink is required to dissipate.
Just because they do not calculate that energy does not mean they haven't considered it! Again, this is NOT an engineering paper. Any junior engineer can do that calculation.
The authors' entire argument ignoring the latent heat of vaporization is presented as:
They haven't ignored anything. It's implicit in their methods and data. Surely you can see this.
The condenser plate in their "practical device" CANNOT remain at a constant temperature.
I'm sure the authors would agree. Again - that's an obvious point, implicit in their methods and data. They made it clear why for data collection purposes, they did so in their device.
A heat sink at ambient temperature dissipates no power. Thermodynamics tells us this, full stop.
Well yes. Are you arguing that the authors imply otherwise? Again, this is not an engineering paper but it seems pretty obvious they assume that the reader can grok that there would be a temperature differential across the heat sink (i.e. hot condenser chamber on one side, cooler ambient air temp on the other side). Surely you can too..
nowhere in the article or the supplementary materials is the heat flux required to maintain the condenser at ambient temperature presented
If this were an engineering paper that might be necessary but it's not.
The bottom line is that the requirements for passive heat dissipation for such a device is a relatively trivial engineering problem. Are you arguing that it's not?
You need to keep in mind that Science publishes noteworthy research in a very condensed form. Much more abbreviated than what a field specific journal might publish. The editors are not going to allow material that are tangent to the research findings.
For someone coming from a strictly engineering background, this may not be obvious. An engineers mind is going to jump to the practical questions that arise in building a usable product. That is not what a research paper is about. And despite your protests, that is what this is.
Forgive me if this is already common knowledge here but research papers are pro forma divided into specific sections: (though in Science they are abbreviated and not clearly delineated due to its condensed, non field-specific format).
Introduction: Presentation of an idea (hypothesis) and brief review of the question and previous relevant research. - In this case MOF-801 might work well as an adsorbent to harvest water in an arid environment.
Material and Methods What they did. Ideally in enough detail for others to replicate their experiment. (Science's abbreviated format often skimps on this)
Results Experimental Data and if appropriate, statistical analysis
Discussion The authors interpretation of their data and it's implications, direction for further research.
I think the inclusion of a small "proof of concept" device in this paper has confounded both the media reporters and some here to think they were trying to demonstrate a prototype meant to be used in the real world. That is the challenge for the engineers to take on.
That's the process, isn't it? Science ---> Engineering ---> Product. Sometimes (often) the engineering problems prove too difficult to solve or uneconomical but that is no reason to fault the science.
Once again, I submit that critiquing the paper, peer-reviewed as it may be (for what, grammar, science, we don't usually know), is valid.
Well, I didn't catch that you'd submitted this before, since previously you seemed to be critiquing the media reports. But yes, of course I agree that critiquing a research paper is valid. A large part of a scientists time is spent doing exactly that. I appreciate the chance to do that here with you. :)
And FWIW - peer review of research papers is about review of the science - the material and methods, the data and the authors conclusions. It's done by experts in the field - often rivals of the PIs who in many cases have much to gain from finding fault with the research. That may not be something you know but anyone who has been involved in research and the publication knows this. It is an integral part of the scientific process!
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mtdoc,
We're going to have to disagree about whether or not this is an engineering paper. :)
I argue that this is an engineering paper erroneously reviewed by scientists and published in a scientific journal. If this was about the development of a new MOF and the quantity of water vapor it could adsorb and release, I would agree it is wholly appropriate to omit engineering evaluation. However, this paper is primarily about the *application* of MOF with the ultimate objective of a "practical device," the author's words, not mine. In my opinion, that squarely puts the discussion into the realm of engineering, not that I think that scientists are exempt from criticism for modeling a heat sink in a fashion in which thermodynamics says a passive heat sink cannot behave.
So there! :phew:
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We're going to have to disagree about whether or not this is an engineering paper. :)
I can agree with that. ;D
And I'll concede that it does have engineering aspects in it. The next step in the process will be for engineers to try and design practical devices that utilize MOF-801 (and publish their findings in an engineering journal with all the engineering details spelled out!) Perhaps a viable real-world product will come from this. Perhaps not - but if so then that's ok too - it's just another step in the process. Viva la science! :)
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Full article seems to be here
http://yaghi.berkeley.edu/publications.html#2017 (http://yaghi.berkeley.edu/publications.html#2017)
Only partial. Does not include the supplemental material.
Well, the author says it is the full article and they publish a link to the supplemental material in the article, so what is the problem?
Link found in the article.
http://science.sciencemag.org/content/suppl/2017/04/12/science.aam8743.DC1 (http://science.sciencemag.org/content/suppl/2017/04/12/science.aam8743.DC1)
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Full article seems to be here
http://yaghi.berkeley.edu/publications.html#2017 (http://yaghi.berkeley.edu/publications.html#2017)
Only partial. Does not include the supplemental material.
Well, the author says it is the full article and they publish a link to the supplemental material in the article, so what is the problem?
Link found in the article.
http://science.sciencemag.org/content/suppl/2017/04/12/science.aam8743.DC1 (http://science.sciencemag.org/content/suppl/2017/04/12/science.aam8743.DC1)
I missed that. I assumed that the supplemental material was paywalled. Thank you.
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Yes, it's a welcome development that they can web link to supplementary material that provides more detail than can be accommodated in the condensed Science format. That brings it closer, detail wise, to what's published in the field specific journals. :-+
That was not an option in my pre-web research days. >:(
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So people can stop with the tears over the solar heat load etc how about this:
Copper tubes coated in adsorbing material in a stainless duct, fan blows air through the duct, and refrigeration compressor cools the tubes so latent heat doesn't warm the adsorber. After x time, close one damper and open another, reverse the refrigerant flow, heat the pipes, circulate the air and condense the water on the refrigerant evapoator. Energy use is reduced by dumping the latent heat of the condensing water into the adsorbing material. Use the roof for solar panels, and it's up and running.
Assuming they can produce the adsorbing material on copper tubing, the hardest part will be getting the licensing from George Lucas to call it a "Moisture Vaporator"
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Thunderfoot's response
https://www.youtube.com/watch?v=EGTRX6pZSns (https://www.youtube.com/watch?v=EGTRX6pZSns)
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I just find it depressing to see this. TF is continuing to reveal himself as a charlatan. I think he is too smart a guy to not understand that he is completely misrepresenting the Science paper. He knows his audience and knows they won't actually read it (or understand its intent if they do). He is simply selling a product and using the typical charlatan's tools to do it. Smarmy indeed.
It would be funny except for the damage it does to the interests of science education and improving science literacy in general.
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(Haven't seen the vid yet, just going by the description.)
Thunderf00t's audience is unlikely to notice this but: (1) TF's day job is as a research chemist; (2) the work addressed in the vid was published in Science; (3) if TF has an actual argument against the paper, Science will publish it as a rejoinder after review; (4) a publication in Science, particularly a rejoinder, is a major win for a research chemist.
So, unless TF sends that rejoinder to Science, he's admitting that the he knows the vid is deceptive. If TF sends it and it's accepted, kudos to him; if it's rejected, one would expect that TF would make a "mea culpa" video. In other words, if there's no rejoinder is Science under TF's real name and no "my bad" video, we can conclude TF's "debunking" has definitely jumped the shark.
Anyone want to lay odds on that rejoinder? I'll take the under.
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It would be funny except for the damage it does to the interests of science education and improving science literacy in general.
And the BS about the paper published by Science magazine, Berkeley, Bill Gates tweeting, and especially that farcically bad WSJ video does no damage to the interests of science education and improving science literacy in general?
Still that is only journalism which in your mind gets a free pass while Thunderf00t is depressing.
His video misrepresents the paper rather less than anything else published about it.
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Now that I've watched the video, I don't think TF realizes how much he overstepped.
The video all but calls the research fraudulent and since it's obvious that (a) he has seen the paper and (b) he's misrepresenting it to push the "fraud" narrative, it's the kind of thing that can have unpredictable effects.
No matter how you parse it, TF is basically calling professional colleagues "frauds" on the sly. That's generally not well received in academia.
What was it that Kissinger said? The fights in academe are so vicious because the stakes are so small. Indeed.
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So, unless TF sends that rejoinder to Science, he's admitting that the he knows the vid is deceptive. If TF sends it and it's accepted, kudos to him; if it's rejected, one would expect that TF would make a "mea culpa" video. In other words, if there's no rejoinder is Science under TF's real name and no "my bad" video, we can conclude TF's "debunking" has definitely jumped the shark.
Exactly right. But that would require actually engaging in the process of science. It's much easier to feed the worst instincts of those who don't understand that process with an all style, no substance "Busted" video.
Still that is only journalism which in your mind gets a free pass while Thunderf00t is depressing.
No free pass for poor journalism as long as it's identified as such. And no free pass for those who are unwilling (or unable) to clearly distinguish between journalism and science. And definitely no free pass to those like TF who try to capitalize on the popularity of videos debunking crowdfund marketing scams -riding the coat tails of these to promote pseudoscience and inaccurate, over hyped critiques of legitimate science and technology - all for personal gain. That's no better ethics than what's displayed by the marketers of Solar Roadways - but even worse, it's damaging to the cause of science education.
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I haven't made it through all 40+ minutes of TF's video (nor do I particularly care to), but:
- The comparison between a thermoelectric dehumidifier and the device presented in the Science paper is fair.
- The emphasis on the tremendous amount of energy needed to vaporize liquid water is fair, but inaccurately presented. TF confuses boiling with vaporization. This surprises me for a working scientist.
- Calling the paper "complete bullshit" based on the failure of one of the paper's claims is unfair.
- Thunderfoot has a tendency to go over the top, and this is video is on par his incorrect claim that Solar Roadways could not power a computer monitor.
- The paper presented in Science only was of enough significance to be published there based upon the extraordinary claim that a heat sink could replace a heat engine - and thus - water could be condensed from the atmosphere at the rates presented with no energy input aside from ambient solar radiation. This claim violates Newton's Law of Cooling and is demonstrably false. The authors of the paper uttered another knowing falsehood in offering that the thermoelectric cooler was only there to assist in visualizing the condensation. The more likely explanation is that the thermoelectric cooler was introduced after a prototype using only a heat sink failed to condense water. Without this extraordinary, free-energy claim for which no extraordinary proof was offered, this paper would likely have been relegated to a more obscure journal focusing on materials science.
I have no more regard for untempered and unfair science criticism that I have for untempered, shameless promotion of junk science. Unfortunately, temperance does not seem to generate as many YouTube views.
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@wilfred, mtdoc and josecamoessilva; you guys are pathetic.
You might not like Thunderf00t's style, but the science is accurate and the representation of the paper is fair. Why do you feel the need to defend science charlatans like the authors of the paper? Which is hyped and marketed by the universities to the media.
@josecamoessilva can you link me to a "rejoinder"?
@LabSpokane Thunderf00t does not confuse boiling and vaporization, his math assumes a phase change only, no temperature change of the water.
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The paper presented in Science only was of enough significance to be published there based upon the extraordinary claim that a heat sink could replace a heat engine - and thus - water could be condensed from the atmosphere at the rates presented with no energy input aside from ambient solar radiation.This claim violates Newton's Law of Cooling and is demonstrably false.
Um . No. :palm:
The authors of the paper uttered another knowing falsehood in offering that the thermoelectric cooler was only there to assist in visualizing the condensation.
:wtf: So your are accusing them of lying? What other reason would there be? No, they make no "free energy claim" as you say. Are you purposely being decietful saying that (TF style)? or did you completely miss their repeated references of 1kW per sq. meter (one sun) of solar heat?
They did not need to include that device. It was a very minor part of their paper. Again - you seem to completely misunderstand the intent of a scientific paper versus an engineering paper. One of the primary reasons for the proof of concept device (which is a very minor part of the paper)was to be able to visualize and document with photos the formation of growth of water droplets as a function of MOF temp and time of day. You simply cannot do that with condensation on the glass. They kept the condenser temp above the dewpoint . Surely you understand the significance of that! The need for visualization is also why they had a much larger than optimal spacing between the MOF and condenser. They explain all this all quite clearly. Why was it important to visualize and document the droplet formation and growth? Because this is science and not engineering. They were not trying to build a practical device. That is for the engineers to do - if it turns out that this MOF 801 is something that is worth pursuing as a basis for better water harvesting devices. Surely there is much more work to be done to determine if that is indeed the case.
The crux of the issue is this:
They have published a scientific research paper in a major scientific journal after it was reviewed by other experts in that field and the editor of Science. In doing so it will now be reviewed by many many more experts in that field, their colleagues and coworkers. People whose opinion of their work is vital to them. The authors reputations among their peers is on the line. There are surely real questions and valid criticisms to be raised as there is with any research. They are accountable to their peers and the scientific community - not to TF or posters on an internet forum who can say anything they want without repercussion or needing to provide evidence or justification of their claims.
It's one thing to critique Solar Roadways or Batterizer or any other such consumer pseudoscientific device being marketed by people who have no accountability to other experts or peers. People whose only consequence of being dishonest or unethical is failure of their marketing scam. They are fair game. It's quite another to accuse working scientists subject to peer review and ongoing peer evaluation of "uttering knowing falsehoods" etc. Easy to say such things when one has no accountability and as such is no more valid than any other of the random BS found on the internet.
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You might not like Thunderf00t's style, but the science is accurate and the representation of the paper is fair. Why do you feel the need to defend science charlatans like the authors of the paper?
Hmm. Lets see. Which is the charlatan?
A) Someone who works for a major scientific research institution, submits a paper for peer review to one of the premier scientific journals and is then subject to ongoing review and evaluation by colleagues, coworkers and by hundreds of other working scientists in that field.
Or:
B) Someone who goes by the name "Thunderfoot" and solicits money and posts Youtube videos plastered with titles like "Busted" or Kill" and which contain mostly him rambling on with only cursory calculations, obvious technical inaccuracies and lots of sensationalistic stock video clips. Whose only accountability is to a bunch of anonymous internet followers - most of whose comments demonstrate a remarkable lack of scientific literacy.
If you chose A then you are demonstrably part of the anti-science crowd.
And just because their research was picked up and inaccurately reported on and hyped by public relations offices does not make it invalid . The inaccurate reporting was surely unwanted by the authors. The science itself is surely imperfect and is just one more piece of the puzzle. Calling the authors charlatans is beyond the pale.
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You might not like Thunderf00t's style, but the science is accurate and the representation of the paper is fair. Why do you feel the need to defend science charlatans like the authors of the paper?
Hmm. Lets see. Which is the charlatan?
A) Someone who works for a major scientific research institution, submits a paper for peer review to one of the premier scientific journals and is then subject to ongoing review and evaluation by colleagues, coworkers and by hundreds of other working scientists in that field.
Or:
B) Someone who goes by the name "Thunderfoot" and solicits money and posts Youtube videos plastered with titles like "Busted" or Kill" and which contain mostly him rambling on with only cursory calculations, obvious technical inaccuracies and lots of sensationalistic stock video clips. Whose only accountability is to a bunch of anonymous internet followers - most of whose comments demonstrate a remarkable lack of scientific literacy.
If you chose A then you are demonstrably part of the anti-science crowd.
And just because their research was picked up and inaccurately reported on and hyped by public relations offices does not make it invalid . The inaccurate reporting was surely unwanted by the authors. The science itself is surely imperfect and is just one more piece of the puzzle. Calling the authors charlatans is beyond the pale.
First claim I see on the first page:
For MOF-801, a temperature swing between 25°C and 65°C can harvest over 0.25 L kg–1 of water above 0.6 kPa vapor pressure (20% RH at 25°C, Fig. 1B). This water harvesting strategy is completely passive, relying only on the high water uptake capacity, low-grade heat requirement for desorption, and ambient to condense and collect the water.
I want you to think for yourself for a moment, not just appeal to Science as authority; how do you imagine this being possible?
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how do you imagine this being possible?
It has nothing to do with imagination. I'll leave that to the artists and religious zealots.
Didn't you read the paper? Are you accusing them of lying? Are you saying they falsified their data?
Do not confuse the process of science with the reporting of it by the media.
They support their claims with both a theoretical model and experimental data. By my admittedly inexpert reading, their data supports their claims. Apparently the reviewers (who are experts in that field) and the editor of Science felt this to be true as well.
All the internet forum postings and youtube videos in the world will not change the science (or convince a scientist) otherwise. That requires- like you know - actual data from research that's high enough quality to be published in a peer reviewed journal. If that was not the case then the creationists and other such anti-science and pseudoscience internet peddlers would be on equal footing with the scientists. They aren't in my world, are they in yours?. I make no apologies for trusting the scientific process. It's imperfect but it's the best path to the truth of the physical world that we have.
It may turn out there are problems with this research which will be discovered in subsequent research. If so, I'm sure it will be published as well (and the media will have moved on - sigh). That's how science works.
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The paper presented in Science only was of enough significance to be published there based upon the extraordinary claim that a heat sink could replace a heat engine - and thus - water could be condensed from the atmosphere at the rates presented with no energy input aside from ambient solar radiation.This claim violates Newton's Law of Cooling and is demonstrably false.
Um . No. :palm:
The authors of the paper uttered another knowing falsehood in offering that the thermoelectric cooler was only there to assist in visualizing the condensation.
:wtf: So your are accusing them of lying? What other reason would there be? No, they make no "free energy claim" as you say. Are you purposely being decietful saying that (TF style)? or did you completely miss their repeated references of 1kW per sq. meter (one sun) of solar heat?
They did not need to include that device. It was a very minor part of their paper. Again - you seem to completely misunderstand the intent of a scientific paper versus an engineering paper. One of the primary reasons for the proof of concept device (which is a very minor part of the paper)was to be able to visualize and document with photos the formation of growth of water droplets as a function of MOF temp and time of day. You simply cannot do that with condensation on the glass. They kept the condenser temp above the dewpoint . Surely you understand the significance of that! The need for visualization is also why they had a much larger than optimal spacing between the MOF and condenser. They explain all this all quite clearly. Why was it important to visualize and document the droplet formation and growth? Because this is science and not engineering. They were not trying to build a practical device. That is for the engineers to do - if it turns out that this MOF 801 is something that is worth pursuing as a basis for better water harvesting devices. Surely there is much more work to be done to determine if that is indeed the case.
The crux of the issue is this:
They have published a scientific research paper in a major scientific journal after it was reviewed by other experts in that field and the editor of Science. In doing so it will now be reviewed by many many more experts in that field, their colleagues and coworkers. People whose opinion of their work is vital to them. The authors reputations among their peers is on the line. There are surely real questions and valid criticisms to be raised as there is with any research. They are accountable to their peers and the scientific community - not to TF or posters on an internet forum who can say anything they want without repercussion or needing to provide evidence or justification of their claims.
It's one thing to critique Solar Roadways or Batterizer or any other such consumer pseudoscientific device being marketed by people who have no accountability to other experts or peers. People whose only consequence of being dishonest or unethical is failure of their marketing scam. They are fair game. It's quite another to accuse working scientists subject to peer review and ongoing peer evaluation of "uttering knowing falsehoods" etc. Easy to say such things when one has no accountability and as such is no more valid than any other of the random BS found on the internet.
Peer review failed miserably in this instance.
I trust Newton's Law of Cooling far more than arguments from authority.
The need to assist in "visualizing" condensation is a blatant falsehood. The evidence of condensation is liquid water, which is visible to the naked eye. Liquid water would have been equally visible on the surface of their magical heat sink which dissipates power without raising its temperature.
Keeping the condenser temp above the dew point is a red herring. Had they used a heat sink only, that criterion would have easily been met as the temperature of the heat sink would have rapidly approached equilibrium with the vapor temperature. Oh, but then a lot less water would condense, wouldn't it? I'm sure you must understand the importance of that.
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@LabSpokane Thunderf00t does not confuse boiling and vaporization, his math assumes a phase change only, no temperature change of the water.
Yes he does. He shows boiling water and states the energy needed to make it boil is the latent heat of vaporization. That is false. It is the energy required to turn all of the water from a 100C liquid to steam.
I have not watched the calculations portion. So that may be correct.
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Another important detail they don't address is the cooling of the MOF, sure it will absorb water at ambient temperature and 20% RH as they say, and when placed in the sun at ~65 C some of that water will evaporate back off.
The water evaporated off the MOF can then re-condense on a passive heatsink placed above which remains at ambient temp - but the MOF won't absorb any more water without being cooled down again, i.e. placed out of the sun. And they plan on doing this passively? .. So humans have to do it?
@LabSpokane If you have water at the boiling point, the energy required to boil it all off is the latent heat of vaporization. The energy required to bring the water to the boiling point is m * C * (T_f - T_i), this amount is very small compared to the latent heat of vaporization, 334 kJ vs. 2.257 MJ for 1 kg of water. (m = mass, C = heat capacity)
If Thunderf00t said that the energy required to bring the water to a boil was the latent heat of vaporization, he was wrong.
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Didn't you read the paper? Are you accusing them of lying? Are you saying they falsified their data?
Of course they are lying and don't publish any data to justify the claims people are complaining about.
We report the design and demonstration of a device based on porous metal-organic framework-801 [Zr6O4(OH)4(fumarate)6] that captures water from the atmosphere at ambient conditions using low-grade heat from natural sunlight below one sun (1 kW per square meter). This device is capable of harvesting 2.8 liters of water per kilogram of MOF daily at relative humidity levels as low as 20%, and requires no additional input of energy.
There is no device and an extrapolation of their (non) proof of concept device and experiment could not produce the claimed performance.
At 20% by weight water absorption by the MOF it would have to pass through 14 collect/condense cycles during say 8 hours of sunlight. It is doubtful that a practical device could achieve a single cycle per day without additional solar panels to provide electricity for active cooling. Then there is the practical problem of passing around say 2000 m^3 of air over the MOF the kind of volume passed by a 30W fan running for 8 hours.
The claims from the paper quoted above are ridiculous and lies.
I look forward to your appeal to authority and face palm response which seems to be the only argument you have.
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@LabSpokane If you have water at the boiling point, the energy required to boil it all off is the latent heat of vaporization. The energy required to bring the water to the boiling point is m * C * (T_f - T_i), this amount is very small compared to the latent heat of vaporization, 334 kJ vs. 2.257 MJ for 1 kg of water. (m = mass, C = heat capacity)
If Thunderf00t said that the energy required to bring the water to a boil was the latent heat of vaporization, he was wrong.
I am well aware of these facts, but thank you.
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How real science is done (e.g. this paper):
1) Have a novel idea/hypothesis (MOF-801 has properties that make it superior to current absorbents).
2) Develop a theory for why your hypothesis might be correct (or incorrect). (Done)
3) Make predictions based on your theoretical model. (Done)
4) Devise and perform an experiment(s) and collect data. (Done)
5). Document and analyze your data. (Done).
6) If necessary revise your hypothesis and go back to step 2.
7) Submit your findings for peer review and (if worthy) publication. (Done).
8.) Await further review by colleagues and other scientists.(In process)
9.) If necessary, and based on further data (yours or as published by others), review and revise, go back to step 2.
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How anti-science and/or pseudoscience is practiced on the interwebs (unfortunately including by some on this forum):
1) Make a claim or refute published research or scientific consensus (in this case published research)
2) Back up your claims with:
A) Verbal statements such as:
"I know this is wrong (or right)"
"They're lying"
"It smells like BS "
"I can't imagine this is true (or not true)"
" Dr X says it's true (or not true)"
"It's only a theory"
Or other such statements which are basically the equivalent of " The bible says so"
B) Cursory calculations or repetition of elementary scientific principles which may or may not have some bearing on your idea or the published science being refuted.
3) If speaking to a general audience use lots of impressive sounding technical jargon that may or may not be accurate, relevant or fairly represent what is being refuted.
4) Accuse the published science of being politically motivated without offering any proof of this.
5) Misrepresent the published science either intentionally or unintentionally based on inaccurate media reports.
6) Use examples of prior research that was later proved wrong while ignoring the fact that the proving wrong is part of the scientific process and was accomplished using real science.
7) Never collect any of your own data and publish it in a reputable peer reviewed journal.
8.) Make highly stylized sensationalistic youtube videos employing the methods above.
9) Accuse those who point these things out of "Appealing to the authority of science".
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I trust Newton's Law of Cooling far more than arguments from authority.
Nothing in this paper violates that law. It's not argument from authority. It's published experimental data. It is science!
The need to assist in "visualizing" condensation is a blatant falsehood. The evidence of condensation is liquid water, which is visible to the naked eye. Liquid water would have been equally visible on the surface of their magical heat sink which dissipates power without raising its temperature.
Keeping the condenser temp above the dew point is a red herring. Had they used a heat sink only, that criterion would have easily been met as the temperature of the heat sink would have rapidly approached equilibrium with the vapor temperature. Oh, but then a lot less water would condense, wouldn't it? I'm sure you must understand the importance of that.
Once again, I believe you are failing to understand the difference between basic science and engineering.
Visualizing and documenting droplet formation and growth as a function of MOF temperature was part of validating their theory. You can't adequately visualize this - even with the naked eye - if the glass is obscured by condensation and you certainly can't document it for publication without clear photographs. If they said "droplet formation and growth occurred in xx manner with increasing temperature over xx time period - we observed this through glass partially obscured by condensation and were unable to provide any clear photographic documentation of this" their paper would rightly be rejected by the reviewers!
If they were trying to deceive someone, why disclose the active controlling of the condenser temperature? They were trying to fully characterize the adsorption-desorption properties of MOF-801, nothing more. They were not attempting to build a working prototype.
Science is very different than engineering in this regard. You can't just build a "black box" and measure data in and out then derive a transfer function and be done. The point of science is trying to understand the underlying process. Sometimes that involves direct visualization. It often involves controlling variables artificially in order to gather data.
A very obvious next step for this would be to build a prototype device with no TE cooled condenser and only passive cooling with adequate heatsinking and measure, refine, measure, etc to try and optimize water production.
Maybe it would work, maybe not. The theory and experimental data presented in this paper suggests that it should and it is worth building. That in a nutshell is what the authors are saying.
If a working prototype was built, THAT would be an engineering paper. As such it would not likely be published in Science.
I think the authors of this study made a big mistake by using the term "Proof of concept device" when really it is just an experimental apparatus. In this case proof of concept != prototype.
Unfortunately - even though it was a small part of their paper - use of that term seems to have triggered engineers and others so inclined to focus on this part of the paper and to think it is an engineering study, therefore looking at it from that perspective (understandable since that is what engineers are familiar with). But even worse, it led to erroneous reporting by the media.
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This idea is not novel or original at all, the last few years of MOF research have all discussed the possible use as atmospheric water generators, first relevant hits on google scholar cited below.
Furukawa, Hiroyasu, et al. "Water adsorption in porous metal–organic frameworks and related materials." Journal of the American Chemical Society 136.11 (2014): 4369-4381.
Canivet, Jérôme, et al. "Water adsorption in MOFs: fundamentals and applications." Chemical Society Reviews 43.16 (2014): 5594-5617.
Burtch, Nicholas C., Himanshu Jasuja, and Krista S. Walton. "Water stability and adsorption in metal–organic frameworks." Chemical reviews 114.20 (2014): 10575-10612.
Biswal, Bishnu P., et al. "Pore surface engineering in porous, chemically stable covalent organic frameworks for water adsorption." Journal of Materials Chemistry A 3.47 (2015): 23664-23669.
Hao, Guang?Ping, et al. "Unusual Ultra?Hydrophilic, Porous Carbon Cuboids for Atmospheric?Water Capture." Angewandte Chemie International Edition 54.6 (2015): 1941-1945.
de Lange, Martijn F., et al. "Adsorption-Driven Heat Pumps: The Potential of Metal–Organic Frameworks." Chemical reviews 115.22 (2015): 12205-12250.
Just look at the relevant discussion from the first paper:
Applications to Thermal Battery and Water Delivery in Remote Desert Regions
With these values, we can estimate how much heat can be stored in 15 kg of MOF-801-P. Assuming that the storage capacity and Qst of MOF-801-P are 20 wt % (at P/P0 = 0.1) and 60 kJ mol–1, respectively, the total heat expected to be released is 10 MJ. If such a system is operated for 1 h with 65% efficiency, the power capability is equivalent to 1.8 kW: a value approaching the 2.5 kW power target for typical thermal batteries as set by DOE.(31)
The temperature effect on water uptake is also important to realize another application of water adsorption in MOFs: temperature-triggered water capture and release systems, where atmospheric water would be captured and delivered at different temperatures in areas with high temperature contrasts between day and night. For example, in the city of Tabuk in Saudi Arabia, the typical summer temperature and relative humidity during day time are respectively 40 °C and 5%, drastically changing at night to 25 °C and 35%. Assuming P/P0 × 100 = RH%, the working capacity of MOF-841 between P/P0 = 0.05–0.35 is more than 40 wt % (Figure S58 in SI), which is the largest obtained among all Zr-MOFs. If 15 kg of MOF-841 is deployed in Tabuk under these optimal conditions, it should be able to deliver 6.3 L of pure water per day.
The reason why all of them haven't been in the news like these MIT graduates is because they did the science properly.
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This idea is not novel or original at all, the last few years of MOF research have all discussed the possible use as atmospheric water generators, first relevant hits on google scholar cited below.
Original science does not require a complete lack of previous research in that area. In fact quite the opposite - almost all science builds on previous published research. The journal Science does not publish research that does not report something new or previously unpublished. Period. Full Stop.
Just look at the relevant discussion from the first paper:
And your point is? That other research has been done in this area - in this case using a different MOF?
The reason why all of them haven't been in the news like these MIT graduates is because they did the science properly.
So your argument is that all science that gets picked up and reported in the mainstream press (usually inaccurately) is not proper science? ::)
(And what makes you think the MIT and UC Berkeley researchers publishing this are all MIT graduates?)
How exactly are researchers supposed to prevent their published research from being reported in the media?
The way to refute published science is by either publishing your own data or if you find some fundamental flaw in a publication, by sending a letter to the journal editor or other reputable publication in the field.
Science is cutthroat competitive so if any such flaw is present (certainly possible), it will be forthcoming in reputable publications. AKA the scientific process
Innuendo, irrelevant or illogical postings on an internet forum and youtube videos just don't cut it I'm afraid.
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If Thunderf00t said that the energy required to bring the water to a boil was the latent heat of vaporization, he was wrong.
He does not say it, but words the sentences in such a way that most people will (erroneously) believe that to be the case. He also played some dubious tricks in a previous vidjeo about CO2 / global warming / atomic bombs and the energy the earth receives from the sun.
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Just look at the relevant discussion from the first paper:
And your point is? That other research has been done in this area - in this case using a different MOF?
Would that be the same first paper that was co-autored by the inventor of Metal-Organic Frameworks (yes, the whole field), Omar Yaghi, who's a coauthor of the Science paper?
"Water Adsorption in Porous Metal–Organic Frameworks and Related Materials" Hiroyasu Furukawa†, Felipe Gándara†, Yue-Biao Zhang†, Juncong Jiang†, Wendy L. Queen§, Matthew R. Hudson?, and Omar M. Yaghi*†
(As usual in these things, the laboratory directors are the last on the author list, in the case of the Science paper, Yaghi (Berkeley) and Wang (MIT). It's one of those things people who read scientific papers tend to know. Hint: "et al." short for "et alli" means "and others.")
Obvious troll is obvious.
Here's the process of science at work:
http://science.sciencemag.org/content/early/2017/05/03/science.aan5763 (http://science.sciencemag.org/content/early/2017/05/03/science.aan5763)
After an investigation, the Central Ethical Review Board in Sweden has recommended the retraction of the Report “Environmentally relevant concentrations of microplastic particles influence larval fish ecology,” by Oona M. Lönnstedt and Peter Eklöv, published in Science on 3 June 2016 (1).
Making youtube videos instead of submitting one's analysis to peer review: not how a real scientist addresses a problem with the science in a peer-reviewed paper. Ironically, that's how Thunderf00t attacks creationists and climate change deniers, that they make videos criticizing evolution and climate science that has been peer-reviewed but never submit their "analysis" to peer review themselves...
A bit sad to see that Dave retweeted the vid.
(I had forgotten how strongly some people are triggered by the three letters "MIT," for reasons that are all too obvious. Also always wondered why Caltech gets a pass.)
Edited to add: Interesting conversation at U of the Berks with Omar Yaghi with some interesting points about science and society:
https://www.youtube.com/watch?v=tOxfp1mjTu0 (https://www.youtube.com/watch?v=tOxfp1mjTu0)
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You guys makes me sad.
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A bit sad to see that Dave retweeted the vid.
I feel the same. I think that Dave has been a big TF fan. But I also know that Dave is very pro science and pro science education. After watching his discussion with Shahriar I'm hoping that he is coming to better appreciate the difference between real science, pseudoscience and anti-science. Niel DeGrasse Tyson is also good in that way. I'm also hoping that he sticks to debunking the crowd funded type pseudoscience scams in the careful, non hyped way he did in his initial debunk videos and does not follow the TF path of ill-informed anti-science videos.
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How exactly are researchers supposed to prevent their published research from being reported in the media?
Maybe they could not include greenwash bullshit lies in their papers clearly intended to get technically illiterate journalists and eco warriors gagging for it.
Just a thought....
If this paper had been honest it would not have been reported.
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How exactly are researchers supposed to prevent their published research from being reported in the media?
Maybe they could not include greenwash bullshit lies in their papers clearly intended to get technically illiterate journalists and eco warriors gagging for it.
Just a thought....
And have one of the largest press offices of any university write and circulate press releases that does nothing but hype, where do you think all the journalists get their story? http://news.mit.edu/2017/MOF-device-harvests-fresh-water-from-air-0414 (http://news.mit.edu/2017/MOF-device-harvests-fresh-water-from-air-0414)
Do you see all the "Press mentions" on the right side? What does it remind you of? Every kickstarter scam I can think of.. "Featured in.."
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I trust Newton's Law of Cooling far more than arguments from authority.
Nothing in this paper violates that law. It's not argument from authority. It's published experimental data. It is science!
From the paper:
During water harvesting (left), the desorbed vapor is condensed at the ambient temperature and delivered via a passive heat sink, requiring no additional energy input.
For visualization purposes, we used a condenser with a temperature controller to maintain the temperature slightly below ambient, but above the dew point, to prevent vapor condensation on the inner walls of the enclosure. However, active cooling is not needed in a practical device since the hot desorbed vapor can condense at the cooler ambient temperature using a passive heat sink.
If water would condense on the walls at ambient temperature, it would whether the TE cooler was there or not.
The authors clearly state that the thermoelectric cooler can be equivalently replaced by a heat sink. Newton's Law of Cooling states this is impossible. A heat sink must become warmer than ambient in order to dissipate power. The water volumes condensed in the paper depend upon a surface that *does not increase in temperature*. You continue to argue from authority on this matter, rather than accept the simple fact that heat cannot be transferred from one body to another without a temperature differential. This reality negates virtually the entire premise of the paper: that it is possible for this hypothetical passive device to condense large amounts of water from the air without becoming warmer or without an input of work.
And the next step is not to use a heat sink to demonstrate this. That was the *first* step. The experimental data, as I've already told you, conveniently omits the energy input required to condense water vapor, despite how ridiculously easy this would be to measure and record. Even easier would have been to not use the thermoelectric cooler at all and simply rely upon its very ample heat sink as shown in the photo.
(https://www.eevblog.com/forum/renewable-energy/water-out-of-desert-air/?action=dlattach;attach=313454;image)
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From first hand experience I will tell you that with rare exception, university scientists have little or no control over what their institution's public relations office publicizes. Anyone who suggests otherwise is just making sh*t up.
Edited to add: Interesting conversation at U of the Berks with Omar Yaghi with some interesting points about science and society:
https://www.youtube.com/watch?v=tOxfp1mjTu0 (https://www.youtube.com/watch?v=tOxfp1mjTu0)
Watching this now. Excellent video. Thanks for posting it.
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rather than accept the simple fact that heat cannot be transferred from one body to another without a temperature differential.
Doh ! Really ::). No one here nor the authors of this paper would refute that fact. If you cannot read the paper and understand why that is not what is being asserted here then I can't help you.
And the next step is not to use a heat sink to demonstrate this. That was the *first* step.
You continue to refuse to acknowledge or are unable to understand that this is not an engineering paper. The intent is not to build or demonstrate a working prototype. The intent is to characterize the adsorption/desorption properites of MOF-801.
The rest of your post is full of similarly unsupported or irrelevant assertions equivalent to a "the bible says so" argument.
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You continue to refuse to acknowledge or are unable to understand that this is not an engineering paper. The intent is not to build or demonstrate a working prototype. The intent is to characterize the adsorption/desorption properites of MOF-801.
Quoting the paper again
Finally, a proof-of-concept MOF-801 water-harvesting prototype was built to demonstrate the viability of this ap-proach outdoors (Fig. 4A). ....
It seems you are the one refusing to acknowledge or understand what was written in the paper.
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Important to keep in mind that the optimistic claims in the paper are based on a computer simulation they did, but they are not clear about this.
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Quoting the paper again
Finally, a proof-of-concept MOF-801 water-harvesting prototype was built to demonstrate the viability of this ap-proach outdoors (Fig. 4A). ....
Yes and it did exactly that by demonstrating and allowing them to characterize the adsorption/desorption properties of MOF-801 over a few hours outdoors.
As I stated earlier, I think the use of the term "proof of concept" was unwise since it seems to have induced a Pavlovian type neurologic tic in some engineers causing them to perseverate on this small portion of the paper thinking it is about engineering a prototype.
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Important to keep in mind that the optimistic claims in the paper are based on a computer simulation they did, but they are not clear about this.
Not exactly true.
(https://www.eevblog.com/forum/renewable-energy/water-out-of-desert-air/?action=dlattach;attach=313480;image)
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At about half the length of TF's video, here's Yaghi talking about the MOFs in general. Because it's educational and not a "look how stupid those people at MIT and Science Magazine are" video, it won't appeal to TF's troll entourage.
https://www.youtube.com/watch?v=bzDIH7olP0c (https://www.youtube.com/watch?v=bzDIH7olP0c)
Note: how often Yaghi mentions collaboration with other scientists, how he attributes major improvements in the technology to his students, the long-ish history of MOFs and their applications, the fact that Yaghi keeps mentioning open problems, the long list of publications in the slide footers, and the large scale use of MOFs being developed by BASF.
And as to the other lab director involved in the Science paper, Evelyn Wang of MIT, she seems to know a bit more about using solar power than people who yell "thermodynamics," Tourrete's-like, at any thing that TF tweets:
https://www.youtube.com/watch?v=P8-8FveMieM (https://www.youtube.com/watch?v=P8-8FveMieM)
Interesting idea, making solar power dispatchable right at the generation point (rather than using grid-scale batteries); that would be a game changer for solar.
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Quoting the paper again
Finally, a proof-of-concept MOF-801 water-harvesting prototype was built to demonstrate the viability of this ap-proach outdoors (Fig. 4A). ....
Yes and it did exactly that by demonstrating and allowing them to characterize the adsorption/desorption properties of MOF-801 over a few hours outdoors.
As I stated earlier, I think the use of the term "proof of concept" was unwise since it seems to have induced a Pavlovian type neurologic tic in some engineers causing them to perseverate on this small portion of the paper thinking it is about engineering a prototype.
All the thermodynamics and water-absorbing properties of MOF-801 have been characterized in previous studies, as I linked earlier. It's just that in those (proper) studies they say MOF-801-P and MOF-801-SC for crystalline powder and single crystal forms, something they do not specify in the Science paper (although they do refer to it as powder).
@mtdoc This is where they get the "2.8 liters per kilogram of MOF" figures from:
Simulated adsorption-desorption dynamics for the MOF-801 layer with the optimized packing porosity of 0.7 are shown in Fig. 3 for 1 sun and realistic boundary conditions for heat loss (a natural heat transfer coefficient of 10 W m–2 K–1 and standard ambient temperature). In this simulation, MOF-801 was initially equilibrated at 20% RH, and the vapor content in the air-vapor mixture that surrounds the layer during desorption increased rapidly from 20 to 100% RH at 25°C. This scenario is more realistic compared with the model experiment described above because water is harvested by a condenser at ambient temperature. Once solar irradiation was stopped, the air-vapor concentration reverted to 20% RH for vapor adsorption from ambient air, and the heat from the adsorption process was transferred to the surroundings. A detailed description of the boundary conditions and idealizations in the simulation is given in section S8 of the supplementary materials. First, water uptake decreased with time during solar heating and water condensation, then increased through adsorption, as shown by the simulated water uptake profiles for the MOF-801 layer at thicknesses of 1, 3, and 5 mm (Fig. 3). The temperature correspondingly increased and then decreased with time. Continuously harvesting water in a cyclic manner for a 24-hour period with low-grade heat at 1 kW m–2 can yield ~2.8 liters kg–1 day–1 or ~0.9 liters m–2 day–1 with a 1-mm-thick layer. Alternatively, per one cycle, a 5-mm-thick layer of MOF-801 can harvest ~0.4 liters m–2. Our findings indicate that MOFs with enhanced sorption capacity and high intracrystalline diffusivity—along with an optimized crystal diameter, crystal density, and thickness of the MOF layer—can further boost the daily quantity of water harvested from an arid environment.
The paper describes three different things, 1. preliminary prototype, 2. Simulation and optimization using COMSOL Multiphysics, 3. proof-of-concept prototype (performed over two days on the roof of MIT and then extrapolated).
Good night, nice fighting with you all. :box:
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All the thermodynamics and water-absorbing properties of MOF-801 have been characterized in previous studies, as I linked earlier. It's just that in those (proper) studies they say MOF-801-P and MOF-801-SC for crystalline powder and single crystal forms, something they do not specify in the Science paper (although they do refer to it as powder).
That is a misrepresentation or perhaps you don't understand the scientific process? In fact if you read the first paragraph, they specifically reference the study you sited earlier (Furukawa et al 2014 - ref 10 in their paper) and go on to detail their further elaboration on the earlier work. That is how science works. One study builds on another.
The paper describes three different things, 1. preliminary prototype, 2. Simulation and optimization using COMSOL Multiphysics, 3. proof-of-concept prototype (performed over two days on the roof of MIT and then extrapolated).
Another misrepresentation. There is no preliminary prototype only the one POC device. And you left out their experiments and data performed in an environmental chamber - probably the most important part of the paper (much more than the POC device). Did you leave that out intentionally?
Good night, nice fighting with you all. :box:
It's an enjoyable debate minus the "pathetic" ad hominens ;)