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> dehumidifiers already do a good job of getting water out of air for the energy price you have to pay They do a terrible job. Condensate dehumidifiers are as
by crazygringo 1y ago
> dehumidifiers already do a good job of getting water out of air for the energy price you have to pay
They do a terrible job. Condensate dehumidifiers are as expensive to run as an AC, produce unwanted heat, and are noisy. Dessicant dehumidifiers are even less energy-efficient.
If there's a way to extract moisture from the air with less energy and less noise, that would be huge.
- simiones 1y agoSo, is this new method less noisy and/or more energy efficient? The article doesn't really say.
- thfuran 1y ago>without the need for any external energy. That sure seems to imply that there's no need for a noisy and power hungry compressor.
- vintermann 1y agoIt also seems to imply that it violates thermodynamics. It takes energy to condense water, so where does it get it? If it isn't external, it runs out.
- freeone3000 1y agoCondensation of water is exothermic. If you add a cold thing to the environment, ie, remove heat from the water, the water will condense all on its own. This reaches steady-state when the cold thing is warm and the water is condensed. No thermodynamics issue! They’re claiming they have a material that will do it at higher temperatures. Assuming such a material gets hotter as it works, there’s no thermodynamics problem here.
- nssnsjsjsjs 1y agoWhat about entropy? The reason you need to power AC for example is that if you didn't you could reduce entropy and generate power for free, and basically reverse time.
- freeone3000 1y agoThe amount of entropy in a closed system is not allowed to decrease, but it is allowed to be constant. The amount of energy released by the phase shift is equal to the amount of energy absorbed by the object as heat.
- simiones 1y agoSure, but then the temperature of the object has to increase. And as its temperature increases, it has to stop condensing water - at the very least, once it reaches ~100C, it will instantly boil off any extra water that it condenses.
- simiones 1y ago> They’re claiming they have a material that will do it at higher temperatures. Assuming such a material gets hotter as it works, there’s no thermodynamics problem here. That's ok, but the amount of water you get is fixed - the process can't continue. You install the device into your room, it condenses 1L of water as droplets on its surface (or, more likely 1ml of water), and it's now done, that's all the water it's going to remove/produce, if this is the right explanation. It would be perfectly equivalent to bringing in a cold slab of metal from your fridge into your room - it will condense some water as it gets hotter, and it will eventually get as warm as the room and stop condensing anymore water, forever. Conversely, if the process were continuous (say, as long as you remove the condensed droplets, new droplets form), as they seem to claim, that would very likely violate thermodynamics again.
- smus 1y agoYou are super confident a thing that exists can't exist https://en.wikipedia.org/wiki/Air_well_(condenser) https://en.wikipedia.org/wiki/Air_well_(condenser) Check out the passive section of the above
- kortilla 1y agoThose depend on energy differentials so the sun is the external heat source.
- petesergeant 1y agoEspecially for somewhere like UAE that in summer has the upsetting combination of massive humidity, no rain, and huge water demand.
- ChrisMarshallNY 1y agoSomeone here once posted a link to a story[0] about the Persian Cooling Towers, that you see all over the ME. Thousands of years old, I think. [0] https://www.bbc.com/future/article/20210810-the-ancient-persian-way-to-keep-cool https://www.bbc.com/future/article/20210810-the-ancient-pers...
- JKCalhoun 1y agoPerhaps OP was describing "swamp coolers" — or evaporative cooling?
- thfuran 1y agoThat's the exact opposite of extracting moisture from the air.
- moffkalast 1y agoRunning a swamp cooler + dehumidifier that doesn't heat up would mean being able to do self contained cooling which would be a massive thing. Currently the only way to do that is with desiccant which needs recharging too often to be practical.
- relwin 1y agoTech Ingredients demonstrates how this works: "Revolutionary Air Conditioner!" https://youtu.be/R_g4nT4a28U?si=MoRSi1mOyHiVbZUr https://youtu.be/R_g4nT4a28U?si=MoRSi1mOyHiVbZUr
- JKCalhoun 1y agoYou're right. I'll leave my original comment because I'm an idiot, ha ha.
- gus_massa 1y ago> If there's a way to extract moisture from the air with less energy and less noise, that would be huge. Less noise: I agree, but you still need some air flow so the corners of the room that are far away also get dehumidified. Perhaps a slow fan in enough, and when you run them slowly they are quieter. Less energy: It's not clear that this uses less total energy. It's easier to imagine what is happening if you compare it to a high tech Dehumidifier Bag. https://www.amazon.com/Wisesorb-Moisture-Eliminator-Fragrance-Dehumidifier/dp/B088N8DGP6?th=1 https://www.amazon.com/Wisesorb-Moisture-Eliminator-Fragranc... But instead of sending the drops down, they get attached to the device. You can use it only once unplugged. Then you have to buy a new one or use energy to extract the water (like boiling the water of the dehumidifier bad until you get the crystals again). It's not clear if building a new copy of this is cheaper than building some new calcium chloride salts, and/or if regenerating the new device is cheaper than regenerating the calcium chloride salts (that is usually not done).
- lolinder 1y agoLess energy would definitely be a huge plus but unless this violates our understanding of thermodynamics there will still be unwanted heat put out into the air. The heat from a dehumidifier comes primarily from the latent heat in the water being released so that the water can become liquid. This heat must be released somehow in this process unless they actually did find something that breaks our understanding of physics. Obligatory Technology Connections video on the topic: https://www.youtube.com/watch?v=j_QfX0SYCE8 https://www.youtube.com/watch?v=j_QfX0SYCE8
- deleted 1y ago[deleted]
- crazygringo 1y agoThat's true, but I was under the impression that most of the heat generated by current compressor dehumidifiers is just waste heat from the mechanical operation of the compressor itself. The phase change heat is there too, but it's significantly less. So there should still be a lot of room for improvement, theoretically.
- lolinder 1y agoYeah, there's certainly some of that, but going off of Alec's numbers and trial above you end up with a larger portion coming from the latent heat than from the mechanism, for the same reason that a heat pump is more efficient than an electric heater: it's condensing more water than it is running mechanisms. That said, his demo is not under typical operating conditions in that a dehumidifier is normally expected to actually be able to catch up and reduce humidity in the room, while his demo ensures that the humidity levels stay high throughout the hour. So it's likely that under normal operating conditions the mechanism's proportion of the waste heat is higher than it is in his demo.
- cyberax 1y ago> That's true, but I was under the impression that most of the heat generated by current compressor dehumidifiers is just waste heat from the mechanical operation of the compressor itself. Nope. It's almost all (>80%) latent heat. I believe, the theoretical limit is around 90% for typical room temperatures.
- 90s_dev 1y ago> If there's a way to extract moisture from the air with less energy and less noise, that would be huge. I vote we write to our legislators to update the laws of thermodynamics to enable this. Typically I would agree we should leave well enough alone, but in this case it seems like the benefits outweigh the costs.
- protocolture 1y agoJust run it in Australia, we already overturned mathematics.
- hackyhacky 1y agoThat's not how the laws of thermodynamics work. In reality, you would need to convene an international consortium to approve to the change, and the Chinese wouldn't sign on unless we agree to a temporary suspension of Newton's third law.
- 90s_dev 1y agoWe would only need a committee's approval if changing it would break things. I say we skip that process, test it in a lab somewhere in rural midwest where nobody lives, and see if gravity starts changing or whatever. As long as cows don't start to float in a 3 mile radius within 4-5 hours, that's probably good enough validation to move forward with changing thermodynamic legislation. [edit] we should also probably make sure the boiling point of water stays the same
- layer8 1y agoI’m not sure the constitution grants Congress that power.
- 90s_dev 1y agoThey already weighted in on the definition of π so why not? https://en.wikipedia.org/wiki/Indiana_pi_bill https://en.wikipedia.org/wiki/Indiana_pi_bill