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Phase change hysteresis


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I've noticed that there's some hysteresis on the phase changes--liquid doesn't want to turn into a gas until a bit above the vaporization point, and once there doesn't want to condense again to a liquid until a bit below. My sense is that this effect may be even stronger inside pipes.

Is this effect well-understood? Is there some well-defined amount by which one can reliably exceed the condensation/vaporization points without damaging conduit?

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It's 5C or so.

The problem is, without it you'd get tons of annoying "flickering" when small puddles vaporize and condense few times a second. This would visibly push gases and liquids around, similar to what you get when polluted and clean water waterfalls combine and splatter "droplets" horizontally.

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17 minutes ago, Coolthulhu said:

It's 5C or so.

The problem is, without it you'd get tons of annoying "flickering" when small puddles vaporize and condense few times a second. This would visibly push gases and liquids around, similar to what you get when polluted and clean water waterfalls combine and splatter "droplets" horizontally.

It still happens

I have seem small balls of ice "flickering" from a little ball to drip and back again

20181113004628_1.thumb.jpg.3396506f86245e8140e04110293c7c06.jpg20181113004625_1.thumb.jpg.b210dd8192503793f9837c459a0e124f.jpg20181113004628_1.thumb.jpg.3396506f86245e8140e04110293c7c06.jpg

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3c afaik in any given direction past the transition point to cause transition for all known types of matter capable of changing in phase or type

except in pipes holding less than 1% of the pipes capacity where the phase will not change unless its been patched

 

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3 hours ago, Neotuck said:

It still happens

I have seem small balls of ice "flickering" from a little ball to drip and back again

That's because their (thermal) exchange partners changes.

As debris, it exchanges with the solid below and gas on the very tile.

As puddle, it exchanges with debris, the solid ground below and gas on the three adjacent tiles.

In your case the polluted ice is obviously colder than ~ -15°C (since otherwise it would be liquid), while the ground is not able to counter that unless the Polluted Ice is taken out of the equation. Debris can not exchange heat with debris directly.

One can frequently find that happening with polluted water and clean water, with the speed of the loop beginning anew increasing the less clean water there is. The Polluted Water at the bottom is warm enough to melt the ice (> +2.6°C) and the top is cold enough to freeze it (< -3.6°C) 

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4 hours ago, Neotuck said:

It still happens

I have seem small balls of ice "flickering" from a little ball to drip and back again

20181113004628_1.thumb.jpg.3396506f86245e8140e04110293c7c06.jpg20181113004625_1.thumb.jpg.b210dd8192503793f9837c459a0e124f.jpg20181113004628_1.thumb.jpg.3396506f86245e8140e04110293c7c06.jpg

The funniest way I've seen this happen is when there's an almost freezing layer of clean water on top of some polluted water. What happens is it becomes a ball of ice, falls down, melts for some reason, then turns to a ball of ice again to fall down etc..
It's a very funny thing to see, if a little weird.

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As I have already stated in another thread, I think it would be important if the evaporation energy and melting energy were simulated in ONI.

Especiallly when dealing with phase changes, I think it would be very important to simulate this.

That way, in order to boil 1000 kg of water that is 50°C, you will need to invest only 209 MJ to heat up the water to its boiling point of 100°C, but 2257 MJ (ten times more energy) to actually boil it, i.e. to make the actual phase change.

Since the energy due to the phase difference is so much higher than the energy due to the heat difference, it does not make sense that ONI neglects it completely.

If the evaporation energy were simulated, then phase changes would be much more gradual, due to the massive amounts of heat energy required for the phase change.

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