this post was submitted on 18 Jul 2023
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Prove me wrong, please?

edit: thanks for all the great comments, this is really helpful. My main take-away is that it does work, but requires dry air. In humid conditions it doesn't really do anything.

Spouse bought this thing that claims to cool the air by blowing across some moist pads. It's about as large as a toaster, and it has a small water tank on the side. The water drips onto the bottom of the device, where it is soaked up by a sort of filter. A fan blows air through the filter.

  1. Spouse insists that the AIR gets cooled by evaporation.
  2. I say the FILTER gets cooled by evaporation.
  3. Spouse says the cooled filter then cools the air, so it works.
  4. I say the evaporation pulls heat (and water) from the filter, so the output is actually air that is both warmer and wetter than the input air. That's not A/C, that's a sauna. (Let's ignore the microscopic amount of heat generated by the cheap Chinese fan.)

By my reckoning, the only way to cool a ROOM is to transport the heat outside. This does not do that.

We can cool OURSELVES by letting a regular fan blow on us = WE are the moist filter, and the evaporation of our sweat cools us. One could argue that the slightly more humid air from this device has a better heat transfer capacity than drier air, but still, it is easier to sweat away heat in dry air than in humid air.

Am I crazy? I welcome your judgment!

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[–] schmieroslav@discuss.tchncs.de 107 points 1 year ago* (last edited 1 year ago) (11 children)

I think that the evaporation in theory is able to cool the room, the heat energy is transferred into launching a bunch of water molecules airborne so to speak. Hanging some wet towels around would also do that.

However, the performance of such small devices is probably not sufficient to significantly cool a room, and it has a lot of drawbacks (filter gets mouldy easily, ...)

Here's an excellent video about these swamp coolers: https://youtu.be/2horH-IeurA (he has many videos on heat pumps and stuff)

[–] eth0p@iusearchlinux.fyi 48 points 1 year ago (1 children)

Aw. I was going to post the link to his video, but you beat me to it.

But yeah, Technology Connections makes some excellent and informative videos. To anyone else who sees this: If heat pumps, refrigeration, or climate control technology aren't your cup of tea, he also covers older technology based around electromechanical designs (as in, pre-dating microcontrollers and programmable logic) and analog media recording devices.

[–] JimmyMcGill@lemmy.world 35 points 1 year ago (2 children)

I mean even if they aren’t your thing you should check out his videos.

I remember watching a 20 or so min video on an antique toaster and since then I’m also pissed at the inferior toasters of today.

His videos are gold.

[–] FlapKap@feddit.dk 5 points 1 year ago (1 children)

Can someone please explain why toasters aren't made like that anymore?? I would happily forgo the led and the obnoxious ding they make to have them make the toast perfectly every time

[–] gears@sh.itjust.works 10 points 1 year ago

It's cheaper to make a shitty time based solution.

[–] Rhaedas@kbin.social 3 points 1 year ago

That may have been my intro video to him. Can't go wrong with any topic, no matter how trivial it may sound. You will come back afterwards saying, wow, never knew that.

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