Probably a stupid question, but will we ever have something like a microwave to make things cold? Is there a reason this can't exist?

Melatonin@lemmy.dbzer0.com to Asklemmy@lemmy.ml – 486 points –
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So this isn't fully what you're looking for, but if you want to cool something more quickly, wrap a wet paper towel around it and stick it in the freezer.

Water has a higher rate of heat transfer than air, so it'll speed up the cooling. Just make sure to check on it occasionally so any sodas you put in don't explode

I expect this post in a couple days: "How do I remove a paper towel that is frozen to my bottle of wine?"

I forgot to mention that the bottle is fractured and the frozen paper towel is the only thing holding it together

barely held together by alcohol and a thin, icy, fragile exterior

I'm in this comment and I'm totally fine so stop asking.

Should work even better with salted wet paper towels

We used to put warm beer, ice, and salt in a cooler to cool the beer down quickly on Friday after work. It worked great for that.

Also it's not only a higher rate of cooling, but the dryness of the freezer makes some of the water evaporate and carry heat away with it!

The water has to be cooled too, and there's still air around it though?

I guess we're talking about direct contact, not around a container, otherwise the water turned ice may even serve as an insulator?

The water creates a better way to transfer heat from the container to the freezer because it has direct contact with the container and replaces the air around it. Yes the water needs to be cooled too, but still the process is way faster because air really is a good insulator for heat. This is why insulating materials for houses e.g. always try to maximize air content (foam, glass wool, styrofoam)

You also get evaporative cooling, as the freezer is a very low humidity environment. This is accelerating the cooling much more than any thermal conductivity the water adds.

The reverse process is why humid air makes your beverages get warm quickly when the water precipitates on a cold can/glass.

N.B. maximize air content while minimising air movement and therefore convection. Otherwise you could just have cavities in your walls for maximum air.