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!

8 points
*

You’re wrong, your spouse is right.

Thermal energy is required both to raise the temperature of a mass of (in this case) water, and additional thermal energy is required to change its state from liquid to gas. This additional thermal energy is spent without creating any actual temperature increase, but it had to come from somewhere.

In this case, the thermal energy for the state change came from the surrounding air. The energy didn’t come from changing the state of the air, so it must have come from lowering the temperature of the air.

As others have noted, this only works in low-humidity environments. If the air is already saturated with water vapor, no more evaporation will occur. This is why high-humidity environments feel hotter: your sweat isn’t evaporating to cool you off.

permalink
report
reply
3 points

You owe your wife an apology.

permalink
report
reply
2 points

I have very good conversations with my spouse, and this is an ongoing one to figure out what’s really at play here. No apologies needed in either direction.

permalink
report
parent
reply
1 point

That’s good, with a sense of humor like that you need to be very careful.

permalink
report
parent
reply
1 point
Deleted by creator
permalink
report
parent
reply
0 points

What do you think they do in prison when the AC burns out?

permalink
report
reply
1 point

Fix the AC?

permalink
report
parent
reply
1 point

AC to run a prison can cost millions of dollars and take weeks to get shipped new parts. That’s the DOC for you, they are very slow to approve anything.

permalink
report
parent
reply
3 points
*

You sound persnickety. You’ll probably like this persnickety video about swamp coolers

permalink
report
reply
2 points

Here is an alternative Piped link(s): https://piped.video/watch?v=2horH-IeurA

Piped is a privacy-respecting open-source alternative frontend to YouTube.

I’m open-source, check me out at GitHub.

permalink
report
parent
reply
-6 points

I think you’re exactly right. That’s a humidifier.

permalink
report
reply
3 points

Unfortunately the spouse is right in this case. Water takes heat/ energy to evaporate. We use the same mechanism to cool ourselves with sweat. The evaporating water pulls heat out of the air and cools it.

permalink
report
parent
reply

Ask Lemmy

!asklemmy@lemmy.world

Create post

A Fediverse community for open-ended, thought provoking questions


Rules: (interactive)


1) Be nice and; have fun

Doxxing, trolling, sealioning, racism, and toxicity are not welcomed in AskLemmy. Remember what your mother said: if you can’t say something nice, don’t say anything at all. In addition, the site-wide Lemmy.world terms of service also apply here. Please familiarize yourself with them


2) All posts must end with a '?'

This is sort of like Jeopardy. Please phrase all post titles in the form of a proper question ending with ?


3) No spam

Please do not flood the community with nonsense. Actual suspected spammers will be banned on site. No astroturfing.


4) NSFW is okay, within reason

Just remember to tag posts with either a content warning or a [NSFW] tag. Overtly sexual posts are not allowed, please direct them to either !asklemmyafterdark@lemmy.world or !asklemmynsfw@lemmynsfw.com. NSFW comments should be restricted to posts tagged [NSFW].


5) This is not a support community.

It is not a place for ‘how do I?’, type questions. If you have any questions regarding the site itself or would like to report a community, please direct them to Lemmy.world Support or email info@lemmy.world. For other questions check our partnered communities list, or use the search function.


Reminder: The terms of service apply here too.

Partnered Communities:

Tech Support

No Stupid Questions

You Should Know

Reddit

Jokes

Ask Ouija


Logo design credit goes to: tubbadu


Community stats

  • 11K

    Monthly active users

  • 3.8K

    Posts

  • 204K

    Comments