A very quick and dirty guide to Phase Change Heatpumps

A very quick and dirty guide to understanding the new Phase Change changes in Stationeers to cool your base and how heat pumps work

Heatpumps crash course

Welcome to this very short crash course in cooling stuff with phase change!

Phase change is the process of changing between Solid, Liquid and Gas state.

All the gasses and liquids in the game that can be pumped through pipes, now has a boiling/condensation point, and a freezing/melting point.

The process of phase change moves energy. This energy is absorbed and released in the form of heat.

This is where heatpumps come in;

A quick refresher/explanation if you don't know how heat pumping through phase change works:
Condensation (gas becoming liquid) causes heat, evaporation (liquid becoming gas) requires heat. Same also applies when going to/from solid form (sublimation being the 'evaporation' of a solid to gas/liquid and deposition being the 'condensation' of a gas/liquid to solid).

This can be used to absorb and deposit heat where desired (by evaporating liquid where you need cooling, and condensing it where you want to deposit heat)

To visualize this, perhaps it makes more sense when you imagine boiling water; it requires heat to boil the water, which then causes it to evaporate-- it may not be obvious there but the boiling of the water actually removes heat. If the heat source is removed, the boiling and evaporation will stop.

The reverse of this process, condensation, causes the heat to be deposited. Perhaps the most intuitive way to visualize this is when you're doing distillation; when you cool the tube, the water that just evaporated will condense due to the cold surface.


Heat pumps are more or less exactly what you'd expect in the game compared to real life, and if you've worked with heatpumps in real life before, the concept of them is basically the same here.

If you raise the pressure of something (by compressing it/pumping it), you'll raise its boiling point.

So e.g pollutant will happily turn into liquid upto ~135C, and gets hot in the process (release of energy).

If you then run that hot liquid through a radiator (like the outside part of an airconditioning), and then you take that room temp gas inside and put it into a radiator at much lower pressure with some valve or a slow pump, that'll cause the liquid to evaporate (lowest Pollutants will evaporate is at around -80C and 6kPa pressure), which then causes the temperature to go down because of the evaporation (energy is required for the gas to evaporate and thus it absorbs heat).



As practical example, you can make an air vent on Vulcan and let it take in outside air at night, at around 5-6MPa pollutants will condense, making the 127C input temperature turn into ~150C, which you then run through a radiator, and run the 127C *liquid* pollutants through a low pressure evaporator/radiator inside, the evaporation will cause the 127C to turn into ~50C, which is technically speaking livable for humans.

If you then add a second stage, using a small chamber where you evaporate some of the pollutants, causing the temperature to drop, and then run the liquid pollutants through some radiators inside that chamber, and you effectively take off another ~30-50C.

You can keep chaining those stages until you hit the minimum evap temperature of Pollutants, which is about -70C to -80C, if you can drop the pressure low enough. Then you can start using something like Nitrogen for the next few stages, and then Hydrogen eventually to get to absolute zero probably, which I haven't tried myself, but I think you should get the gist of heat pumps and phase change now, if not, feel free to comment below and I'll explain it and add it to this guide.

Simplest heat pump (without evaporation chamber)

The simplest stationeers heat pump consists of:

• a (turbo) volume pump
  
• Followed by a high pressure resistant pipe with preferably at least one tank on it (the pressure will quickly rise if your coolant evaporates)
  
• that pipe either has to have a lot of radiators on it, or a heat exchanger to another cooling phase if you want to chain phases
  
• that pipe also needs to have a lot of 'condensation valves'
  
• the condensation valves lead to a liquid buffer which is your main coolant to use with either:
  
• >radiators -- putting heat directly into the buffer and making it evaporate
  
• >evaporation chambers -- connect your room or thing to cool directly to the 'heat exchanger' port on the side, the gas will have to go back to the turbo volume pump/gas buffer before the turbo volume pump
  
• >Heat exchangers -- Chaining multiple coolant loops allows you to reach very low temperatures.
  
  
• One or more 'Purge valves', which can be found in the 'regulator' kit. These allow the liquid buffer to work like the evaporation chamber, and siphon off evaporated gas. Note that the pressure you set here will regulate the (relative) temperature of the coolant buffer.
  
• a bunch of piping coming from your stuff and the above purge valves, you can add a tank here but it's not required. All the piping goes back to the (turbo) volume pump; this completes the loop.

Connect an icecrusher or tank connector to the gas input of the (turbo) volume pump, any liquid inputs should pump directly into the liquid resevoir.

Pollutant is a good all-purpose coolant with a very wide range of operation (+152C to -99.8C) that works in most cases.

If you're on Vulcan or another medium-hot planet your best bet is to use water which has a maximum liquid temperature of 370C- but do note the environment needs to be below that temperature in order to give off heat, so you have to make a system that only turns on at night. You may also have to chain multiple phases in order to reach the desired temperature.

For Venus and other high temperature planets you're still stuck with wall coolers (which I guess are like really efficient Peltier elements?) by my knowledge; phase change doesn't work there.

Things to watch out for

Liquids and gas pipes don't mix

Phase change can also bite you in the arse if you don't know what it can cause. I recommend checking the gasses part of the ingame guide (press F1) to see what temperatures and pressures your system needs to run at.

For example, storing a water tank with 99999C water will obviously be a problem now, as this water will turn into steam, gaining a lot of pressure in the process, and likely blowing apart whatever containment vessel it was in.

But less obviously, if you have a coolant system with gas pipes with Pollutant as coolant, you might want to make sure the temperature of the pollutants stays above ~150C to avoid accidental condensation when you raise the pressure.

For example if you have 20C pollutants in a tank at 10MPa, a lot of that is going to condensate in the tank, raising the temperature in the process.

For tanks this is not an issue, but the gas pipes appear to currently have a 'stress' mechanic that causes them to burst if there's too much liquid in them.

Liquid pipes do not have this issue, so right now personally I'm using Liquid Pipes as my 'high pressure pipe', injecting gasses into it with valves if needed. That way I don't risk accidentally blowing everything up when I experiment with heat pumps.

Vacuums and very low temperatures

Likewise, when you're on a very cold planet, or in space or on the moon where you're exposed to vacuum, you may end up causing things to freeze solid.

Solids inside a pipe will cause the pipe to burst.

A safe way to make sure that doesn't happen to you, is keeping the outdoor radiator loop as close to vacuum as possible, only cycling a little bit of coolant through it at a time at a low pressure, to make sure it doesn't under-cool and freeze.

Every gas has their lowest condensation and freezing points at the lowest pressures, so keeping the pressure low will help prevent freezing and accidental condensation from happening.

Cooling setups with the evaporation chamber

After some toying around I figured out how to best use the Evaporation chamber.

It seems that it's best when you use the 'Gas heat exchange connection' to actually interface with whatever you want to cool, such as a room, the contents of a tank, or whatever else, and use radiators on that, rather than on its output.

So rather than just an 'evaporation chamber' it's actually sort of the whole indoor unit of an airconditioning. You should just siphon off its output and send it for cooling immediately. The 'gas heat exchange connection' is the main relevant part.

Additionally it's worth noting the pressure setting is important for the temperature you're trying to reach. If you want a very low temperature you set a very low pressure. If you want to move a lot of heat but the temperature delta isn't that important, set the pressure a bit higher.

Example setup:

On Vulcan:
Water can evaporate as low as 0C if you lower the pressure of the evaporation chamber to 6kPa.
The highest boiling point it can have, is 370C at 6MPa.
This makes it a good candidate to use for cooling on Vulcan, as you can go as high as 200C above ambient at night.

You can't vent heat by day, though. Maybe if you chain multiple gas cooling setups with wall coolers you could reach that temperature, but water is the highest temperature liquid I found in the game, which won't be liquid above 370C anymore, so the 600C is out of range for that.

To cool a base you'd have something like:

• [liquid water resevoir that you cool with the atmosphere at night, and don't expose to the atmosphere by day]
  
• [evaporation chamber] < 'gas heat exchanger connection' --- > [the air in your base or whatever you want to cool]
  
• [(turbo) volume pump taking the evaporation chamber's output]
  
• [high pressure gas pipe outside with condensation valve at the end and pipe radiators]
  
• [back to your liquid water resevoir]
  edit: testing this in practice seems to cause less cooling than expected, trying to figure out why, though I guess it still makes for a nice second stage and using something like pollutants for your actual indoor cooling?

[a]

haha I like the thought of that, and yea kinda! if it helps you remember then that's a fine analogy

[Frission]

Thought about it in terms of cat memes and it was like that scene from Scott Pilgrim where the gauge in his head suddenly flips from 'Doesn't Get It' to 'Gets it' XD

[Frission]

So evaporation is a gas kitty stealing all the warms from the surroundings so it can be gas, and condensation is the gas kitty sitting on ur face when you're trying to sleep an' makin you too hot and sweaty xD

[Frission]

Taaankoo <3

[a]

I added a bit to the guide in the intro to more intuitively explain phase change. If you need further explanation let me know, I'm happy to adjust the explanation such that everyone who reads the guide can understand it :)

[a]

Basically, condensation (gas becoming liquid) causes heat, evaporation (liquid becoming gas) requires heat. Same also applies when going to/from solid form (sublimation being the 'evaporation' of a solid to gas/liquid and deposition being the 'condensation' of a gas/liquid to solid).

Perhaps it makes more sense when you imagine boiling water; it requires heat to boil the water, which then causes it to evaporate-- it may not be obvious there but the boiling of the water actually removes heat. If the heat source is removed, the boiling and evaporation will stop.

The reverse of this process, condensation, causes the heat to be deposited. Perhaps the most intuitive way to visualize this is when you're doing distillation; when you cool the tube, the water that just evaporated will condense due to the cold surface.

[Frission]

I think the most confusing part of it is it doesn't make sense to me that gas becoming liquid means it's getting hot. I thought liquid became gas when the liquid got too hot, not the other way around? x_x

[a]

It kinda depends on your environment, but if you're in space, the moon, mars, or some other cool place, you can still do what you would do in ye olde times and put a big tower of heatsinks on a pipe outside, then either fill it with something that doesn't condense (like volatiles/oxygen until they get really cold), or something that does and add condensation valves to siphon off the liquid and use it for cooling elsewhere. evaporating liquid in an evaporation chamber will cause cooling to happen on the 'heat exchange' port. If you then take the gasses it put out and put that back in the cooling loop to condense back to liquid, you got yourself a full phase change cooling setup (kinda like NASA's heatpipes) :)

[Frission]

Hehe yeah that's why I came looking for this in the first place, the phase changes and new machines are all new to me (haven't played for 2-3 years) and I'm totally lost when it comes to figuring out how to make my gasses cold ^^;

[a]

oh, interesting, thanks for the heads up! is funny because I actually kinda need to upgrade the guide, you should really be using the ingame's evaporator/condenser if you want efficient cooling, but this guide explains the basic concept of heat pumping well at least I suppose