I was reading about this water bottle by Botl that behaves like a canvas water bags to keep water cool. I found out that this idea is an old idea and cars would drive with water bags in front as shown below.
Here is what I found out about them: it seeps water through the bag and evaporates, causing the water to cool inside. Here is where I need some help:
Why does the water seep through the bag? Is it because the water molecules have a Maxwell speed distribution and only the fastest molecules seep out?
What mechanism is occurring for heat being removed from the water to evaporate the water on the bag’s surface? Doesn't radiation also contribute here?
Why does moving increases the cooling effect faster?
Answer
As far as I understand the idea is very simple:
as the bottle is covered in a film of water (due to a leakage of the container), this can evaporate. Due to the Boltzman distribution this will also happen well below $100°C$. The process of evaporating though takes energy from the system (called latent heat). This cools down the bottle.
If the surrounding air is "filled with water" it is harder for the liquid to evaporate and thus slowing the process, so always bringing fresh air to the system helps.
This is basically the concept of sweating as well, where you can immediately feel the effect of wind blowing on your moist skin.
Hope this helps and I didn't miss something.
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