The curse of transporting liquid H and O2 to rockets

[Tobruk]

Every time I read posts from you guys claiming all you need is ceramic insulated pipe, I'm in disbelief. Are we playing the same game?

The somewhat curious property of pipes (in general? or insulated? or ceramic insulated? I dunno) is that the rate at which the pipes cool themselves down is much slower than the rate at which they warm up the incoming liquid.

Because of this, I've lost a 5x5 tank worth of hydrogen to evaporation before the insulated pipes dropped from 40 C to 30 C. And that's still way off to stop evaporation. Now imagine I added rocket exhaust heat into the equation. It's impossible.

Even though you're transporting liquids through vacuum, they're still bound to heat up because of the damn pipes!

[Steve Raptor]

Nothing will prevent that except insulation pipes.

The solution I'm using is circulating the liquid O2 and H back and forth to prevent it from heating.

[silverbluep]

The heat transfer between the pipes and the liquid is equal and oppoosite. But one is 400kg and the other 10kg at max, so there is that effect.

Hydrogen melting point is -252.15, freezing point is 259.15
Oxygen melting point is -182.96, freezing point is -218.79.

Supercoolant melting point is 436.85, freezing point is 271.15. Now here is the deal, for actual phase change to happen, the material needs to be pushed a few degrees further (i think 4, but can't find the true value at the moment.) than the point. That's why super coolant is safe to use in thermal aquatuners, since the actual transition point of supercoolant is below absolute 0.

There are a few things you must do:

* The pipes should be ceramic the least. Buildings have clamped temperature so when you build them they will be around -15 the maximum (again i forgot what exact temp the clamping has). So just the insulation property is not enough; it should also have natural low conductivity.

* Return the fluids back. You can route the piping back to your tank, so once the tank is filled the fluid can flow back. You can automate using the memory toggle; activate the pumps when a rocket lands and disable the pumps when the fluid moves past the input ports of all your tanks. Brothgar has been continuously looping oxygen thorough his pipes to do this point and one of my later suggestions simultaneously but he has only like 10 20 pipe segments to his rockets. If the fluid stays in pipes, it will only be a matter until when they break.

Things you can do;

* Minimize the pipe length. Less time outside cooling chamber, less heat transfer.

* Limit flow rate to 1kg/s so no phase change orcurs in pipes. As long as the fluid constantly flows, no packets can accumilate.

* Precool the pipes. You could run cold supercoolant through them. Or the hydrogen and oxygen. This is what brothgar does by circulating o2/h2 continuously but I think that's only viable if you do that right where your rockets are which is not always convenient.

* Use insulation to build the pipes. Very expensive but if you can get massive amounts of reed fiber and isoresin perfectly doable.

* Build insulated tiles on top of the insulated pipes. These tiles will interactely minimally with the surrounding and buffer pipe temp increase by hot gasses. This I do.

[chemie]

put LO2 and LH2 production in vaccum.  Run pipes in a vacuum.  Let the liquid recirc back to tank continuously.  Never had an issue.

[zergologist]

Just reduce the size of the packets to 1000g. They'll never evaporate in the pipes, and as long as the rocket is in a vacuum, it'll never evaporate. Although, it will take 10 times the time to fill the rocket

[Steve Raptor]

6 minutes ago, Xenologist said:

Just reduce the size of the packets to 1000g. They'll never evaporate in the pipes, and as long as the rocket is in a vacuum, it'll never evaporate. Although, it will take 10 times the time to fill the rocket

But when the rocket is away, the the liquid will start stacking back to 10kg in each pipe.

[badgamer123]

19 minutes ago, Steve Raptor said:

But when the rocket is away, the the liquid will start stacking back to 10kg in each pipe.

overflow...or loop back

[Yoma_Nosme]

@Tobruk

Mhhh....i just thought,.. Use bridges...bridge,piece of piece, bridge,  piece of pipe, etc...you'll remove 50% of breaking points plus the pipe pieces can cool down more easily bc there's 50% less pipe. 

Pipes just "teleport" contents. perfect iinsulator if you didn't knew...

[Sasza22]

Another technique is using radiant pipes and piping cold super coolant through them first (all in vacuum). The pipes reach the liquid O2 & H2 temperatures fast and won`t break as long as you maintain the vacuum around them. The last segments should be out of Insulation though so it can handle the rocket exhaust.

[avc15]

2 hours ago, Tobruk said:

I've lost a 5x5 tank worth of hydrogen to evaporation before the insulated pipes dropped from 40 C to 30 C. And that's still way off to stop evaporation. Now imagine I added rocket exhaust heat into the equation. It's impossible.

From your supply tank pipe lh2 into a pair of liquid reservoirs, in series, with a full pipe sensor to shut off the supply pump when the first tank fills up (don't leave lh2 standing in pipes, keep it all in reservoirs, which don't interact with their contents)

Now, set the output pipe up with a shutoff that only opens up when there's a rocket to fuel. Also loop the output pipe back to the inputs of your reservoirs so pipes empty back out when you're done fueling.

Also, use a redirect to send some lh2 back to the cold tank as your pipes leak heat back to the reservoirs. Your supply pump will replenish from the cold tank.

Lastly. Pipe everything in such a way that the minimum possible number of segments interact directly with heat plumes from your rockets. This means, build your supply pipes up from below, and more than 9 tiles below the rocket itself. If they can't be in space, isolated with insulation tiles at a minimum.

[chemie]

guys, dont make this so complicated.  No need for 1000g/s loops or reservoirs. These pipes have never broken. The loop back goes through the liquid in the tank so it cooled back down

[BLACKBERREST3]

Combination of gas element sensor (if in space and not collecting exhaust) with shutoff + liquid bypass for non stagnant pipes. Or something like a door under a reservoir to bring the liquid back in.

Even in space, the exhaust can still heat up insulated pipes because the rate of deletion from the void cannot keep up.