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by femto
4388 days ago
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Point taken! I'm not an expert. As I understand it, a container of boiling water will have liquid in the bottom half and steam in the top half. As the pressure and temperature rise, the steam/water goes supercritial, meaning the water/steam boundary disappears and the whole container becomes a homogenous mush of supercritical fluid. Am I right in thinking that this supercritical fluid can flash into steam faster than a combination of water and steam? My thinking is that for a water/steam combination to convert into steam, the water molecules have to take the time to break their bonds and separate into a gas. For a supercritical fluid it's faster because there are no bonds to be broken? I'd be grateful if you can correct the above, as I can learn something here. |
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The reason for that would be that there is a nucleation process in forming gas from liquid, which does take some time. Or at least more than not needing to do so.
There is some terminology you're using that bothers me, like "flash into steam" isn't really a good way to describe it. At that point you'd be better off describing it as "super pressurized steam" converting to "normal pressure steam" or something. It's just expanding, but there is no flash (which to implies a sudden change). It's gradually and continuously decreasing in density.
I think part of this may be confusion over how we overload the word "water" to mean "liquid water" as well as "water the chemical". I am meaning "water the chemical" which can be a solid, liquid, or gas. Steam is water that is a gas.
With a supercritical system, you can take liquid water, stay in the liquid state until the water becomes supercritical (where the liquid and gas phases are indistinguishable), and then move across a boundary from "liquid like" to "gas like", go back into a sub-critical state as gas, and never formally boil/flash/etc.