[petermcneeley]

I actually had a discussion on this subject with Phil Mason aka Thunderfoot who has a Phd in chemistry and is the creator of the video that is critical of this announcement ( https://www.youtube.com/watch?v=e3s-xI895zc )

The discussion was about how much work is actually required to condense the water vapor. The fact is that it is thermodynamically possible to MOVE more heat energy (Q) than work (W) applied. The efficiency of heat movement is dependent on temperature gradient but is more than 100% efficient. So as bizarre as this sounds it actually requires effectively zero work to condense water from the air at 100% humidity.

[mchannon]

At 100% humidity, sure. If it's raining, it takes no work to get wet.

I have a unit in my garage that can actually produce water at less than 10% relative humidity, moves a lot more air so it has more chances to actually capture the water, and smokes these other units under price/performance, particularly when tested in a desert. It's not a dehumidifier-based system. It's also cheaper to build.

Email me for details.

[Sephr]

Details I received from emailing mchannon:

> Thanks for reaching out. Mine uses a deliquescent salt, which requires no energy to absorb water from the air. It's pretty messy, but does the job. Getting the water back out is where the energy is required, and this is non-trivial, but still far better than those dehumidifier approaches, which are unfortunately the perpetual motion machines of our era.

[jessriedel]

Isnt the assumption here that he didn't want to share this publicly? It seems like a betrayl of trust, regardless of the merits.

[mchannon]

It’s a slightly different motivation. There is something worse than a forum troll, and that’s a forum censor.

I could post all the stuff publicly, but then I’d get more downvotes, because a lot of forum users enforce the norms they like.

I see the number of points in my posts like this one jockey up and down repeatedly, meaning equal double-digit numbers of readers approve and don’t. Being able to follow that history would prove fascinating, but it’s not a feature on HN.

I’ve even attracted a following of a couple of readers who downvote anything I post.

So it’s with the norm—enforcing downvoter in mind when I want to reach out.

Share away. I can’t even give my technology ideas away.

[Sephr]

I never told him that I would keep his correspondence private, nor did he ask me to do so.

Here is the entire email chain between myself and mchannon: https://go.eligrey.com/t/mchannon-email

[jessriedel]

That's why I said "assumption", i.e., from the context that he didn't post on HN but would respond to private messages.

[petermcneeley]

* Not to clutter hn but here are my notes for that discussion:

http://www.sfu.ca/~mbahrami/ENSC%20461/Notes/Refrigeration%2... http://hyperphysics.phy-astr.gsu.edu/hbase/Kinetic/watvap.ht... this shows that its quite large amount Efficiency fridge = 1 / ( Th / Tl - 1)

There is actually way more water in the air than 0.04 grams... i think this is because liters not m^3 for 1m^3 there is 30 grams at 30 degrees and 17.3 at 20 degrees. its at least ~15/10 - > 1.5 grams per Centigrade Say we do small diff of 4 degrees, 30 to 26. We gain 1.5 * 4 = 6 grams / m^3 To do this we need to cool 1m^3 water at 30 to 20. Now this is tricky because humidity but https://www.engineeringtoolbox.com/heating-humid-air-d_693.h... h = 1.01 (kJ/kg.oC) t + x [1.84 (kJ/kg.oC) t + 2502 (kJ/kg)] x is relative weight so its actually small like 0.03 so it changes the result very little h = 1.06 (kJ/kg.oC) t + x 2502 Kj/kg partial diff with t gives us 4.24kJ/kg change for cooling the air (sensible) partial diff with x gives us (0.006kg delta) 2500 - > 15kJ/kg for this 4 degree change for condensation with 6g/m^3 of water Since the cooling of air that didnt result in water is reclaimable energy lets ignore it Now efficiency of this heat transfer 1/ (303.15 / 299.15 - 1) = 75x heat transfer efficiency. Does this make sense? we know heat pumps are amazing :) so per gram its like 15kJ/6g = 2.5kJ/gram -> this is really expected as 2.3MJ/kg from original video!

However this heat (Q) is moved via work (W) at 75x rate This means to get 1kg (1L really) it only takes 30KJ So at 15watts (J/sec) -> 2000sec -> 33 min Perhaps this wont work because the MASSSIVE heat sink required :)

How much air needs to be moved? we get 6 grams for each meter cubed of air. Not great thats about 166m^3 of air that needs to filter. https://www.amazon.ca/Ultra-Strong-DC12V-Cooling-200CFM/dp/B... 200CFM -> 5.66 m^3/min 60 min/h = 339 ... this is double what we need. its about 1.6A 12v = 15 watt... but its more than we need. Half it?

[robotrout]

> Perhaps this wont work because the MASSSIVE heat sink required

Perhaps not! Thanks for running the numbers.

[andbberger]

Sort of topic, but man is his presentation format tiresome.

I would never have guessed that he has a PhD in chemistry... he comes across as rather off his rocker

I think it's his rhetoric - there's some substantive argument under the surface but it gets washed out with all the aggression and rhetorical fallacies.... it's very schizophrenic...

[andbberger]

Following up on my comment because this is driving me nuts...

His aggressive diatribe manner of speaking seems all too ubiquitous these days, as we find ourselves conducting the vast majority of our communications with the 'hivemind' on platforms where ability to attract attention wins out over quality discourse.

And it's just fucking impossible to have any real conversation in that context. There's no room to entertain subtleties, the higher-order structure of the subject, if you will.

For instance.... he makes it out like everyone involved in this prize is absolutely clueless about thermodynamics and that there are no conceivable advancements to be made for this particular scenario because thermodynamics.

Bullshit. There's plenty of innovation to be had. You can take advantage of daily temperature swings, use a ground-source heat pump... and almost certainly current humidifiers aren't operating at the thermodynamic limit; there's probably work to do in developing better materials, optimizing the design for efficiency, etc

[tastroder]

I kind of see what you're saying in regards to leaving no room for subtleties but that argument goes both ways.

I tried to find accurate information on the technology and how they differentiate from the regular old dehumidifier spiel when I first heard about the prize, even spending a few minutes on Google scholar searches for their contributors. It was all drowned out by marketing materials and fancy graphics.

On one side we have a person with a Youtube brand that lives off of these kinds of debunkings, including their over the top tone. On the other side we have multiple companies with a product and accompanying marketing budgets. Both clearly lacking in room for discussion and subtlety. Could the youtuber get their point accross more objectively and clear? Sure. Would somebody listen or even discover their argument? I kind of doubt that. Just like the product would not gain traction from scientific papers alone.

Trying to make my point clearer, I do not feel like that the Youtube person is solely at fault for a weirdly framed discussion here. If the XPrize winners have more innovation to show than combining two technologies that they seem to have used before they should clearly communicate that, including scientific analysis that are easy to discover. They got a prize for a product that claims to be better than competition with similar tech in a space that previously saw players that absolutely were pure snake-oil. Just put facts next to your pitch decks and fancy marketing materials people.