A bit familiar with latent heat of vaporization. And the surface roughness both holds more water due to more surface area, but also is what makes for water being able to get out without bulk air flow. It is what it is.
This is very different from your four burner example too. First, there is a misconception. The pans look dry but they are not. There’s still multiple layers of water stuck to them unless you’re starting to approach heats where they glow. You can’t see the water but it’s there. The water that was stuck to water is easier to remove than the water stuck to the metal that you can’t see. Water will evaporate down until the attraction to the surface through the closer layers gets strong enough to stop net evaporation. At that point, just like with filament - you have to start adding energy to get more water to let go. You are trying to rationalize bulk effects when what we are concerned with are molecular affinities for surfaces. (And in reality, there’s energy as long as the system is above absolute zero. Again, it comes down to if there is enough energy (heat in this case) to promote molecules to the vapor phase.)
Ask anyone who has ever worked with high vacuum systems about baking them out to get rid of those water layers right at the metal surface. It takes lots of heat and time - heat that would melt filaments. You bake at 300-400C under vacuum. Metal starts to glow around 460C.
Different materials have different affinities for water. Sure, water evaporates. We all have seen it. But can you explain setting a chunk of dry calcium chloride on a table and watching as the surface wets and it just ends up a puddle of liquid? A pan of water evaporates “dry” all on its own but a chunk of something else (I picked a deliquescent salt to go to the extreme) pulls water out of the air and dissolves in that water?
The difference is the attraction felt between the molecule and a metal surface and the molecule and the filament surface where different atoms in the plastic can make fairly strong bonds with the water. But because of the extreme surface area of the pitted and rough filament surface, there’s lots of active sites where water can stick down.
I don’t know this helps but the burner analogy doesn’t apply. There’s books on surface chemistry. It’s a huge field because that’s key to many catalysts among other things.
And now to dryers. I’ve got a single Sunlu S2 (single bay) filament dryer and just counted I’ve got 28 spools of filament dried hard and stored in polyethylene cereal boxes.
How do I manage my S2 (with 1/4 the capacity of an S4)? Right now my dryer is sitting unused and off while stuff is printing from the AMS which is reporting “1” for humidity.
I change out filaments as needed with no problem. I don’t leave them sitting out, I have hygrometers in the boxes, and all are pegged at the low end and displaying “10” which is the minimum they can and will ever display.
What is required to keep my filament dry? Not much, really. The filament I dried this summer is still at the ready. I don’t have to dry it since it’s already dry. Hygrometers confirm it. That’s why my Sunlu isn’t running. I fire it up when I need a color that isn’t already dry. It’s also how I have to operate here. I’ve had this printer for a year now and had seen moisture effects. I’m doing more PETG HF and if I stored open with that I couldn’t print. PLA too at certain times of the year.
Good info all around, but let’s get back to it.
