Water out of desert air

[mtdoc]

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! 

Here's the last page:

[tronde]

Full article seems to be here

http://yaghi.berkeley.edu/publications.html#2017

[LabSpokane]

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! 

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)

[LabSpokane]

Full article seems to be here

http://yaghi.berkeley.edu/publications.html#2017

Only partial. Does not include the supplemental material.

[LabSpokane]

Oh, and a Thank You to mtdoc for the final impetus to join AAAS.  This discussion got me off the fence. 

[mtdoc]

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!

[LabSpokane]

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!   

[mtdoc]

We're going to have to disagree about whether or not this is an engineering paper. 

I can agree with that.

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!

[tronde]

Full article seems to be here

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

[LabSpokane]

Full article seems to be here

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

I missed that.  I assumed that the supplemental material was paywalled.  Thank you.

[mtdoc]

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. 

[ConKbot]

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"

[gameridian]

Thunderfoot's response

[mtdoc]

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.

[josecamoessilva]

(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.

[Hensingler]

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.

[josecamoessilva]

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.

[mtdoc]

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.

[LabSpokane]

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.

[TheAmmoniacal]

@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.

[mtdoc]

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.

The authors of the paper uttered another knowing falsehood in offering that the thermoelectric cooler was only there to assist in visualizing the condensation. 

    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. 

[mtdoc]

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.

[TheAmmoniacal]

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?

[mtdoc]

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.

[LabSpokane]

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.

The authors of the paper uttered another knowing falsehood in offering that the thermoelectric cooler was only there to assist in visualizing the condensation. 

    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.