lh2 Liquid Hydrogen

[KittenIsAGeek]

In some ways, making liquid hydrogen was easy with the new materials.  In other ways, its a real pain in the tail.  Even with the new super-coolant, it is very hard to make liquid hydrogen.  However, I did succeed!

Alright, so.. here's what I found:

1. Ceramic pipes, steel aquatuners, and steel radiator pipes work perfectly fine.  So long as the liquid hydrogen room is also vacuum isolated.
2. Liquid Reserviors are necessary.  Using a pool of super-coolant won't work because the pump itself will create too much heat.
3. The hydrogen must be pre-cooled somewhat close to its condensation point as a SEPARATE process. -200c works pretty well. -250c works even better.
4. Once you get your coolant to temperature, its pretty efficient, but the trick is getting it to temperature.
5. The aquatuner cools by 14c.  This is a problem.  -255c is NOT cold enough for hydrogen to condense, but if the coolant is any colder when it goes through the aquatuner, it will break pipes and cause lots of problems.  So it is nessary to use the under 1kg trick to bring the coolant down the last few degrees.
6. -256c is cold enough -- barely.  It will be slow. Especially if your hydrogen isn't already close to the condensation point.  With your coolant at -258c you can make liquid hydrogen at 500g/s (one fan).  You could probably do it faster, but I had way too much difficulty with broken pipes.  -258.8c was about as cold as I could get my coolant.
7. Getting your coolant cold enough produces a LOT of heat.  Once things stabilize, however, it isn't too bad.  If you want to use steel, make sure your aquatuners stay below 300c.  Boiling water and running it through a steam generator works great.  You can then pump your steam into a rocket engine.  Once you are cold enough to condense hydrogen, however, your aquatuners won't be running enough to boil water anymore.

Here's are some spoiler shots of my test build.  I call it the Steam Powered Lh2 Automation Technology (SPLAT):

Spoiler

Turn 28! Yay!  .. Ok, so I used Sandbox mode.  Whatever.  You can build it in survival easy peasy -- once you get super coolant.

I used thermal sensors in the hydrogen rooms to turn on/off shutoff valves.  Getting the coolant to temperature is MUCH faster when you're not already circulating it, so keep the radiators turned off until you're reasonably close to -250c.

It powers itself, really. Used a 3-door pump to push steam back around and chlorine-isolated pools of 300c super-coolant to 'trick' the generators into always running.  At its hottest, the coolant around the aquatuners was about 278c.

The left liquid pipe thermo sensor is set to 'above -258c.'  The right is set to 'above -255c.'  The left side needed some extra management to work, but at -255c you won't break pipes at all.

This is.. a mess. Sorry.  Let me explain.  Once the coolant reaches -255c, you MUST reduce the flow through the aquatuner to 999g/s.  It is also EXTREMELY important that the super cold super-coolant must never stop moving. So, bridge mechanics were used to make certain that the output from the aquatuner had priority.  Bridge mechanics were also used in conjunction with the valve to prevent alternating flows  The output from the tank goes through a valve set at 6000g/s.  It could probably be set at 9000g/s with no problems, but you want to make sure that you never have more than 10kg/s going into your storage tank.  If you do, you can get broken pipes.  You're working with a coolant that is sometimes below its freezing point.

 

[Male_zvire]

OK.... one simple (and maybe stupid) question: why?

[KittenIsAGeek]

2 minutes ago, Male_zvire said:

OK.... one simple (and maybe stupid) question: why?

Liquid Hydrogen Rocket Fuel.

[Carnis]

Why cant you bring your supercoolant to -269? Eg 4K. 260 should be the trouble point, where you go below 1K & break game.

[chemie]

57 minutes ago, Carnis said:

Why cant you bring your supercoolant to -269? Eg 4K. 260 should be the trouble point, where you go below 1K & break game.

You can.  OP is reducing target due to 14 c of last aquatuner.  However a valve and bridge can allow an aquatuner to control to an exact temp allowing anything from 0 to 14c. (as long as total flow is less than 10 kg/s in the pipe)

[Carnis]

I used hydrogen to Make LOX earlier without Pipe sensors. Should Be simple pipework now with reservoir + supercoolant + aquatuner.

Where are you dumping the heat, space?

[Neotuck]

7 minutes ago, Carnis said:

Where are you dumping the heat, space?

Looks like OP is dumping the heat into steam turbines

[chemie]

7 minutes ago, Carnis said:

I used hydrogen to Make LOX earlier without Pipe sensors. Should Be simple pipework now with reservoir + supercoolant + aquatuner.

Where are you dumping the heat, space?

This is LH2 not lox.  Lox is easy with h2 and regulator in closed loop.  You can dump heat to steam gen or vacuum.

[Lancar]

I'm thinking you could have a pool of coolant which is regulated by an aquatuner to produce a solution exactly 14c above the target, and then in turn send that through a different aquatuner to the hydrogen liquifier.

[Carnis]

16 minutes ago, Lancar said:

I'm thinking you could have a pool of coolant which is regulated by an aquatuner to produce a solution exactly 14c above the target, and then in turn send that through a different aquatuner to the hydrogen liquifier.

Many solutions, but regardless its easy with The new SC+ automations, trigger cooling on another temp controlled prioritized circuit.

If temp *above 256 use aquatuner, If less, skip.

I dont think 1kg trick is needed at all. Will Post after tests.

[crypticorb]

Having never tried to build a LOX or LH2 system, forgive me if this sounds naive.

Would it not be easier to use a heat sink (steam turbine or space) to aquatune supercoolant down to -265, and use tempshift plates, radiant pipes, etc to draw heat out of the hydrogen until it condensed? The setup you outlined, while impressive, seems needlessly complex. Is there something that I missed that prevents hydrogen from sinking heat into supercoolant past -250C? Is it the hard limit of absolute zero and crashing?

Second issue, how do you move the LH2 to the rocket without it heating up a tiiiiny bit and exploding back into gas?

[KittenIsAGeek]

My aquatuner bridge set-up was at first set to bring the temp down to -260c, but I ran in to the problem that when coolant reached the aquatuner at less than -255c, pipes broke on the other side.  The fix, then, was to use a valve to control flow and limit it to under 1kg/s.

The steam generator system can be pretty much ignored for this.  It was there to provide free power and get rid of the heat -- but condensing hydrogen isn't nearly as energy intensive as LOX.  The problem in the case of LH2 is that you have to get the coolant to around -258c (or preferably cooler) which is troublesome.  

To the question of using a pool: I am; its just shaped like a reservoir.   As outlined in my initial post, the action of the pump will affect the temperature of the coolant just enough to make it difficult, so my solution was to use a reservoir instead.  Along those lines...

Pumping LH2 out of the room proved to be difficult as well.  I ended up solving the issue by using a micro pump with a liquid sensor set to 50kg.  This let me pump it into another vacuum isolated reservoir.

Spoiler

You might notice that my stored hydrogen is at -253.9c.  In the condensation chamber, the hydrogen was -257c to -258c.  The action of pumping adds heat.  

I thought of extending my condensation room a little and adding some supercoolant at the bottom as a temperature stabilizer.  Maybe my next build will do so.  Pump the LH2 into a pipe, run it through the super-coolant to drop it back to -258, then send it on to the reservoir.

[Evillevi]

Err, you'll probably find this funny but there is an easy-ish way to cool Hydrogen. 

 

Namely you can make a super coolant loop and and stick a pipe thermo senso + valve combo to prevent excessively cold liquid from going to the Aquatuner, And eventually you'll get near perfectly cold supercoolant chilling in your radiant pipes while it warms up enough to go pass your valve. 

[KittenIsAGeek]

17 minutes ago, Evillevi said:

Namely you can make a super coolant loop and and stick a pipe thermo senso + valve combo to prevent excessively cold liquid from going to the Aquatuner, And eventually you'll get near perfectly cold supercoolant chilling in your radiant pipes while it warms up enough to go pass your valve. 

You mean the temperature sensor and stop valve I already have in place?

Spoiler

The problem, again, is that you're working with temperatures at the limit of your coolant's range.  Getting it down to -255c is no problem at all.  Coolant at -255c comes out of the aquatuner at -267c.  The freezing point for the coolant is -266.2c, so you're actually colder than freezing at that point but you won't break pipes.  However, after time, your coolant will settle in to a temperature just under -255c and no colder.

Hydrogen is liquid at -252.2c -- except that it isn't.  Its the transition point.  Which means sometimes its liquid, sometimes its gas.  There's also some entropy involved when the hydrogen changes state. I found by experimentation that in order to get hydrogen to turn to liquid and stay liquid your coolant must be at least -257c, but -258c works MUCH better.

Unfortunately, to get your coolant to -257c, your aquatuner must process any coolant warmer than -257.  At -256c, coolant comes out of the aquatuner at -268c.  This is far enough below the freezing point that pipes will break.

I'm currently working on a dual-reservoir setup that will split out the coolant after the aquatuner has finished processing as well as before.  This will let me collect -260c and colder coolant separately.  I'll also have to split out the coolant in the return so that it doesn't warm my super-cold tank.

[Carnis]

13 minutes ago, KittenIsAGeek said:

You mean the temperature sensor and stop valve I already have in place?

  Reveal hidden contents

 

Unfortunately, to get your coolant to -257c, your aquatuner must process any coolant warmer than -257.  At -256c, coolant comes out of the aquatuner at -268c. 

I'm currently working on a dual-reservoir setup that will split out the coolant after the aquatuner has finished processing as well as before.  This will let me collect -260c and colder coolant separately.  I'll also have to split out the coolant in the return so that it doesn't warm my super-cold tank.

Im intrigued.

Why not eliminate The reservoir, & use pipes only. If its the averaging on the reservoir that is the problem.

I Will run My own debug version & get a sample out today.

[KittenIsAGeek]

Just now, Carnis said:

Im intrigued.

Why not eliminate The reservoir, & use pipes only. If its the averaging on the reservoir that is the problem.

I Will run My own debug version & get a sample out today.

Because if your coolant is fluctuating in temperature, your hydrogen fluctuates between gas and liquid.  If, like LOX, the coolant could be substantially below the liquifiation point, this wouldn't be an issue.  -255c? Gas.  -257c? Liquid. Hydrogen is extremely susceptible to temperature changes.  I tried without a reservoir and ran into the problem of continually transitioning between gas and liquid states.  If you've got a build where this works, I'd like to see it.

[Evillevi]

https://steamcommunity.com/sharedfiles/filedetails/?id=1545551458

259 Hydrogen with a stop valve + temp sensor combo. 

With a little refinement I can probably get it further down into -261 but there's a diminishing return at that point. Basically you place the temp + stop valve in teh LH2 chamber itself + a continous source of hydrogen next to that sensor.

[KittenIsAGeek]

4 minutes ago, Evillevi said:

https://steamcommunity.com/sharedfiles/filedetails/?id=1545551458

259 Hydrogen with a stop valve + temp sensor combo. 

With a little refinement I can probably get it further down into -261 but there's a diminishing return at that point. Basically you place the temp + stop valve in teh LH2 chamber itself + a continous source of hydrogen next to that sensor.

OK, I see what you're doing. I hadn't thought of stopping the coolant inside the condensation chamber. 

[Evillevi]

Just now, KittenIsAGeek said:

OK, I see what you're doing. I hadn't thought of stopping the coolant inside the condensation chamber. 

The only issue with this design is the placement of the liquid pipes. Basically you want to have the coolant circulate from the bottom. This is to Force the first batch of Liquid Coolant entering the system to predominantly cool the liquid hydrogen which I didn't do in the picture . Additionally This system only got that cold because I used a constant supply of warmHydrogen to force the system to run. 

An Upgrade to the system is to use a second  Sensor + Valve  to warm up the liquid enough so it will be your required minimum temperature (after the coolant goes through the aquatuner)while using the first sensor and valve in the chamber to dictate your maximum tempterature that you want that coolant to be. . 

[KittenIsAGeek]

Yeah, I was thinking about those issues when I saw your system.  I have some ideas now to work with.  Thanks!

[Carnis]

Seems to work, to have a counter current radiator.

the only issue with this system is, it needs a backup temp sensor to make sure no packets of sub -255 supercoolant enter that aquatuner when the flow is interrupted.

Using a normal vent so whenever there's vacuum, heat / hydrogen gets added.