Three-phase hands-off oxygen evaporation and warming chamber

[Kasuha]

This is what I use in my base to convert liquid oxygen back into gas and to warm it up to temperature pleasant for duplicants.

Above it there is a polluted oxygen liquefier and storage, for purposes of this post it's the place where we draw the liquid oxygen from.

Here the chamber is shown at the end of the cycle when warm oxygen is drawn out with the gas pump. The cycle itself starts with the activation of the atmo switch on the right, set up to pressure lower than 1000 g/tile. That starts up the liquid pump in the storage and that sends some liquid oxygen into the chamber.

The oxygen quickly evaporates since the chamber is warm, and generates about 6 kg/tile pressure which shuts down the switch activating the pump. 

The wave of cold oxygen across the chamber first deactivates the gas pump's thermo switch, activates the left atmo switch set to above 1000 g, and activates the bottom thermo switch set to detect low temperatures, powering up space heaters. The temperature in the chamber abruptly changed from about 30 C down to -170 C.

The following phase takes some time as space heaters keep heating the room up until the thermo switch detects temperatures higher than 17 C. Then the heaters are shut down, but their thermal inertia is still driving the temperature up.

After a short while, the temperature in the chamber reaches 23 C which activates the thermo switch of the gas pump. It then sends the warm oxygen to the pipe and wherever it is needed. 

When the pressure in the chamber drops below 1000 g/tile, the left atmo switch deactivates the pump, the right atmo switch activates the liquid pump, and the cycle repeats.

Here's the power overlay:

The performance of the chamber approximately matches (slightly exceeds) performance of my oxygen liquefier but there's no problem making it faster by adding more space heaters, or by lowering the temperature at which the oxygen is removed. What I like on this setup, it's very easy to set up temperature of the generated oxygen within range of about 10 C. With careful settings it could be likely made even more accurate.

 

[Masterpintsman]

Nice one. Definitvely more successfull than my try to use a very long gas pipe in the opposit direction of the cold oxygen coming down through a long corridor, the idea was to cool the incoming contaminated oxygen down to the temperatur of the just evaporated oxygen (@ ~-175°) to save on the cost of cooling it to liquify - sadly the thermal transfer through granit gas pipes into the packets dosn't pan out, plus the gas is moving very slow in the corridor.

Leaving it here as a deterrant for everyone not to waste time on it (as long as the thermal bugs are not fixed), it only managed to cool the incoming gas (fed in at the bottom, exiting at the top toward my LOX cooler) from ~35° to ~-30:

 

[The Flying Fox]

I like it, Kasuha!  I would like to see the rest of the unit, the radiator/piping/etc.  Just for comparison.

 

One thing that might be able to improve the unit is if you could use a tepidizer, somehow, to heat the oxygen as the tepidizer is far more efficient at heating then the space heater.  A room with a swallow pool of heated water with wirebridges sticking out of it?  ..Or even using hot geyser water?  It would have to be waaay bigger though.  I like this as it's compact.

[Kasuha]

7 minutes ago, The Flying Fox said:

I would like to see the rest of the unit, the radiator/piping/etc.  Just for comparison.

Here's the whole unit. But there's nothing special about the condenser, you just send polluted oxygen to it and it condenses eventually. I calculated that this one should be making about 160 g/s of liquid oxygen as I don't bother with pre-cooling it with wheezeworts. It's not meant to make oxygen for my dupes, it's meant to get rid of polluted oxygen.

 

[The Flying Fox]

48 minutes ago, Masterpintsman said:

...

Leaving it here as a deterrant for everyone not to waste time on it (as long as the thermal bugs are not fixed), it only managed to cool the incoming gas (fed in at the bottom, exiting at the top toward my LOX cooler) from ~35° to ~-30:
 

That is  roughly similar in performance for my pre-cooler, although it is less since my unit is much smaller in comparison.  2-tile wide corridors are too small to effectively let air move through them I've found, in general.

 

Polluted O2 goes into the pre-cooler around 25-30c and goes into the main freezing room around -25 to -30c, just depends on how long the PO2 has been sitting in the pipes before moving.

 

Kasuha, I like that idea of that thermal switch sitting in that 1-tile room of liquid oxygen.  That's clever.  Good way to prevent the hydrogen from getting too cold in the pipes.  I wonder if a 1-tile room of hydrogen gas would work just as effectively for that.

[Kasuha]

16 minutes ago, The Flying Fox said:

Kasuha, I like that idea of that thermal switch sitting in that 1-tile room of liquid oxygen.  That's clever.  Good way to prevent the hydrogen from getting too cold in the pipes.  I wonder if a 1-tile room of hydrogen gas would work just as effectively for that.

The problem with that switch is that it is unbelievably slow. That's why I have the manual switches around (I know I can "cheat" by playing with the switch itself but I don't want to do that).

The switch detects temperature of gases/liquids around it. But that gas/liquid is in contact with the pipe (25 kg of granite) and with the switch itself (200 kg !!! of wolframite). So when the temperature of the gas in the pipe changes, it slooowly pulls the heat from the pipe and it has to convince the pipe, the gas in the chamber, and the switch itself to get a reading of that temperature.

Once the pump blocked, the chamber dried out, and the regulator went overboard with cooling. When the switch acted, the gas in the pipe was already way below freezing of oxygen - and that had only some 3 C to traverse. If there was less liquid oxygen at the pump, it would probably have frozen. This way it survived without change.

I don't think hydrogen would be better in that chamber. It would stay gas with thermal conductivity 0.168 W/m/K while liquid oxygen has thermal conductivity 2 W/m/K.

There was a different, much more reliable thermometer there originally - the hydrogen went out of the pipe, around a thermo switch, and through a gas pump back to the pipe, while the rest that did not squeeze through the vent went forth through the pipe. I just didn't like that I have to pay 240 W of continuous power just to measure the temperature.

[Masterpintsman]

1 hour ago, The Flying Fox said:

That is  roughly similar in performance for my pre-cooler, although it is less since my unit is much smaller in comparison.  2-tile wide corridors are too small to effectively let air move through them I've found, in general.

The issue isn't that much that the air dosn't move quick enough (sure it sucks and is completely unrealistic, but it would balance at some point and I couldn't care less if some metric tonnes of oxygen per tile would be stuck in the tiles at the beginning of the corridor), it is that the pipes are -175°C but the gas moving inside them dosn't really care about that.

After freely (non-blocked) flowing through 720 pipe tiles, all of them colder than the packet, most of them >100°C colder than the packet at that point, thevpackets should have lost (nearly) all heat and be at least colder than -150°C (or below). IMHO.