Qustions on Fuel

[Captain Brann]

HI
As we were starting the game session last night, we have been playing for about 4 sessions so far, I was asked by a player about what happens if the hydrogen fuel hits the air and a spark.
He was thinking of the Hindenburg.

I presume if it vents to space all is fine but overwise???

How is the fuel stored?
Is it kept as a gas?
Is it presuried and kept as a liquid?
How does depresurisanion of the fuel effect the ship?


Thanks for your help.

Chris

 

[rust]

As we were starting the game session last night, we have been playing for about 4 sessions so far, I was asked by a player about what happens if the hydrogen fuel hits the air and a spark.
He was thinking of the Hindenburg.

If the hydrogen fuel would somehow leak into the ship and the ship would
have oxygen in its atmosphere, a spark would indeed have a good chance
to turn the ship into a fireball.

I presume if it vents to space all is fine but overwise???

In fact most of the fuel is there to be vented into space in order to form
the jump bubble around the ship, otherwise it would be unable to jump.

How is the fuel stored?
Is it kept as a gas?
Is it presuried and kept as a liquid?
How does depresurisanion of the fuel effect the ship?

The current version of Traveller, Mongoose Traveller, does not really ex-
plain this in any detail, and there is some discussion about the interpreta-
tion of the explanations in previous versions of Traveller.

I think I will leave these questions to those who know the source material
better than I do, I never cared for this because it normally does not have
much (if any) influence on the game.

 

[Fedmahn Kassad]

In Most Traveller Universes the fuel is stored as a liquid (L-HYD Fuel stands for Liquid Hydrogen). I am assuming that some pressure and temprature control is used to keep it in its liquid form. The liquid form will take up less volume than gaseous form to allow for efficient storage.

A fuel leak into the pressurized hull area of a ship would be dangerous as the L-HYD evaporates into gas, At concentrations ranging from 4 to 75% the mixture of Oxygen and Hydrogen would be very combustable.

Once again, in the Old Traveller Univerces, the fuel was kept near the surface/hull of the ship so that if a puncture should occur, the gas would vent out to space. This 'layer' of L-Hyd would also provide some extra protection from incoming fire.

Venting the L-HYD directly to space would not cause issue unless there was an atmosphere leak as well, as the L-Hyd would not have any oxygen to mix with, and would therefore be inert.

Loss oif fuel pressurization would have an effect on ship drive and power production, and as a possible engineering mishap, failure of the machinery that controls the L-Hyd temp and pressure could make for some interesting adventures =)

 

[BP]

Hydrogen mixing with air in a ship's confined space could definitely be a problem.

Hydrogen is odorless, colorless, and tasteless and does not produce fumes, so human senses won’t detect a leak and its burning is largely invisible to the human eye (blue if seen at all). Given hydrogen’s tendency to rise quickly, if gravitics is working, a hydrogen leak would briefly collect on the ceiling and eventually move toward the corners.

Hydrogen burning will produce heat and water. The water produced (H2O) will reduce the radiant heat, but the quick spreading hydrogen gas will possibly ignite other materials before the ignition heat is mitigated. These will likely produce visible flames and smells - hydrogen itself will likely burn too clean and fast to be directly noticed or felt - though the pressure, heat and humidity (and singed hairs) in the confined space of a ship may be noticeable.

Of course, ships will have hydrogen sensors to help detect hydrogen leaks, and automated pumps to collect the leaking hydrogen and in extreme cases vent it or the atmo to space (planetside, this would should present little problem). Interior materials will also likely be resistant to thermal effects (i.e. not ignite).

Prior or during a battle - decompression would largely remove the risks, as hydrogen needs an oxidizer. Metals and such with oxygen might burn given enough heat, but quickly extinguish without an oxygen source.

 

[Ishmael]

I have always treated fuel as being ammonia.
Stored as a liquid at sane temperatures and pressures.
Actually contains more Hydrogen for a given volume than liquid Hydrogen.
It is toxic though, and flammable, and can be used as a fuel for internal combustion engines.
Extract the Hydrogen with a fuel purifier and you have Nitrogen left over for reaction mass and cooling.

iirc, hydrogen fuel in old versions of Traveller was an abstraction that covered fuel, coolants and lubricants without having to work with individual micro-detail stuff thats not overly important.

 

[AndrewW]

There is an option for Metal Hydride storage in High Guard:

Instead of storing the ship's hydrogen in liquid form at extremely low temperature with a high risk of explosion if a leak occurs into the inhabited space of the ship, it is possible to store hydrogen in a more bulky form in a room temperature non-flammable metal hydride matrix.

 

[Captain Brann]

Thanks for that.

Would the venting of presuried L Hy be enough to chance the vector of a ship?

I like the idea of depresuried ships in combat.

Could you have a inert supresser mixed in with it?

Could the outer hull be thin then fuel cells then the armour so fuel is lost as you suffer hits but it will have gone before the inner hul is breached..

 

[BP]

I have always treated fuel as being ammonia...

Cute - less explosive, easier to store in liquid form, and leaks would be readily detected by smell enabled Sophonts. Of course, exposure is a greater risk as is handling (over all in atmo). Storage has advantages and disadvantages - particularly at the volumes MGT uses - and bear in mind many atmos will contain chlorine

Gas Giants and planet atmos (even space) contain ammonia - but absolutely no where near the concentration of H2. Likewise, Nitrogen would be required to make ammonia - and energy. Electrolysis from water in a high-N atmo would be no problem - but water to H2 is more practical and leaves the Oxygen for other uses and it also works without any Nitrogen.

 

[Fedmahn Kassad]

Cap'n Brann,

The answer to all those questions is: Sure, if that is how you want it in Your Traveller Universe(tm)! =)

Any thrust added to a ship will change it's vector, unless compensated for... IMTU the maneuver drive compensates for the small things that might change the vector, but a large venting of L-Hyud fuel would most surely change it...

I am sure certian navy doctrines include vacc-suits and ship depressurization before battle...especially in smaller ships.

The suppressor might have a negative effect on drive efficiency, trading safety for efficiency.

IMTU Navy ships store their jump fuel in two locations: Enough fuel for J1 is stored deep in the ship and protected as a last ditch retreat option, the rest of the fuel surrounds vital ships components to act as a barrier to critical/crippling damage during combat...

 

[BP]

...
Could you have a inert supresser mixed in with it?...

Instead of decompressing (or as partial decompression) - replacing Oxygen with an Inert gas can be good. However, it leaves explosive decompression as an option - which ain't so good. Either way, materials needs to be resistant to pressure loss (out-gassing) and fire resistant (fire would be a big deal aboard ship - as with submarines today, only worse). Decompressing eliminates need for 'suppressor' as by definition the oxygen and oxidizers are removed.