Transporting Liquid hydrogen

[Steve Raptor]

I'm interested to know how you guys transport your liquid H to the rocket.

I'm having serious issues of liquid hydrogen changes phase in ceramic/igneous rock insulated pipes before it even reaches the rocket fuel tank.

Are there any ways to do it without a manual valve setting to 1000 g/s?

 

[DonDegow]

First thing is to supercool your hydrogen, only pump it when it's almost a solid (about -260°C).

Best way to move full packets is granite standard pipes in vacuum; hydrogen will exchange temp with its pipe no matter what. So having a low SHC pipe is the way to go (in vacuum).

You will lose a few of the first packets but it quickly stabilize and you're good to go. Also, use insulated pipes where vacuum isn't an option (rocket silo itself).

NB : actual best is radiant pipe with low SHC metal but not always practical.

[bobe17]

you can also "pre-cool" the pipe by sending only packets of 1000g. This prevent liquid to change state.

[Chthonicone]

7 minutes ago, DonDegow said:

First thing is to supercool your hydrogen, only pump it when it's almost a solid (about -260°C).

Best way to move full packets is granite standard pipes in vacuum; hydrogen will exchange temp with its pipe no matter what. So having a low SHC pipe is the way to go (in vacuum).

You will lose a few of the first packets but it quickly stabilize and you're good to go. Also, use insulated pipes where vacuum isn't an option (rocket silo itself).

NB : actual best is radiant pipe with low SHC metal but not always practical.

Couldn't you also just transport 1 kg/s so it can't phase change in the pipe?

[KittenIsAGeek]

One other thing you should do: Make a feedback loop so that whatever hydrogen your rocket doesn't take ends up going back to the storage pool.  Otherwise at launch your pipes will break.

[Steve Raptor]

5 hours ago, Chthonicone said:

Couldn't you also just transport 1 kg/s so it can't phase change in the pipe?

It takes an eternity to fill the tanks that way, I would like a different solution.

4 hours ago, KittenIsAGeek said:

One other thing you should do: Make a feedback loop so that whatever hydrogen your rocket doesn't take ends up going back to the storage pool.  Otherwise at launch your pipes will break.

I have this, but the hydrogen changes phase before even reaching the tank, I think its not cold enough (250C).

Its just that the temperature range is so narrow, compared to LOX.

5 hours ago, bobe17 said:

you can also "pre-cool" the pipe by sending only packets of 1000g. This prevent liquid to change state.

 I like this idea, il combine it with radiant pipes suggested by DonDegow and Il give it a shot.

I think I have enough insulation for the pipes in the silo.

[StarSquid]

Hold on, do the tanks take wrong element damage or do they just let anything besides fuel past? Because if it's the latter you could pump chilled super coolant through the lines beforehand to cool them down, or even alternate it with the liquid hydrogen if the math on that one works out. Of course, if the tanks do take wrong element damage, this won't work. 

[Chthonicone]

3 hours ago, Steve Raptor said:

It takes an eternity to fill the tanks that way, I would like a different solution.

I have this, but the hydrogen changes phase before even reaching the tank, I think its not cold enough (250C).

Its just that the temperature range is so narrow, compared to LOX.

 I like this idea, il combine it with radiant pipes suggested by DonDegow and Il give it a shot.

I think I have enough insulation for the pipes in the silo.

The one you liked is very similar to mine, just fyi. You can even set a detector that detects when the pipe is cool enough and then it turns up the hydrogen flow.

[Nitroturtle]

3 hours ago, Steve Raptor said:

I have this, but the hydrogen changes phase before even reaching the tank, I think its not cold enough (250C).

Its just that the temperature range is so narrow, compared to LOX.

I'd suggest looking at the path to see where the heat is being lost.  I've built rocket setups with recirculating piping for hydrogen and never had any issues with phase change.  The key is to run pipes in a vacuum.  If you need to cross a wall, especially the hot walls of a rocket silo, make sure you're using bridges to avoid heat transfer.

Maybe post a picture or a save file and we can assist further.

[Steve Raptor]

7 hours ago, Chthonicone said:

The one you liked is very similar to mine, just fyi. You can even set a detector that detects when the pipe is cool enough and then it turns up the hydrogen flow.

I thought your meant just pump in 1000 g/s permanently.

I was aiming at temporarily pre-cool the pipes and them pump in hydrogen at full capacity after reading the other comments.

7 hours ago, Nitroturtle said:

I'd suggest looking at the path to see where the heat is being lost.  I've built rocket setups with recirculating piping for hydrogen and never had any issues with phase change.  The key is to run pipes in a vacuum.  If you need to cross a wall, especially the hot walls of a rocket silo, make sure you're using bridges to avoid heat transfer.

Maybe post a picture or a save file and we can assist further.

Here is a picture:

Spoiler

I think the biggest problem here is the hydrogen is too hot, at -250C.

I just can't seem to find the temperature sensor sweet spot on the aqua tuner loop to get it cold enough without freezing it.

I think I will drain the tank back into the pool and try to cool it to at least 255-260C

 

EDIT: I found a major oversight of my parts, there are sections of the pipe that goes through the bunker tiles below the rocket engines.

Also, I had conveyor rails passing through a large section of the pipes, also causing heat exchange when the hydrogen was flowing. (rails were 266C).

I also cooled the hydrogen to -256C and now its looping fine and nothing breaks.

I set the thermo sensor temp on the aqua tuner to -251C.

[suxkar]

Radiant pipes will make a mess if they are in range of rocket exhaust, which is almost certain. Ceramic pipes with a feedback loop, as said before, are in my opinion the best option until you reach insulation. Abusing bridges also helps

[Steve Raptor]

8 minutes ago, suxkar said:

Radiant pipes will make a mess if they are in range of rocket exhaust, which is almost certain. Ceramic pipes with a feedback loop, as said before, are in my opinion the best option until you reach insulation. Abusing bridges also helps

Even insulation isn't a practical solution, one segment of insulated pipe takes 400 insulation, you will need tones of it.

[suxkar]

2 hours ago, Steve Raptor said:

Even insulation isn't a practical solution, one segment of insulated pipe takes 400 insulation, you will need tones of it.

That is precisely why I wild plant thimble reeds pretty much constantly. I had 11k reed fiber by cycle 600.

[Nitroturtle]

3 hours ago, Steve Raptor said:

EDIT: I found a major oversight of my parts, there are sections of the pipe that goes through the bunker tiles below the rocket engines.

Also, I had conveyor rails passing through a large section of the pipes, also causing heat exchange when the hydrogen was flowing. (rails were 266C).

Yup this is exactly what I was referring to in my post.  If you just use bridges to hop over the hot tiles (which it sounds like you've done) you shouldn't have any more issues.

[Steve Raptor]

1 hour ago, suxkar said:

That is precisely why I wild plant thimble reeds pretty much constantly. I had 11k reed fiber by cycle 600.

Reeds are not the bottle neck for me, its the space material.

1 hour ago, Nitroturtle said:

Yup this is exactly what I was referring to in my post.  If you just use bridges to hop over the hot tiles (which it sounds like you've done) you shouldn't have any more issues.

Aye, I did just that.

[suxkar]

2 minutes ago, Steve Raptor said:

Reeds are not the bottle neck for me, its the space material.

Aye, I did just that.

I usually do oxylite runs to close planets until i have enough isoresing to plumb 3 liquid oxygen petroleum rockets, which among other things will harvest isoresin, but I agree, initially isoresin is the bottleneck. With 3 rockets harvesting isoresin thought you will usually have enough of it to keep 2-3 molecular forges busy.

[Stoned]

I run my liquid H in mostly insulated igneous rock pipes. Works if you just have to stick to some simple rules.
Only pump liquid in when it is needed for for refueling.
Make a feedback loop so that the liquid flow never stops..

Cool the H as low as possible.

Avoid hot areas. Never let hot regolith pile over your pipes.
I use ceramics where that does not work and insulation pipes when I cross the rocket silo.

As mentioned above, you might loose some of the first packages if your igneous rock was a bit hot, but then you are good to go.

 

[Rebrait]

use a lot of bridges, and you only will have a problem with less pipes!

like this

pipe--bridge--pipe--bridge--pipe--bridge

 

[Svarin]

May I suggest keeping the LOX/LHY inside their cooling tanks, and only send the packets you need to your rocket ? Instead of looping the fluid in difficult conditions, like this :

And of course, you will need some automation to send a counted number of LHY packets into the pipes-to-rocket, like this :

The automation relies on a clock-filter-memory system, tell the filter how many seconds of pump operation you need, and off you go.

Served me well for many rocket launches.

Best regards,

Svarin

PS : I am being voluntarily not too specific, because I think you may like to use your own thinking, but I will happily give more detail if requested.

[Steve Raptor]

3 hours ago, Svarin said:

May I suggest keeping the LOX/LHY inside their cooling tanks, and only send the packets you need to your rocket ? Instead of looping the fluid in difficult conditions, like this :

And of course, you will need some automation to send a counted number of LHY packets into the pipes-to-rocket, like this :

The automation relies on a clock-filter-memory system, tell the filter how many seconds of pump operation you need, and off you go.

Served me well for many rocket launches.

Best regards,

Svarin

PS : I am being voluntarily not too specific, because I think you may like to use your own thinking, but I will happily give more detail if requested.

Hi, Welcome to the forums!

 

I understand what your trying to do, but how do you know how many seconds do you need to set on the clock to allow the pump to work?

Say I want you transfer 900 kg of LH to my rocket, how do you set the sensor to transfer exactly this amount?

[bobe17]

you specify the amount with the filter (90s)

[fishoutofwater]

4 hours ago, Steve Raptor said:

Hi, Welcome to the forums!

 

I understand what your trying to do, but how do you know how many seconds do you need to set on the clock to allow the pump to work?

Say I want you transfer 900 kg of LH to my rocket, how do you set the sensor to transfer exactly this amount?

I'd say instead pump use liquid tank+liquid shutoff, just to make sure exactly 10kg in pipe.

also there is a dispenser here

 

[biopon]

On 10/5/2019 at 4:31 AM, Steve Raptor said:

I just can't seem to find the temperature sensor sweet spot on the aqua tuner loop to get it cold enough without freezing it.

In general, use a liquid reservoir with your cooling loop, and have at least a few hundred kilos of coolant in there. Then measure right at the output of the reservoir, and not at the input of the AT. This will give you very precise temperature control.

But for liquid hydrogen, you don't even need to do this. Just stick a temp sensor in the H2 pool, and run the AT until the pool is at the right temp. The AT won't freeze supercoolant, so you don't have to worry about coolant temp at all. Just stop .1 degree before your H2 freezes into solid, then you can send it wherever in ceramic pipes, no need for the hassle with pre-cooling radiant pipes and whatnot.

[Svarin]

On 10/10/2019 at 11:42 PM, Steve Raptor said:

Hi, Welcome to the forums!

 

I understand what your trying to do, but how do you know how many seconds do you need to set on the clock to allow the pump to work?

Say I want you transfer 900 kg of LH to my rocket, how do you set the sensor to transfer exactly this amount?

Thank you !

The other contributors have said it best.

bobe17 - use the filter timer

I would add that with this specific setup, you need to stop the clock only when the filter has run its complete amount of time. There is another setup (with a NOT and a buffer, instead of a simple filter) which I have used where you would only need a single active tick of the clock to activate the counter and it would complete and reset without further intervention :

fishoutofwater : use a shutoff instead of the pump for accurate packet size.

This is absolutely correct, it is more accurate. I did it and then dispensed with the added complexity. However, you need to make sure your shutoff is -inside- the cool LHY tank, otherwise your stagnant hydrogen will heat up and vaporize.

biopon : about the mass of supercoolant.

A larger mass of supercoolant will be much more temperature stable. I found that a full circuit, plus about 600kg in the SC reservoir, with a -255 or -256 Celsius temp at Autotuner entry worked well. Of course a liquid reservoir of supercoolant is a must-have, as it allows fluid temperature to homogenize before going to the cooling loop.

biopon : temp probe in the cool LHY tank.

I did not think of that one, but I love it. Smart and simple. I will give it a try.

Then, how do you use all that heat ? I have a crude-to-petroleum high temp conversion system, the 400C hot petroleum then going to heat up some steam and cooling almost instantly to a safer 125C. What do you guys do ?

Best regards,

Svarin

[calibayzone]

With the new mass depletion mechanic, hydrogen is only needed for places so far away that the 1000g/s fill time is relatively small compared to rocket flight.