[2023] The Phase Change Update : Liquids, gases, solids

A lil somethin somethin: You can find the details for this event on the announcement page here.

Stationeers has the bold aim of modelling many very complex systems, and trying to do so in a way that will run acceptably on most computers. For a long time we have wanted to better model phase change (movement of state between gases, liquids, and solids). This will allow us to make more interesting mechanics such as rocket fuels in future updates. The task has come with significant challenges, trying to maintain support for existing worlds and not make the game even more complex for new players than it already is. This is the first step in making our overhaul of Rockets, as it was necessary to do this work before continuing with the work on Rockets.

Description
Gasses now can phase change, when under different pressures/temperatures. Normal Atmospheric pipes break from the stress/weight of condensing liquids, so use a condenser valve to ensure liquids can drop safely into liquid pipes. You can reference a phase diagram in the Stationpedia to figure out what a gas or liquid wants to be at a given temperature and pressure. Liquids are all incompressible, and don't generate pressure themselves, so any isolated liquid will boil off, and create a vapor pressure to stay stable even in liquid pipes.

Boiling a liquid takes energy, so things get colder (condensing gas, releases the same energy). If you were to use a purge valve to constantly remove the boiling off gasses from a liquid pipe, you'd notice that the liquid will keep boiling until it's cold enough to reach its freezing point. Freezing liquids in pipes will burst the pipe and create ices in world. Conversely, Pressurizing a gas can Condense it into a liquid, which will release energy, causing it to heat up, and the liquid can be tapped away with a condensation valve. Moving the liquid around, and controlling where it condenses and evaporates will let you control what should be hot, and what should be cold.

There are two structures built from the Phase Change Kit, the Evaporation Chamber and the Condensation Chamber, that can assist in helping you control phase change. They act like tanks with an input pump, pressure regulator, and heat exchanger, so that you can control the temperature of a fluid (taking the energy, or giving more energy) while trying to make it phase change. These do the same thing as building a system of pipes, pumps and heat exchangers yourself, but the cost of this more stable environment, comes at a hit to throughput, and scalability.



A specific example (with ball-parked numbers) is on Mars, where pollutants exist outside around 0c as gas. Collect Pollutants from outside, filter, and pressurize them and they will become liquid around 2000Kpa. You can then move the liquids to a place you want cold, then vent off the gas off. The pollutants will start around 0c and boiling half of them by creating a vacuum, will drop the temperature to around -20c. You now have made a basic cooler.

It starts to get more interesting when you then use the waste vented gas, to cool off the incoming liquid, and that now becomes -20c, and when it vents, the new gas is closer to -40c. There are many decisions to make, and problems to solve with phase change and there are countless systems to build, that we haven't even dreamed of.

Despite this sounding, and being, very complex, most starting out gameplay remains the same, with condensation and evaporation really only showing themselves as problems AND solutions in larger builds and on extreme worlds. On Europa, the Co2 you've been breathing out can freeze out of the air and fly around during a small accident. Gasses on Vulcan might be fine to slowly pump around, but over collect and pressurize them too much, and the liquidized fluids will burst through your stressed pipes.

Liquids in world
Currently liquids can exist in the world and behave and mix like any other gas. They are visualized by a vapor particle effect. In the future we may explore a more liquid-like behavior in the atmospheric system and a more traditional way of visualizing them. Liquids can often end up in world after a pipe has burst. Gas pipes have a max pressure of 60Mpa, but get stress from liquids existing in them, and have had their volume reduced to 1/10th of their former value. Liquid pipes however have larger volumes, and don't take stress damage from liquids, but only support up to 6Mpa of pressure. Both pipes will rupture very quickly if liquids start to freeze in them.

We have some ideas about how to truly represent liquids in world, but we don't want to rush out solutions for this without carefully thinking them through. This is a lot of work, and we need to make sure it's performant. We will update on possible steps in future updates.

Gas Pumping
With the changes to pipe volumes, gas movement speed on pressure regulators, mixers, and filtration machines has been changed to no longer increase with pipe network volume. Instead pressure differentials increase the speed, meaning if you actively pump, or pre pressurize the inputs, these machines will let large amounts of gas through. Conversely, if you let their outputs build up to pressures higher than their inputs, they will slow down, and forced pumping will be needed to clear their output. This also means back pressure regulators now function very well as safety release valves.

New Devices
A range of new, but familiar, devices have been added to help deal with the new liquid behaviors. These are mostly different types of pumps, valves, and vents to help control the flow of gasses and liquids.

Condensation and Evaporation Chambers The Evaporation Chamber and Condensation Chamber are integral devices for safe phase transitions between liquids and gasses. Together, these chambers can be utilized to construct a DIY air conditioner, capitalizing on the phase change properties of gasses.



Inline Tanks Inline Tanks are basically just oversized pipes with a large volume. With the reduction of normal pipe volumes these can be used in the specific places where you may have just used a number of pipes by themselves.

Passive Liquid Inlet The Passive Liquid Inlet will quickly remove liquids from the world into the connected pipe network while equalizing gasses between the world atmosphere and the pipe network.

Expansion Valve The Expansion Valve allows for a one way movement of liquids from a liquid pipe into a gas pipe. This can be used to allow liquid into a gas pipe to evaporate.

Condensation Valve Allows for the one way movement of any liquids from a gas pipe into a liquid pipe.


Pressurant Valve Pumps gas into a liquid pipe in order to raise the pressure.

Purge Valve Allows for the removal of gas from a liquid pipe, and behaves similarly to the back pressure regulator.

Gas States Each gas now has a solid, liquid, and gas form. Each gas has different temperatures, in relation to pressure, that define which state it will be in. You can see the relationship between temperature and pressure in the Stationpedia using the phase change diagram on the gas pages.





Save Migration
With so many changes around atmospherics, including changing the properties of gas mixes as well as some volume changes of devices and pipes, it was necessary to provide a tool to modify saves when they are opened. This tool will do its best effort to put everything in a stable state allowing you to safely load your games. The old default version has been shifted to “previous” so that if you need to load the game to make modifications to your saves you can do so there before loading it on the current version.

Artwork Wallpaper
[expand type=Click to reveal a wallpaper version of this weeks wonderful patch artwork][/expand]
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